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Commit c302e6d5 authored by YOSHIFUJI Hideaki's avatar YOSHIFUJI Hideaki Committed by David S. Miller
Browse files

[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: default avatarDavid S. Miller <davem@davemloft.net>
parent e959d812

net/ipv6/route.c

+4 −1
Original line number Diff line number Diff line
@@ -317,7 +317,7 @@ static struct rt6_info *rt6_select(struct rt6_info **head, int oif, 
		  __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 @@ static struct rt6_info *rt6_select(struct rt6_info **head, int oif, 
	    (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",