Messages in this thread | | | Subject | Re: Kernel crash after using new Intel NIC (igb) | From | Eric Dumazet <> | Date | Wed, 25 May 2011 08:35:31 +0200 |
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Le mardi 24 mai 2011 à 23:06 -0700, Arun Sharma a écrit : > On Wed, May 25, 2011 at 04:44:29AM +0200, Eric Dumazet wrote: > > > > Hmm, thanks for the report. Are you running x86 or another arch ? > > > > This was on x86. > > > We probably need some sort of memory barrier. > > > > However, locking this central lock makes the thing too slow, I'll try to > > use an atomic_inc_return on p->refcnt instead. (and then lock > > unused_peers.lock if we got a 0->1 transition) > > Another possibility is to do the list_empty() check twice. Once without > taking the lock and again with the spinlock held. >
Why ?
list_del_init(&p->unused); (done under lock of course) is safe, you can call it twice, no problem.
No, the real problem is the (!list_empty(&p->unused) test : It seems to not always tell the truth if not done under lock.
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