fedora core 6 1.2949 + vserver 2.2.0

[linux-2.6.git] / Documentation / networking / netdevices.txt

diff --git a/Documentation/networking/netdevices.txt b/Documentation/networking/netdevices.txt
index 8c456ed..847cedb 100644 (file)
--- a/Documentation/networking/netdevices.txt
+++ b/Documentation/networking/netdevices.txt
@@ -42,17 +42,32 @@ dev->get_stats:
        Context: nominally process, but don't sleep inside an rwlock
 
 dev->hard_start_xmit:
-       Synchronization: dev->xmit_lock spinlock.
+       Synchronization: netif_tx_lock spinlock.
+       When the driver sets NETIF_F_LLTX in dev->features this will be
+       called without holding netif_tx_lock. In this case the driver
+       has to lock by itself when needed. It is recommended to use a try lock
+       for this and return -1 when the spin lock fails. 
+       The locking there should also properly protect against 
+       set_multicast_list
        Context: BHs disabled
        Notes: netif_queue_stopped() is guaranteed false
+               Interrupts must be enabled when calling hard_start_xmit.
+                (Interrupts must also be enabled when enabling the BH handler.)
+       Return codes: 
+       o NETDEV_TX_OK everything ok. 
+       o NETDEV_TX_BUSY Cannot transmit packet, try later 
+         Usually a bug, means queue start/stop flow control is broken in
+         the driver. Note: the driver must NOT put the skb in its DMA ring.
+       o NETDEV_TX_LOCKED Locking failed, please retry quickly.
+         Only valid when NETIF_F_LLTX is set.
 
 dev->tx_timeout:
-       Synchronization: dev->xmit_lock spinlock.
+       Synchronization: netif_tx_lock spinlock.
        Context: BHs disabled
        Notes: netif_queue_stopped() is guaranteed true
 
 dev->set_multicast_list:
-       Synchronization: dev->xmit_lock spinlock.
+       Synchronization: netif_tx_lock spinlock.
        Context: BHs disabled
 
 dev->poll: