From mboxrd@z Thu Jan  1 00:00:00 1970
From: Eric Dumazet <eric.dumazet@gmail.com>
Subject: Re: [PATCH net-next] packet: Protect packet sk list with mutex
Date: Mon, 20 Aug 2012 21:05:33 +0200
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Cc: David Miller <davem@davemloft.net>,
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To: Pavel Emelyanov <xemul@parallels.com>
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On Mon, 2012-08-20 at 22:10 +0400, Pavel Emelyanov wrote:

> AFAIU now this is the case for e.g. TCP sockets since they can be created in 
> rx code. For packet I've found no places where these stats can be modified other
> than those two in af_packet.c

sock_prot_inuse_add() uses __this_cpu_add(), and on non x86, needs to be
safe against preemption ( or irq if applicable)

Changing spin_lock_bh() to mutex_lock() breaks this.