diff options
| author | David S. Miller <davem@sunset.davemloft.net> | 2007-10-29 21:28:47 -0700 |
|---|---|---|
| committer | David S. Miller <davem@sunset.davemloft.net> | 2007-10-29 22:37:28 -0700 |
| commit | 0a7606c121d58c1831805262c5b764e181429e7d (patch) | |
| tree | 4ba68e147c569c83dfedc3b45edf88ce21cde001 /net/core/dev.c | |
| parent | b0a713e9e6091b30d0e615d2be88017a57f37c76 (diff) | |
[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>
Diffstat (limited to 'net/core/dev.c')
| -rw-r--r-- | net/core/dev.c | 10 |
1 files changed, 9 insertions, 1 deletions
diff --git a/net/core/dev.c b/net/core/dev.c index 853c8b575f1d..02e7d8377c4a 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -2172,7 +2172,15 @@ static void net_rx_action(struct softirq_action *h) weight = n->weight; - work = n->poll(n, weight); + /* This NAPI_STATE_SCHED test is for avoiding a race + * with netpoll's poll_napi(). Only the entity which + * obtains the lock and sees NAPI_STATE_SCHED set will + * actually make the ->poll() call. Therefore we avoid + * accidently calling ->poll() when NAPI is not scheduled. + */ + work = 0; + if (test_bit(NAPI_STATE_SCHED, &n->state)) + work = n->poll(n, weight); WARN_ON_ONCE(work > weight); |