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authorNikolay Aleksandrov <nikolay@cumulusnetworks.com>2015-06-06 06:49:00 -0700
committerDavid S. Miller <davem@davemloft.net>2015-06-07 19:44:13 -0700
commitc4c832f89dc468cf11dc0dd17206bace44526651 (patch)
treeb1bc4d2d1ffeea6cef222a89aeb6149481295751 /net
parent7ff46e79fb7df5b09c46c36857929fdf039f8b31 (diff)
downloadlinux-linaro-stable-c4c832f89dc468cf11dc0dd17206bace44526651.tar.gz
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 <nikolay@cumulusnetworks.com> Fixes: 292d1398983f ("bridge: add NTF_USE support") Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net')
-rw-r--r--net/bridge/br_fdb.c2
1 files changed, 2 insertions, 0 deletions
diff --git a/net/bridge/br_fdb.c b/net/bridge/br_fdb.c
index e0670d7054f9..659fb96672e4 100644
--- a/net/bridge/br_fdb.c
+++ b/net/bridge/br_fdb.c
@@ -796,9 +796,11 @@ static int __br_fdb_add(struct ndmsg *ndm, struct net_bridge_port *p,
int err = 0;
if (ndm->ndm_flags & NTF_USE) {
+ local_bh_disable();
rcu_read_lock();
br_fdb_update(p->br, p, addr, vid, true);
rcu_read_unlock();
+ local_bh_enable();
} else {
spin_lock_bh(&p->br->hash_lock);
err = fdb_add_entry(p, addr, ndm->ndm_state,