diff options
| author | Nikolay Aleksandrov <nikolay@cumulusnetworks.com> | 2015-06-06 06:49:00 -0700 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2015-06-07 19:44:13 -0700 |
| commit | c4c832f89dc468cf11dc0dd17206bace44526651 (patch) | |
| tree | b1bc4d2d1ffeea6cef222a89aeb6149481295751 | |
| parent | 7ff46e79fb7df5b09c46c36857929fdf039f8b31 (diff) | |
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>
| -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 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, |