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Commit add9f2a4 authored by Greg Kroah-Hartman's avatar Greg Kroah-Hartman
Browse files

Revert "ipv6: grab rt->rt6i_ref before allocating pcpu rt" 



This reverts commit 9704f814 which was
upstream commit a94b9367e044ba672c9f4105eb1516ff6ff4948a.

Shouldn't have been here, sorry about that.

Reported-by: default avatarChris Rankin <rankincj@gmail.com>
Reported-by: default avatarWilly Tarreau <w@1wt.eu>
Cc: Ido Schimmel <idosch@idosch.org>
Cc: Ozgur <ozgur@goosey.org>
Cc: Wei Wang <weiwan@google.com>
Cc: Martin KaFai Lau <kafai@fb.com>
Cc: Eric Dumazet <edumazet@google.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent dad5c140

net/ipv6/route.c

+29 −29
Original line number Diff line number Diff line
@@ -1055,6 +1055,7 @@ static struct rt6_info *rt6_get_pcpu_route(struct rt6_info *rt) 


static struct rt6_info *rt6_make_pcpu_route(struct rt6_info *rt)

{

	struct fib6_table *table = rt->rt6i_table;

	struct rt6_info *pcpu_rt, *prev, **p;



	pcpu_rt = ip6_rt_pcpu_alloc(rt);
@@ -1065,20 +1066,28 @@ static struct rt6_info *rt6_make_pcpu_route(struct rt6_info *rt) 
		return net->ipv6.ip6_null_entry;

	}



	dst_hold(&pcpu_rt->dst);

	read_lock_bh(&table->tb6_lock);

	if (rt->rt6i_pcpu) {

		p = this_cpu_ptr(rt->rt6i_pcpu);

		prev = cmpxchg(p, NULL, pcpu_rt);

		if (prev) {

			/* If someone did it before us, return prev instead */

		/* release refcnt taken by ip6_rt_pcpu_alloc() */

			dst_release_immediate(&pcpu_rt->dst);

		/* release refcnt taken by above dst_hold() */

		dst_release_immediate(&pcpu_rt->dst);

		dst_hold(&prev->dst);

			pcpu_rt = prev;

		}



	} else {

		/* rt has been removed from the fib6 tree

		 * before we have a chance to acquire the read_lock.

		 * In this case, don't brother to create a pcpu rt

		 * since rt is going away anyway.  The next

		 * dst_check() will trigger a re-lookup.

		 */

		dst_release_immediate(&pcpu_rt->dst);

		pcpu_rt = rt;

	}

	dst_hold(&pcpu_rt->dst);

	rt6_dst_from_metrics_check(pcpu_rt);

	read_unlock_bh(&table->tb6_lock);

	return pcpu_rt;

}
@@ -1168,28 +1177,19 @@ struct rt6_info *ip6_pol_route(struct net *net, struct fib6_table *table, 
		if (pcpu_rt) {

			read_unlock_bh(&table->tb6_lock);

		} else {

			/* atomic_inc_not_zero() is needed when using rcu */

			if (atomic_inc_not_zero(&rt->rt6i_ref)) {

			/* We have to do the read_unlock first

			 * because rt6_make_pcpu_route() may trigger

			 * ip6_dst_gc() which will take the write_lock.

				 *

				 * No dst_hold() on rt is needed because grabbing

				 * rt->rt6i_ref makes sure rt can't be released.

			 */

			dst_hold(&rt->dst);

			read_unlock_bh(&table->tb6_lock);

			pcpu_rt = rt6_make_pcpu_route(rt);

				rt6_release(rt);

			} else {

				/* rt is already removed from tree */

				read_unlock_bh(&table->tb6_lock);

				pcpu_rt = net->ipv6.ip6_null_entry;

				dst_hold(&pcpu_rt->dst);

			}

			dst_release(&rt->dst);

		}



		trace_fib6_table_lookup(net, pcpu_rt, table->tb6_id, fl6);

		return pcpu_rt;



	}

}

EXPORT_SYMBOL_GPL(ip6_pol_route);