From: Dominic Curran Date: Wed, 22 Jan 2014 03:03:23 +0000 (+0000) Subject: tuntap: Fix for a race in accessing numqueues X-Git-Tag: v3.14-rc1~94^2~32 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=fa35864e0bb7f7c13b9c6d6751ddac9b42d4810f;p=pandora-kernel.git tuntap: Fix for a race in accessing numqueues A patch for fixing a race between queue selection and changing queues was introduced in commit 92bb73ea2("tuntap: fix a possible race between queue selection and changing queues"). The fix was to prevent the driver from re-reading the tun->numqueues more than once within tun_select_queue() using ACCESS_ONCE(). We have been experiancing 'Divide-by-zero' errors in tun_net_xmit() since we moved from 3.6 to 3.10, and believe that they come from a simular source where the value of tun->numqueues changes to zero between the first and a subsequent read of tun->numqueues. The fix is a simular use of ACCESS_ONCE(), as well as a multiply instead of a divide in the if statement. Signed-off-by: Dominic Curran Cc: Jason Wang Cc: Maxim Krasnyansky Acked-by: Jason Wang Acked-by: Max Krasnyansky Signed-off-by: David S. Miller --- Reading git-diff-tree failed