net: Optimize hard_start_xmit() return checking

[linux-beck.git] / include / linux / netdevice.h

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 61425d0c612321a87d00d5ae269606be5d9a2fb2..7043f85e643dcb4c433862e19d8810bd80d8b9bf 100644 (file)
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -63,6 +63,10 @@ struct wireless_dev;
 #define HAVE_FREE_NETDEV               /* free_netdev() */
 #define HAVE_NETDEV_PRIV               /* netdev_priv() */
 
+/* Backlog congestion levels */
+#define NET_RX_SUCCESS         0       /* keep 'em coming, baby */
+#define NET_RX_DROP            1       /* packet dropped */
+
 /*
  * Transmit return codes: transmit return codes originate from three different
  * namespaces:
@@ -82,14 +86,10 @@ struct wireless_dev;
 
 /* qdisc ->enqueue() return codes. */
 #define NET_XMIT_SUCCESS       0x00
-#define NET_XMIT_DROP          0x10    /* skb dropped                  */
-#define NET_XMIT_CN            0x20    /* congestion notification      */
-#define NET_XMIT_POLICED       0x30    /* skb is shot by police        */
-#define NET_XMIT_MASK          0xf0    /* qdisc flags in net/sch_generic.h */
-
-/* Backlog congestion levels */
-#define NET_RX_SUCCESS         0       /* keep 'em coming, baby */
-#define NET_RX_DROP            1       /* packet dropped */
+#define NET_XMIT_DROP          0x01    /* skb dropped                  */
+#define NET_XMIT_CN            0x02    /* congestion notification      */
+#define NET_XMIT_POLICED       0x03    /* skb is shot by police        */
+#define NET_XMIT_MASK          0x0f    /* qdisc flags in net/sch_generic.h */
 
 /* NET_XMIT_CN is special. It does not guarantee that this packet is lost. It
  * indicates that the device will soon be dropping packets, or already drops
@@ -98,16 +98,34 @@ struct wireless_dev;
 #define net_xmit_errno(e)      ((e) != NET_XMIT_CN ? -ENOBUFS : 0)
 
 /* Driver transmit return codes */
-#define NETDEV_TX_MASK         0xf
+#define NETDEV_TX_MASK         0xf0
 
 enum netdev_tx {
        __NETDEV_TX_MIN  = INT_MIN,     /* make sure enum is signed */
-       NETDEV_TX_OK     = 0,           /* driver took care of packet */
-       NETDEV_TX_BUSY   = 1,           /* driver tx path was busy*/
-       NETDEV_TX_LOCKED = 2,           /* driver tx lock was already taken */
+       NETDEV_TX_OK     = 0x00,        /* driver took care of packet */
+       NETDEV_TX_BUSY   = 0x10,        /* driver tx path was busy*/
+       NETDEV_TX_LOCKED = 0x20,        /* driver tx lock was already taken */
 };
 typedef enum netdev_tx netdev_tx_t;
 
+/*
+ * Current order: NETDEV_TX_MASK > NET_XMIT_MASK >= 0 is significant;
+ * hard_start_xmit() return < NET_XMIT_MASK means skb was consumed.
+ */
+static inline bool dev_xmit_complete(int rc)
+{
+       /*
+        * Positive cases with an skb consumed by a driver:
+        * - successful transmission (rc == NETDEV_TX_OK)
+        * - error while transmitting (rc < 0)
+        * - error while queueing to a different device (rc & NET_XMIT_MASK)
+        */
+       if (likely(rc < NET_XMIT_MASK))
+               return true;
+
+       return false;
+}
+
 #endif
 
 #define MAX_ADDR_LEN   32              /* Largest hardware address length */