From: Nikolay Aleksandrov Date: Sat, 6 Jun 2015 13:49:00 +0000 (-0700) Subject: bridge: disable softirqs around br_fdb_update to avoid lockup X-Git-Tag: omap-for-v4.2/fixes-rc1^2~214^2~5 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=c4c832f89dc468cf11dc0dd17206bace44526651;p=pandora-kernel.git bridge: disable softirqs around br_fdb_update to avoid lockup br_fdb_update() can be called in process context in the following way: br_fdb_add() -> __br_fdb_add() -> br_fdb_update() (if NTF_USE flag is set) so we need to disable softirqs because there are softirq users of the hash_lock. One easy way to reproduce this is to modify the bridge utility to set NTF_USE, enable stp and then set maxageing to a low value so br_fdb_cleanup() is called frequently and then just add new entries in a loop. This happens because br_fdb_cleanup() is called from timer/softirq context. The spin locks in br_fdb_update were _bh before commit f8ae737deea1 ("[BRIDGE]: forwarding remove unneeded preempt and bh diasables") and at the time that commit was correct because br_fdb_update() couldn't be called from process context, but that changed after commit: 292d1398983f ("bridge: add NTF_USE support") Using local_bh_disable/enable around br_fdb_update() allows us to keep using the spin_lock/unlock in br_fdb_update for the fast-path. Signed-off-by: Nikolay Aleksandrov Fixes: 292d1398983f ("bridge: add NTF_USE support") Signed-off-by: David S. Miller --- Reading git-diff-tree failed