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Message-ID: <4DDFE4D6.4010000@fb.com>
Date: Fri, 27 May 2011 10:52:22 -0700
From: Arun Sharma <asharma@...com>
To: Eric Dumazet <eric.dumazet@...il.com>
CC: David Miller <davem@...emloft.net>,
Maximilian Engelhardt <maxi@...monizer.de>,
linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
StuStaNet Vorstand <vorstand@...sta.mhn.de>,
Yann Dupont <Yann.Dupont@...v-nantes.fr>,
Denys Fedoryshchenko <denys@...p.net.lb>
Subject: Re: Kernel crash after using new Intel NIC (igb)
On 5/26/11 8:27 PM, Eric Dumazet wrote:
Looks good. Thanks for taking care of this.
> +static bool atomic_add_unless_return(atomic_t *ptr, int a, int u, int *newv)
> +{
> + int cur, old = atomic_read(ptr);
> +
> + while (old != u) {
> + *newv = old + a;
> + cur = atomic_cmpxchg(ptr, old, *newv);
> + if (cur == old)
> + return true;
> + old = cur;
> + }
> + return false;
> +}
This looks very similar to atomic_add_unless(). If we had a
__atomic_add_unless() that returned "old", we could then do:
atomic_add_unless() { return __atomic_add_unless() != u }
atomic_add_unless_return() { return __atomic_add_unless() + a}
-Arun
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