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authorWilson Kok <wkok@cumulusnetworks.com>2015-06-05 00:52:57 -0700
committerDavid S. Miller <davem@davemloft.net>2015-06-07 15:24:54 -0700
commit1d7c49037b12016e7056b9f2c990380e2187e766 (patch)
treeeddf23c9e9aa73e2e91447ea9ff8ed2f087d63eb /net/bridge
parent078b29d7e92e4254b6de16097d0369dde17efe21 (diff)
bridge: use _bh spinlock variant for 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 use spin_lock_bh 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. These locks 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") Signed-off-by: Wilson Kok <wkok@cumulusnetworks.com> 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/bridge')
-rw-r--r--net/bridge/br_fdb.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/net/bridge/br_fdb.c b/net/bridge/br_fdb.c
index e0670d7054f9..7eacc8ae9779 100644
--- a/net/bridge/br_fdb.c
+++ b/net/bridge/br_fdb.c
@@ -569,7 +569,7 @@ void br_fdb_update(struct net_bridge *br, struct net_bridge_port *source,
fdb_notify(br, fdb, RTM_NEWNEIGH);
}
} else {
- spin_lock(&br->hash_lock);
+ spin_lock_bh(&br->hash_lock);
if (likely(!fdb_find(head, addr, vid))) {
fdb = fdb_create(head, source, addr, vid);
if (fdb) {
@@ -581,7 +581,7 @@ void br_fdb_update(struct net_bridge *br, struct net_bridge_port *source,
/* else we lose race and someone else inserts
* it first, don't bother updating
*/
- spin_unlock(&br->hash_lock);
+ spin_unlock_bh(&br->hash_lock);
}
}

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