[IPV6]: Fix race in route selection.
We eliminated rt6_dflt_lock (to protect default router pointer)
at 2.6.17-rc1, and introduced rt6_select() for general router selection.
The function is called in the context of rt6_lock read-lock held,
but this means, we have some race conditions when we do round-robin.
Signed-off-by; YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 7907874..0190e39 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -317,7 +317,7 @@
__FUNCTION__, head, head ? *head : NULL, oif);
for (rt = rt0, metric = rt0->rt6i_metric;
- rt && rt->rt6i_metric == metric;
+ rt && rt->rt6i_metric == metric && (!last || rt != rt0);
rt = rt->u.next) {
int m;
@@ -343,9 +343,12 @@
(strict & RT6_SELECT_F_REACHABLE) &&
last && last != rt0) {
/* no entries matched; do round-robin */
+ static spinlock_t lock = SPIN_LOCK_UNLOCKED;
+ spin_lock(&lock);
*head = rt0->u.next;
rt0->u.next = last->u.next;
last->u.next = rt0;
+ spin_unlock(&lock);
}
RT6_TRACE("%s() => %p, score=%d\n",