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authorJarek Poplawski <jarkao2@gmail.com>2009-11-15 07:20:12 +0000
committerDavid S. Miller <davem@davemloft.net>2009-11-15 22:08:33 -0800
commit9a1654ba0b50402a6bd03c7b0fe9b0200a5ea7b1 (patch)
tree3defd37672da2069e6c0ffd86b0b99c694324985 /include
parentcb43e23435a66d5ed90f804af9efe9096503979f (diff)
net: Optimize hard_start_xmit() return checking
Recent changes in the TX error propagation require additional checking and masking of values returned from hard_start_xmit(), mainly to separate cases where skb was consumed. This aim can be simplified by changing the order of NETDEV_TX and NET_XMIT codes, because the latter are treated similarly to negative (ERRNO) values. After this change much simpler dev_xmit_complete() is also used in sch_direct_xmit(), so it is moved to netdevice.h. Additionally NET_RX definitions in netdevice.h are moved up from between TX codes to avoid confusion while reading the TX comment. Signed-off-by: Jarek Poplawski <jarkao2@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'include')
-rw-r--r--include/linux/netdevice.h42
1 files changed, 30 insertions, 12 deletions
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 61425d0c612..7043f85e643 100644
--- 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 */