diff options
| author | Nikolay Aleksandrov <nikolay@cumulusnetworks.com> | 2015-06-06 06:49:00 -0700 |
|---|---|---|
| committer | Zefan Li <lizefan@huawei.com> | 2015-09-18 09:20:45 +0800 |
| commit | 4845c5376dbbf46853b53d5241fbe4d4a2c94b59 (patch) | |
| tree | 1f4fa836cc5d606220ae6fbc5b39d57671cd3c54 | |
| parent | 0b6afbdd165890743b64c57c07cbc4e6e3174b35 (diff) | |
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>
[lizf: Backported to 3.4: adjust context]
Signed-off-by: Zefan Li <lizefan@huawei.com>
| -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 b5597bb37e7a..3cb93e85d221 100644 --- a/net/bridge/br_fdb.c +++ b/net/bridge/br_fdb.c @@ -665,9 +665,11 @@ int br_fdb_add(struct sk_buff *skb, struct nlmsghdr *nlh, void *arg) } if (ndm->ndm_flags & NTF_USE) { + local_bh_disable(); rcu_read_lock(); br_fdb_update(p->br, p, addr); rcu_read_unlock(); + local_bh_enable(); } else { spin_lock_bh(&p->br->hash_lock); err = fdb_add_entry(p, addr, ndm->ndm_state, nlh->nlmsg_flags); |