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| author | Jarek Poplawski <jarkao2@gmail.com> | 2009-11-15 07:20:12 +0000 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2009-11-15 22:08:33 -0800 |
| commit | 9a1654ba0b50402a6bd03c7b0fe9b0200a5ea7b1 (patch) | |
| tree | 3defd37672da2069e6c0ffd86b0b99c694324985 /include/linux/netdevice.h | |
| parent | cb43e23435a66d5ed90f804af9efe9096503979f (diff) | |
| download | lwn-9a1654ba0b50402a6bd03c7b0fe9b0200a5ea7b1.tar.gz lwn-9a1654ba0b50402a6bd03c7b0fe9b0200a5ea7b1.zip | |
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/linux/netdevice.h')
| -rw-r--r-- | include/linux/netdevice.h | 42 |
1 files changed, 30 insertions, 12 deletions
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h index 61425d0c6123..7043f85e643d 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 */ |