Merge branch 'rt6_probe_write_lock'

Martin KaFai Lau says:

====================
ipv6: Avoid rt6_probe() taking writer lock in the fast path

v1 -> v2:
1. Separate the code re-arrangement into another patch
2. Fix style
====================
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv6/route.c

@@ -545,6 +545,7 @@ static void rt6_probe_deferred(struct work_struct *w)
 
 static void rt6_probe(struct rt6_info *rt)
 {
+	struct __rt6_probe_work *work;
 	struct neighbour *neigh;
 	/*
 	 * Okay, this does not seem to be appropriate
@@ -559,22 +560,23 @@ static void rt6_probe(struct rt6_info *rt)
 	rcu_read_lock_bh();
 	neigh = __ipv6_neigh_lookup_noref(rt->dst.dev, &rt->rt6i_gateway);
 	if (neigh) {
-		write_lock(&neigh->lock);
 		if (neigh->nud_state & NUD_VALID)
 			goto out;
-	}
-
-	if (!neigh ||
-	    time_after(jiffies, neigh->updated + rt->rt6i_idev->cnf.rtr_probe_interval)) {
-		struct __rt6_probe_work *work;
 
+		work = NULL;
+		write_lock(&neigh->lock);
+		if (!(neigh->nud_state & NUD_VALID) &&
+		    time_after(jiffies,
+			       neigh->updated +
+			       rt->rt6i_idev->cnf.rtr_probe_interval)) {
 			work = kmalloc(sizeof(*work), GFP_ATOMIC);
-
-		if (neigh && work)
+			if (work)
 				__neigh_set_probe_once(neigh);
-
-		if (neigh)
+		}
 		write_unlock(&neigh->lock);
+	} else {
+		work = kmalloc(sizeof(*work), GFP_ATOMIC);
+	}
 
 	if (work) {
 		INIT_WORK(&work->work, rt6_probe_deferred);
@@ -583,10 +585,8 @@ static void rt6_probe(struct rt6_info *rt)
 		work->dev = rt->dst.dev;
 		schedule_work(&work->work);
 	}
-	} else {
+
 out:
-		write_unlock(&neigh->lock);
-	}
 	rcu_read_unlock_bh();
 }
 #else