diff options
author | Curt Brune <curt@cumulusnetworks.com> | 2014-01-06 14:00:32 -0500 |
---|---|---|
committer | David S. Miller <davem@davemloft.net> | 2014-01-06 16:39:47 -0500 |
commit | fe0d692bbc645786bce1a98439e548ae619269f5 (patch) | |
tree | 4b4dc38d69dc7c876d04bc17619c41006f4ea2f4 | |
parent | 88ad31491e21f5dec347911d9804c673af414a09 (diff) |
bridge: use spin_lock_bh() in br_multicast_set_hash_max
br_multicast_set_hash_max() is called from process context in
net/bridge/br_sysfs_br.c by the sysfs store_hash_max() function.
br_multicast_set_hash_max() calls spin_lock(&br->multicast_lock),
which can deadlock the CPU if a softirq that also tries to take the
same lock interrupts br_multicast_set_hash_max() while the lock is
held . This can happen quite easily when any of the bridge multicast
timers expire, which try to take the same lock.
The fix here is to use spin_lock_bh(), preventing other softirqs from
executing on this CPU.
Steps to reproduce:
1. Create a bridge with several interfaces (I used 4).
2. Set the "multicast query interval" to a low number, like 2.
3. Enable the bridge as a multicast querier.
4. Repeatedly set the bridge hash_max parameter via sysfs.
# brctl addbr br0
# brctl addif br0 eth1 eth2 eth3 eth4
# brctl setmcqi br0 2
# brctl setmcquerier br0 1
# while true ; do echo 4096 > /sys/class/net/br0/bridge/hash_max; done
Signed-off-by: Curt Brune <curt@cumulusnetworks.com>
Signed-off-by: Scott Feldman <sfeldma@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r-- | net/bridge/br_multicast.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/net/bridge/br_multicast.c b/net/bridge/br_multicast.c index 4c214b2b88ef..ef66365b7354 100644 --- a/net/bridge/br_multicast.c +++ b/net/bridge/br_multicast.c | |||
@@ -1998,7 +1998,7 @@ int br_multicast_set_hash_max(struct net_bridge *br, unsigned long val) | |||
1998 | u32 old; | 1998 | u32 old; |
1999 | struct net_bridge_mdb_htable *mdb; | 1999 | struct net_bridge_mdb_htable *mdb; |
2000 | 2000 | ||
2001 | spin_lock(&br->multicast_lock); | 2001 | spin_lock_bh(&br->multicast_lock); |
2002 | if (!netif_running(br->dev)) | 2002 | if (!netif_running(br->dev)) |
2003 | goto unlock; | 2003 | goto unlock; |
2004 | 2004 | ||
@@ -2030,7 +2030,7 @@ rollback: | |||
2030 | } | 2030 | } |
2031 | 2031 | ||
2032 | unlock: | 2032 | unlock: |
2033 | spin_unlock(&br->multicast_lock); | 2033 | spin_unlock_bh(&br->multicast_lock); |
2034 | 2034 | ||
2035 | return err; | 2035 | return err; |
2036 | } | 2036 | } |