commit 0a7606c121d58c1831805262c5b764e181429e7d
author David S. Miller <davem@sunset.davemloft.net> Mon Oct 29 21:28:47 2007 -0700
committer David S. Miller <davem@sunset.davemloft.net> Mon Oct 29 22:37:28 2007 -0700
tree 4ba68e147c569c83dfedc3b45edf88ce21cde001
parent b0a713e9e6091b30d0e615d2be88017a57f37c76

[NET]: Fix race between poll_napi() and net_rx_action()

netpoll_poll_lock() synchronizes the ->poll() invocation
code paths, but once we have the lock we have to make
sure that NAPI_STATE_SCHED is still set.  Otherwise we
get:

	cpu 0			cpu 1

	net_rx_action()		poll_napi()
	netpoll_poll_lock()	... spin on ->poll_lock
	->poll()
	  netif_rx_complete
	netpoll_poll_unlock()	acquire ->poll_lock()
				->poll()
				 netif_rx_complete()
				 CRASH

Based upon a bug report from Tina Yang.

Signed-off-by: David S. Miller <davem@davemloft.net>