Subject: Re: Kernel crash after using new Intel NIC (igb)

From: Arun Sharma <[email-masked]>
Date: Tue, 24 May 2011 23:06:09 -0700

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.

 -Arun