[NET]: netdevice locking assumptions documentation

Update the documentation about locking assumptions.
Signed-off-by: NStephen Hemminger <shemminger@linux-foundation.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Documentation/networking/netdevices.txt

@@ -20,7 +20,6 @@ private data which gets freed when the network device is freed. If
 separately allocated data is attached to the network device
 (dev->priv) then it is up to the module exit handler to free that.
 
-
 struct net_device synchronization rules
 =======================================
 dev->open:
@@ -43,16 +42,17 @@ dev->get_stats:
 
 dev->hard_start_xmit:
 	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. 
+	for this and return NETDEV_TX_LOCKED when the spin lock fails.
 	The locking there should also properly protect against 
-	set_multicast_list
-	Context: Process with BHs disabled or BH (timer).
-	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.)
+	set_multicast_list.
+
+	Context: Process with BHs disabled or BH (timer),
+	         will be called with interrupts disabled by netconsole.
+
 	Return codes: 
 	o NETDEV_TX_OK everything ok. 
 	o NETDEV_TX_BUSY Cannot transmit packet, try later 
@@ -74,4 +74,5 @@ dev->poll:
 	Synchronization: __LINK_STATE_RX_SCHED bit in dev->state.  See
 		dev_close code and comments in net/core/dev.c for more info.
 	Context: softirq
+	         will be called with interrupts disabled by netconsole.