[NET]: netdevice locking assumptions documentation
Update the documentation about locking assumptions.
Signed-off-by: Stephen Hemminger <shemminger@linux-foundation.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/Documentation/networking/netdevices.txt b/Documentation/networking/netdevices.txt
index ce1361f..a6cab67 100644
--- a/Documentation/networking/netdevices.txt
+++ b/Documentation/networking/netdevices.txt
@@ -20,7 +20,6 @@
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->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 @@
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.