[PATCH 3.4 093/107] ipv6: probe routes asynchronous in rt6_probe

[lizf]

From: Hannes Frederic Sowa <hannes@xxxxxxxxxxxxxxxxxxx>

3.4.111-rc1 review patch.  If anyone has any objections, please let me know.

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


commit c2f17e827b419918c856131f592df9521e1a38e3 upstream.

Routes need to be probed asynchronous otherwise the call stack gets
exhausted when the kernel attemps to deliver another skb inline, like
e.g. xt_TEE does, and we probe at the same time.

We update neigh->updated still at once, otherwise we would send to
many probes.

Cc: Julian Anastasov <ja@xxxxxx>
Signed-off-by: Hannes Frederic Sowa <hannes@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
[lizf: Backported to 3.4: adjust context]
Signed-off-by: Zefan Li <lizefan@xxxxxxxxxx>
---
 net/ipv6/route.c | 37 +++++++++++++++++++++++++++++++------
 1 file changed, 31 insertions(+), 6 deletions(-)

diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 23b3304..c909217 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -404,6 +404,24 @@ out:
 }
 
 #ifdef CONFIG_IPV6_ROUTER_PREF
+struct __rt6_probe_work {
+	struct work_struct work;
+	struct in6_addr target;
+	struct net_device *dev;
+};
+
+static void rt6_probe_deferred(struct work_struct *w)
+{
+	struct in6_addr mcaddr;
+	struct __rt6_probe_work *work =
+		container_of(w, struct __rt6_probe_work, work);
+
+	addrconf_addr_solict_mult(&work->target, &mcaddr);
+	ndisc_send_ns(work->dev, NULL, &work->target, &mcaddr, NULL);
+	dev_put(work->dev);
+	kfree(w);
+}
+
 static void rt6_probe(struct rt6_info *rt)
 {
 	struct neighbour *neigh;
@@ -422,15 +440,22 @@ static void rt6_probe(struct rt6_info *rt)
 	read_lock_bh(&neigh->lock);
 	if (!(neigh->nud_state & NUD_VALID) &&
 	    time_after(jiffies, neigh->updated + rt->rt6i_idev->cnf.rtr_probe_interval)) {
-		struct in6_addr mcaddr;
-		struct in6_addr *target;
+		struct __rt6_probe_work *work;
+
+		work = kmalloc(sizeof(*work), GFP_ATOMIC);
+
+		if (work)
+			neigh->updated = jiffies;
 
-		neigh->updated = jiffies;
 		read_unlock_bh(&neigh->lock);
 
-		target = (struct in6_addr *)&neigh->primary_key;
-		addrconf_addr_solict_mult(target, &mcaddr);
-		ndisc_send_ns(rt->dst.dev, NULL, target, &mcaddr, NULL);
+		if (work) {
+			INIT_WORK(&work->work, rt6_probe_deferred);
+			work->target = rt->rt6i_gateway;
+			dev_hold(rt->dst.dev);
+			work->dev = rt->dst.dev;
+			schedule_work(&work->work);
+		}
 	} else {
 		read_unlock_bh(&neigh->lock);
 	}
-- 
1.9.1