diff options
| author | Nikolay Aleksandrov <nikolay@cumulusnetworks.com> | 2015-06-06 06:49:00 -0700 |
|---|---|---|
| committer | Sasha Levin <sasha.levin@oracle.com> | 2015-06-15 14:26:54 -0400 |
| commit | b824a7f09eb82df2f54774e95c284a0d72eb58af (patch) | |
| tree | f9923dd5c92d7294ff9e379655f6d34014bc7f09 /net | |
| parent | f938f18c8c6babf8200ea1007b20ea784aae243f (diff) | |
bridge: disable softirqs around br_fdb_update to avoid lockup
[ Upstream commit c4c832f89dc468cf11dc0dd17206bace44526651 ]
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>
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
Diffstat (limited to 'net')
| -rw-r--r-- | net/bridge/br_fdb.c | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/net/bridge/br_fdb.c b/net/bridge/br_fdb.c index 6f6c95cfe8f2..eab8862d9f88 100644 --- a/net/bridge/br_fdb.c +++ b/net/bridge/br_fdb.c @@ -789,9 +789,11 @@ 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, |