[PATCH RT 12/13] net: use trylock in icmp_sk

[Steven Rostedt]

3.18.91-rt98-rc1 stable review patch.
If anyone has any objections, please let me know.

------------------

From: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>

The locking path can be recursive (same as for sk->sk_lock.slock) and
therefore we need a trylock version for the locallock, too.

Cc: stable-rt@xxxxxxxxxxxxxxx
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
Signed-off-by: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx>
---
 net/ipv4/icmp.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/net/ipv4/icmp.c b/net/ipv4/icmp.c
index 76b11e3e2b95..434eef536092 100644
--- a/net/ipv4/icmp.c
+++ b/net/ipv4/icmp.c
@@ -218,7 +218,11 @@ static inline struct sock *icmp_xmit_lock(struct net *net)
 
 	local_bh_disable();
 
-	local_lock(icmp_sk_lock);
+	if (!local_trylock(icmp_sk_lock)) {
+		local_bh_enable();
+		return NULL;
+	}
+
 	sk = icmp_sk(net);
 
 	if (unlikely(!spin_trylock(&sk->sk_lock.slock))) {
-- 
2.13.2