drivers/net/ethernet/sfc/tx.c

   1 /****************************************************************************
   2  * Driver for Solarflare network controllers and boards
   3  * Copyright 2005-2006 Fen Systems Ltd.
   4  * Copyright 2005-2013 Solarflare Communications Inc.
   5  *
   6  * This program is free software; you can redistribute it and/or modify it
   7  * under the terms of the GNU General Public License version 2 as published
   8  * by the Free Software Foundation, incorporated herein by reference.
   9  */
  10
  11 #include <linux/pci.h>
  12 #include <linux/tcp.h>
  13 #include <linux/ip.h>
  14 #include <linux/in.h>
  15 #include <linux/ipv6.h>
  16 #include <linux/slab.h>
  17 #include <net/ipv6.h>
  18 #include <linux/if_ether.h>
  19 #include <linux/highmem.h>
  20 #include <linux/cache.h>
  21 #include "net_driver.h"
  22 #include "efx.h"
  23 #include "io.h"
  24 #include "nic.h"
  25 #include "workarounds.h"
  26 #include "ef10_regs.h"
  27
  28 #ifdef EFX_USE_PIO
  29
  30 #define EFX_PIOBUF_SIZE_MAX ER_DZ_TX_PIOBUF_SIZE
  31 #define EFX_PIOBUF_SIZE_DEF ALIGN(256, L1_CACHE_BYTES)
  32 unsigned int efx_piobuf_size __read_mostly = EFX_PIOBUF_SIZE_DEF;
  33
  34 #endif /* EFX_USE_PIO */
  35
  36 static inline unsigned int
  37 efx_tx_queue_get_insert_index(const struct efx_tx_queue *tx_queue)
  38 {
  39         return tx_queue->insert_count & tx_queue->ptr_mask;
  40 }
  41
  42 static inline struct efx_tx_buffer *
  43 __efx_tx_queue_get_insert_buffer(const struct efx_tx_queue *tx_queue)
  44 {
  45         return &tx_queue->buffer[efx_tx_queue_get_insert_index(tx_queue)];
  46 }
  47
  48 static inline struct efx_tx_buffer *
  49 efx_tx_queue_get_insert_buffer(const struct efx_tx_queue *tx_queue)
  50 {
  51         struct efx_tx_buffer *buffer =
  52                 __efx_tx_queue_get_insert_buffer(tx_queue);
  53
  54         EFX_BUG_ON_PARANOID(buffer->len);
  55         EFX_BUG_ON_PARANOID(buffer->flags);
  56         EFX_BUG_ON_PARANOID(buffer->unmap_len);
  57
  58         return buffer;
  59 }
  60
  61 static void efx_dequeue_buffer(struct efx_tx_queue *tx_queue,
  62                                struct efx_tx_buffer *buffer,
  63                                unsigned int *pkts_compl,
  64                                unsigned int *bytes_compl)
  65 {
  66         if (buffer->unmap_len) {
  67                 struct device *dma_dev = &tx_queue->efx->pci_dev->dev;
  68                 dma_addr_t unmap_addr = (buffer->dma_addr + buffer->len -
  69                                          buffer->unmap_len);
  70                 if (buffer->flags & EFX_TX_BUF_MAP_SINGLE)
  71                         dma_unmap_single(dma_dev, unmap_addr, buffer->unmap_len,
  72                                          DMA_TO_DEVICE);
  73                 else
  74                         dma_unmap_page(dma_dev, unmap_addr, buffer->unmap_len,
  75                                        DMA_TO_DEVICE);
  76                 buffer->unmap_len = 0;
  77         }
  78
  79         if (buffer->flags & EFX_TX_BUF_SKB) {
  80                 (*pkts_compl)++;
  81                 (*bytes_compl) += buffer->skb->len;
  82                 dev_kfree_skb_any((struct sk_buff *) buffer->skb);
  83                 netif_vdbg(tx_queue->efx, tx_done, tx_queue->efx->net_dev,
  84                            "TX queue %d transmission id %x complete\n",
  85                            tx_queue->queue, tx_queue->read_count);
  86         } else if (buffer->flags & EFX_TX_BUF_HEAP) {
  87                 kfree(buffer->heap_buf);
  88         }
  89
  90         buffer->len = 0;
  91         buffer->flags = 0;
  92 }
  93
  94 static int efx_enqueue_skb_tso(struct efx_tx_queue *tx_queue,
  95                                struct sk_buff *skb);
  96
  97 static inline unsigned
  98 efx_max_tx_len(struct efx_nic *efx, dma_addr_t dma_addr)
  99 {
 100         /* Depending on the NIC revision, we can use descriptor
 101          * lengths up to 8K or 8K-1.  However, since PCI Express
 102          * devices must split read requests at 4K boundaries, there is
 103          * little benefit from using descriptors that cross those
 104          * boundaries and we keep things simple by not doing so.
 105          */
 106         unsigned len = (~dma_addr & (EFX_PAGE_SIZE - 1)) + 1;
 107
 108         /* Work around hardware bug for unaligned buffers. */
 109         if (EFX_WORKAROUND_5391(efx) && (dma_addr & 0xf))
 110                 len = min_t(unsigned, len, 512 - (dma_addr & 0xf));
 111
 112         return len;
 113 }
 114
 115 unsigned int efx_tx_max_skb_descs(struct efx_nic *efx)
 116 {
 117         /* Header and payload descriptor for each output segment, plus
 118          * one for every input fragment boundary within a segment
 119          */
 120         unsigned int max_descs = EFX_TSO_MAX_SEGS * 2 + MAX_SKB_FRAGS;
 121
 122         /* Possibly one more per segment for the alignment workaround,
 123          * or for option descriptors
 124          */
 125         if (EFX_WORKAROUND_5391(efx) || efx_nic_rev(efx) >= EFX_REV_HUNT_A0)
 126                 max_descs += EFX_TSO_MAX_SEGS;
 127
 128         /* Possibly more for PCIe page boundaries within input fragments */
 129         if (PAGE_SIZE > EFX_PAGE_SIZE)
 130                 max_descs += max_t(unsigned int, MAX_SKB_FRAGS,
 131                                    DIV_ROUND_UP(GSO_MAX_SIZE, EFX_PAGE_SIZE));
 132
 133         return max_descs;
 134 }
 135
 136 /* Get partner of a TX queue, seen as part of the same net core queue */
 137 static struct efx_tx_queue *efx_tx_queue_partner(struct efx_tx_queue *tx_queue)
 138 {
 139         if (tx_queue->queue & EFX_TXQ_TYPE_OFFLOAD)
 140                 return tx_queue - EFX_TXQ_TYPE_OFFLOAD;
 141         else
 142                 return tx_queue + EFX_TXQ_TYPE_OFFLOAD;
 143 }
 144
 145 static void efx_tx_maybe_stop_queue(struct efx_tx_queue *txq1)
 146 {
 147         /* We need to consider both queues that the net core sees as one */
 148         struct efx_tx_queue *txq2 = efx_tx_queue_partner(txq1);
 149         struct efx_nic *efx = txq1->efx;
 150         unsigned int fill_level;
 151
 152         fill_level = max(txq1->insert_count - txq1->old_read_count,
 153                          txq2->insert_count - txq2->old_read_count);
 154         if (likely(fill_level < efx->txq_stop_thresh))
 155                 return;
 156
 157         /* We used the stale old_read_count above, which gives us a
 158          * pessimistic estimate of the fill level (which may even
 159          * validly be >= efx->txq_entries).  Now try again using
 160          * read_count (more likely to be a cache miss).
 161          *
 162          * If we read read_count and then conditionally stop the
 163          * queue, it is possible for the completion path to race with
 164          * us and complete all outstanding descriptors in the middle,
 165          * after which there will be no more completions to wake it.
 166          * Therefore we stop the queue first, then read read_count
 167          * (with a memory barrier to ensure the ordering), then
 168          * restart the queue if the fill level turns out to be low
 169          * enough.
 170          */
 171         netif_tx_stop_queue(txq1->core_txq);
 172         smp_mb();
 173         txq1->old_read_count = ACCESS_ONCE(txq1->read_count);
 174         txq2->old_read_count = ACCESS_ONCE(txq2->read_count);
 175
 176         fill_level = max(txq1->insert_count - txq1->old_read_count,
 177                          txq2->insert_count - txq2->old_read_count);
 178         EFX_BUG_ON_PARANOID(fill_level >= efx->txq_entries);
 179         if (likely(fill_level < efx->txq_stop_thresh)) {
 180                 smp_mb();
 181                 if (likely(!efx->loopback_selftest))
 182                         netif_tx_start_queue(txq1->core_txq);
 183         }
 184 }
 185
 186 #ifdef EFX_USE_PIO
 187
 188 struct efx_short_copy_buffer {
 189         int used;
 190         u8 buf[L1_CACHE_BYTES];
 191 };
 192
 193 /* Copy to PIO, respecting that writes to PIO buffers must be dword aligned.
 194  * Advances piobuf pointer. Leaves additional data in the copy buffer.
 195  */
 196 static void efx_memcpy_toio_aligned(struct efx_nic *efx, u8 __iomem **piobuf,
 197                                     u8 *data, int len,
 198                                     struct efx_short_copy_buffer *copy_buf)
 199 {
 200         int block_len = len & ~(sizeof(copy_buf->buf) - 1);
 201
 202         memcpy_toio(*piobuf, data, block_len);
 203         *piobuf += block_len;
 204         len -= block_len;
 205
 206         if (len) {
 207                 data += block_len;
 208                 BUG_ON(copy_buf->used);
 209                 BUG_ON(len > sizeof(copy_buf->buf));
 210                 memcpy(copy_buf->buf, data, len);
 211                 copy_buf->used = len;
 212         }
 213 }
 214
 215 /* Copy to PIO, respecting dword alignment, popping data from copy buffer first.
 216  * Advances piobuf pointer. Leaves additional data in the copy buffer.
 217  */
 218 static void efx_memcpy_toio_aligned_cb(struct efx_nic *efx, u8 __iomem **piobuf,
 219                                        u8 *data, int len,
 220                                        struct efx_short_copy_buffer *copy_buf)
 221 {
 222         if (copy_buf->used) {
 223                 /* if the copy buffer is partially full, fill it up and write */
 224                 int copy_to_buf =
 225                         min_t(int, sizeof(copy_buf->buf) - copy_buf->used, len);
 226
 227                 memcpy(copy_buf->buf + copy_buf->used, data, copy_to_buf);
 228                 copy_buf->used += copy_to_buf;
 229
 230                 /* if we didn't fill it up then we're done for now */
 231                 if (copy_buf->used < sizeof(copy_buf->buf))
 232                         return;
 233
 234                 memcpy_toio(*piobuf, copy_buf->buf, sizeof(copy_buf->buf));
 235                 *piobuf += sizeof(copy_buf->buf);
 236                 data += copy_to_buf;
 237                 len -= copy_to_buf;
 238                 copy_buf->used = 0;
 239         }
 240
 241         efx_memcpy_toio_aligned(efx, piobuf, data, len, copy_buf);
 242 }
 243
 244 static void efx_flush_copy_buffer(struct efx_nic *efx, u8 __iomem *piobuf,
 245                                   struct efx_short_copy_buffer *copy_buf)
 246 {
 247         /* if there's anything in it, write the whole buffer, including junk */
 248         if (copy_buf->used)
 249                 memcpy_toio(piobuf, copy_buf->buf, sizeof(copy_buf->buf));
 250 }
 251
 252 /* Traverse skb structure and copy fragments in to PIO buffer.
 253  * Advances piobuf pointer.
 254  */
 255 static void efx_skb_copy_bits_to_pio(struct efx_nic *efx, struct sk_buff *skb,
 256                                      u8 __iomem **piobuf,
 257                                      struct efx_short_copy_buffer *copy_buf)
 258 {
 259         int i;
 260
 261         efx_memcpy_toio_aligned(efx, piobuf, skb->data, skb_headlen(skb),
 262                                 copy_buf);
 263
 264         for (i = 0; i < skb_shinfo(skb)->nr_frags; ++i) {
 265                 skb_frag_t *f = &skb_shinfo(skb)->frags[i];
 266                 u8 *vaddr;
 267
 268                 vaddr = kmap_atomic(skb_frag_page(f));
 269
 270                 efx_memcpy_toio_aligned_cb(efx, piobuf, vaddr + f->page_offset,
 271                                            skb_frag_size(f), copy_buf);
 272                 kunmap_atomic(vaddr);
 273         }
 274
 275         EFX_BUG_ON_PARANOID(skb_shinfo(skb)->frag_list);
 276 }
 277
 278 static struct efx_tx_buffer *
 279 efx_enqueue_skb_pio(struct efx_tx_queue *tx_queue, struct sk_buff *skb)
 280 {
 281         struct efx_tx_buffer *buffer =
 282                 efx_tx_queue_get_insert_buffer(tx_queue);
 283         u8 __iomem *piobuf = tx_queue->piobuf;
 284
 285         /* Copy to PIO buffer. Ensure the writes are padded to the end
 286          * of a cache line, as this is required for write-combining to be
 287          * effective on at least x86.
 288          */
 289
 290         if (skb_shinfo(skb)->nr_frags) {
 291                 /* The size of the copy buffer will ensure all writes
 292                  * are the size of a cache line.
 293                  */
 294                 struct efx_short_copy_buffer copy_buf;
 295
 296                 copy_buf.used = 0;
 297
 298                 efx_skb_copy_bits_to_pio(tx_queue->efx, skb,
 299                                          &piobuf, &copy_buf);
 300                 efx_flush_copy_buffer(tx_queue->efx, piobuf, &copy_buf);
 301         } else {
 302                 /* Pad the write to the size of a cache line.
 303                  * We can do this because we know the skb_shared_info sruct is
 304                  * after the source, and the destination buffer is big enough.
 305                  */
 306                 BUILD_BUG_ON(L1_CACHE_BYTES >
 307                              SKB_DATA_ALIGN(sizeof(struct skb_shared_info)));
 308                 memcpy_toio(tx_queue->piobuf, skb->data,
 309                             ALIGN(skb->len, L1_CACHE_BYTES));
 310         }
 311
 312         EFX_POPULATE_QWORD_5(buffer->option,
 313                              ESF_DZ_TX_DESC_IS_OPT, 1,
 314                              ESF_DZ_TX_OPTION_TYPE, ESE_DZ_TX_OPTION_DESC_PIO,
 315                              ESF_DZ_TX_PIO_CONT, 0,
 316                              ESF_DZ_TX_PIO_BYTE_CNT, skb->len,
 317                              ESF_DZ_TX_PIO_BUF_ADDR,
 318                              tx_queue->piobuf_offset);
 319         ++tx_queue->pio_packets;
 320         ++tx_queue->insert_count;
 321         return buffer;
 322 }
 323 #endif /* EFX_USE_PIO */
 324
 325 /*
 326  * Add a socket buffer to a TX queue
 327  *
 328  * This maps all fragments of a socket buffer for DMA and adds them to
 329  * the TX queue.  The queue's insert pointer will be incremented by
 330  * the number of fragments in the socket buffer.
 331  *
 332  * If any DMA mapping fails, any mapped fragments will be unmapped,
 333  * the queue's insert pointer will be restored to its original value.
 334  *
 335  * This function is split out from efx_hard_start_xmit to allow the
 336  * loopback test to direct packets via specific TX queues.
 337  *
 338  * Returns NETDEV_TX_OK.
 339  * You must hold netif_tx_lock() to call this function.
 340  */
 341 netdev_tx_t efx_enqueue_skb(struct efx_tx_queue *tx_queue, struct sk_buff *skb)
 342 {
 343         struct efx_nic *efx = tx_queue->efx;
 344         struct device *dma_dev = &efx->pci_dev->dev;
 345         struct efx_tx_buffer *buffer;
 346         skb_frag_t *fragment;
 347         unsigned int len, unmap_len = 0;
 348         dma_addr_t dma_addr, unmap_addr = 0;
 349         unsigned int dma_len;
 350         unsigned short dma_flags;
 351         int i = 0;
 352
 353         EFX_BUG_ON_PARANOID(tx_queue->write_count != tx_queue->insert_count);
 354
 355         if (skb_shinfo(skb)->gso_size)
 356                 return efx_enqueue_skb_tso(tx_queue, skb);
 357
 358         /* Get size of the initial fragment */
 359         len = skb_headlen(skb);
 360
 361         /* Pad if necessary */
 362         if (EFX_WORKAROUND_15592(efx) && skb->len <= 32) {
 363                 EFX_BUG_ON_PARANOID(skb->data_len);
 364                 len = 32 + 1;
 365                 if (skb_pad(skb, len - skb->len))
 366                         return NETDEV_TX_OK;
 367         }
 368
 369         /* Consider using PIO for short packets */
 370 #ifdef EFX_USE_PIO
 371         if (skb->len <= efx_piobuf_size && tx_queue->piobuf &&
 372             efx_nic_tx_is_empty(tx_queue) &&
 373             efx_nic_tx_is_empty(efx_tx_queue_partner(tx_queue))) {
 374                 buffer = efx_enqueue_skb_pio(tx_queue, skb);
 375                 dma_flags = EFX_TX_BUF_OPTION;
 376                 goto finish_packet;
 377         }
 378 #endif
 379
 380         /* Map for DMA.  Use dma_map_single rather than dma_map_page
 381          * since this is more efficient on machines with sparse
 382          * memory.
 383          */
 384         dma_flags = EFX_TX_BUF_MAP_SINGLE;
 385         dma_addr = dma_map_single(dma_dev, skb->data, len, PCI_DMA_TODEVICE);
 386
 387         /* Process all fragments */
 388         while (1) {
 389                 if (unlikely(dma_mapping_error(dma_dev, dma_addr)))
 390                         goto dma_err;
 391
 392                 /* Store fields for marking in the per-fragment final
 393                  * descriptor */
 394                 unmap_len = len;
 395                 unmap_addr = dma_addr;
 396
 397                 /* Add to TX queue, splitting across DMA boundaries */
 398                 do {
 399                         buffer = efx_tx_queue_get_insert_buffer(tx_queue);
 400
 401                         dma_len = efx_max_tx_len(efx, dma_addr);
 402                         if (likely(dma_len >= len))
 403                                 dma_len = len;
 404
 405                         /* Fill out per descriptor fields */
 406                         buffer->len = dma_len;
 407                         buffer->dma_addr = dma_addr;
 408                         buffer->flags = EFX_TX_BUF_CONT;
 409                         len -= dma_len;
 410                         dma_addr += dma_len;
 411                         ++tx_queue->insert_count;
 412                 } while (len);
 413
 414                 /* Transfer ownership of the unmapping to the final buffer */
 415                 buffer->flags = EFX_TX_BUF_CONT | dma_flags;
 416                 buffer->unmap_len = unmap_len;
 417                 unmap_len = 0;
 418
 419                 /* Get address and size of next fragment */
 420                 if (i >= skb_shinfo(skb)->nr_frags)
 421                         break;
 422                 fragment = &skb_shinfo(skb)->frags[i];
 423                 len = skb_frag_size(fragment);
 424                 i++;
 425                 /* Map for DMA */
 426                 dma_flags = 0;
 427                 dma_addr = skb_frag_dma_map(dma_dev, fragment, 0, len,
 428                                             DMA_TO_DEVICE);
 429         }
 430
 431         /* Transfer ownership of the skb to the final buffer */
 432 finish_packet:
 433         buffer->skb = skb;
 434         buffer->flags = EFX_TX_BUF_SKB | dma_flags;
 435
 436         netdev_tx_sent_queue(tx_queue->core_txq, skb->len);
 437
 438         /* Pass off to hardware */
 439         efx_nic_push_buffers(tx_queue);
 440
 441         efx_tx_maybe_stop_queue(tx_queue);
 442
 443         return NETDEV_TX_OK;
 444
 445  dma_err:
 446         netif_err(efx, tx_err, efx->net_dev,
 447                   " TX queue %d could not map skb with %d bytes %d "
 448                   "fragments for DMA\n", tx_queue->queue, skb->len,
 449                   skb_shinfo(skb)->nr_frags + 1);
 450
 451         /* Mark the packet as transmitted, and free the SKB ourselves */
 452         dev_kfree_skb_any(skb);
 453
 454         /* Work backwards until we hit the original insert pointer value */
 455         while (tx_queue->insert_count != tx_queue->write_count) {
 456                 unsigned int pkts_compl = 0, bytes_compl = 0;
 457                 --tx_queue->insert_count;
 458                 buffer = __efx_tx_queue_get_insert_buffer(tx_queue);
 459                 efx_dequeue_buffer(tx_queue, buffer, &pkts_compl, &bytes_compl);
 460         }
 461
 462         /* Free the fragment we were mid-way through pushing */
 463         if (unmap_len) {
 464                 if (dma_flags & EFX_TX_BUF_MAP_SINGLE)
 465                         dma_unmap_single(dma_dev, unmap_addr, unmap_len,
 466                                          DMA_TO_DEVICE);
 467                 else
 468                         dma_unmap_page(dma_dev, unmap_addr, unmap_len,
 469                                        DMA_TO_DEVICE);
 470         }
 471
 472         return NETDEV_TX_OK;
 473 }
 474
 475 /* Remove packets from the TX queue
 476  *
 477  * This removes packets from the TX queue, up to and including the
 478  * specified index.
 479  */
 480 static void efx_dequeue_buffers(struct efx_tx_queue *tx_queue,
 481                                 unsigned int index,
 482                                 unsigned int *pkts_compl,
 483                                 unsigned int *bytes_compl)
 484 {
 485         struct efx_nic *efx = tx_queue->efx;
 486         unsigned int stop_index, read_ptr;
 487
 488         stop_index = (index + 1) & tx_queue->ptr_mask;
 489         read_ptr = tx_queue->read_count & tx_queue->ptr_mask;
 490
 491         while (read_ptr != stop_index) {
 492                 struct efx_tx_buffer *buffer = &tx_queue->buffer[read_ptr];
 493
 494                 if (!(buffer->flags & EFX_TX_BUF_OPTION) &&
 495                     unlikely(buffer->len == 0)) {
 496                         netif_err(efx, tx_err, efx->net_dev,
 497                                   "TX queue %d spurious TX completion id %x\n",
 498                                   tx_queue->queue, read_ptr);
 499                         efx_schedule_reset(efx, RESET_TYPE_TX_SKIP);
 500                         return;
 501                 }
 502
 503                 efx_dequeue_buffer(tx_queue, buffer, pkts_compl, bytes_compl);
 504
 505                 ++tx_queue->read_count;
 506                 read_ptr = tx_queue->read_count & tx_queue->ptr_mask;
 507         }
 508 }
 509
 510 /* Initiate a packet transmission.  We use one channel per CPU
 511  * (sharing when we have more CPUs than channels).  On Falcon, the TX
 512  * completion events will be directed back to the CPU that transmitted
 513  * the packet, which should be cache-efficient.
 514  *
 515  * Context: non-blocking.
 516  * Note that returning anything other than NETDEV_TX_OK will cause the
 517  * OS to free the skb.
 518  */
 519 netdev_tx_t efx_hard_start_xmit(struct sk_buff *skb,
 520                                 struct net_device *net_dev)
 521 {
 522         struct efx_nic *efx = netdev_priv(net_dev);
 523         struct efx_tx_queue *tx_queue;
 524         unsigned index, type;
 525
 526         EFX_WARN_ON_PARANOID(!netif_device_present(net_dev));
 527
 528         /* PTP "event" packet */
 529         if (unlikely(efx_xmit_with_hwtstamp(skb)) &&
 530             unlikely(efx_ptp_is_ptp_tx(efx, skb))) {
 531                 return efx_ptp_tx(efx, skb);
 532         }
 533
 534         index = skb_get_queue_mapping(skb);
 535         type = skb->ip_summed == CHECKSUM_PARTIAL ? EFX_TXQ_TYPE_OFFLOAD : 0;
 536         if (index >= efx->n_tx_channels) {
 537                 index -= efx->n_tx_channels;
 538                 type |= EFX_TXQ_TYPE_HIGHPRI;
 539         }
 540         tx_queue = efx_get_tx_queue(efx, index, type);
 541
 542         return efx_enqueue_skb(tx_queue, skb);
 543 }
 544
 545 void efx_init_tx_queue_core_txq(struct efx_tx_queue *tx_queue)
 546 {
 547         struct efx_nic *efx = tx_queue->efx;
 548
 549         /* Must be inverse of queue lookup in efx_hard_start_xmit() */
 550         tx_queue->core_txq =
 551                 netdev_get_tx_queue(efx->net_dev,
 552                                     tx_queue->queue / EFX_TXQ_TYPES +
 553                                     ((tx_queue->queue & EFX_TXQ_TYPE_HIGHPRI) ?
 554                                      efx->n_tx_channels : 0));
 555 }
 556
 557 int efx_setup_tc(struct net_device *net_dev, u8 num_tc)
 558 {
 559         struct efx_nic *efx = netdev_priv(net_dev);
 560         struct efx_channel *channel;
 561         struct efx_tx_queue *tx_queue;
 562         unsigned tc;
 563         int rc;
 564
 565         if (efx_nic_rev(efx) < EFX_REV_FALCON_B0 || num_tc > EFX_MAX_TX_TC)
 566                 return -EINVAL;
 567
 568         if (num_tc == net_dev->num_tc)
 569                 return 0;
 570
 571         for (tc = 0; tc < num_tc; tc++) {
 572                 net_dev->tc_to_txq[tc].offset = tc * efx->n_tx_channels;
 573                 net_dev->tc_to_txq[tc].count = efx->n_tx_channels;
 574         }
 575
 576         if (num_tc > net_dev->num_tc) {
 577                 /* Initialise high-priority queues as necessary */
 578                 efx_for_each_channel(channel, efx) {
 579                         efx_for_each_possible_channel_tx_queue(tx_queue,
 580                                                                channel) {
 581                                 if (!(tx_queue->queue & EFX_TXQ_TYPE_HIGHPRI))
 582                                         continue;
 583                                 if (!tx_queue->buffer) {
 584                                         rc = efx_probe_tx_queue(tx_queue);
 585                                         if (rc)
 586                                                 return rc;
 587                                 }
 588                                 if (!tx_queue->initialised)
 589                                         efx_init_tx_queue(tx_queue);
 590                                 efx_init_tx_queue_core_txq(tx_queue);
 591                         }
 592                 }
 593         } else {
 594                 /* Reduce number of classes before number of queues */
 595                 net_dev->num_tc = num_tc;
 596         }
 597
 598         rc = netif_set_real_num_tx_queues(net_dev,
 599                                           max_t(int, num_tc, 1) *
 600                                           efx->n_tx_channels);
 601         if (rc)
 602                 return rc;
 603
 604         /* Do not destroy high-priority queues when they become
 605          * unused.  We would have to flush them first, and it is
 606          * fairly difficult to flush a subset of TX queues.  Leave
 607          * it to efx_fini_channels().
 608          */
 609
 610         net_dev->num_tc = num_tc;
 611         return 0;
 612 }
 613
 614 void efx_xmit_done(struct efx_tx_queue *tx_queue, unsigned int index)
 615 {
 616         unsigned fill_level;
 617         struct efx_nic *efx = tx_queue->efx;
 618         struct efx_tx_queue *txq2;
 619         unsigned int pkts_compl = 0, bytes_compl = 0;
 620
 621         EFX_BUG_ON_PARANOID(index > tx_queue->ptr_mask);
 622
 623         efx_dequeue_buffers(tx_queue, index, &pkts_compl, &bytes_compl);
 624         netdev_tx_completed_queue(tx_queue->core_txq, pkts_compl, bytes_compl);
 625
 626         if (pkts_compl > 1)
 627                 ++tx_queue->merge_events;
 628
 629         /* See if we need to restart the netif queue.  This memory
 630          * barrier ensures that we write read_count (inside
 631          * efx_dequeue_buffers()) before reading the queue status.
 632          */
 633         smp_mb();
 634         if (unlikely(netif_tx_queue_stopped(tx_queue->core_txq)) &&
 635             likely(efx->port_enabled) &&
 636             likely(netif_device_present(efx->net_dev))) {
 637                 txq2 = efx_tx_queue_partner(tx_queue);
 638                 fill_level = max(tx_queue->insert_count - tx_queue->read_count,
 639                                  txq2->insert_count - txq2->read_count);
 640                 if (fill_level <= efx->txq_wake_thresh)
 641                         netif_tx_wake_queue(tx_queue->core_txq);
 642         }
 643
 644         /* Check whether the hardware queue is now empty */
 645         if ((int)(tx_queue->read_count - tx_queue->old_write_count) >= 0) {
 646                 tx_queue->old_write_count = ACCESS_ONCE(tx_queue->write_count);
 647                 if (tx_queue->read_count == tx_queue->old_write_count) {
 648                         smp_mb();
 649                         tx_queue->empty_read_count =
 650                                 tx_queue->read_count | EFX_EMPTY_COUNT_VALID;
 651                 }
 652         }
 653 }
 654
 655 /* Size of page-based TSO header buffers.  Larger blocks must be
 656  * allocated from the heap.
 657  */
 658 #define TSOH_STD_SIZE   128
 659 #define TSOH_PER_PAGE   (PAGE_SIZE / TSOH_STD_SIZE)
 660
 661 /* At most half the descriptors in the queue at any time will refer to
 662  * a TSO header buffer, since they must always be followed by a
 663  * payload descriptor referring to an skb.
 664  */
 665 static unsigned int efx_tsoh_page_count(struct efx_tx_queue *tx_queue)
 666 {
 667         return DIV_ROUND_UP(tx_queue->ptr_mask + 1, 2 * TSOH_PER_PAGE);
 668 }
 669
 670 int efx_probe_tx_queue(struct efx_tx_queue *tx_queue)
 671 {
 672         struct efx_nic *efx = tx_queue->efx;
 673         unsigned int entries;
 674         int rc;
 675
 676         /* Create the smallest power-of-two aligned ring */
 677         entries = max(roundup_pow_of_two(efx->txq_entries), EFX_MIN_DMAQ_SIZE);
 678         EFX_BUG_ON_PARANOID(entries > EFX_MAX_DMAQ_SIZE);
 679         tx_queue->ptr_mask = entries - 1;
 680
 681         netif_dbg(efx, probe, efx->net_dev,
 682                   "creating TX queue %d size %#x mask %#x\n",
 683                   tx_queue->queue, efx->txq_entries, tx_queue->ptr_mask);
 684
 685         /* Allocate software ring */
 686         tx_queue->buffer = kcalloc(entries, sizeof(*tx_queue->buffer),
 687                                    GFP_KERNEL);
 688         if (!tx_queue->buffer)
 689                 return -ENOMEM;
 690
 691         if (tx_queue->queue & EFX_TXQ_TYPE_OFFLOAD) {
 692                 tx_queue->tsoh_page =
 693                         kcalloc(efx_tsoh_page_count(tx_queue),
 694                                 sizeof(tx_queue->tsoh_page[0]), GFP_KERNEL);
 695                 if (!tx_queue->tsoh_page) {
 696                         rc = -ENOMEM;
 697                         goto fail1;
 698                 }
 699         }
 700
 701         /* Allocate hardware ring */
 702         rc = efx_nic_probe_tx(tx_queue);
 703         if (rc)
 704                 goto fail2;
 705
 706         return 0;
 707
 708 fail2:
 709         kfree(tx_queue->tsoh_page);
 710         tx_queue->tsoh_page = NULL;
 711 fail1:
 712         kfree(tx_queue->buffer);
 713         tx_queue->buffer = NULL;
 714         return rc;
 715 }
 716
 717 void efx_init_tx_queue(struct efx_tx_queue *tx_queue)
 718 {
 719         netif_dbg(tx_queue->efx, drv, tx_queue->efx->net_dev,
 720                   "initialising TX queue %d\n", tx_queue->queue);
 721
 722         tx_queue->insert_count = 0;
 723         tx_queue->write_count = 0;
 724         tx_queue->old_write_count = 0;
 725         tx_queue->read_count = 0;
 726         tx_queue->old_read_count = 0;
 727         tx_queue->empty_read_count = 0 | EFX_EMPTY_COUNT_VALID;
 728
 729         /* Set up TX descriptor ring */
 730         efx_nic_init_tx(tx_queue);
 731
 732         tx_queue->initialised = true;
 733 }
 734
 735 void efx_fini_tx_queue(struct efx_tx_queue *tx_queue)
 736 {
 737         struct efx_tx_buffer *buffer;
 738
 739         netif_dbg(tx_queue->efx, drv, tx_queue->efx->net_dev,
 740                   "shutting down TX queue %d\n", tx_queue->queue);
 741
 742         if (!tx_queue->buffer)
 743                 return;
 744
 745         /* Free any buffers left in the ring */
 746         while (tx_queue->read_count != tx_queue->write_count) {
 747                 unsigned int pkts_compl = 0, bytes_compl = 0;
 748                 buffer = &tx_queue->buffer[tx_queue->read_count & tx_queue->ptr_mask];
 749                 efx_dequeue_buffer(tx_queue, buffer, &pkts_compl, &bytes_compl);
 750
 751                 ++tx_queue->read_count;
 752         }
 753         netdev_tx_reset_queue(tx_queue->core_txq);
 754 }
 755
 756 void efx_remove_tx_queue(struct efx_tx_queue *tx_queue)
 757 {
 758         int i;
 759
 760         if (!tx_queue->buffer)
 761                 return;
 762
 763         netif_dbg(tx_queue->efx, drv, tx_queue->efx->net_dev,
 764                   "destroying TX queue %d\n", tx_queue->queue);
 765         efx_nic_remove_tx(tx_queue);
 766
 767         if (tx_queue->tsoh_page) {
 768                 for (i = 0; i < efx_tsoh_page_count(tx_queue); i++)
 769                         efx_nic_free_buffer(tx_queue->efx,
 770                                             &tx_queue->tsoh_page[i]);
 771                 kfree(tx_queue->tsoh_page);
 772                 tx_queue->tsoh_page = NULL;
 773         }
 774
 775         kfree(tx_queue->buffer);
 776         tx_queue->buffer = NULL;
 777 }
 778
 779
 780 /* Efx TCP segmentation acceleration.
 781  *
 782  * Why?  Because by doing it here in the driver we can go significantly
 783  * faster than the GSO.
 784  *
 785  * Requires TX checksum offload support.
 786  */
 787
 788 /* Number of bytes inserted at the start of a TSO header buffer,
 789  * similar to NET_IP_ALIGN.
 790  */
 791 #ifdef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
 792 #define TSOH_OFFSET     0
 793 #else
 794 #define TSOH_OFFSET     NET_IP_ALIGN
 795 #endif
 796
 797 #define PTR_DIFF(p1, p2)  ((u8 *)(p1) - (u8 *)(p2))
 798
 799 /**
 800  * struct tso_state - TSO state for an SKB
 801  * @out_len: Remaining length in current segment
 802  * @seqnum: Current sequence number
 803  * @ipv4_id: Current IPv4 ID, host endian
 804  * @packet_space: Remaining space in current packet
 805  * @dma_addr: DMA address of current position
 806  * @in_len: Remaining length in current SKB fragment
 807  * @unmap_len: Length of SKB fragment
 808  * @unmap_addr: DMA address of SKB fragment
 809  * @dma_flags: TX buffer flags for DMA mapping - %EFX_TX_BUF_MAP_SINGLE or 0
 810  * @protocol: Network protocol (after any VLAN header)
 811  * @ip_off: Offset of IP header
 812  * @tcp_off: Offset of TCP header
 813  * @header_len: Number of bytes of header
 814  * @ip_base_len: IPv4 tot_len or IPv6 payload_len, before TCP payload
 815  * @header_dma_addr: Header DMA address, when using option descriptors
 816  * @header_unmap_len: Header DMA mapped length, or 0 if not using option
 817  *      descriptors
 818  *
 819  * The state used during segmentation.  It is put into this data structure
 820  * just to make it easy to pass into inline functions.
 821  */
 822 struct tso_state {
 823         /* Output position */
 824         unsigned out_len;
 825         unsigned seqnum;
 826         u16 ipv4_id;
 827         unsigned packet_space;
 828
 829         /* Input position */
 830         dma_addr_t dma_addr;
 831         unsigned in_len;
 832         unsigned unmap_len;
 833         dma_addr_t unmap_addr;
 834         unsigned short dma_flags;
 835
 836         __be16 protocol;
 837         unsigned int ip_off;
 838         unsigned int tcp_off;
 839         unsigned header_len;
 840         unsigned int ip_base_len;
 841         dma_addr_t header_dma_addr;
 842         unsigned int header_unmap_len;
 843 };
 844
 845
 846 /*
 847  * Verify that our various assumptions about sk_buffs and the conditions
 848  * under which TSO will be attempted hold true.  Return the protocol number.
 849  */
 850 static __be16 efx_tso_check_protocol(struct sk_buff *skb)
 851 {
 852         __be16 protocol = skb->protocol;
 853
 854         EFX_BUG_ON_PARANOID(((struct ethhdr *)skb->data)->h_proto !=
 855                             protocol);
 856         if (protocol == htons(ETH_P_8021Q)) {
 857                 struct vlan_ethhdr *veh = (struct vlan_ethhdr *)skb->data;
 858                 protocol = veh->h_vlan_encapsulated_proto;
 859         }
 860
 861         if (protocol == htons(ETH_P_IP)) {
 862                 EFX_BUG_ON_PARANOID(ip_hdr(skb)->protocol != IPPROTO_TCP);
 863         } else {
 864                 EFX_BUG_ON_PARANOID(protocol != htons(ETH_P_IPV6));
 865                 EFX_BUG_ON_PARANOID(ipv6_hdr(skb)->nexthdr != NEXTHDR_TCP);
 866         }
 867         EFX_BUG_ON_PARANOID((PTR_DIFF(tcp_hdr(skb), skb->data)
 868                              + (tcp_hdr(skb)->doff << 2u)) >
 869                             skb_headlen(skb));
 870
 871         return protocol;
 872 }
 873
 874 static u8 *efx_tsoh_get_buffer(struct efx_tx_queue *tx_queue,
 875                                struct efx_tx_buffer *buffer, unsigned int len)
 876 {
 877         u8 *result;
 878
 879         EFX_BUG_ON_PARANOID(buffer->len);
 880         EFX_BUG_ON_PARANOID(buffer->flags);
 881         EFX_BUG_ON_PARANOID(buffer->unmap_len);
 882
 883         if (likely(len <= TSOH_STD_SIZE - TSOH_OFFSET)) {
 884                 unsigned index =
 885                         (tx_queue->insert_count & tx_queue->ptr_mask) / 2;
 886                 struct efx_buffer *page_buf =
 887                         &tx_queue->tsoh_page[index / TSOH_PER_PAGE];
 888                 unsigned offset =
 889                         TSOH_STD_SIZE * (index % TSOH_PER_PAGE) + TSOH_OFFSET;
 890
 891                 if (unlikely(!page_buf->addr) &&
 892                     efx_nic_alloc_buffer(tx_queue->efx, page_buf, PAGE_SIZE,
 893                                          GFP_ATOMIC))
 894                         return NULL;
 895
 896                 result = (u8 *)page_buf->addr + offset;
 897                 buffer->dma_addr = page_buf->dma_addr + offset;
 898                 buffer->flags = EFX_TX_BUF_CONT;
 899         } else {
 900                 tx_queue->tso_long_headers++;
 901
 902                 buffer->heap_buf = kmalloc(TSOH_OFFSET + len, GFP_ATOMIC);
 903                 if (unlikely(!buffer->heap_buf))
 904                         return NULL;
 905                 result = (u8 *)buffer->heap_buf + TSOH_OFFSET;
 906                 buffer->flags = EFX_TX_BUF_CONT | EFX_TX_BUF_HEAP;
 907         }
 908
 909         buffer->len = len;
 910
 911         return result;
 912 }
 913
 914 /**
 915  * efx_tx_queue_insert - push descriptors onto the TX queue
 916  * @tx_queue:           Efx TX queue
 917  * @dma_addr:           DMA address of fragment
 918  * @len:                Length of fragment
 919  * @final_buffer:       The final buffer inserted into the queue
 920  *
 921  * Push descriptors onto the TX queue.
 922  */
 923 static void efx_tx_queue_insert(struct efx_tx_queue *tx_queue,
 924                                 dma_addr_t dma_addr, unsigned len,
 925                                 struct efx_tx_buffer **final_buffer)
 926 {
 927         struct efx_tx_buffer *buffer;
 928         struct efx_nic *efx = tx_queue->efx;
 929         unsigned dma_len;
 930
 931         EFX_BUG_ON_PARANOID(len <= 0);
 932
 933         while (1) {
 934                 buffer = efx_tx_queue_get_insert_buffer(tx_queue);
 935                 ++tx_queue->insert_count;
 936
 937                 EFX_BUG_ON_PARANOID(tx_queue->insert_count -
 938                                     tx_queue->read_count >=
 939                                     efx->txq_entries);
 940
 941                 buffer->dma_addr = dma_addr;
 942
 943                 dma_len = efx_max_tx_len(efx, dma_addr);
 944
 945                 /* If there is enough space to send then do so */
 946                 if (dma_len >= len)
 947                         break;
 948
 949                 buffer->len = dma_len;
 950                 buffer->flags = EFX_TX_BUF_CONT;
 951                 dma_addr += dma_len;
 952                 len -= dma_len;
 953         }
 954
 955         EFX_BUG_ON_PARANOID(!len);
 956         buffer->len = len;
 957         *final_buffer = buffer;
 958 }
 959
 960
 961 /*
 962  * Put a TSO header into the TX queue.
 963  *
 964  * This is special-cased because we know that it is small enough to fit in
 965  * a single fragment, and we know it doesn't cross a page boundary.  It
 966  * also allows us to not worry about end-of-packet etc.
 967  */
 968 static int efx_tso_put_header(struct efx_tx_queue *tx_queue,
 969                               struct efx_tx_buffer *buffer, u8 *header)
 970 {
 971         if (unlikely(buffer->flags & EFX_TX_BUF_HEAP)) {
 972                 buffer->dma_addr = dma_map_single(&tx_queue->efx->pci_dev->dev,
 973                                                   header, buffer->len,
 974                                                   DMA_TO_DEVICE);
 975                 if (unlikely(dma_mapping_error(&tx_queue->efx->pci_dev->dev,
 976                                                buffer->dma_addr))) {
 977                         kfree(buffer->heap_buf);
 978                         buffer->len = 0;
 979                         buffer->flags = 0;
 980                         return -ENOMEM;
 981                 }
 982                 buffer->unmap_len = buffer->len;
 983                 buffer->flags |= EFX_TX_BUF_MAP_SINGLE;
 984         }
 985
 986         ++tx_queue->insert_count;
 987         return 0;
 988 }
 989
 990
 991 /* Remove buffers put into a tx_queue.  None of the buffers must have
 992  * an skb attached.
 993  */
 994 static void efx_enqueue_unwind(struct efx_tx_queue *tx_queue)
 995 {
 996         struct efx_tx_buffer *buffer;
 997
 998         /* Work backwards until we hit the original insert pointer value */
 999         while (tx_queue->insert_count != tx_queue->write_count) {
1000                 --tx_queue->insert_count;
1001                 buffer = __efx_tx_queue_get_insert_buffer(tx_queue);
1002                 efx_dequeue_buffer(tx_queue, buffer, NULL, NULL);
1003         }
1004 }
1005
1006
1007 /* Parse the SKB header and initialise state. */
1008 static int tso_start(struct tso_state *st, struct efx_nic *efx,
1009                      const struct sk_buff *skb)
1010 {
1011         bool use_options = efx_nic_rev(efx) >= EFX_REV_HUNT_A0;
1012         struct device *dma_dev = &efx->pci_dev->dev;
1013         unsigned int header_len, in_len;
1014         dma_addr_t dma_addr;
1015
1016         st->ip_off = skb_network_header(skb) - skb->data;
1017         st->tcp_off = skb_transport_header(skb) - skb->data;
1018         header_len = st->tcp_off + (tcp_hdr(skb)->doff << 2u);
1019         in_len = skb_headlen(skb) - header_len;
1020         st->header_len = header_len;
1021         st->in_len = in_len;
1022         if (st->protocol == htons(ETH_P_IP)) {
1023                 st->ip_base_len = st->header_len - st->ip_off;
1024                 st->ipv4_id = ntohs(ip_hdr(skb)->id);
1025         } else {
1026                 st->ip_base_len = st->header_len - st->tcp_off;
1027                 st->ipv4_id = 0;
1028         }
1029         st->seqnum = ntohl(tcp_hdr(skb)->seq);
1030
1031         EFX_BUG_ON_PARANOID(tcp_hdr(skb)->urg);
1032         EFX_BUG_ON_PARANOID(tcp_hdr(skb)->syn);
1033         EFX_BUG_ON_PARANOID(tcp_hdr(skb)->rst);
1034
1035         st->out_len = skb->len - header_len;
1036
1037         if (!use_options) {
1038                 st->header_unmap_len = 0;
1039
1040                 if (likely(in_len == 0)) {
1041                         st->dma_flags = 0;
1042                         st->unmap_len = 0;
1043                         return 0;
1044                 }
1045
1046                 dma_addr = dma_map_single(dma_dev, skb->data + header_len,
1047                                           in_len, DMA_TO_DEVICE);
1048                 st->dma_flags = EFX_TX_BUF_MAP_SINGLE;
1049                 st->dma_addr = dma_addr;
1050                 st->unmap_addr = dma_addr;
1051                 st->unmap_len = in_len;
1052         } else {
1053                 dma_addr = dma_map_single(dma_dev, skb->data,
1054                                           skb_headlen(skb), DMA_TO_DEVICE);
1055                 st->header_dma_addr = dma_addr;
1056                 st->header_unmap_len = skb_headlen(skb);
1057                 st->dma_flags = 0;
1058                 st->dma_addr = dma_addr + header_len;
1059                 st->unmap_len = 0;
1060         }
1061
1062         return unlikely(dma_mapping_error(dma_dev, dma_addr)) ? -ENOMEM : 0;
1063 }
1064
1065 static int tso_get_fragment(struct tso_state *st, struct efx_nic *efx,
1066                             skb_frag_t *frag)
1067 {
1068         st->unmap_addr = skb_frag_dma_map(&efx->pci_dev->dev, frag, 0,
1069                                           skb_frag_size(frag), DMA_TO_DEVICE);
1070         if (likely(!dma_mapping_error(&efx->pci_dev->dev, st->unmap_addr))) {
1071                 st->dma_flags = 0;
1072                 st->unmap_len = skb_frag_size(frag);
1073                 st->in_len = skb_frag_size(frag);
1074                 st->dma_addr = st->unmap_addr;
1075                 return 0;
1076         }
1077         return -ENOMEM;
1078 }
1079
1080
1081 /**
1082  * tso_fill_packet_with_fragment - form descriptors for the current fragment
1083  * @tx_queue:           Efx TX queue
1084  * @skb:                Socket buffer
1085  * @st:                 TSO state
1086  *
1087  * Form descriptors for the current fragment, until we reach the end
1088  * of fragment or end-of-packet.
1089  */
1090 static void tso_fill_packet_with_fragment(struct efx_tx_queue *tx_queue,
1091                                           const struct sk_buff *skb,
1092                                           struct tso_state *st)
1093 {
1094         struct efx_tx_buffer *buffer;
1095         int n;
1096
1097         if (st->in_len == 0)
1098                 return;
1099         if (st->packet_space == 0)
1100                 return;
1101
1102         EFX_BUG_ON_PARANOID(st->in_len <= 0);
1103         EFX_BUG_ON_PARANOID(st->packet_space <= 0);
1104
1105         n = min(st->in_len, st->packet_space);
1106
1107         st->packet_space -= n;
1108         st->out_len -= n;
1109         st->in_len -= n;
1110
1111         efx_tx_queue_insert(tx_queue, st->dma_addr, n, &buffer);
1112
1113         if (st->out_len == 0) {
1114                 /* Transfer ownership of the skb */
1115                 buffer->skb = skb;
1116                 buffer->flags = EFX_TX_BUF_SKB;
1117         } else if (st->packet_space != 0) {
1118                 buffer->flags = EFX_TX_BUF_CONT;
1119         }
1120
1121         if (st->in_len == 0) {
1122                 /* Transfer ownership of the DMA mapping */
1123                 buffer->unmap_len = st->unmap_len;
1124                 buffer->flags |= st->dma_flags;
1125                 st->unmap_len = 0;
1126         }
1127
1128         st->dma_addr += n;
1129 }
1130
1131
1132 /**
1133  * tso_start_new_packet - generate a new header and prepare for the new packet
1134  * @tx_queue:           Efx TX queue
1135  * @skb:                Socket buffer
1136  * @st:                 TSO state
1137  *
1138  * Generate a new header and prepare for the new packet.  Return 0 on
1139  * success, or -%ENOMEM if failed to alloc header.
1140  */
1141 static int tso_start_new_packet(struct efx_tx_queue *tx_queue,
1142                                 const struct sk_buff *skb,
1143                                 struct tso_state *st)
1144 {
1145         struct efx_tx_buffer *buffer =
1146                 efx_tx_queue_get_insert_buffer(tx_queue);
1147         bool is_last = st->out_len <= skb_shinfo(skb)->gso_size;
1148         u8 tcp_flags_clear;
1149
1150         if (!is_last) {
1151                 st->packet_space = skb_shinfo(skb)->gso_size;
1152                 tcp_flags_clear = 0x09; /* mask out FIN and PSH */
1153         } else {
1154                 st->packet_space = st->out_len;
1155                 tcp_flags_clear = 0x00;
1156         }
1157
1158         if (!st->header_unmap_len) {
1159                 /* Allocate and insert a DMA-mapped header buffer. */
1160                 struct tcphdr *tsoh_th;
1161                 unsigned ip_length;
1162                 u8 *header;
1163                 int rc;
1164
1165                 header = efx_tsoh_get_buffer(tx_queue, buffer, st->header_len);
1166                 if (!header)
1167                         return -ENOMEM;
1168
1169                 tsoh_th = (struct tcphdr *)(header + st->tcp_off);
1170
1171                 /* Copy and update the headers. */
1172                 memcpy(header, skb->data, st->header_len);
1173
1174                 tsoh_th->seq = htonl(st->seqnum);
1175                 ((u8 *)tsoh_th)[13] &= ~tcp_flags_clear;
1176
1177                 ip_length = st->ip_base_len + st->packet_space;
1178
1179                 if (st->protocol == htons(ETH_P_IP)) {
1180                         struct iphdr *tsoh_iph =
1181                                 (struct iphdr *)(header + st->ip_off);
1182
1183                         tsoh_iph->tot_len = htons(ip_length);
1184                         tsoh_iph->id = htons(st->ipv4_id);
1185                 } else {
1186                         struct ipv6hdr *tsoh_iph =
1187                                 (struct ipv6hdr *)(header + st->ip_off);
1188
1189                         tsoh_iph->payload_len = htons(ip_length);
1190                 }
1191
1192                 rc = efx_tso_put_header(tx_queue, buffer, header);
1193                 if (unlikely(rc))
1194                         return rc;
1195         } else {
1196                 /* Send the original headers with a TSO option descriptor
1197                  * in front
1198                  */
1199                 u8 tcp_flags = ((u8 *)tcp_hdr(skb))[13] & ~tcp_flags_clear;
1200
1201                 buffer->flags = EFX_TX_BUF_OPTION;
1202                 buffer->len = 0;
1203                 buffer->unmap_len = 0;
1204                 EFX_POPULATE_QWORD_5(buffer->option,
1205                                      ESF_DZ_TX_DESC_IS_OPT, 1,
1206                                      ESF_DZ_TX_OPTION_TYPE,
1207                                      ESE_DZ_TX_OPTION_DESC_TSO,
1208                                      ESF_DZ_TX_TSO_TCP_FLAGS, tcp_flags,
1209                                      ESF_DZ_TX_TSO_IP_ID, st->ipv4_id,
1210                                      ESF_DZ_TX_TSO_TCP_SEQNO, st->seqnum);
1211                 ++tx_queue->insert_count;
1212
1213                 /* We mapped the headers in tso_start().  Unmap them
1214                  * when the last segment is completed.
1215                  */
1216                 buffer = efx_tx_queue_get_insert_buffer(tx_queue);
1217                 buffer->dma_addr = st->header_dma_addr;
1218                 buffer->len = st->header_len;
1219                 if (is_last) {
1220                         buffer->flags = EFX_TX_BUF_CONT | EFX_TX_BUF_MAP_SINGLE;
1221                         buffer->unmap_len = st->header_unmap_len;
1222                         /* Ensure we only unmap them once in case of a
1223                          * later DMA mapping error and rollback
1224                          */
1225                         st->header_unmap_len = 0;
1226                 } else {
1227                         buffer->flags = EFX_TX_BUF_CONT;
1228                         buffer->unmap_len = 0;
1229                 }
1230                 ++tx_queue->insert_count;
1231         }
1232
1233         st->seqnum += skb_shinfo(skb)->gso_size;
1234
1235         /* Linux leaves suitable gaps in the IP ID space for us to fill. */
1236         ++st->ipv4_id;
1237
1238         ++tx_queue->tso_packets;
1239
1240         return 0;
1241 }
1242
1243
1244 /**
1245  * efx_enqueue_skb_tso - segment and transmit a TSO socket buffer
1246  * @tx_queue:           Efx TX queue
1247  * @skb:                Socket buffer
1248  *
1249  * Context: You must hold netif_tx_lock() to call this function.
1250  *
1251  * Add socket buffer @skb to @tx_queue, doing TSO or return != 0 if
1252  * @skb was not enqueued.  In all cases @skb is consumed.  Return
1253  * %NETDEV_TX_OK.
1254  */
1255 static int efx_enqueue_skb_tso(struct efx_tx_queue *tx_queue,
1256                                struct sk_buff *skb)
1257 {
1258         struct efx_nic *efx = tx_queue->efx;
1259         int frag_i, rc;
1260         struct tso_state state;
1261
1262         /* Find the packet protocol and sanity-check it */
1263         state.protocol = efx_tso_check_protocol(skb);
1264
1265         EFX_BUG_ON_PARANOID(tx_queue->write_count != tx_queue->insert_count);
1266
1267         rc = tso_start(&state, efx, skb);
1268         if (rc)
1269                 goto mem_err;
1270
1271         if (likely(state.in_len == 0)) {
1272                 /* Grab the first payload fragment. */
1273                 EFX_BUG_ON_PARANOID(skb_shinfo(skb)->nr_frags < 1);
1274                 frag_i = 0;
1275                 rc = tso_get_fragment(&state, efx,
1276                                       skb_shinfo(skb)->frags + frag_i);
1277                 if (rc)
1278                         goto mem_err;
1279         } else {
1280                 /* Payload starts in the header area. */
1281                 frag_i = -1;
1282         }
1283
1284         if (tso_start_new_packet(tx_queue, skb, &state) < 0)
1285                 goto mem_err;
1286
1287         while (1) {
1288                 tso_fill_packet_with_fragment(tx_queue, skb, &state);
1289
1290                 /* Move onto the next fragment? */
1291                 if (state.in_len == 0) {
1292                         if (++frag_i >= skb_shinfo(skb)->nr_frags)
1293                                 /* End of payload reached. */
1294                                 break;
1295                         rc = tso_get_fragment(&state, efx,
1296                                               skb_shinfo(skb)->frags + frag_i);
1297                         if (rc)
1298                                 goto mem_err;
1299                 }
1300
1301                 /* Start at new packet? */
1302                 if (state.packet_space == 0 &&
1303                     tso_start_new_packet(tx_queue, skb, &state) < 0)
1304                         goto mem_err;
1305         }
1306
1307         netdev_tx_sent_queue(tx_queue->core_txq, skb->len);
1308
1309         /* Pass off to hardware */
1310         efx_nic_push_buffers(tx_queue);
1311
1312         efx_tx_maybe_stop_queue(tx_queue);
1313
1314         tx_queue->tso_bursts++;
1315         return NETDEV_TX_OK;
1316
1317  mem_err:
1318         netif_err(efx, tx_err, efx->net_dev,
1319                   "Out of memory for TSO headers, or DMA mapping error\n");
1320         dev_kfree_skb_any(skb);
1321
1322         /* Free the DMA mapping we were in the process of writing out */
1323         if (state.unmap_len) {
1324                 if (state.dma_flags & EFX_TX_BUF_MAP_SINGLE)
1325                         dma_unmap_single(&efx->pci_dev->dev, state.unmap_addr,
1326                                          state.unmap_len, DMA_TO_DEVICE);
1327                 else
1328                         dma_unmap_page(&efx->pci_dev->dev, state.unmap_addr,
1329                                        state.unmap_len, DMA_TO_DEVICE);
1330         }
1331
1332         /* Free the header DMA mapping, if using option descriptors */
1333         if (state.header_unmap_len)
1334                 dma_unmap_single(&efx->pci_dev->dev, state.header_dma_addr,
1335                                  state.header_unmap_len, DMA_TO_DEVICE);
1336
1337         efx_enqueue_unwind(tx_queue);
1338         return NETDEV_TX_OK;
1339 }