2 * Definitions for the 'struct sk_buff' memory handlers.
5 * Alan Cox, <gw4pts@gw4pts.ampr.org>
6 * Florian La Roche, <rzsfl@rz.uni-sb.de>
8 * This program is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU General Public License
10 * as published by the Free Software Foundation; either version
11 * 2 of the License, or (at your option) any later version.
14 #ifndef _LINUX_SKBUFF_H
15 #define _LINUX_SKBUFF_H
17 #include <linux/kernel.h>
18 #include <linux/kmemcheck.h>
19 #include <linux/compiler.h>
20 #include <linux/time.h>
21 #include <linux/bug.h>
22 #include <linux/cache.h>
23 #include <linux/rbtree.h>
24 #include <linux/socket.h>
26 #include <linux/atomic.h>
27 #include <asm/types.h>
28 #include <linux/spinlock.h>
29 #include <linux/net.h>
30 #include <linux/textsearch.h>
31 #include <net/checksum.h>
32 #include <linux/rcupdate.h>
33 #include <linux/hrtimer.h>
34 #include <linux/dma-mapping.h>
35 #include <linux/netdev_features.h>
36 #include <linux/sched.h>
37 #include <linux/sched/clock.h>
38 #include <net/flow_dissector.h>
39 #include <linux/splice.h>
40 #include <linux/in6.h>
41 #include <linux/if_packet.h>
44 /* The interface for checksum offload between the stack and networking drivers
47 * A. IP checksum related features
49 * Drivers advertise checksum offload capabilities in the features of a device.
50 * From the stack's point of view these are capabilities offered by the driver,
51 * a driver typically only advertises features that it is capable of offloading
54 * The checksum related features are:
56 * NETIF_F_HW_CSUM - The driver (or its device) is able to compute one
57 * IP (one's complement) checksum for any combination
58 * of protocols or protocol layering. The checksum is
59 * computed and set in a packet per the CHECKSUM_PARTIAL
60 * interface (see below).
62 * NETIF_F_IP_CSUM - Driver (device) is only able to checksum plain
63 * TCP or UDP packets over IPv4. These are specifically
64 * unencapsulated packets of the form IPv4|TCP or
65 * IPv4|UDP where the Protocol field in the IPv4 header
66 * is TCP or UDP. The IPv4 header may contain IP options
67 * This feature cannot be set in features for a device
68 * with NETIF_F_HW_CSUM also set. This feature is being
69 * DEPRECATED (see below).
71 * NETIF_F_IPV6_CSUM - Driver (device) is only able to checksum plain
72 * TCP or UDP packets over IPv6. These are specifically
73 * unencapsulated packets of the form IPv6|TCP or
74 * IPv4|UDP where the Next Header field in the IPv6
75 * header is either TCP or UDP. IPv6 extension headers
76 * are not supported with this feature. This feature
77 * cannot be set in features for a device with
78 * NETIF_F_HW_CSUM also set. This feature is being
79 * DEPRECATED (see below).
81 * NETIF_F_RXCSUM - Driver (device) performs receive checksum offload.
82 * This flag is used only used to disable the RX checksum
83 * feature for a device. The stack will accept receive
84 * checksum indication in packets received on a device
85 * regardless of whether NETIF_F_RXCSUM is set.
87 * B. Checksumming of received packets by device. Indication of checksum
88 * verification is in set skb->ip_summed. Possible values are:
92 * Device did not checksum this packet e.g. due to lack of capabilities.
93 * The packet contains full (though not verified) checksum in packet but
94 * not in skb->csum. Thus, skb->csum is undefined in this case.
96 * CHECKSUM_UNNECESSARY:
98 * The hardware you're dealing with doesn't calculate the full checksum
99 * (as in CHECKSUM_COMPLETE), but it does parse headers and verify checksums
100 * for specific protocols. For such packets it will set CHECKSUM_UNNECESSARY
101 * if their checksums are okay. skb->csum is still undefined in this case
102 * though. A driver or device must never modify the checksum field in the
103 * packet even if checksum is verified.
105 * CHECKSUM_UNNECESSARY is applicable to following protocols:
106 * TCP: IPv6 and IPv4.
107 * UDP: IPv4 and IPv6. A device may apply CHECKSUM_UNNECESSARY to a
108 * zero UDP checksum for either IPv4 or IPv6, the networking stack
109 * may perform further validation in this case.
110 * GRE: only if the checksum is present in the header.
111 * SCTP: indicates the CRC in SCTP header has been validated.
113 * skb->csum_level indicates the number of consecutive checksums found in
114 * the packet minus one that have been verified as CHECKSUM_UNNECESSARY.
115 * For instance if a device receives an IPv6->UDP->GRE->IPv4->TCP packet
116 * and a device is able to verify the checksums for UDP (possibly zero),
117 * GRE (checksum flag is set), and TCP-- skb->csum_level would be set to
118 * two. If the device were only able to verify the UDP checksum and not
119 * GRE, either because it doesn't support GRE checksum of because GRE
120 * checksum is bad, skb->csum_level would be set to zero (TCP checksum is
121 * not considered in this case).
125 * This is the most generic way. The device supplied checksum of the _whole_
126 * packet as seen by netif_rx() and fills out in skb->csum. Meaning, the
127 * hardware doesn't need to parse L3/L4 headers to implement this.
129 * Note: Even if device supports only some protocols, but is able to produce
130 * skb->csum, it MUST use CHECKSUM_COMPLETE, not CHECKSUM_UNNECESSARY.
134 * A checksum is set up to be offloaded to a device as described in the
135 * output description for CHECKSUM_PARTIAL. This may occur on a packet
136 * received directly from another Linux OS, e.g., a virtualized Linux kernel
137 * on the same host, or it may be set in the input path in GRO or remote
138 * checksum offload. For the purposes of checksum verification, the checksum
139 * referred to by skb->csum_start + skb->csum_offset and any preceding
140 * checksums in the packet are considered verified. Any checksums in the
141 * packet that are after the checksum being offloaded are not considered to
144 * C. Checksumming on transmit for non-GSO. The stack requests checksum offload
145 * in the skb->ip_summed for a packet. Values are:
149 * The driver is required to checksum the packet as seen by hard_start_xmit()
150 * from skb->csum_start up to the end, and to record/write the checksum at
151 * offset skb->csum_start + skb->csum_offset. A driver may verify that the
152 * csum_start and csum_offset values are valid values given the length and
153 * offset of the packet, however they should not attempt to validate that the
154 * checksum refers to a legitimate transport layer checksum-- it is the
155 * purview of the stack to validate that csum_start and csum_offset are set
158 * When the stack requests checksum offload for a packet, the driver MUST
159 * ensure that the checksum is set correctly. A driver can either offload the
160 * checksum calculation to the device, or call skb_checksum_help (in the case
161 * that the device does not support offload for a particular checksum).
163 * NETIF_F_IP_CSUM and NETIF_F_IPV6_CSUM are being deprecated in favor of
164 * NETIF_F_HW_CSUM. New devices should use NETIF_F_HW_CSUM to indicate
165 * checksum offload capability. If a device has limited checksum capabilities
166 * (for instance can only perform NETIF_F_IP_CSUM or NETIF_F_IPV6_CSUM as
167 * described above) a helper function can be called to resolve
168 * CHECKSUM_PARTIAL. The helper functions are skb_csum_off_chk*. The helper
169 * function takes a spec argument that describes the protocol layer that is
170 * supported for checksum offload and can be called for each packet. If a
171 * packet does not match the specification for offload, skb_checksum_help
172 * is called to resolve the checksum.
176 * The skb was already checksummed by the protocol, or a checksum is not
179 * CHECKSUM_UNNECESSARY:
181 * This has the same meaning on as CHECKSUM_NONE for checksum offload on
185 * Not used in checksum output. If a driver observes a packet with this value
186 * set in skbuff, if should treat as CHECKSUM_NONE being set.
188 * D. Non-IP checksum (CRC) offloads
190 * NETIF_F_SCTP_CRC - This feature indicates that a device is capable of
191 * offloading the SCTP CRC in a packet. To perform this offload the stack
192 * will set ip_summed to CHECKSUM_PARTIAL and set csum_start and csum_offset
193 * accordingly. Note the there is no indication in the skbuff that the
194 * CHECKSUM_PARTIAL refers to an SCTP checksum, a driver that supports
195 * both IP checksum offload and SCTP CRC offload must verify which offload
196 * is configured for a packet presumably by inspecting packet headers.
198 * NETIF_F_FCOE_CRC - This feature indicates that a device is capable of
199 * offloading the FCOE CRC in a packet. To perform this offload the stack
200 * will set ip_summed to CHECKSUM_PARTIAL and set csum_start and csum_offset
201 * accordingly. Note the there is no indication in the skbuff that the
202 * CHECKSUM_PARTIAL refers to an FCOE checksum, a driver that supports
203 * both IP checksum offload and FCOE CRC offload must verify which offload
204 * is configured for a packet presumably by inspecting packet headers.
206 * E. Checksumming on output with GSO.
208 * In the case of a GSO packet (skb_is_gso(skb) is true), checksum offload
209 * is implied by the SKB_GSO_* flags in gso_type. Most obviously, if the
210 * gso_type is SKB_GSO_TCPV4 or SKB_GSO_TCPV6, TCP checksum offload as
211 * part of the GSO operation is implied. If a checksum is being offloaded
212 * with GSO then ip_summed is CHECKSUM_PARTIAL, csum_start and csum_offset
213 * are set to refer to the outermost checksum being offload (two offloaded
214 * checksums are possible with UDP encapsulation).
217 /* Don't change this without changing skb_csum_unnecessary! */
218 #define CHECKSUM_NONE 0
219 #define CHECKSUM_UNNECESSARY 1
220 #define CHECKSUM_COMPLETE 2
221 #define CHECKSUM_PARTIAL 3
223 /* Maximum value in skb->csum_level */
224 #define SKB_MAX_CSUM_LEVEL 3
226 #define SKB_DATA_ALIGN(X) ALIGN(X, SMP_CACHE_BYTES)
227 #define SKB_WITH_OVERHEAD(X) \
228 ((X) - SKB_DATA_ALIGN(sizeof(struct skb_shared_info)))
229 #define SKB_MAX_ORDER(X, ORDER) \
230 SKB_WITH_OVERHEAD((PAGE_SIZE << (ORDER)) - (X))
231 #define SKB_MAX_HEAD(X) (SKB_MAX_ORDER((X), 0))
232 #define SKB_MAX_ALLOC (SKB_MAX_ORDER(0, 2))
234 /* return minimum truesize of one skb containing X bytes of data */
235 #define SKB_TRUESIZE(X) ((X) + \
236 SKB_DATA_ALIGN(sizeof(struct sk_buff)) + \
237 SKB_DATA_ALIGN(sizeof(struct skb_shared_info)))
241 struct pipe_inode_info;
245 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
246 struct nf_conntrack {
251 #if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
252 struct nf_bridge_info {
255 BRNF_PROTO_UNCHANGED,
263 struct net_device *physindev;
265 /* always valid & non-NULL from FORWARD on, for physdev match */
266 struct net_device *physoutdev;
268 /* prerouting: detect dnat in orig/reply direction */
270 struct in6_addr ipv6_daddr;
272 /* after prerouting + nat detected: store original source
273 * mac since neigh resolution overwrites it, only used while
274 * skb is out in neigh layer.
276 char neigh_header[8];
281 struct sk_buff_head {
282 /* These two members must be first. */
283 struct sk_buff *next;
284 struct sk_buff *prev;
292 /* To allow 64K frame to be packed as single skb without frag_list we
293 * require 64K/PAGE_SIZE pages plus 1 additional page to allow for
294 * buffers which do not start on a page boundary.
296 * Since GRO uses frags we allocate at least 16 regardless of page
299 #if (65536/PAGE_SIZE + 1) < 16
300 #define MAX_SKB_FRAGS 16UL
302 #define MAX_SKB_FRAGS (65536/PAGE_SIZE + 1)
304 extern int sysctl_max_skb_frags;
306 /* Set skb_shinfo(skb)->gso_size to this in case you want skb_segment to
307 * segment using its current segmentation instead.
309 #define GSO_BY_FRAGS 0xFFFF
311 typedef struct skb_frag_struct skb_frag_t;
313 struct skb_frag_struct {
317 #if (BITS_PER_LONG > 32) || (PAGE_SIZE >= 65536)
326 static inline unsigned int skb_frag_size(const skb_frag_t *frag)
331 static inline void skb_frag_size_set(skb_frag_t *frag, unsigned int size)
336 static inline void skb_frag_size_add(skb_frag_t *frag, int delta)
341 static inline void skb_frag_size_sub(skb_frag_t *frag, int delta)
346 #define HAVE_HW_TIME_STAMP
349 * struct skb_shared_hwtstamps - hardware time stamps
350 * @hwtstamp: hardware time stamp transformed into duration
351 * since arbitrary point in time
353 * Software time stamps generated by ktime_get_real() are stored in
356 * hwtstamps can only be compared against other hwtstamps from
359 * This structure is attached to packets as part of the
360 * &skb_shared_info. Use skb_hwtstamps() to get a pointer.
362 struct skb_shared_hwtstamps {
366 /* Definitions for tx_flags in struct skb_shared_info */
368 /* generate hardware time stamp */
369 SKBTX_HW_TSTAMP = 1 << 0,
371 /* generate software time stamp when queueing packet to NIC */
372 SKBTX_SW_TSTAMP = 1 << 1,
374 /* device driver is going to provide hardware time stamp */
375 SKBTX_IN_PROGRESS = 1 << 2,
377 /* device driver supports TX zero-copy buffers */
378 SKBTX_DEV_ZEROCOPY = 1 << 3,
380 /* generate wifi status information (where possible) */
381 SKBTX_WIFI_STATUS = 1 << 4,
383 /* This indicates at least one fragment might be overwritten
384 * (as in vmsplice(), sendfile() ...)
385 * If we need to compute a TX checksum, we'll need to copy
386 * all frags to avoid possible bad checksum
388 SKBTX_SHARED_FRAG = 1 << 5,
390 /* generate software time stamp when entering packet scheduling */
391 SKBTX_SCHED_TSTAMP = 1 << 6,
394 #define SKBTX_ANY_SW_TSTAMP (SKBTX_SW_TSTAMP | \
396 #define SKBTX_ANY_TSTAMP (SKBTX_HW_TSTAMP | SKBTX_ANY_SW_TSTAMP)
399 * The callback notifies userspace to release buffers when skb DMA is done in
400 * lower device, the skb last reference should be 0 when calling this.
401 * The zerocopy_success argument is true if zero copy transmit occurred,
402 * false on data copy or out of memory error caused by data copy attempt.
403 * The ctx field is used to track device context.
404 * The desc field is used to track userspace buffer index.
407 void (*callback)(struct ubuf_info *, bool zerocopy_success);
412 /* This data is invariant across clones and lives at
413 * the end of the header data, ie. at skb->end.
415 struct skb_shared_info {
416 unsigned char nr_frags;
418 unsigned short gso_size;
419 /* Warning: this field is not always filled in (UFO)! */
420 unsigned short gso_segs;
421 unsigned short gso_type;
422 struct sk_buff *frag_list;
423 struct skb_shared_hwtstamps hwtstamps;
428 * Warning : all fields before dataref are cleared in __alloc_skb()
432 /* Intermediate layers must ensure that destructor_arg
433 * remains valid until skb destructor */
434 void * destructor_arg;
436 /* must be last field, see pskb_expand_head() */
437 skb_frag_t frags[MAX_SKB_FRAGS];
440 /* We divide dataref into two halves. The higher 16 bits hold references
441 * to the payload part of skb->data. The lower 16 bits hold references to
442 * the entire skb->data. A clone of a headerless skb holds the length of
443 * the header in skb->hdr_len.
445 * All users must obey the rule that the skb->data reference count must be
446 * greater than or equal to the payload reference count.
448 * Holding a reference to the payload part means that the user does not
449 * care about modifications to the header part of skb->data.
451 #define SKB_DATAREF_SHIFT 16
452 #define SKB_DATAREF_MASK ((1 << SKB_DATAREF_SHIFT) - 1)
456 SKB_FCLONE_UNAVAILABLE, /* skb has no fclone (from head_cache) */
457 SKB_FCLONE_ORIG, /* orig skb (from fclone_cache) */
458 SKB_FCLONE_CLONE, /* companion fclone skb (from fclone_cache) */
462 SKB_GSO_TCPV4 = 1 << 0,
463 SKB_GSO_UDP = 1 << 1,
465 /* This indicates the skb is from an untrusted source. */
466 SKB_GSO_DODGY = 1 << 2,
468 /* This indicates the tcp segment has CWR set. */
469 SKB_GSO_TCP_ECN = 1 << 3,
471 SKB_GSO_TCP_FIXEDID = 1 << 4,
473 SKB_GSO_TCPV6 = 1 << 5,
475 SKB_GSO_FCOE = 1 << 6,
477 SKB_GSO_GRE = 1 << 7,
479 SKB_GSO_GRE_CSUM = 1 << 8,
481 SKB_GSO_IPXIP4 = 1 << 9,
483 SKB_GSO_IPXIP6 = 1 << 10,
485 SKB_GSO_UDP_TUNNEL = 1 << 11,
487 SKB_GSO_UDP_TUNNEL_CSUM = 1 << 12,
489 SKB_GSO_PARTIAL = 1 << 13,
491 SKB_GSO_TUNNEL_REMCSUM = 1 << 14,
493 SKB_GSO_SCTP = 1 << 15,
496 #if BITS_PER_LONG > 32
497 #define NET_SKBUFF_DATA_USES_OFFSET 1
500 #ifdef NET_SKBUFF_DATA_USES_OFFSET
501 typedef unsigned int sk_buff_data_t;
503 typedef unsigned char *sk_buff_data_t;
507 * struct skb_mstamp - multi resolution time stamps
508 * @stamp_us: timestamp in us resolution
509 * @stamp_jiffies: timestamp in jiffies
522 * skb_mstamp_get - get current timestamp
523 * @cl: place to store timestamps
525 static inline void skb_mstamp_get(struct skb_mstamp *cl)
527 u64 val = local_clock();
529 do_div(val, NSEC_PER_USEC);
530 cl->stamp_us = (u32)val;
531 cl->stamp_jiffies = (u32)jiffies;
535 * skb_mstamp_delta - compute the difference in usec between two skb_mstamp
536 * @t1: pointer to newest sample
537 * @t0: pointer to oldest sample
539 static inline u32 skb_mstamp_us_delta(const struct skb_mstamp *t1,
540 const struct skb_mstamp *t0)
542 s32 delta_us = t1->stamp_us - t0->stamp_us;
543 u32 delta_jiffies = t1->stamp_jiffies - t0->stamp_jiffies;
545 /* If delta_us is negative, this might be because interval is too big,
546 * or local_clock() drift is too big : fallback using jiffies.
549 delta_jiffies >= (INT_MAX / (USEC_PER_SEC / HZ)))
551 delta_us = jiffies_to_usecs(delta_jiffies);
556 static inline bool skb_mstamp_after(const struct skb_mstamp *t1,
557 const struct skb_mstamp *t0)
559 s32 diff = t1->stamp_jiffies - t0->stamp_jiffies;
562 diff = t1->stamp_us - t0->stamp_us;
567 * struct sk_buff - socket buffer
568 * @next: Next buffer in list
569 * @prev: Previous buffer in list
570 * @tstamp: Time we arrived/left
571 * @rbnode: RB tree node, alternative to next/prev for netem/tcp
572 * @sk: Socket we are owned by
573 * @dev: Device we arrived on/are leaving by
574 * @cb: Control buffer. Free for use by every layer. Put private vars here
575 * @_skb_refdst: destination entry (with norefcount bit)
576 * @sp: the security path, used for xfrm
577 * @len: Length of actual data
578 * @data_len: Data length
579 * @mac_len: Length of link layer header
580 * @hdr_len: writable header length of cloned skb
581 * @csum: Checksum (must include start/offset pair)
582 * @csum_start: Offset from skb->head where checksumming should start
583 * @csum_offset: Offset from csum_start where checksum should be stored
584 * @priority: Packet queueing priority
585 * @ignore_df: allow local fragmentation
586 * @cloned: Head may be cloned (check refcnt to be sure)
587 * @ip_summed: Driver fed us an IP checksum
588 * @nohdr: Payload reference only, must not modify header
589 * @pkt_type: Packet class
590 * @fclone: skbuff clone status
591 * @ipvs_property: skbuff is owned by ipvs
592 * @tc_skip_classify: do not classify packet. set by IFB device
593 * @tc_at_ingress: used within tc_classify to distinguish in/egress
594 * @tc_redirected: packet was redirected by a tc action
595 * @tc_from_ingress: if tc_redirected, tc_at_ingress at time of redirect
596 * @peeked: this packet has been seen already, so stats have been
597 * done for it, don't do them again
598 * @nf_trace: netfilter packet trace flag
599 * @protocol: Packet protocol from driver
600 * @destructor: Destruct function
601 * @_nfct: Associated connection, if any (with nfctinfo bits)
602 * @nf_bridge: Saved data about a bridged frame - see br_netfilter.c
603 * @skb_iif: ifindex of device we arrived on
604 * @tc_index: Traffic control index
605 * @hash: the packet hash
606 * @queue_mapping: Queue mapping for multiqueue devices
607 * @xmit_more: More SKBs are pending for this queue
608 * @ndisc_nodetype: router type (from link layer)
609 * @ooo_okay: allow the mapping of a socket to a queue to be changed
610 * @l4_hash: indicate hash is a canonical 4-tuple hash over transport
612 * @sw_hash: indicates hash was computed in software stack
613 * @wifi_acked_valid: wifi_acked was set
614 * @wifi_acked: whether frame was acked on wifi or not
615 * @no_fcs: Request NIC to treat last 4 bytes as Ethernet FCS
616 * @dst_pending_confirm: need to confirm neighbour
617 * @napi_id: id of the NAPI struct this skb came from
618 * @secmark: security marking
619 * @mark: Generic packet mark
620 * @vlan_proto: vlan encapsulation protocol
621 * @vlan_tci: vlan tag control information
622 * @inner_protocol: Protocol (encapsulation)
623 * @inner_transport_header: Inner transport layer header (encapsulation)
624 * @inner_network_header: Network layer header (encapsulation)
625 * @inner_mac_header: Link layer header (encapsulation)
626 * @transport_header: Transport layer header
627 * @network_header: Network layer header
628 * @mac_header: Link layer header
629 * @tail: Tail pointer
631 * @head: Head of buffer
632 * @data: Data head pointer
633 * @truesize: Buffer size
634 * @users: User count - see {datagram,tcp}.c
640 /* These two members must be first. */
641 struct sk_buff *next;
642 struct sk_buff *prev;
646 struct skb_mstamp skb_mstamp;
649 struct rb_node rbnode; /* used in netem & tcp stack */
654 struct net_device *dev;
655 /* Some protocols might use this space to store information,
656 * while device pointer would be NULL.
657 * UDP receive path is one user.
659 unsigned long dev_scratch;
662 * This is the control buffer. It is free to use for every
663 * layer. Please put your private variables there. If you
664 * want to keep them across layers you have to do a skb_clone()
665 * first. This is owned by whoever has the skb queued ATM.
667 char cb[48] __aligned(8);
669 unsigned long _skb_refdst;
670 void (*destructor)(struct sk_buff *skb);
674 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
677 #if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
678 struct nf_bridge_info *nf_bridge;
685 /* Following fields are _not_ copied in __copy_skb_header()
686 * Note that queue_mapping is here mostly to fill a hole.
688 kmemcheck_bitfield_begin(flags1);
691 /* if you move cloned around you also must adapt those constants */
692 #ifdef __BIG_ENDIAN_BITFIELD
693 #define CLONED_MASK (1 << 7)
695 #define CLONED_MASK 1
697 #define CLONED_OFFSET() offsetof(struct sk_buff, __cloned_offset)
699 __u8 __cloned_offset[0];
706 __unused:1; /* one bit hole */
707 kmemcheck_bitfield_end(flags1);
709 /* fields enclosed in headers_start/headers_end are copied
710 * using a single memcpy() in __copy_skb_header()
713 __u32 headers_start[0];
716 /* if you move pkt_type around you also must adapt those constants */
717 #ifdef __BIG_ENDIAN_BITFIELD
718 #define PKT_TYPE_MAX (7 << 5)
720 #define PKT_TYPE_MAX 7
722 #define PKT_TYPE_OFFSET() offsetof(struct sk_buff, __pkt_type_offset)
724 __u8 __pkt_type_offset[0];
734 __u8 wifi_acked_valid:1;
738 /* Indicates the inner headers are valid in the skbuff. */
739 __u8 encapsulation:1;
740 __u8 encap_hdr_csum:1;
742 __u8 csum_complete_sw:1;
746 __u8 dst_pending_confirm:1;
747 #ifdef CONFIG_IPV6_NDISC_NODETYPE
748 __u8 ndisc_nodetype:2;
750 __u8 ipvs_property:1;
751 __u8 inner_protocol_type:1;
752 __u8 remcsum_offload:1;
753 #ifdef CONFIG_NET_SWITCHDEV
754 __u8 offload_fwd_mark:1;
756 #ifdef CONFIG_NET_CLS_ACT
757 __u8 tc_skip_classify:1;
758 __u8 tc_at_ingress:1;
759 __u8 tc_redirected:1;
760 __u8 tc_from_ingress:1;
763 #ifdef CONFIG_NET_SCHED
764 __u16 tc_index; /* traffic control index */
779 #if defined(CONFIG_NET_RX_BUSY_POLL) || defined(CONFIG_XPS)
781 unsigned int napi_id;
782 unsigned int sender_cpu;
785 #ifdef CONFIG_NETWORK_SECMARK
791 __u32 reserved_tailroom;
795 __be16 inner_protocol;
799 __u16 inner_transport_header;
800 __u16 inner_network_header;
801 __u16 inner_mac_header;
804 __u16 transport_header;
805 __u16 network_header;
809 __u32 headers_end[0];
812 /* These elements must be at the end, see alloc_skb() for details. */
817 unsigned int truesize;
823 * Handling routines are only of interest to the kernel
825 #include <linux/slab.h>
828 #define SKB_ALLOC_FCLONE 0x01
829 #define SKB_ALLOC_RX 0x02
830 #define SKB_ALLOC_NAPI 0x04
832 /* Returns true if the skb was allocated from PFMEMALLOC reserves */
833 static inline bool skb_pfmemalloc(const struct sk_buff *skb)
835 return unlikely(skb->pfmemalloc);
839 * skb might have a dst pointer attached, refcounted or not.
840 * _skb_refdst low order bit is set if refcount was _not_ taken
842 #define SKB_DST_NOREF 1UL
843 #define SKB_DST_PTRMASK ~(SKB_DST_NOREF)
845 #define SKB_NFCT_PTRMASK ~(7UL)
847 * skb_dst - returns skb dst_entry
850 * Returns skb dst_entry, regardless of reference taken or not.
852 static inline struct dst_entry *skb_dst(const struct sk_buff *skb)
854 /* If refdst was not refcounted, check we still are in a
855 * rcu_read_lock section
857 WARN_ON((skb->_skb_refdst & SKB_DST_NOREF) &&
858 !rcu_read_lock_held() &&
859 !rcu_read_lock_bh_held());
860 return (struct dst_entry *)(skb->_skb_refdst & SKB_DST_PTRMASK);
864 * skb_dst_set - sets skb dst
868 * Sets skb dst, assuming a reference was taken on dst and should
869 * be released by skb_dst_drop()
871 static inline void skb_dst_set(struct sk_buff *skb, struct dst_entry *dst)
873 skb->_skb_refdst = (unsigned long)dst;
877 * skb_dst_set_noref - sets skb dst, hopefully, without taking reference
881 * Sets skb dst, assuming a reference was not taken on dst.
882 * If dst entry is cached, we do not take reference and dst_release
883 * will be avoided by refdst_drop. If dst entry is not cached, we take
884 * reference, so that last dst_release can destroy the dst immediately.
886 static inline void skb_dst_set_noref(struct sk_buff *skb, struct dst_entry *dst)
888 WARN_ON(!rcu_read_lock_held() && !rcu_read_lock_bh_held());
889 skb->_skb_refdst = (unsigned long)dst | SKB_DST_NOREF;
893 * skb_dst_is_noref - Test if skb dst isn't refcounted
896 static inline bool skb_dst_is_noref(const struct sk_buff *skb)
898 return (skb->_skb_refdst & SKB_DST_NOREF) && skb_dst(skb);
901 static inline struct rtable *skb_rtable(const struct sk_buff *skb)
903 return (struct rtable *)skb_dst(skb);
906 /* For mangling skb->pkt_type from user space side from applications
907 * such as nft, tc, etc, we only allow a conservative subset of
908 * possible pkt_types to be set.
910 static inline bool skb_pkt_type_ok(u32 ptype)
912 return ptype <= PACKET_OTHERHOST;
915 void kfree_skb(struct sk_buff *skb);
916 void kfree_skb_list(struct sk_buff *segs);
917 void skb_tx_error(struct sk_buff *skb);
918 void consume_skb(struct sk_buff *skb);
919 void __kfree_skb(struct sk_buff *skb);
920 extern struct kmem_cache *skbuff_head_cache;
922 void kfree_skb_partial(struct sk_buff *skb, bool head_stolen);
923 bool skb_try_coalesce(struct sk_buff *to, struct sk_buff *from,
924 bool *fragstolen, int *delta_truesize);
926 struct sk_buff *__alloc_skb(unsigned int size, gfp_t priority, int flags,
928 struct sk_buff *__build_skb(void *data, unsigned int frag_size);
929 struct sk_buff *build_skb(void *data, unsigned int frag_size);
930 static inline struct sk_buff *alloc_skb(unsigned int size,
933 return __alloc_skb(size, priority, 0, NUMA_NO_NODE);
936 struct sk_buff *alloc_skb_with_frags(unsigned long header_len,
937 unsigned long data_len,
942 /* Layout of fast clones : [skb1][skb2][fclone_ref] */
943 struct sk_buff_fclones {
952 * skb_fclone_busy - check if fclone is busy
956 * Returns true if skb is a fast clone, and its clone is not freed.
957 * Some drivers call skb_orphan() in their ndo_start_xmit(),
958 * so we also check that this didnt happen.
960 static inline bool skb_fclone_busy(const struct sock *sk,
961 const struct sk_buff *skb)
963 const struct sk_buff_fclones *fclones;
965 fclones = container_of(skb, struct sk_buff_fclones, skb1);
967 return skb->fclone == SKB_FCLONE_ORIG &&
968 atomic_read(&fclones->fclone_ref) > 1 &&
969 fclones->skb2.sk == sk;
972 static inline struct sk_buff *alloc_skb_fclone(unsigned int size,
975 return __alloc_skb(size, priority, SKB_ALLOC_FCLONE, NUMA_NO_NODE);
978 struct sk_buff *__alloc_skb_head(gfp_t priority, int node);
979 static inline struct sk_buff *alloc_skb_head(gfp_t priority)
981 return __alloc_skb_head(priority, -1);
984 struct sk_buff *skb_morph(struct sk_buff *dst, struct sk_buff *src);
985 int skb_copy_ubufs(struct sk_buff *skb, gfp_t gfp_mask);
986 struct sk_buff *skb_clone(struct sk_buff *skb, gfp_t priority);
987 struct sk_buff *skb_copy(const struct sk_buff *skb, gfp_t priority);
988 struct sk_buff *__pskb_copy_fclone(struct sk_buff *skb, int headroom,
989 gfp_t gfp_mask, bool fclone);
990 static inline struct sk_buff *__pskb_copy(struct sk_buff *skb, int headroom,
993 return __pskb_copy_fclone(skb, headroom, gfp_mask, false);
996 int pskb_expand_head(struct sk_buff *skb, int nhead, int ntail, gfp_t gfp_mask);
997 struct sk_buff *skb_realloc_headroom(struct sk_buff *skb,
998 unsigned int headroom);
999 struct sk_buff *skb_copy_expand(const struct sk_buff *skb, int newheadroom,
1000 int newtailroom, gfp_t priority);
1001 int skb_to_sgvec_nomark(struct sk_buff *skb, struct scatterlist *sg,
1002 int offset, int len);
1003 int skb_to_sgvec(struct sk_buff *skb, struct scatterlist *sg, int offset,
1005 int skb_cow_data(struct sk_buff *skb, int tailbits, struct sk_buff **trailer);
1006 int skb_pad(struct sk_buff *skb, int pad);
1007 #define dev_kfree_skb(a) consume_skb(a)
1009 int skb_append_datato_frags(struct sock *sk, struct sk_buff *skb,
1010 int getfrag(void *from, char *to, int offset,
1011 int len, int odd, struct sk_buff *skb),
1012 void *from, int length);
1014 int skb_append_pagefrags(struct sk_buff *skb, struct page *page,
1015 int offset, size_t size);
1017 struct skb_seq_state {
1021 __u32 stepped_offset;
1022 struct sk_buff *root_skb;
1023 struct sk_buff *cur_skb;
1027 void skb_prepare_seq_read(struct sk_buff *skb, unsigned int from,
1028 unsigned int to, struct skb_seq_state *st);
1029 unsigned int skb_seq_read(unsigned int consumed, const u8 **data,
1030 struct skb_seq_state *st);
1031 void skb_abort_seq_read(struct skb_seq_state *st);
1033 unsigned int skb_find_text(struct sk_buff *skb, unsigned int from,
1034 unsigned int to, struct ts_config *config);
1037 * Packet hash types specify the type of hash in skb_set_hash.
1039 * Hash types refer to the protocol layer addresses which are used to
1040 * construct a packet's hash. The hashes are used to differentiate or identify
1041 * flows of the protocol layer for the hash type. Hash types are either
1042 * layer-2 (L2), layer-3 (L3), or layer-4 (L4).
1044 * Properties of hashes:
1046 * 1) Two packets in different flows have different hash values
1047 * 2) Two packets in the same flow should have the same hash value
1049 * A hash at a higher layer is considered to be more specific. A driver should
1050 * set the most specific hash possible.
1052 * A driver cannot indicate a more specific hash than the layer at which a hash
1053 * was computed. For instance an L3 hash cannot be set as an L4 hash.
1055 * A driver may indicate a hash level which is less specific than the
1056 * actual layer the hash was computed on. For instance, a hash computed
1057 * at L4 may be considered an L3 hash. This should only be done if the
1058 * driver can't unambiguously determine that the HW computed the hash at
1059 * the higher layer. Note that the "should" in the second property above
1062 enum pkt_hash_types {
1063 PKT_HASH_TYPE_NONE, /* Undefined type */
1064 PKT_HASH_TYPE_L2, /* Input: src_MAC, dest_MAC */
1065 PKT_HASH_TYPE_L3, /* Input: src_IP, dst_IP */
1066 PKT_HASH_TYPE_L4, /* Input: src_IP, dst_IP, src_port, dst_port */
1069 static inline void skb_clear_hash(struct sk_buff *skb)
1076 static inline void skb_clear_hash_if_not_l4(struct sk_buff *skb)
1079 skb_clear_hash(skb);
1083 __skb_set_hash(struct sk_buff *skb, __u32 hash, bool is_sw, bool is_l4)
1085 skb->l4_hash = is_l4;
1086 skb->sw_hash = is_sw;
1091 skb_set_hash(struct sk_buff *skb, __u32 hash, enum pkt_hash_types type)
1093 /* Used by drivers to set hash from HW */
1094 __skb_set_hash(skb, hash, false, type == PKT_HASH_TYPE_L4);
1098 __skb_set_sw_hash(struct sk_buff *skb, __u32 hash, bool is_l4)
1100 __skb_set_hash(skb, hash, true, is_l4);
1103 void __skb_get_hash(struct sk_buff *skb);
1104 u32 __skb_get_hash_symmetric(const struct sk_buff *skb);
1105 u32 skb_get_poff(const struct sk_buff *skb);
1106 u32 __skb_get_poff(const struct sk_buff *skb, void *data,
1107 const struct flow_keys *keys, int hlen);
1108 __be32 __skb_flow_get_ports(const struct sk_buff *skb, int thoff, u8 ip_proto,
1109 void *data, int hlen_proto);
1111 static inline __be32 skb_flow_get_ports(const struct sk_buff *skb,
1112 int thoff, u8 ip_proto)
1114 return __skb_flow_get_ports(skb, thoff, ip_proto, NULL, 0);
1117 void skb_flow_dissector_init(struct flow_dissector *flow_dissector,
1118 const struct flow_dissector_key *key,
1119 unsigned int key_count);
1121 bool __skb_flow_dissect(const struct sk_buff *skb,
1122 struct flow_dissector *flow_dissector,
1123 void *target_container,
1124 void *data, __be16 proto, int nhoff, int hlen,
1125 unsigned int flags);
1127 static inline bool skb_flow_dissect(const struct sk_buff *skb,
1128 struct flow_dissector *flow_dissector,
1129 void *target_container, unsigned int flags)
1131 return __skb_flow_dissect(skb, flow_dissector, target_container,
1132 NULL, 0, 0, 0, flags);
1135 static inline bool skb_flow_dissect_flow_keys(const struct sk_buff *skb,
1136 struct flow_keys *flow,
1139 memset(flow, 0, sizeof(*flow));
1140 return __skb_flow_dissect(skb, &flow_keys_dissector, flow,
1141 NULL, 0, 0, 0, flags);
1144 static inline bool skb_flow_dissect_flow_keys_buf(struct flow_keys *flow,
1145 void *data, __be16 proto,
1146 int nhoff, int hlen,
1149 memset(flow, 0, sizeof(*flow));
1150 return __skb_flow_dissect(NULL, &flow_keys_buf_dissector, flow,
1151 data, proto, nhoff, hlen, flags);
1154 static inline __u32 skb_get_hash(struct sk_buff *skb)
1156 if (!skb->l4_hash && !skb->sw_hash)
1157 __skb_get_hash(skb);
1162 __u32 __skb_get_hash_flowi6(struct sk_buff *skb, const struct flowi6 *fl6);
1164 static inline __u32 skb_get_hash_flowi6(struct sk_buff *skb, const struct flowi6 *fl6)
1166 if (!skb->l4_hash && !skb->sw_hash) {
1167 struct flow_keys keys;
1168 __u32 hash = __get_hash_from_flowi6(fl6, &keys);
1170 __skb_set_sw_hash(skb, hash, flow_keys_have_l4(&keys));
1176 __u32 __skb_get_hash_flowi4(struct sk_buff *skb, const struct flowi4 *fl);
1178 static inline __u32 skb_get_hash_flowi4(struct sk_buff *skb, const struct flowi4 *fl4)
1180 if (!skb->l4_hash && !skb->sw_hash) {
1181 struct flow_keys keys;
1182 __u32 hash = __get_hash_from_flowi4(fl4, &keys);
1184 __skb_set_sw_hash(skb, hash, flow_keys_have_l4(&keys));
1190 __u32 skb_get_hash_perturb(const struct sk_buff *skb, u32 perturb);
1192 static inline __u32 skb_get_hash_raw(const struct sk_buff *skb)
1197 static inline void skb_copy_hash(struct sk_buff *to, const struct sk_buff *from)
1199 to->hash = from->hash;
1200 to->sw_hash = from->sw_hash;
1201 to->l4_hash = from->l4_hash;
1204 #ifdef NET_SKBUFF_DATA_USES_OFFSET
1205 static inline unsigned char *skb_end_pointer(const struct sk_buff *skb)
1207 return skb->head + skb->end;
1210 static inline unsigned int skb_end_offset(const struct sk_buff *skb)
1215 static inline unsigned char *skb_end_pointer(const struct sk_buff *skb)
1220 static inline unsigned int skb_end_offset(const struct sk_buff *skb)
1222 return skb->end - skb->head;
1227 #define skb_shinfo(SKB) ((struct skb_shared_info *)(skb_end_pointer(SKB)))
1229 static inline struct skb_shared_hwtstamps *skb_hwtstamps(struct sk_buff *skb)
1231 return &skb_shinfo(skb)->hwtstamps;
1235 * skb_queue_empty - check if a queue is empty
1238 * Returns true if the queue is empty, false otherwise.
1240 static inline int skb_queue_empty(const struct sk_buff_head *list)
1242 return list->next == (const struct sk_buff *) list;
1246 * skb_queue_is_last - check if skb is the last entry in the queue
1250 * Returns true if @skb is the last buffer on the list.
1252 static inline bool skb_queue_is_last(const struct sk_buff_head *list,
1253 const struct sk_buff *skb)
1255 return skb->next == (const struct sk_buff *) list;
1259 * skb_queue_is_first - check if skb is the first entry in the queue
1263 * Returns true if @skb is the first buffer on the list.
1265 static inline bool skb_queue_is_first(const struct sk_buff_head *list,
1266 const struct sk_buff *skb)
1268 return skb->prev == (const struct sk_buff *) list;
1272 * skb_queue_next - return the next packet in the queue
1274 * @skb: current buffer
1276 * Return the next packet in @list after @skb. It is only valid to
1277 * call this if skb_queue_is_last() evaluates to false.
1279 static inline struct sk_buff *skb_queue_next(const struct sk_buff_head *list,
1280 const struct sk_buff *skb)
1282 /* This BUG_ON may seem severe, but if we just return then we
1283 * are going to dereference garbage.
1285 BUG_ON(skb_queue_is_last(list, skb));
1290 * skb_queue_prev - return the prev packet in the queue
1292 * @skb: current buffer
1294 * Return the prev packet in @list before @skb. It is only valid to
1295 * call this if skb_queue_is_first() evaluates to false.
1297 static inline struct sk_buff *skb_queue_prev(const struct sk_buff_head *list,
1298 const struct sk_buff *skb)
1300 /* This BUG_ON may seem severe, but if we just return then we
1301 * are going to dereference garbage.
1303 BUG_ON(skb_queue_is_first(list, skb));
1308 * skb_get - reference buffer
1309 * @skb: buffer to reference
1311 * Makes another reference to a socket buffer and returns a pointer
1314 static inline struct sk_buff *skb_get(struct sk_buff *skb)
1316 atomic_inc(&skb->users);
1321 * If users == 1, we are the only owner and are can avoid redundant
1326 * skb_cloned - is the buffer a clone
1327 * @skb: buffer to check
1329 * Returns true if the buffer was generated with skb_clone() and is
1330 * one of multiple shared copies of the buffer. Cloned buffers are
1331 * shared data so must not be written to under normal circumstances.
1333 static inline int skb_cloned(const struct sk_buff *skb)
1335 return skb->cloned &&
1336 (atomic_read(&skb_shinfo(skb)->dataref) & SKB_DATAREF_MASK) != 1;
1339 static inline int skb_unclone(struct sk_buff *skb, gfp_t pri)
1341 might_sleep_if(gfpflags_allow_blocking(pri));
1343 if (skb_cloned(skb))
1344 return pskb_expand_head(skb, 0, 0, pri);
1350 * skb_header_cloned - is the header a clone
1351 * @skb: buffer to check
1353 * Returns true if modifying the header part of the buffer requires
1354 * the data to be copied.
1356 static inline int skb_header_cloned(const struct sk_buff *skb)
1363 dataref = atomic_read(&skb_shinfo(skb)->dataref);
1364 dataref = (dataref & SKB_DATAREF_MASK) - (dataref >> SKB_DATAREF_SHIFT);
1365 return dataref != 1;
1368 static inline int skb_header_unclone(struct sk_buff *skb, gfp_t pri)
1370 might_sleep_if(gfpflags_allow_blocking(pri));
1372 if (skb_header_cloned(skb))
1373 return pskb_expand_head(skb, 0, 0, pri);
1379 * skb_header_release - release reference to header
1380 * @skb: buffer to operate on
1382 * Drop a reference to the header part of the buffer. This is done
1383 * by acquiring a payload reference. You must not read from the header
1384 * part of skb->data after this.
1385 * Note : Check if you can use __skb_header_release() instead.
1387 static inline void skb_header_release(struct sk_buff *skb)
1391 atomic_add(1 << SKB_DATAREF_SHIFT, &skb_shinfo(skb)->dataref);
1395 * __skb_header_release - release reference to header
1396 * @skb: buffer to operate on
1398 * Variant of skb_header_release() assuming skb is private to caller.
1399 * We can avoid one atomic operation.
1401 static inline void __skb_header_release(struct sk_buff *skb)
1404 atomic_set(&skb_shinfo(skb)->dataref, 1 + (1 << SKB_DATAREF_SHIFT));
1409 * skb_shared - is the buffer shared
1410 * @skb: buffer to check
1412 * Returns true if more than one person has a reference to this
1415 static inline int skb_shared(const struct sk_buff *skb)
1417 return atomic_read(&skb->users) != 1;
1421 * skb_share_check - check if buffer is shared and if so clone it
1422 * @skb: buffer to check
1423 * @pri: priority for memory allocation
1425 * If the buffer is shared the buffer is cloned and the old copy
1426 * drops a reference. A new clone with a single reference is returned.
1427 * If the buffer is not shared the original buffer is returned. When
1428 * being called from interrupt status or with spinlocks held pri must
1431 * NULL is returned on a memory allocation failure.
1433 static inline struct sk_buff *skb_share_check(struct sk_buff *skb, gfp_t pri)
1435 might_sleep_if(gfpflags_allow_blocking(pri));
1436 if (skb_shared(skb)) {
1437 struct sk_buff *nskb = skb_clone(skb, pri);
1449 * Copy shared buffers into a new sk_buff. We effectively do COW on
1450 * packets to handle cases where we have a local reader and forward
1451 * and a couple of other messy ones. The normal one is tcpdumping
1452 * a packet thats being forwarded.
1456 * skb_unshare - make a copy of a shared buffer
1457 * @skb: buffer to check
1458 * @pri: priority for memory allocation
1460 * If the socket buffer is a clone then this function creates a new
1461 * copy of the data, drops a reference count on the old copy and returns
1462 * the new copy with the reference count at 1. If the buffer is not a clone
1463 * the original buffer is returned. When called with a spinlock held or
1464 * from interrupt state @pri must be %GFP_ATOMIC
1466 * %NULL is returned on a memory allocation failure.
1468 static inline struct sk_buff *skb_unshare(struct sk_buff *skb,
1471 might_sleep_if(gfpflags_allow_blocking(pri));
1472 if (skb_cloned(skb)) {
1473 struct sk_buff *nskb = skb_copy(skb, pri);
1475 /* Free our shared copy */
1486 * skb_peek - peek at the head of an &sk_buff_head
1487 * @list_: list to peek at
1489 * Peek an &sk_buff. Unlike most other operations you _MUST_
1490 * be careful with this one. A peek leaves the buffer on the
1491 * list and someone else may run off with it. You must hold
1492 * the appropriate locks or have a private queue to do this.
1494 * Returns %NULL for an empty list or a pointer to the head element.
1495 * The reference count is not incremented and the reference is therefore
1496 * volatile. Use with caution.
1498 static inline struct sk_buff *skb_peek(const struct sk_buff_head *list_)
1500 struct sk_buff *skb = list_->next;
1502 if (skb == (struct sk_buff *)list_)
1508 * skb_peek_next - peek skb following the given one from a queue
1509 * @skb: skb to start from
1510 * @list_: list to peek at
1512 * Returns %NULL when the end of the list is met or a pointer to the
1513 * next element. The reference count is not incremented and the
1514 * reference is therefore volatile. Use with caution.
1516 static inline struct sk_buff *skb_peek_next(struct sk_buff *skb,
1517 const struct sk_buff_head *list_)
1519 struct sk_buff *next = skb->next;
1521 if (next == (struct sk_buff *)list_)
1527 * skb_peek_tail - peek at the tail of an &sk_buff_head
1528 * @list_: list to peek at
1530 * Peek an &sk_buff. Unlike most other operations you _MUST_
1531 * be careful with this one. A peek leaves the buffer on the
1532 * list and someone else may run off with it. You must hold
1533 * the appropriate locks or have a private queue to do this.
1535 * Returns %NULL for an empty list or a pointer to the tail element.
1536 * The reference count is not incremented and the reference is therefore
1537 * volatile. Use with caution.
1539 static inline struct sk_buff *skb_peek_tail(const struct sk_buff_head *list_)
1541 struct sk_buff *skb = list_->prev;
1543 if (skb == (struct sk_buff *)list_)
1550 * skb_queue_len - get queue length
1551 * @list_: list to measure
1553 * Return the length of an &sk_buff queue.
1555 static inline __u32 skb_queue_len(const struct sk_buff_head *list_)
1561 * __skb_queue_head_init - initialize non-spinlock portions of sk_buff_head
1562 * @list: queue to initialize
1564 * This initializes only the list and queue length aspects of
1565 * an sk_buff_head object. This allows to initialize the list
1566 * aspects of an sk_buff_head without reinitializing things like
1567 * the spinlock. It can also be used for on-stack sk_buff_head
1568 * objects where the spinlock is known to not be used.
1570 static inline void __skb_queue_head_init(struct sk_buff_head *list)
1572 list->prev = list->next = (struct sk_buff *)list;
1577 * This function creates a split out lock class for each invocation;
1578 * this is needed for now since a whole lot of users of the skb-queue
1579 * infrastructure in drivers have different locking usage (in hardirq)
1580 * than the networking core (in softirq only). In the long run either the
1581 * network layer or drivers should need annotation to consolidate the
1582 * main types of usage into 3 classes.
1584 static inline void skb_queue_head_init(struct sk_buff_head *list)
1586 spin_lock_init(&list->lock);
1587 __skb_queue_head_init(list);
1590 static inline void skb_queue_head_init_class(struct sk_buff_head *list,
1591 struct lock_class_key *class)
1593 skb_queue_head_init(list);
1594 lockdep_set_class(&list->lock, class);
1598 * Insert an sk_buff on a list.
1600 * The "__skb_xxxx()" functions are the non-atomic ones that
1601 * can only be called with interrupts disabled.
1603 void skb_insert(struct sk_buff *old, struct sk_buff *newsk,
1604 struct sk_buff_head *list);
1605 static inline void __skb_insert(struct sk_buff *newsk,
1606 struct sk_buff *prev, struct sk_buff *next,
1607 struct sk_buff_head *list)
1611 next->prev = prev->next = newsk;
1615 static inline void __skb_queue_splice(const struct sk_buff_head *list,
1616 struct sk_buff *prev,
1617 struct sk_buff *next)
1619 struct sk_buff *first = list->next;
1620 struct sk_buff *last = list->prev;
1630 * skb_queue_splice - join two skb lists, this is designed for stacks
1631 * @list: the new list to add
1632 * @head: the place to add it in the first list
1634 static inline void skb_queue_splice(const struct sk_buff_head *list,
1635 struct sk_buff_head *head)
1637 if (!skb_queue_empty(list)) {
1638 __skb_queue_splice(list, (struct sk_buff *) head, head->next);
1639 head->qlen += list->qlen;
1644 * skb_queue_splice_init - join two skb lists and reinitialise the emptied list
1645 * @list: the new list to add
1646 * @head: the place to add it in the first list
1648 * The list at @list is reinitialised
1650 static inline void skb_queue_splice_init(struct sk_buff_head *list,
1651 struct sk_buff_head *head)
1653 if (!skb_queue_empty(list)) {
1654 __skb_queue_splice(list, (struct sk_buff *) head, head->next);
1655 head->qlen += list->qlen;
1656 __skb_queue_head_init(list);
1661 * skb_queue_splice_tail - join two skb lists, each list being a queue
1662 * @list: the new list to add
1663 * @head: the place to add it in the first list
1665 static inline void skb_queue_splice_tail(const struct sk_buff_head *list,
1666 struct sk_buff_head *head)
1668 if (!skb_queue_empty(list)) {
1669 __skb_queue_splice(list, head->prev, (struct sk_buff *) head);
1670 head->qlen += list->qlen;
1675 * skb_queue_splice_tail_init - join two skb lists and reinitialise the emptied list
1676 * @list: the new list to add
1677 * @head: the place to add it in the first list
1679 * Each of the lists is a queue.
1680 * The list at @list is reinitialised
1682 static inline void skb_queue_splice_tail_init(struct sk_buff_head *list,
1683 struct sk_buff_head *head)
1685 if (!skb_queue_empty(list)) {
1686 __skb_queue_splice(list, head->prev, (struct sk_buff *) head);
1687 head->qlen += list->qlen;
1688 __skb_queue_head_init(list);
1693 * __skb_queue_after - queue a buffer at the list head
1694 * @list: list to use
1695 * @prev: place after this buffer
1696 * @newsk: buffer to queue
1698 * Queue a buffer int the middle of a list. This function takes no locks
1699 * and you must therefore hold required locks before calling it.
1701 * A buffer cannot be placed on two lists at the same time.
1703 static inline void __skb_queue_after(struct sk_buff_head *list,
1704 struct sk_buff *prev,
1705 struct sk_buff *newsk)
1707 __skb_insert(newsk, prev, prev->next, list);
1710 void skb_append(struct sk_buff *old, struct sk_buff *newsk,
1711 struct sk_buff_head *list);
1713 static inline void __skb_queue_before(struct sk_buff_head *list,
1714 struct sk_buff *next,
1715 struct sk_buff *newsk)
1717 __skb_insert(newsk, next->prev, next, list);
1721 * __skb_queue_head - queue a buffer at the list head
1722 * @list: list to use
1723 * @newsk: buffer to queue
1725 * Queue a buffer at the start of a list. This function takes no locks
1726 * and you must therefore hold required locks before calling it.
1728 * A buffer cannot be placed on two lists at the same time.
1730 void skb_queue_head(struct sk_buff_head *list, struct sk_buff *newsk);
1731 static inline void __skb_queue_head(struct sk_buff_head *list,
1732 struct sk_buff *newsk)
1734 __skb_queue_after(list, (struct sk_buff *)list, newsk);
1738 * __skb_queue_tail - queue a buffer at the list tail
1739 * @list: list to use
1740 * @newsk: buffer to queue
1742 * Queue a buffer at the end of a list. This function takes no locks
1743 * and you must therefore hold required locks before calling it.
1745 * A buffer cannot be placed on two lists at the same time.
1747 void skb_queue_tail(struct sk_buff_head *list, struct sk_buff *newsk);
1748 static inline void __skb_queue_tail(struct sk_buff_head *list,
1749 struct sk_buff *newsk)
1751 __skb_queue_before(list, (struct sk_buff *)list, newsk);
1755 * remove sk_buff from list. _Must_ be called atomically, and with
1758 void skb_unlink(struct sk_buff *skb, struct sk_buff_head *list);
1759 static inline void __skb_unlink(struct sk_buff *skb, struct sk_buff_head *list)
1761 struct sk_buff *next, *prev;
1766 skb->next = skb->prev = NULL;
1772 * __skb_dequeue - remove from the head of the queue
1773 * @list: list to dequeue from
1775 * Remove the head of the list. This function does not take any locks
1776 * so must be used with appropriate locks held only. The head item is
1777 * returned or %NULL if the list is empty.
1779 struct sk_buff *skb_dequeue(struct sk_buff_head *list);
1780 static inline struct sk_buff *__skb_dequeue(struct sk_buff_head *list)
1782 struct sk_buff *skb = skb_peek(list);
1784 __skb_unlink(skb, list);
1789 * __skb_dequeue_tail - remove from the tail of the queue
1790 * @list: list to dequeue from
1792 * Remove the tail of the list. This function does not take any locks
1793 * so must be used with appropriate locks held only. The tail item is
1794 * returned or %NULL if the list is empty.
1796 struct sk_buff *skb_dequeue_tail(struct sk_buff_head *list);
1797 static inline struct sk_buff *__skb_dequeue_tail(struct sk_buff_head *list)
1799 struct sk_buff *skb = skb_peek_tail(list);
1801 __skb_unlink(skb, list);
1806 static inline bool skb_is_nonlinear(const struct sk_buff *skb)
1808 return skb->data_len;
1811 static inline unsigned int skb_headlen(const struct sk_buff *skb)
1813 return skb->len - skb->data_len;
1816 static inline unsigned int skb_pagelen(const struct sk_buff *skb)
1818 unsigned int i, len = 0;
1820 for (i = skb_shinfo(skb)->nr_frags - 1; (int)i >= 0; i--)
1821 len += skb_frag_size(&skb_shinfo(skb)->frags[i]);
1822 return len + skb_headlen(skb);
1826 * __skb_fill_page_desc - initialise a paged fragment in an skb
1827 * @skb: buffer containing fragment to be initialised
1828 * @i: paged fragment index to initialise
1829 * @page: the page to use for this fragment
1830 * @off: the offset to the data with @page
1831 * @size: the length of the data
1833 * Initialises the @i'th fragment of @skb to point to &size bytes at
1834 * offset @off within @page.
1836 * Does not take any additional reference on the fragment.
1838 static inline void __skb_fill_page_desc(struct sk_buff *skb, int i,
1839 struct page *page, int off, int size)
1841 skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
1844 * Propagate page pfmemalloc to the skb if we can. The problem is
1845 * that not all callers have unique ownership of the page but rely
1846 * on page_is_pfmemalloc doing the right thing(tm).
1848 frag->page.p = page;
1849 frag->page_offset = off;
1850 skb_frag_size_set(frag, size);
1852 page = compound_head(page);
1853 if (page_is_pfmemalloc(page))
1854 skb->pfmemalloc = true;
1858 * skb_fill_page_desc - initialise a paged fragment in an skb
1859 * @skb: buffer containing fragment to be initialised
1860 * @i: paged fragment index to initialise
1861 * @page: the page to use for this fragment
1862 * @off: the offset to the data with @page
1863 * @size: the length of the data
1865 * As per __skb_fill_page_desc() -- initialises the @i'th fragment of
1866 * @skb to point to @size bytes at offset @off within @page. In
1867 * addition updates @skb such that @i is the last fragment.
1869 * Does not take any additional reference on the fragment.
1871 static inline void skb_fill_page_desc(struct sk_buff *skb, int i,
1872 struct page *page, int off, int size)
1874 __skb_fill_page_desc(skb, i, page, off, size);
1875 skb_shinfo(skb)->nr_frags = i + 1;
1878 void skb_add_rx_frag(struct sk_buff *skb, int i, struct page *page, int off,
1879 int size, unsigned int truesize);
1881 void skb_coalesce_rx_frag(struct sk_buff *skb, int i, int size,
1882 unsigned int truesize);
1884 #define SKB_PAGE_ASSERT(skb) BUG_ON(skb_shinfo(skb)->nr_frags)
1885 #define SKB_FRAG_ASSERT(skb) BUG_ON(skb_has_frag_list(skb))
1886 #define SKB_LINEAR_ASSERT(skb) BUG_ON(skb_is_nonlinear(skb))
1888 #ifdef NET_SKBUFF_DATA_USES_OFFSET
1889 static inline unsigned char *skb_tail_pointer(const struct sk_buff *skb)
1891 return skb->head + skb->tail;
1894 static inline void skb_reset_tail_pointer(struct sk_buff *skb)
1896 skb->tail = skb->data - skb->head;
1899 static inline void skb_set_tail_pointer(struct sk_buff *skb, const int offset)
1901 skb_reset_tail_pointer(skb);
1902 skb->tail += offset;
1905 #else /* NET_SKBUFF_DATA_USES_OFFSET */
1906 static inline unsigned char *skb_tail_pointer(const struct sk_buff *skb)
1911 static inline void skb_reset_tail_pointer(struct sk_buff *skb)
1913 skb->tail = skb->data;
1916 static inline void skb_set_tail_pointer(struct sk_buff *skb, const int offset)
1918 skb->tail = skb->data + offset;
1921 #endif /* NET_SKBUFF_DATA_USES_OFFSET */
1924 * Add data to an sk_buff
1926 unsigned char *pskb_put(struct sk_buff *skb, struct sk_buff *tail, int len);
1927 unsigned char *skb_put(struct sk_buff *skb, unsigned int len);
1928 static inline unsigned char *__skb_put(struct sk_buff *skb, unsigned int len)
1930 unsigned char *tmp = skb_tail_pointer(skb);
1931 SKB_LINEAR_ASSERT(skb);
1937 unsigned char *skb_push(struct sk_buff *skb, unsigned int len);
1938 static inline unsigned char *__skb_push(struct sk_buff *skb, unsigned int len)
1945 unsigned char *skb_pull(struct sk_buff *skb, unsigned int len);
1946 static inline unsigned char *__skb_pull(struct sk_buff *skb, unsigned int len)
1949 BUG_ON(skb->len < skb->data_len);
1950 return skb->data += len;
1953 static inline unsigned char *skb_pull_inline(struct sk_buff *skb, unsigned int len)
1955 return unlikely(len > skb->len) ? NULL : __skb_pull(skb, len);
1958 unsigned char *__pskb_pull_tail(struct sk_buff *skb, int delta);
1960 static inline unsigned char *__pskb_pull(struct sk_buff *skb, unsigned int len)
1962 if (len > skb_headlen(skb) &&
1963 !__pskb_pull_tail(skb, len - skb_headlen(skb)))
1966 return skb->data += len;
1969 static inline unsigned char *pskb_pull(struct sk_buff *skb, unsigned int len)
1971 return unlikely(len > skb->len) ? NULL : __pskb_pull(skb, len);
1974 static inline int pskb_may_pull(struct sk_buff *skb, unsigned int len)
1976 if (likely(len <= skb_headlen(skb)))
1978 if (unlikely(len > skb->len))
1980 return __pskb_pull_tail(skb, len - skb_headlen(skb)) != NULL;
1983 void skb_condense(struct sk_buff *skb);
1986 * skb_headroom - bytes at buffer head
1987 * @skb: buffer to check
1989 * Return the number of bytes of free space at the head of an &sk_buff.
1991 static inline unsigned int skb_headroom(const struct sk_buff *skb)
1993 return skb->data - skb->head;
1997 * skb_tailroom - bytes at buffer end
1998 * @skb: buffer to check
2000 * Return the number of bytes of free space at the tail of an sk_buff
2002 static inline int skb_tailroom(const struct sk_buff *skb)
2004 return skb_is_nonlinear(skb) ? 0 : skb->end - skb->tail;
2008 * skb_availroom - bytes at buffer end
2009 * @skb: buffer to check
2011 * Return the number of bytes of free space at the tail of an sk_buff
2012 * allocated by sk_stream_alloc()
2014 static inline int skb_availroom(const struct sk_buff *skb)
2016 if (skb_is_nonlinear(skb))
2019 return skb->end - skb->tail - skb->reserved_tailroom;
2023 * skb_reserve - adjust headroom
2024 * @skb: buffer to alter
2025 * @len: bytes to move
2027 * Increase the headroom of an empty &sk_buff by reducing the tail
2028 * room. This is only allowed for an empty buffer.
2030 static inline void skb_reserve(struct sk_buff *skb, int len)
2037 * skb_tailroom_reserve - adjust reserved_tailroom
2038 * @skb: buffer to alter
2039 * @mtu: maximum amount of headlen permitted
2040 * @needed_tailroom: minimum amount of reserved_tailroom
2042 * Set reserved_tailroom so that headlen can be as large as possible but
2043 * not larger than mtu and tailroom cannot be smaller than
2045 * The required headroom should already have been reserved before using
2048 static inline void skb_tailroom_reserve(struct sk_buff *skb, unsigned int mtu,
2049 unsigned int needed_tailroom)
2051 SKB_LINEAR_ASSERT(skb);
2052 if (mtu < skb_tailroom(skb) - needed_tailroom)
2053 /* use at most mtu */
2054 skb->reserved_tailroom = skb_tailroom(skb) - mtu;
2056 /* use up to all available space */
2057 skb->reserved_tailroom = needed_tailroom;
2060 #define ENCAP_TYPE_ETHER 0
2061 #define ENCAP_TYPE_IPPROTO 1
2063 static inline void skb_set_inner_protocol(struct sk_buff *skb,
2066 skb->inner_protocol = protocol;
2067 skb->inner_protocol_type = ENCAP_TYPE_ETHER;
2070 static inline void skb_set_inner_ipproto(struct sk_buff *skb,
2073 skb->inner_ipproto = ipproto;
2074 skb->inner_protocol_type = ENCAP_TYPE_IPPROTO;
2077 static inline void skb_reset_inner_headers(struct sk_buff *skb)
2079 skb->inner_mac_header = skb->mac_header;
2080 skb->inner_network_header = skb->network_header;
2081 skb->inner_transport_header = skb->transport_header;
2084 static inline void skb_reset_mac_len(struct sk_buff *skb)
2086 skb->mac_len = skb->network_header - skb->mac_header;
2089 static inline unsigned char *skb_inner_transport_header(const struct sk_buff
2092 return skb->head + skb->inner_transport_header;
2095 static inline int skb_inner_transport_offset(const struct sk_buff *skb)
2097 return skb_inner_transport_header(skb) - skb->data;
2100 static inline void skb_reset_inner_transport_header(struct sk_buff *skb)
2102 skb->inner_transport_header = skb->data - skb->head;
2105 static inline void skb_set_inner_transport_header(struct sk_buff *skb,
2108 skb_reset_inner_transport_header(skb);
2109 skb->inner_transport_header += offset;
2112 static inline unsigned char *skb_inner_network_header(const struct sk_buff *skb)
2114 return skb->head + skb->inner_network_header;
2117 static inline void skb_reset_inner_network_header(struct sk_buff *skb)
2119 skb->inner_network_header = skb->data - skb->head;
2122 static inline void skb_set_inner_network_header(struct sk_buff *skb,
2125 skb_reset_inner_network_header(skb);
2126 skb->inner_network_header += offset;
2129 static inline unsigned char *skb_inner_mac_header(const struct sk_buff *skb)
2131 return skb->head + skb->inner_mac_header;
2134 static inline void skb_reset_inner_mac_header(struct sk_buff *skb)
2136 skb->inner_mac_header = skb->data - skb->head;
2139 static inline void skb_set_inner_mac_header(struct sk_buff *skb,
2142 skb_reset_inner_mac_header(skb);
2143 skb->inner_mac_header += offset;
2145 static inline bool skb_transport_header_was_set(const struct sk_buff *skb)
2147 return skb->transport_header != (typeof(skb->transport_header))~0U;
2150 static inline unsigned char *skb_transport_header(const struct sk_buff *skb)
2152 return skb->head + skb->transport_header;
2155 static inline void skb_reset_transport_header(struct sk_buff *skb)
2157 skb->transport_header = skb->data - skb->head;
2160 static inline void skb_set_transport_header(struct sk_buff *skb,
2163 skb_reset_transport_header(skb);
2164 skb->transport_header += offset;
2167 static inline unsigned char *skb_network_header(const struct sk_buff *skb)
2169 return skb->head + skb->network_header;
2172 static inline void skb_reset_network_header(struct sk_buff *skb)
2174 skb->network_header = skb->data - skb->head;
2177 static inline void skb_set_network_header(struct sk_buff *skb, const int offset)
2179 skb_reset_network_header(skb);
2180 skb->network_header += offset;
2183 static inline unsigned char *skb_mac_header(const struct sk_buff *skb)
2185 return skb->head + skb->mac_header;
2188 static inline int skb_mac_offset(const struct sk_buff *skb)
2190 return skb_mac_header(skb) - skb->data;
2193 static inline int skb_mac_header_was_set(const struct sk_buff *skb)
2195 return skb->mac_header != (typeof(skb->mac_header))~0U;
2198 static inline void skb_reset_mac_header(struct sk_buff *skb)
2200 skb->mac_header = skb->data - skb->head;
2203 static inline void skb_set_mac_header(struct sk_buff *skb, const int offset)
2205 skb_reset_mac_header(skb);
2206 skb->mac_header += offset;
2209 static inline void skb_pop_mac_header(struct sk_buff *skb)
2211 skb->mac_header = skb->network_header;
2214 static inline void skb_probe_transport_header(struct sk_buff *skb,
2215 const int offset_hint)
2217 struct flow_keys keys;
2219 if (skb_transport_header_was_set(skb))
2221 else if (skb_flow_dissect_flow_keys(skb, &keys, 0))
2222 skb_set_transport_header(skb, keys.control.thoff);
2224 skb_set_transport_header(skb, offset_hint);
2227 static inline void skb_mac_header_rebuild(struct sk_buff *skb)
2229 if (skb_mac_header_was_set(skb)) {
2230 const unsigned char *old_mac = skb_mac_header(skb);
2232 skb_set_mac_header(skb, -skb->mac_len);
2233 memmove(skb_mac_header(skb), old_mac, skb->mac_len);
2237 static inline int skb_checksum_start_offset(const struct sk_buff *skb)
2239 return skb->csum_start - skb_headroom(skb);
2242 static inline unsigned char *skb_checksum_start(const struct sk_buff *skb)
2244 return skb->head + skb->csum_start;
2247 static inline int skb_transport_offset(const struct sk_buff *skb)
2249 return skb_transport_header(skb) - skb->data;
2252 static inline u32 skb_network_header_len(const struct sk_buff *skb)
2254 return skb->transport_header - skb->network_header;
2257 static inline u32 skb_inner_network_header_len(const struct sk_buff *skb)
2259 return skb->inner_transport_header - skb->inner_network_header;
2262 static inline int skb_network_offset(const struct sk_buff *skb)
2264 return skb_network_header(skb) - skb->data;
2267 static inline int skb_inner_network_offset(const struct sk_buff *skb)
2269 return skb_inner_network_header(skb) - skb->data;
2272 static inline int pskb_network_may_pull(struct sk_buff *skb, unsigned int len)
2274 return pskb_may_pull(skb, skb_network_offset(skb) + len);
2278 * CPUs often take a performance hit when accessing unaligned memory
2279 * locations. The actual performance hit varies, it can be small if the
2280 * hardware handles it or large if we have to take an exception and fix it
2283 * Since an ethernet header is 14 bytes network drivers often end up with
2284 * the IP header at an unaligned offset. The IP header can be aligned by
2285 * shifting the start of the packet by 2 bytes. Drivers should do this
2288 * skb_reserve(skb, NET_IP_ALIGN);
2290 * The downside to this alignment of the IP header is that the DMA is now
2291 * unaligned. On some architectures the cost of an unaligned DMA is high
2292 * and this cost outweighs the gains made by aligning the IP header.
2294 * Since this trade off varies between architectures, we allow NET_IP_ALIGN
2297 #ifndef NET_IP_ALIGN
2298 #define NET_IP_ALIGN 2
2302 * The networking layer reserves some headroom in skb data (via
2303 * dev_alloc_skb). This is used to avoid having to reallocate skb data when
2304 * the header has to grow. In the default case, if the header has to grow
2305 * 32 bytes or less we avoid the reallocation.
2307 * Unfortunately this headroom changes the DMA alignment of the resulting
2308 * network packet. As for NET_IP_ALIGN, this unaligned DMA is expensive
2309 * on some architectures. An architecture can override this value,
2310 * perhaps setting it to a cacheline in size (since that will maintain
2311 * cacheline alignment of the DMA). It must be a power of 2.
2313 * Various parts of the networking layer expect at least 32 bytes of
2314 * headroom, you should not reduce this.
2316 * Using max(32, L1_CACHE_BYTES) makes sense (especially with RPS)
2317 * to reduce average number of cache lines per packet.
2318 * get_rps_cpus() for example only access one 64 bytes aligned block :
2319 * NET_IP_ALIGN(2) + ethernet_header(14) + IP_header(20/40) + ports(8)
2322 #define NET_SKB_PAD max(32, L1_CACHE_BYTES)
2325 int ___pskb_trim(struct sk_buff *skb, unsigned int len);
2327 static inline void __skb_set_length(struct sk_buff *skb, unsigned int len)
2329 if (unlikely(skb_is_nonlinear(skb))) {
2334 skb_set_tail_pointer(skb, len);
2337 static inline void __skb_trim(struct sk_buff *skb, unsigned int len)
2339 __skb_set_length(skb, len);
2342 void skb_trim(struct sk_buff *skb, unsigned int len);
2344 static inline int __pskb_trim(struct sk_buff *skb, unsigned int len)
2347 return ___pskb_trim(skb, len);
2348 __skb_trim(skb, len);
2352 static inline int pskb_trim(struct sk_buff *skb, unsigned int len)
2354 return (len < skb->len) ? __pskb_trim(skb, len) : 0;
2358 * pskb_trim_unique - remove end from a paged unique (not cloned) buffer
2359 * @skb: buffer to alter
2362 * This is identical to pskb_trim except that the caller knows that
2363 * the skb is not cloned so we should never get an error due to out-
2366 static inline void pskb_trim_unique(struct sk_buff *skb, unsigned int len)
2368 int err = pskb_trim(skb, len);
2372 static inline int __skb_grow(struct sk_buff *skb, unsigned int len)
2374 unsigned int diff = len - skb->len;
2376 if (skb_tailroom(skb) < diff) {
2377 int ret = pskb_expand_head(skb, 0, diff - skb_tailroom(skb),
2382 __skb_set_length(skb, len);
2387 * skb_orphan - orphan a buffer
2388 * @skb: buffer to orphan
2390 * If a buffer currently has an owner then we call the owner's
2391 * destructor function and make the @skb unowned. The buffer continues
2392 * to exist but is no longer charged to its former owner.
2394 static inline void skb_orphan(struct sk_buff *skb)
2396 if (skb->destructor) {
2397 skb->destructor(skb);
2398 skb->destructor = NULL;
2406 * skb_orphan_frags - orphan the frags contained in a buffer
2407 * @skb: buffer to orphan frags from
2408 * @gfp_mask: allocation mask for replacement pages
2410 * For each frag in the SKB which needs a destructor (i.e. has an
2411 * owner) create a copy of that frag and release the original
2412 * page by calling the destructor.
2414 static inline int skb_orphan_frags(struct sk_buff *skb, gfp_t gfp_mask)
2416 if (likely(!(skb_shinfo(skb)->tx_flags & SKBTX_DEV_ZEROCOPY)))
2418 return skb_copy_ubufs(skb, gfp_mask);
2422 * __skb_queue_purge - empty a list
2423 * @list: list to empty
2425 * Delete all buffers on an &sk_buff list. Each buffer is removed from
2426 * the list and one reference dropped. This function does not take the
2427 * list lock and the caller must hold the relevant locks to use it.
2429 void skb_queue_purge(struct sk_buff_head *list);
2430 static inline void __skb_queue_purge(struct sk_buff_head *list)
2432 struct sk_buff *skb;
2433 while ((skb = __skb_dequeue(list)) != NULL)
2437 void skb_rbtree_purge(struct rb_root *root);
2439 void *netdev_alloc_frag(unsigned int fragsz);
2441 struct sk_buff *__netdev_alloc_skb(struct net_device *dev, unsigned int length,
2445 * netdev_alloc_skb - allocate an skbuff for rx on a specific device
2446 * @dev: network device to receive on
2447 * @length: length to allocate
2449 * Allocate a new &sk_buff and assign it a usage count of one. The
2450 * buffer has unspecified headroom built in. Users should allocate
2451 * the headroom they think they need without accounting for the
2452 * built in space. The built in space is used for optimisations.
2454 * %NULL is returned if there is no free memory. Although this function
2455 * allocates memory it can be called from an interrupt.
2457 static inline struct sk_buff *netdev_alloc_skb(struct net_device *dev,
2458 unsigned int length)
2460 return __netdev_alloc_skb(dev, length, GFP_ATOMIC);
2463 /* legacy helper around __netdev_alloc_skb() */
2464 static inline struct sk_buff *__dev_alloc_skb(unsigned int length,
2467 return __netdev_alloc_skb(NULL, length, gfp_mask);
2470 /* legacy helper around netdev_alloc_skb() */
2471 static inline struct sk_buff *dev_alloc_skb(unsigned int length)
2473 return netdev_alloc_skb(NULL, length);
2477 static inline struct sk_buff *__netdev_alloc_skb_ip_align(struct net_device *dev,
2478 unsigned int length, gfp_t gfp)
2480 struct sk_buff *skb = __netdev_alloc_skb(dev, length + NET_IP_ALIGN, gfp);
2482 if (NET_IP_ALIGN && skb)
2483 skb_reserve(skb, NET_IP_ALIGN);
2487 static inline struct sk_buff *netdev_alloc_skb_ip_align(struct net_device *dev,
2488 unsigned int length)
2490 return __netdev_alloc_skb_ip_align(dev, length, GFP_ATOMIC);
2493 static inline void skb_free_frag(void *addr)
2495 page_frag_free(addr);
2498 void *napi_alloc_frag(unsigned int fragsz);
2499 struct sk_buff *__napi_alloc_skb(struct napi_struct *napi,
2500 unsigned int length, gfp_t gfp_mask);
2501 static inline struct sk_buff *napi_alloc_skb(struct napi_struct *napi,
2502 unsigned int length)
2504 return __napi_alloc_skb(napi, length, GFP_ATOMIC);
2506 void napi_consume_skb(struct sk_buff *skb, int budget);
2508 void __kfree_skb_flush(void);
2509 void __kfree_skb_defer(struct sk_buff *skb);
2512 * __dev_alloc_pages - allocate page for network Rx
2513 * @gfp_mask: allocation priority. Set __GFP_NOMEMALLOC if not for network Rx
2514 * @order: size of the allocation
2516 * Allocate a new page.
2518 * %NULL is returned if there is no free memory.
2520 static inline struct page *__dev_alloc_pages(gfp_t gfp_mask,
2523 /* This piece of code contains several assumptions.
2524 * 1. This is for device Rx, therefor a cold page is preferred.
2525 * 2. The expectation is the user wants a compound page.
2526 * 3. If requesting a order 0 page it will not be compound
2527 * due to the check to see if order has a value in prep_new_page
2528 * 4. __GFP_MEMALLOC is ignored if __GFP_NOMEMALLOC is set due to
2529 * code in gfp_to_alloc_flags that should be enforcing this.
2531 gfp_mask |= __GFP_COLD | __GFP_COMP | __GFP_MEMALLOC;
2533 return alloc_pages_node(NUMA_NO_NODE, gfp_mask, order);
2536 static inline struct page *dev_alloc_pages(unsigned int order)
2538 return __dev_alloc_pages(GFP_ATOMIC | __GFP_NOWARN, order);
2542 * __dev_alloc_page - allocate a page for network Rx
2543 * @gfp_mask: allocation priority. Set __GFP_NOMEMALLOC if not for network Rx
2545 * Allocate a new page.
2547 * %NULL is returned if there is no free memory.
2549 static inline struct page *__dev_alloc_page(gfp_t gfp_mask)
2551 return __dev_alloc_pages(gfp_mask, 0);
2554 static inline struct page *dev_alloc_page(void)
2556 return dev_alloc_pages(0);
2560 * skb_propagate_pfmemalloc - Propagate pfmemalloc if skb is allocated after RX page
2561 * @page: The page that was allocated from skb_alloc_page
2562 * @skb: The skb that may need pfmemalloc set
2564 static inline void skb_propagate_pfmemalloc(struct page *page,
2565 struct sk_buff *skb)
2567 if (page_is_pfmemalloc(page))
2568 skb->pfmemalloc = true;
2572 * skb_frag_page - retrieve the page referred to by a paged fragment
2573 * @frag: the paged fragment
2575 * Returns the &struct page associated with @frag.
2577 static inline struct page *skb_frag_page(const skb_frag_t *frag)
2579 return frag->page.p;
2583 * __skb_frag_ref - take an addition reference on a paged fragment.
2584 * @frag: the paged fragment
2586 * Takes an additional reference on the paged fragment @frag.
2588 static inline void __skb_frag_ref(skb_frag_t *frag)
2590 get_page(skb_frag_page(frag));
2594 * skb_frag_ref - take an addition reference on a paged fragment of an skb.
2596 * @f: the fragment offset.
2598 * Takes an additional reference on the @f'th paged fragment of @skb.
2600 static inline void skb_frag_ref(struct sk_buff *skb, int f)
2602 __skb_frag_ref(&skb_shinfo(skb)->frags[f]);
2606 * __skb_frag_unref - release a reference on a paged fragment.
2607 * @frag: the paged fragment
2609 * Releases a reference on the paged fragment @frag.
2611 static inline void __skb_frag_unref(skb_frag_t *frag)
2613 put_page(skb_frag_page(frag));
2617 * skb_frag_unref - release a reference on a paged fragment of an skb.
2619 * @f: the fragment offset
2621 * Releases a reference on the @f'th paged fragment of @skb.
2623 static inline void skb_frag_unref(struct sk_buff *skb, int f)
2625 __skb_frag_unref(&skb_shinfo(skb)->frags[f]);
2629 * skb_frag_address - gets the address of the data contained in a paged fragment
2630 * @frag: the paged fragment buffer
2632 * Returns the address of the data within @frag. The page must already
2635 static inline void *skb_frag_address(const skb_frag_t *frag)
2637 return page_address(skb_frag_page(frag)) + frag->page_offset;
2641 * skb_frag_address_safe - gets the address of the data contained in a paged fragment
2642 * @frag: the paged fragment buffer
2644 * Returns the address of the data within @frag. Checks that the page
2645 * is mapped and returns %NULL otherwise.
2647 static inline void *skb_frag_address_safe(const skb_frag_t *frag)
2649 void *ptr = page_address(skb_frag_page(frag));
2653 return ptr + frag->page_offset;
2657 * __skb_frag_set_page - sets the page contained in a paged fragment
2658 * @frag: the paged fragment
2659 * @page: the page to set
2661 * Sets the fragment @frag to contain @page.
2663 static inline void __skb_frag_set_page(skb_frag_t *frag, struct page *page)
2665 frag->page.p = page;
2669 * skb_frag_set_page - sets the page contained in a paged fragment of an skb
2671 * @f: the fragment offset
2672 * @page: the page to set
2674 * Sets the @f'th fragment of @skb to contain @page.
2676 static inline void skb_frag_set_page(struct sk_buff *skb, int f,
2679 __skb_frag_set_page(&skb_shinfo(skb)->frags[f], page);
2682 bool skb_page_frag_refill(unsigned int sz, struct page_frag *pfrag, gfp_t prio);
2685 * skb_frag_dma_map - maps a paged fragment via the DMA API
2686 * @dev: the device to map the fragment to
2687 * @frag: the paged fragment to map
2688 * @offset: the offset within the fragment (starting at the
2689 * fragment's own offset)
2690 * @size: the number of bytes to map
2691 * @dir: the direction of the mapping (%PCI_DMA_*)
2693 * Maps the page associated with @frag to @device.
2695 static inline dma_addr_t skb_frag_dma_map(struct device *dev,
2696 const skb_frag_t *frag,
2697 size_t offset, size_t size,
2698 enum dma_data_direction dir)
2700 return dma_map_page(dev, skb_frag_page(frag),
2701 frag->page_offset + offset, size, dir);
2704 static inline struct sk_buff *pskb_copy(struct sk_buff *skb,
2707 return __pskb_copy(skb, skb_headroom(skb), gfp_mask);
2711 static inline struct sk_buff *pskb_copy_for_clone(struct sk_buff *skb,
2714 return __pskb_copy_fclone(skb, skb_headroom(skb), gfp_mask, true);
2719 * skb_clone_writable - is the header of a clone writable
2720 * @skb: buffer to check
2721 * @len: length up to which to write
2723 * Returns true if modifying the header part of the cloned buffer
2724 * does not requires the data to be copied.
2726 static inline int skb_clone_writable(const struct sk_buff *skb, unsigned int len)
2728 return !skb_header_cloned(skb) &&
2729 skb_headroom(skb) + len <= skb->hdr_len;
2732 static inline int skb_try_make_writable(struct sk_buff *skb,
2733 unsigned int write_len)
2735 return skb_cloned(skb) && !skb_clone_writable(skb, write_len) &&
2736 pskb_expand_head(skb, 0, 0, GFP_ATOMIC);
2739 static inline int __skb_cow(struct sk_buff *skb, unsigned int headroom,
2744 if (headroom > skb_headroom(skb))
2745 delta = headroom - skb_headroom(skb);
2747 if (delta || cloned)
2748 return pskb_expand_head(skb, ALIGN(delta, NET_SKB_PAD), 0,
2754 * skb_cow - copy header of skb when it is required
2755 * @skb: buffer to cow
2756 * @headroom: needed headroom
2758 * If the skb passed lacks sufficient headroom or its data part
2759 * is shared, data is reallocated. If reallocation fails, an error
2760 * is returned and original skb is not changed.
2762 * The result is skb with writable area skb->head...skb->tail
2763 * and at least @headroom of space at head.
2765 static inline int skb_cow(struct sk_buff *skb, unsigned int headroom)
2767 return __skb_cow(skb, headroom, skb_cloned(skb));
2771 * skb_cow_head - skb_cow but only making the head writable
2772 * @skb: buffer to cow
2773 * @headroom: needed headroom
2775 * This function is identical to skb_cow except that we replace the
2776 * skb_cloned check by skb_header_cloned. It should be used when
2777 * you only need to push on some header and do not need to modify
2780 static inline int skb_cow_head(struct sk_buff *skb, unsigned int headroom)
2782 return __skb_cow(skb, headroom, skb_header_cloned(skb));
2786 * skb_padto - pad an skbuff up to a minimal size
2787 * @skb: buffer to pad
2788 * @len: minimal length
2790 * Pads up a buffer to ensure the trailing bytes exist and are
2791 * blanked. If the buffer already contains sufficient data it
2792 * is untouched. Otherwise it is extended. Returns zero on
2793 * success. The skb is freed on error.
2795 static inline int skb_padto(struct sk_buff *skb, unsigned int len)
2797 unsigned int size = skb->len;
2798 if (likely(size >= len))
2800 return skb_pad(skb, len - size);
2804 * skb_put_padto - increase size and pad an skbuff up to a minimal size
2805 * @skb: buffer to pad
2806 * @len: minimal length
2808 * Pads up a buffer to ensure the trailing bytes exist and are
2809 * blanked. If the buffer already contains sufficient data it
2810 * is untouched. Otherwise it is extended. Returns zero on
2811 * success. The skb is freed on error.
2813 static inline int skb_put_padto(struct sk_buff *skb, unsigned int len)
2815 unsigned int size = skb->len;
2817 if (unlikely(size < len)) {
2819 if (skb_pad(skb, len))
2821 __skb_put(skb, len);
2826 static inline int skb_add_data(struct sk_buff *skb,
2827 struct iov_iter *from, int copy)
2829 const int off = skb->len;
2831 if (skb->ip_summed == CHECKSUM_NONE) {
2833 if (csum_and_copy_from_iter_full(skb_put(skb, copy), copy,
2835 skb->csum = csum_block_add(skb->csum, csum, off);
2838 } else if (copy_from_iter_full(skb_put(skb, copy), copy, from))
2841 __skb_trim(skb, off);
2845 static inline bool skb_can_coalesce(struct sk_buff *skb, int i,
2846 const struct page *page, int off)
2849 const struct skb_frag_struct *frag = &skb_shinfo(skb)->frags[i - 1];
2851 return page == skb_frag_page(frag) &&
2852 off == frag->page_offset + skb_frag_size(frag);
2857 static inline int __skb_linearize(struct sk_buff *skb)
2859 return __pskb_pull_tail(skb, skb->data_len) ? 0 : -ENOMEM;
2863 * skb_linearize - convert paged skb to linear one
2864 * @skb: buffer to linarize
2866 * If there is no free memory -ENOMEM is returned, otherwise zero
2867 * is returned and the old skb data released.
2869 static inline int skb_linearize(struct sk_buff *skb)
2871 return skb_is_nonlinear(skb) ? __skb_linearize(skb) : 0;
2875 * skb_has_shared_frag - can any frag be overwritten
2876 * @skb: buffer to test
2878 * Return true if the skb has at least one frag that might be modified
2879 * by an external entity (as in vmsplice()/sendfile())
2881 static inline bool skb_has_shared_frag(const struct sk_buff *skb)
2883 return skb_is_nonlinear(skb) &&
2884 skb_shinfo(skb)->tx_flags & SKBTX_SHARED_FRAG;
2888 * skb_linearize_cow - make sure skb is linear and writable
2889 * @skb: buffer to process
2891 * If there is no free memory -ENOMEM is returned, otherwise zero
2892 * is returned and the old skb data released.
2894 static inline int skb_linearize_cow(struct sk_buff *skb)
2896 return skb_is_nonlinear(skb) || skb_cloned(skb) ?
2897 __skb_linearize(skb) : 0;
2900 static __always_inline void
2901 __skb_postpull_rcsum(struct sk_buff *skb, const void *start, unsigned int len,
2904 if (skb->ip_summed == CHECKSUM_COMPLETE)
2905 skb->csum = csum_block_sub(skb->csum,
2906 csum_partial(start, len, 0), off);
2907 else if (skb->ip_summed == CHECKSUM_PARTIAL &&
2908 skb_checksum_start_offset(skb) < 0)
2909 skb->ip_summed = CHECKSUM_NONE;
2913 * skb_postpull_rcsum - update checksum for received skb after pull
2914 * @skb: buffer to update
2915 * @start: start of data before pull
2916 * @len: length of data pulled
2918 * After doing a pull on a received packet, you need to call this to
2919 * update the CHECKSUM_COMPLETE checksum, or set ip_summed to
2920 * CHECKSUM_NONE so that it can be recomputed from scratch.
2922 static inline void skb_postpull_rcsum(struct sk_buff *skb,
2923 const void *start, unsigned int len)
2925 __skb_postpull_rcsum(skb, start, len, 0);
2928 static __always_inline void
2929 __skb_postpush_rcsum(struct sk_buff *skb, const void *start, unsigned int len,
2932 if (skb->ip_summed == CHECKSUM_COMPLETE)
2933 skb->csum = csum_block_add(skb->csum,
2934 csum_partial(start, len, 0), off);
2938 * skb_postpush_rcsum - update checksum for received skb after push
2939 * @skb: buffer to update
2940 * @start: start of data after push
2941 * @len: length of data pushed
2943 * After doing a push on a received packet, you need to call this to
2944 * update the CHECKSUM_COMPLETE checksum.
2946 static inline void skb_postpush_rcsum(struct sk_buff *skb,
2947 const void *start, unsigned int len)
2949 __skb_postpush_rcsum(skb, start, len, 0);
2952 unsigned char *skb_pull_rcsum(struct sk_buff *skb, unsigned int len);
2955 * skb_push_rcsum - push skb and update receive checksum
2956 * @skb: buffer to update
2957 * @len: length of data pulled
2959 * This function performs an skb_push on the packet and updates
2960 * the CHECKSUM_COMPLETE checksum. It should be used on
2961 * receive path processing instead of skb_push unless you know
2962 * that the checksum difference is zero (e.g., a valid IP header)
2963 * or you are setting ip_summed to CHECKSUM_NONE.
2965 static inline unsigned char *skb_push_rcsum(struct sk_buff *skb,
2969 skb_postpush_rcsum(skb, skb->data, len);
2974 * pskb_trim_rcsum - trim received skb and update checksum
2975 * @skb: buffer to trim
2978 * This is exactly the same as pskb_trim except that it ensures the
2979 * checksum of received packets are still valid after the operation.
2982 static inline int pskb_trim_rcsum(struct sk_buff *skb, unsigned int len)
2984 if (likely(len >= skb->len))
2986 if (skb->ip_summed == CHECKSUM_COMPLETE)
2987 skb->ip_summed = CHECKSUM_NONE;
2988 return __pskb_trim(skb, len);
2991 static inline int __skb_trim_rcsum(struct sk_buff *skb, unsigned int len)
2993 if (skb->ip_summed == CHECKSUM_COMPLETE)
2994 skb->ip_summed = CHECKSUM_NONE;
2995 __skb_trim(skb, len);
2999 static inline int __skb_grow_rcsum(struct sk_buff *skb, unsigned int len)
3001 if (skb->ip_summed == CHECKSUM_COMPLETE)
3002 skb->ip_summed = CHECKSUM_NONE;
3003 return __skb_grow(skb, len);
3006 #define skb_queue_walk(queue, skb) \
3007 for (skb = (queue)->next; \
3008 skb != (struct sk_buff *)(queue); \
3011 #define skb_queue_walk_safe(queue, skb, tmp) \
3012 for (skb = (queue)->next, tmp = skb->next; \
3013 skb != (struct sk_buff *)(queue); \
3014 skb = tmp, tmp = skb->next)
3016 #define skb_queue_walk_from(queue, skb) \
3017 for (; skb != (struct sk_buff *)(queue); \
3020 #define skb_queue_walk_from_safe(queue, skb, tmp) \
3021 for (tmp = skb->next; \
3022 skb != (struct sk_buff *)(queue); \
3023 skb = tmp, tmp = skb->next)
3025 #define skb_queue_reverse_walk(queue, skb) \
3026 for (skb = (queue)->prev; \
3027 skb != (struct sk_buff *)(queue); \
3030 #define skb_queue_reverse_walk_safe(queue, skb, tmp) \
3031 for (skb = (queue)->prev, tmp = skb->prev; \
3032 skb != (struct sk_buff *)(queue); \
3033 skb = tmp, tmp = skb->prev)
3035 #define skb_queue_reverse_walk_from_safe(queue, skb, tmp) \
3036 for (tmp = skb->prev; \
3037 skb != (struct sk_buff *)(queue); \
3038 skb = tmp, tmp = skb->prev)
3040 static inline bool skb_has_frag_list(const struct sk_buff *skb)
3042 return skb_shinfo(skb)->frag_list != NULL;
3045 static inline void skb_frag_list_init(struct sk_buff *skb)
3047 skb_shinfo(skb)->frag_list = NULL;
3050 #define skb_walk_frags(skb, iter) \
3051 for (iter = skb_shinfo(skb)->frag_list; iter; iter = iter->next)
3054 int __skb_wait_for_more_packets(struct sock *sk, int *err, long *timeo_p,
3055 const struct sk_buff *skb);
3056 struct sk_buff *__skb_try_recv_datagram(struct sock *sk, unsigned flags,
3057 void (*destructor)(struct sock *sk,
3058 struct sk_buff *skb),
3059 int *peeked, int *off, int *err,
3060 struct sk_buff **last);
3061 struct sk_buff *__skb_recv_datagram(struct sock *sk, unsigned flags,
3062 void (*destructor)(struct sock *sk,
3063 struct sk_buff *skb),
3064 int *peeked, int *off, int *err);
3065 struct sk_buff *skb_recv_datagram(struct sock *sk, unsigned flags, int noblock,
3067 unsigned int datagram_poll(struct file *file, struct socket *sock,
3068 struct poll_table_struct *wait);
3069 int skb_copy_datagram_iter(const struct sk_buff *from, int offset,
3070 struct iov_iter *to, int size);
3071 static inline int skb_copy_datagram_msg(const struct sk_buff *from, int offset,
3072 struct msghdr *msg, int size)
3074 return skb_copy_datagram_iter(from, offset, &msg->msg_iter, size);
3076 int skb_copy_and_csum_datagram_msg(struct sk_buff *skb, int hlen,
3077 struct msghdr *msg);
3078 int skb_copy_datagram_from_iter(struct sk_buff *skb, int offset,
3079 struct iov_iter *from, int len);
3080 int zerocopy_sg_from_iter(struct sk_buff *skb, struct iov_iter *frm);
3081 void skb_free_datagram(struct sock *sk, struct sk_buff *skb);
3082 void __skb_free_datagram_locked(struct sock *sk, struct sk_buff *skb, int len);
3083 static inline void skb_free_datagram_locked(struct sock *sk,
3084 struct sk_buff *skb)
3086 __skb_free_datagram_locked(sk, skb, 0);
3088 int skb_kill_datagram(struct sock *sk, struct sk_buff *skb, unsigned int flags);
3089 int skb_copy_bits(const struct sk_buff *skb, int offset, void *to, int len);
3090 int skb_store_bits(struct sk_buff *skb, int offset, const void *from, int len);
3091 __wsum skb_copy_and_csum_bits(const struct sk_buff *skb, int offset, u8 *to,
3092 int len, __wsum csum);
3093 int skb_splice_bits(struct sk_buff *skb, struct sock *sk, unsigned int offset,
3094 struct pipe_inode_info *pipe, unsigned int len,
3095 unsigned int flags);
3096 void skb_copy_and_csum_dev(const struct sk_buff *skb, u8 *to);
3097 unsigned int skb_zerocopy_headlen(const struct sk_buff *from);
3098 int skb_zerocopy(struct sk_buff *to, struct sk_buff *from,
3100 void skb_split(struct sk_buff *skb, struct sk_buff *skb1, const u32 len);
3101 int skb_shift(struct sk_buff *tgt, struct sk_buff *skb, int shiftlen);
3102 void skb_scrub_packet(struct sk_buff *skb, bool xnet);
3103 unsigned int skb_gso_transport_seglen(const struct sk_buff *skb);
3104 bool skb_gso_validate_mtu(const struct sk_buff *skb, unsigned int mtu);
3105 struct sk_buff *skb_segment(struct sk_buff *skb, netdev_features_t features);
3106 struct sk_buff *skb_vlan_untag(struct sk_buff *skb);
3107 int skb_ensure_writable(struct sk_buff *skb, int write_len);
3108 int __skb_vlan_pop(struct sk_buff *skb, u16 *vlan_tci);
3109 int skb_vlan_pop(struct sk_buff *skb);
3110 int skb_vlan_push(struct sk_buff *skb, __be16 vlan_proto, u16 vlan_tci);
3111 struct sk_buff *pskb_extract(struct sk_buff *skb, int off, int to_copy,
3114 static inline int memcpy_from_msg(void *data, struct msghdr *msg, int len)
3116 return copy_from_iter(data, len, &msg->msg_iter) == len ? 0 : -EFAULT;
3119 static inline int memcpy_to_msg(struct msghdr *msg, void *data, int len)
3121 return copy_to_iter(data, len, &msg->msg_iter) == len ? 0 : -EFAULT;
3124 struct skb_checksum_ops {
3125 __wsum (*update)(const void *mem, int len, __wsum wsum);
3126 __wsum (*combine)(__wsum csum, __wsum csum2, int offset, int len);
3129 __wsum __skb_checksum(const struct sk_buff *skb, int offset, int len,
3130 __wsum csum, const struct skb_checksum_ops *ops);
3131 __wsum skb_checksum(const struct sk_buff *skb, int offset, int len,
3134 static inline void * __must_check
3135 __skb_header_pointer(const struct sk_buff *skb, int offset,
3136 int len, void *data, int hlen, void *buffer)
3138 if (hlen - offset >= len)
3139 return data + offset;
3142 skb_copy_bits(skb, offset, buffer, len) < 0)
3148 static inline void * __must_check
3149 skb_header_pointer(const struct sk_buff *skb, int offset, int len, void *buffer)
3151 return __skb_header_pointer(skb, offset, len, skb->data,
3152 skb_headlen(skb), buffer);
3156 * skb_needs_linearize - check if we need to linearize a given skb
3157 * depending on the given device features.
3158 * @skb: socket buffer to check
3159 * @features: net device features
3161 * Returns true if either:
3162 * 1. skb has frag_list and the device doesn't support FRAGLIST, or
3163 * 2. skb is fragmented and the device does not support SG.
3165 static inline bool skb_needs_linearize(struct sk_buff *skb,
3166 netdev_features_t features)
3168 return skb_is_nonlinear(skb) &&
3169 ((skb_has_frag_list(skb) && !(features & NETIF_F_FRAGLIST)) ||
3170 (skb_shinfo(skb)->nr_frags && !(features & NETIF_F_SG)));
3173 static inline void skb_copy_from_linear_data(const struct sk_buff *skb,
3175 const unsigned int len)
3177 memcpy(to, skb->data, len);
3180 static inline void skb_copy_from_linear_data_offset(const struct sk_buff *skb,
3181 const int offset, void *to,
3182 const unsigned int len)
3184 memcpy(to, skb->data + offset, len);
3187 static inline void skb_copy_to_linear_data(struct sk_buff *skb,
3189 const unsigned int len)
3191 memcpy(skb->data, from, len);
3194 static inline void skb_copy_to_linear_data_offset(struct sk_buff *skb,
3197 const unsigned int len)
3199 memcpy(skb->data + offset, from, len);
3202 void skb_init(void);
3204 static inline ktime_t skb_get_ktime(const struct sk_buff *skb)
3210 * skb_get_timestamp - get timestamp from a skb
3211 * @skb: skb to get stamp from
3212 * @stamp: pointer to struct timeval to store stamp in
3214 * Timestamps are stored in the skb as offsets to a base timestamp.
3215 * This function converts the offset back to a struct timeval and stores
3218 static inline void skb_get_timestamp(const struct sk_buff *skb,
3219 struct timeval *stamp)
3221 *stamp = ktime_to_timeval(skb->tstamp);
3224 static inline void skb_get_timestampns(const struct sk_buff *skb,
3225 struct timespec *stamp)
3227 *stamp = ktime_to_timespec(skb->tstamp);
3230 static inline void __net_timestamp(struct sk_buff *skb)
3232 skb->tstamp = ktime_get_real();
3235 static inline ktime_t net_timedelta(ktime_t t)
3237 return ktime_sub(ktime_get_real(), t);
3240 static inline ktime_t net_invalid_timestamp(void)
3245 struct sk_buff *skb_clone_sk(struct sk_buff *skb);
3247 #ifdef CONFIG_NETWORK_PHY_TIMESTAMPING
3249 void skb_clone_tx_timestamp(struct sk_buff *skb);
3250 bool skb_defer_rx_timestamp(struct sk_buff *skb);
3252 #else /* CONFIG_NETWORK_PHY_TIMESTAMPING */
3254 static inline void skb_clone_tx_timestamp(struct sk_buff *skb)
3258 static inline bool skb_defer_rx_timestamp(struct sk_buff *skb)
3263 #endif /* !CONFIG_NETWORK_PHY_TIMESTAMPING */
3266 * skb_complete_tx_timestamp() - deliver cloned skb with tx timestamps
3268 * PHY drivers may accept clones of transmitted packets for
3269 * timestamping via their phy_driver.txtstamp method. These drivers
3270 * must call this function to return the skb back to the stack with a
3273 * @skb: clone of the the original outgoing packet
3274 * @hwtstamps: hardware time stamps
3277 void skb_complete_tx_timestamp(struct sk_buff *skb,
3278 struct skb_shared_hwtstamps *hwtstamps);
3280 void __skb_tstamp_tx(struct sk_buff *orig_skb,
3281 struct skb_shared_hwtstamps *hwtstamps,
3282 struct sock *sk, int tstype);
3285 * skb_tstamp_tx - queue clone of skb with send time stamps
3286 * @orig_skb: the original outgoing packet
3287 * @hwtstamps: hardware time stamps, may be NULL if not available
3289 * If the skb has a socket associated, then this function clones the
3290 * skb (thus sharing the actual data and optional structures), stores
3291 * the optional hardware time stamping information (if non NULL) or
3292 * generates a software time stamp (otherwise), then queues the clone
3293 * to the error queue of the socket. Errors are silently ignored.
3295 void skb_tstamp_tx(struct sk_buff *orig_skb,
3296 struct skb_shared_hwtstamps *hwtstamps);
3298 static inline void sw_tx_timestamp(struct sk_buff *skb)
3300 if (skb_shinfo(skb)->tx_flags & SKBTX_SW_TSTAMP &&
3301 !(skb_shinfo(skb)->tx_flags & SKBTX_IN_PROGRESS))
3302 skb_tstamp_tx(skb, NULL);
3306 * skb_tx_timestamp() - Driver hook for transmit timestamping
3308 * Ethernet MAC Drivers should call this function in their hard_xmit()
3309 * function immediately before giving the sk_buff to the MAC hardware.
3311 * Specifically, one should make absolutely sure that this function is
3312 * called before TX completion of this packet can trigger. Otherwise
3313 * the packet could potentially already be freed.
3315 * @skb: A socket buffer.
3317 static inline void skb_tx_timestamp(struct sk_buff *skb)
3319 skb_clone_tx_timestamp(skb);
3320 sw_tx_timestamp(skb);
3324 * skb_complete_wifi_ack - deliver skb with wifi status
3326 * @skb: the original outgoing packet
3327 * @acked: ack status
3330 void skb_complete_wifi_ack(struct sk_buff *skb, bool acked);
3332 __sum16 __skb_checksum_complete_head(struct sk_buff *skb, int len);
3333 __sum16 __skb_checksum_complete(struct sk_buff *skb);
3335 static inline int skb_csum_unnecessary(const struct sk_buff *skb)
3337 return ((skb->ip_summed == CHECKSUM_UNNECESSARY) ||
3339 (skb->ip_summed == CHECKSUM_PARTIAL &&
3340 skb_checksum_start_offset(skb) >= 0));
3344 * skb_checksum_complete - Calculate checksum of an entire packet
3345 * @skb: packet to process
3347 * This function calculates the checksum over the entire packet plus
3348 * the value of skb->csum. The latter can be used to supply the
3349 * checksum of a pseudo header as used by TCP/UDP. It returns the
3352 * For protocols that contain complete checksums such as ICMP/TCP/UDP,
3353 * this function can be used to verify that checksum on received
3354 * packets. In that case the function should return zero if the
3355 * checksum is correct. In particular, this function will return zero
3356 * if skb->ip_summed is CHECKSUM_UNNECESSARY which indicates that the
3357 * hardware has already verified the correctness of the checksum.
3359 static inline __sum16 skb_checksum_complete(struct sk_buff *skb)
3361 return skb_csum_unnecessary(skb) ?
3362 0 : __skb_checksum_complete(skb);
3365 static inline void __skb_decr_checksum_unnecessary(struct sk_buff *skb)
3367 if (skb->ip_summed == CHECKSUM_UNNECESSARY) {
3368 if (skb->csum_level == 0)
3369 skb->ip_summed = CHECKSUM_NONE;
3375 static inline void __skb_incr_checksum_unnecessary(struct sk_buff *skb)
3377 if (skb->ip_summed == CHECKSUM_UNNECESSARY) {
3378 if (skb->csum_level < SKB_MAX_CSUM_LEVEL)
3380 } else if (skb->ip_summed == CHECKSUM_NONE) {
3381 skb->ip_summed = CHECKSUM_UNNECESSARY;
3382 skb->csum_level = 0;
3386 static inline void __skb_mark_checksum_bad(struct sk_buff *skb)
3388 /* Mark current checksum as bad (typically called from GRO
3389 * path). In the case that ip_summed is CHECKSUM_NONE
3390 * this must be the first checksum encountered in the packet.
3391 * When ip_summed is CHECKSUM_UNNECESSARY, this is the first
3392 * checksum after the last one validated. For UDP, a zero
3393 * checksum can not be marked as bad.
3396 if (skb->ip_summed == CHECKSUM_NONE ||
3397 skb->ip_summed == CHECKSUM_UNNECESSARY)
3401 /* Check if we need to perform checksum complete validation.
3403 * Returns true if checksum complete is needed, false otherwise
3404 * (either checksum is unnecessary or zero checksum is allowed).
3406 static inline bool __skb_checksum_validate_needed(struct sk_buff *skb,
3410 if (skb_csum_unnecessary(skb) || (zero_okay && !check)) {
3411 skb->csum_valid = 1;
3412 __skb_decr_checksum_unnecessary(skb);
3419 /* For small packets <= CHECKSUM_BREAK peform checksum complete directly
3422 #define CHECKSUM_BREAK 76
3424 /* Unset checksum-complete
3426 * Unset checksum complete can be done when packet is being modified
3427 * (uncompressed for instance) and checksum-complete value is
3430 static inline void skb_checksum_complete_unset(struct sk_buff *skb)
3432 if (skb->ip_summed == CHECKSUM_COMPLETE)
3433 skb->ip_summed = CHECKSUM_NONE;
3436 /* Validate (init) checksum based on checksum complete.
3439 * 0: checksum is validated or try to in skb_checksum_complete. In the latter
3440 * case the ip_summed will not be CHECKSUM_UNNECESSARY and the pseudo
3441 * checksum is stored in skb->csum for use in __skb_checksum_complete
3442 * non-zero: value of invalid checksum
3445 static inline __sum16 __skb_checksum_validate_complete(struct sk_buff *skb,
3449 if (skb->ip_summed == CHECKSUM_COMPLETE) {
3450 if (!csum_fold(csum_add(psum, skb->csum))) {
3451 skb->csum_valid = 1;
3454 } else if (skb->csum_bad) {
3455 /* ip_summed == CHECKSUM_NONE in this case */
3456 return (__force __sum16)1;
3461 if (complete || skb->len <= CHECKSUM_BREAK) {
3464 csum = __skb_checksum_complete(skb);
3465 skb->csum_valid = !csum;
3472 static inline __wsum null_compute_pseudo(struct sk_buff *skb, int proto)
3477 /* Perform checksum validate (init). Note that this is a macro since we only
3478 * want to calculate the pseudo header which is an input function if necessary.
3479 * First we try to validate without any computation (checksum unnecessary) and
3480 * then calculate based on checksum complete calling the function to compute
3484 * 0: checksum is validated or try to in skb_checksum_complete
3485 * non-zero: value of invalid checksum
3487 #define __skb_checksum_validate(skb, proto, complete, \
3488 zero_okay, check, compute_pseudo) \
3490 __sum16 __ret = 0; \
3491 skb->csum_valid = 0; \
3492 if (__skb_checksum_validate_needed(skb, zero_okay, check)) \
3493 __ret = __skb_checksum_validate_complete(skb, \
3494 complete, compute_pseudo(skb, proto)); \
3498 #define skb_checksum_init(skb, proto, compute_pseudo) \
3499 __skb_checksum_validate(skb, proto, false, false, 0, compute_pseudo)
3501 #define skb_checksum_init_zero_check(skb, proto, check, compute_pseudo) \
3502 __skb_checksum_validate(skb, proto, false, true, check, compute_pseudo)
3504 #define skb_checksum_validate(skb, proto, compute_pseudo) \
3505 __skb_checksum_validate(skb, proto, true, false, 0, compute_pseudo)
3507 #define skb_checksum_validate_zero_check(skb, proto, check, \
3509 __skb_checksum_validate(skb, proto, true, true, check, compute_pseudo)
3511 #define skb_checksum_simple_validate(skb) \
3512 __skb_checksum_validate(skb, 0, true, false, 0, null_compute_pseudo)
3514 static inline bool __skb_checksum_convert_check(struct sk_buff *skb)
3516 return (skb->ip_summed == CHECKSUM_NONE &&
3517 skb->csum_valid && !skb->csum_bad);
3520 static inline void __skb_checksum_convert(struct sk_buff *skb,
3521 __sum16 check, __wsum pseudo)
3523 skb->csum = ~pseudo;
3524 skb->ip_summed = CHECKSUM_COMPLETE;
3527 #define skb_checksum_try_convert(skb, proto, check, compute_pseudo) \
3529 if (__skb_checksum_convert_check(skb)) \
3530 __skb_checksum_convert(skb, check, \
3531 compute_pseudo(skb, proto)); \
3534 static inline void skb_remcsum_adjust_partial(struct sk_buff *skb, void *ptr,
3535 u16 start, u16 offset)
3537 skb->ip_summed = CHECKSUM_PARTIAL;
3538 skb->csum_start = ((unsigned char *)ptr + start) - skb->head;
3539 skb->csum_offset = offset - start;
3542 /* Update skbuf and packet to reflect the remote checksum offload operation.
3543 * When called, ptr indicates the starting point for skb->csum when
3544 * ip_summed is CHECKSUM_COMPLETE. If we need create checksum complete
3545 * here, skb_postpull_rcsum is done so skb->csum start is ptr.
3547 static inline void skb_remcsum_process(struct sk_buff *skb, void *ptr,
3548 int start, int offset, bool nopartial)
3553 skb_remcsum_adjust_partial(skb, ptr, start, offset);
3557 if (unlikely(skb->ip_summed != CHECKSUM_COMPLETE)) {
3558 __skb_checksum_complete(skb);
3559 skb_postpull_rcsum(skb, skb->data, ptr - (void *)skb->data);
3562 delta = remcsum_adjust(ptr, skb->csum, start, offset);
3564 /* Adjust skb->csum since we changed the packet */
3565 skb->csum = csum_add(skb->csum, delta);
3568 static inline struct nf_conntrack *skb_nfct(const struct sk_buff *skb)
3570 #if IS_ENABLED(CONFIG_NF_CONNTRACK)
3571 return (void *)(skb->_nfct & SKB_NFCT_PTRMASK);
3577 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
3578 void nf_conntrack_destroy(struct nf_conntrack *nfct);
3579 static inline void nf_conntrack_put(struct nf_conntrack *nfct)
3581 if (nfct && atomic_dec_and_test(&nfct->use))
3582 nf_conntrack_destroy(nfct);
3584 static inline void nf_conntrack_get(struct nf_conntrack *nfct)
3587 atomic_inc(&nfct->use);
3590 #if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
3591 static inline void nf_bridge_put(struct nf_bridge_info *nf_bridge)
3593 if (nf_bridge && atomic_dec_and_test(&nf_bridge->use))
3596 static inline void nf_bridge_get(struct nf_bridge_info *nf_bridge)
3599 atomic_inc(&nf_bridge->use);
3601 #endif /* CONFIG_BRIDGE_NETFILTER */
3602 static inline void nf_reset(struct sk_buff *skb)
3604 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
3605 nf_conntrack_put(skb_nfct(skb));
3608 #if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
3609 nf_bridge_put(skb->nf_bridge);
3610 skb->nf_bridge = NULL;
3614 static inline void nf_reset_trace(struct sk_buff *skb)
3616 #if IS_ENABLED(CONFIG_NETFILTER_XT_TARGET_TRACE) || defined(CONFIG_NF_TABLES)
3621 /* Note: This doesn't put any conntrack and bridge info in dst. */
3622 static inline void __nf_copy(struct sk_buff *dst, const struct sk_buff *src,
3625 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
3626 dst->_nfct = src->_nfct;
3627 nf_conntrack_get(skb_nfct(src));
3629 #if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
3630 dst->nf_bridge = src->nf_bridge;
3631 nf_bridge_get(src->nf_bridge);
3633 #if IS_ENABLED(CONFIG_NETFILTER_XT_TARGET_TRACE) || defined(CONFIG_NF_TABLES)
3635 dst->nf_trace = src->nf_trace;
3639 static inline void nf_copy(struct sk_buff *dst, const struct sk_buff *src)
3641 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
3642 nf_conntrack_put(skb_nfct(dst));
3644 #if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
3645 nf_bridge_put(dst->nf_bridge);
3647 __nf_copy(dst, src, true);
3650 #ifdef CONFIG_NETWORK_SECMARK
3651 static inline void skb_copy_secmark(struct sk_buff *to, const struct sk_buff *from)
3653 to->secmark = from->secmark;
3656 static inline void skb_init_secmark(struct sk_buff *skb)
3661 static inline void skb_copy_secmark(struct sk_buff *to, const struct sk_buff *from)
3664 static inline void skb_init_secmark(struct sk_buff *skb)
3668 static inline bool skb_irq_freeable(const struct sk_buff *skb)
3670 return !skb->destructor &&
3671 #if IS_ENABLED(CONFIG_XFRM)
3675 !skb->_skb_refdst &&
3676 !skb_has_frag_list(skb);
3679 static inline void skb_set_queue_mapping(struct sk_buff *skb, u16 queue_mapping)
3681 skb->queue_mapping = queue_mapping;
3684 static inline u16 skb_get_queue_mapping(const struct sk_buff *skb)
3686 return skb->queue_mapping;
3689 static inline void skb_copy_queue_mapping(struct sk_buff *to, const struct sk_buff *from)
3691 to->queue_mapping = from->queue_mapping;
3694 static inline void skb_record_rx_queue(struct sk_buff *skb, u16 rx_queue)
3696 skb->queue_mapping = rx_queue + 1;
3699 static inline u16 skb_get_rx_queue(const struct sk_buff *skb)
3701 return skb->queue_mapping - 1;
3704 static inline bool skb_rx_queue_recorded(const struct sk_buff *skb)
3706 return skb->queue_mapping != 0;
3709 static inline void skb_set_dst_pending_confirm(struct sk_buff *skb, u32 val)
3711 skb->dst_pending_confirm = val;
3714 static inline bool skb_get_dst_pending_confirm(const struct sk_buff *skb)
3716 return skb->dst_pending_confirm != 0;
3719 static inline struct sec_path *skb_sec_path(struct sk_buff *skb)
3728 /* Keeps track of mac header offset relative to skb->head.
3729 * It is useful for TSO of Tunneling protocol. e.g. GRE.
3730 * For non-tunnel skb it points to skb_mac_header() and for
3731 * tunnel skb it points to outer mac header.
3732 * Keeps track of level of encapsulation of network headers.
3743 #define SKB_SGO_CB_OFFSET 32
3744 #define SKB_GSO_CB(skb) ((struct skb_gso_cb *)((skb)->cb + SKB_SGO_CB_OFFSET))
3746 static inline int skb_tnl_header_len(const struct sk_buff *inner_skb)
3748 return (skb_mac_header(inner_skb) - inner_skb->head) -
3749 SKB_GSO_CB(inner_skb)->mac_offset;
3752 static inline int gso_pskb_expand_head(struct sk_buff *skb, int extra)
3754 int new_headroom, headroom;
3757 headroom = skb_headroom(skb);
3758 ret = pskb_expand_head(skb, extra, 0, GFP_ATOMIC);
3762 new_headroom = skb_headroom(skb);
3763 SKB_GSO_CB(skb)->mac_offset += (new_headroom - headroom);
3767 static inline void gso_reset_checksum(struct sk_buff *skb, __wsum res)
3769 /* Do not update partial checksums if remote checksum is enabled. */
3770 if (skb->remcsum_offload)
3773 SKB_GSO_CB(skb)->csum = res;
3774 SKB_GSO_CB(skb)->csum_start = skb_checksum_start(skb) - skb->head;
3777 /* Compute the checksum for a gso segment. First compute the checksum value
3778 * from the start of transport header to SKB_GSO_CB(skb)->csum_start, and
3779 * then add in skb->csum (checksum from csum_start to end of packet).
3780 * skb->csum and csum_start are then updated to reflect the checksum of the
3781 * resultant packet starting from the transport header-- the resultant checksum
3782 * is in the res argument (i.e. normally zero or ~ of checksum of a pseudo
3785 static inline __sum16 gso_make_checksum(struct sk_buff *skb, __wsum res)
3787 unsigned char *csum_start = skb_transport_header(skb);
3788 int plen = (skb->head + SKB_GSO_CB(skb)->csum_start) - csum_start;
3789 __wsum partial = SKB_GSO_CB(skb)->csum;
3791 SKB_GSO_CB(skb)->csum = res;
3792 SKB_GSO_CB(skb)->csum_start = csum_start - skb->head;
3794 return csum_fold(csum_partial(csum_start, plen, partial));
3797 static inline bool skb_is_gso(const struct sk_buff *skb)
3799 return skb_shinfo(skb)->gso_size;
3802 /* Note: Should be called only if skb_is_gso(skb) is true */
3803 static inline bool skb_is_gso_v6(const struct sk_buff *skb)
3805 return skb_shinfo(skb)->gso_type & SKB_GSO_TCPV6;
3808 static inline void skb_gso_reset(struct sk_buff *skb)
3810 skb_shinfo(skb)->gso_size = 0;
3811 skb_shinfo(skb)->gso_segs = 0;
3812 skb_shinfo(skb)->gso_type = 0;
3815 void __skb_warn_lro_forwarding(const struct sk_buff *skb);
3817 static inline bool skb_warn_if_lro(const struct sk_buff *skb)
3819 /* LRO sets gso_size but not gso_type, whereas if GSO is really
3820 * wanted then gso_type will be set. */
3821 const struct skb_shared_info *shinfo = skb_shinfo(skb);
3823 if (skb_is_nonlinear(skb) && shinfo->gso_size != 0 &&
3824 unlikely(shinfo->gso_type == 0)) {
3825 __skb_warn_lro_forwarding(skb);
3831 static inline void skb_forward_csum(struct sk_buff *skb)
3833 /* Unfortunately we don't support this one. Any brave souls? */
3834 if (skb->ip_summed == CHECKSUM_COMPLETE)
3835 skb->ip_summed = CHECKSUM_NONE;
3839 * skb_checksum_none_assert - make sure skb ip_summed is CHECKSUM_NONE
3840 * @skb: skb to check
3842 * fresh skbs have their ip_summed set to CHECKSUM_NONE.
3843 * Instead of forcing ip_summed to CHECKSUM_NONE, we can
3844 * use this helper, to document places where we make this assertion.
3846 static inline void skb_checksum_none_assert(const struct sk_buff *skb)
3849 BUG_ON(skb->ip_summed != CHECKSUM_NONE);
3853 bool skb_partial_csum_set(struct sk_buff *skb, u16 start, u16 off);
3855 int skb_checksum_setup(struct sk_buff *skb, bool recalculate);
3856 struct sk_buff *skb_checksum_trimmed(struct sk_buff *skb,
3857 unsigned int transport_len,
3858 __sum16(*skb_chkf)(struct sk_buff *skb));
3861 * skb_head_is_locked - Determine if the skb->head is locked down
3862 * @skb: skb to check
3864 * The head on skbs build around a head frag can be removed if they are
3865 * not cloned. This function returns true if the skb head is locked down
3866 * due to either being allocated via kmalloc, or by being a clone with
3867 * multiple references to the head.
3869 static inline bool skb_head_is_locked(const struct sk_buff *skb)
3871 return !skb->head_frag || skb_cloned(skb);
3875 * skb_gso_network_seglen - Return length of individual segments of a gso packet
3879 * skb_gso_network_seglen is used to determine the real size of the
3880 * individual segments, including Layer3 (IP, IPv6) and L4 headers (TCP/UDP).
3882 * The MAC/L2 header is not accounted for.
3884 static inline unsigned int skb_gso_network_seglen(const struct sk_buff *skb)
3886 unsigned int hdr_len = skb_transport_header(skb) -
3887 skb_network_header(skb);
3888 return hdr_len + skb_gso_transport_seglen(skb);
3891 /* Local Checksum Offload.
3892 * Compute outer checksum based on the assumption that the
3893 * inner checksum will be offloaded later.
3894 * See Documentation/networking/checksum-offloads.txt for
3895 * explanation of how this works.
3896 * Fill in outer checksum adjustment (e.g. with sum of outer
3897 * pseudo-header) before calling.
3898 * Also ensure that inner checksum is in linear data area.
3900 static inline __wsum lco_csum(struct sk_buff *skb)
3902 unsigned char *csum_start = skb_checksum_start(skb);
3903 unsigned char *l4_hdr = skb_transport_header(skb);
3906 /* Start with complement of inner checksum adjustment */
3907 partial = ~csum_unfold(*(__force __sum16 *)(csum_start +
3910 /* Add in checksum of our headers (incl. outer checksum
3911 * adjustment filled in by caller) and return result.
3913 return csum_partial(l4_hdr, csum_start - l4_hdr, partial);
3916 #endif /* __KERNEL__ */
3917 #endif /* _LINUX_SKBUFF_H */