| Message ID | 1434986104-26670-1-git-send-email-luis.henriques@canonical.com |
|---|---|
| State | New |
| Headers | show |
diff --git a/net/bridge/br_fdb.c b/net/bridge/br_fdb.c index b524c36c1273..a10c1f87becc 100644 --- a/net/bridge/br_fdb.c +++ b/net/bridge/br_fdb.c @@ -777,9 +777,11 @@ 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,
This is a note to let you know that I have just added a patch titled bridge: disable softirqs around br_fdb_update to avoid lockup to the linux-3.16.y-queue branch of the 3.16.y-ckt extended stable tree which can be found at: http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-3.16.y-queue This patch is scheduled to be released in version 3.16.7-ckt14. If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 3.16.y-ckt tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Luis ------ From b897e70426b347f372e94e55de0a72241998745d Mon Sep 17 00:00:00 2001 From: Nikolay Aleksandrov <nikolay@cumulusnetworks.com> Date: Sat, 6 Jun 2015 06:49:00 -0700 Subject: bridge: disable softirqs around br_fdb_update to avoid lockup commit c4c832f89dc468cf11dc0dd17206bace44526651 upstream. 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: Luis Henriques <luis.henriques@canonical.com> --- net/bridge/br_fdb.c | 2 ++ 1 file changed, 2 insertions(+)