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Commit 560fd93b authored by Wei Wang's avatar Wei Wang Committed by David S. Miller
Browse files

decnet: take dst->__refcnt when struct dn_route is created 



struct dn_route is inserted into dn_rt_hash_table but no dst->__refcnt
is taken.
This patch makes sure the dn_rt_hash_table's reference to the dst is ref
counted.

As the dst is always ref counted properly, we can safely mark
DST_NOGC flag so dst_release() will release dst based on refcnt only.
And dst gc is no longer needed and all dst_free() or its related
function calls should be replaced with dst_release() or
dst_release_immediate(). And dst_dev_put() is called when removing dst
from the hash table to release the reference on dst->dev before we lose
pointer to it.

Also, correct the logic in dn_dst_check_expire() and dn_dst_gc() to
check dst->__refcnt to be > 1 to indicate it is referenced by other
users.

Signed-off-by: default avatarWei Wang <weiwan@google.com>
Acked-by: default avatarMartin KaFai Lau <kafai@fb.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 52df157f

net/decnet/dn_route.c

+19 −17
Original line number Diff line number Diff line
@@ -183,11 +183,6 @@ static __inline__ unsigned int dn_hash(__le16 src, __le16 dst) 
	return dn_rt_hash_mask & (unsigned int)tmp;

}



static inline void dnrt_free(struct dn_route *rt)

{

	call_rcu_bh(&rt->dst.rcu_head, dst_rcu_free);

}



static void dn_dst_check_expire(unsigned long dummy)

{

	int i;
@@ -202,14 +197,15 @@ static void dn_dst_check_expire(unsigned long dummy) 
		spin_lock(&dn_rt_hash_table[i].lock);

		while ((rt = rcu_dereference_protected(*rtp,

						lockdep_is_held(&dn_rt_hash_table[i].lock))) != NULL) {

			if (atomic_read(&rt->dst.__refcnt) ||

			if (atomic_read(&rt->dst.__refcnt) > 1 ||

			    (now - rt->dst.lastuse) < expire) {

				rtp = &rt->dst.dn_next;

				continue;

			}

			*rtp = rt->dst.dn_next;

			rt->dst.dn_next = NULL;

			dnrt_free(rt);

			dst_dev_put(&rt->dst);

			dst_release(&rt->dst);

		}

		spin_unlock(&dn_rt_hash_table[i].lock);
@@ -235,14 +231,15 @@ static int dn_dst_gc(struct dst_ops *ops) 


		while ((rt = rcu_dereference_protected(*rtp,

						lockdep_is_held(&dn_rt_hash_table[i].lock))) != NULL) {

			if (atomic_read(&rt->dst.__refcnt) ||

			if (atomic_read(&rt->dst.__refcnt) > 1 ||

			    (now - rt->dst.lastuse) < expire) {

				rtp = &rt->dst.dn_next;

				continue;

			}

			*rtp = rt->dst.dn_next;

			rt->dst.dn_next = NULL;

			dnrt_free(rt);

			dst_dev_put(&rt->dst);

			dst_release(&rt->dst);

			break;

		}

		spin_unlock_bh(&dn_rt_hash_table[i].lock);
@@ -344,7 +341,7 @@ static int dn_insert_route(struct dn_route *rt, unsigned int hash, struct dn_rou 
			dst_use(&rth->dst, now);

			spin_unlock_bh(&dn_rt_hash_table[hash].lock);



			dst_free(&rt->dst);

			dst_release_immediate(&rt->dst);

			*rp = rth;

			return 0;

		}
@@ -374,7 +371,8 @@ static void dn_run_flush(unsigned long dummy) 
		for(; rt; rt = next) {

			next = rcu_dereference_raw(rt->dst.dn_next);

			RCU_INIT_POINTER(rt->dst.dn_next, NULL);

			dnrt_free(rt);

			dst_dev_put(&rt->dst);

			dst_release(&rt->dst);

		}



nothing_to_declare:
@@ -1181,7 +1179,8 @@ static int dn_route_output_slow(struct dst_entry **pprt, const struct flowidn *o 
	if (dev_out->flags & IFF_LOOPBACK)

		flags |= RTCF_LOCAL;



	rt = dst_alloc(&dn_dst_ops, dev_out, 0, DST_OBSOLETE_NONE, DST_HOST);

	rt = dst_alloc(&dn_dst_ops, dev_out, 1, DST_OBSOLETE_NONE,

		       DST_HOST | DST_NOGC);

	if (rt == NULL)

		goto e_nobufs;
@@ -1215,6 +1214,7 @@ static int dn_route_output_slow(struct dst_entry **pprt, const struct flowidn *o 
		goto e_neighbour;



	hash = dn_hash(rt->fld.saddr, rt->fld.daddr);

	/* dn_insert_route() increments dst->__refcnt */

	dn_insert_route(rt, hash, (struct dn_route **)pprt);



done:
@@ -1237,7 +1237,7 @@ static int dn_route_output_slow(struct dst_entry **pprt, const struct flowidn *o 
	err = -ENOBUFS;

	goto done;

e_neighbour:

	dst_free(&rt->dst);

	dst_release_immediate(&rt->dst);

	goto e_nobufs;

}
@@ -1445,7 +1445,8 @@ static int dn_route_input_slow(struct sk_buff *skb) 
	}



make_route:

	rt = dst_alloc(&dn_dst_ops, out_dev, 0, DST_OBSOLETE_NONE, DST_HOST);

	rt = dst_alloc(&dn_dst_ops, out_dev, 1, DST_OBSOLETE_NONE,

		       DST_HOST | DST_NOGC);

	if (rt == NULL)

		goto e_nobufs;
@@ -1491,6 +1492,7 @@ static int dn_route_input_slow(struct sk_buff *skb) 
		goto e_neighbour;



	hash = dn_hash(rt->fld.saddr, rt->fld.daddr);

	/* dn_insert_route() increments dst->__refcnt */

	dn_insert_route(rt, hash, &rt);

	skb_dst_set(skb, &rt->dst);
@@ -1514,7 +1516,7 @@ static int dn_route_input_slow(struct sk_buff *skb) 
	goto done;



e_neighbour:

	dst_free(&rt->dst);

	dst_release_immediate(&rt->dst);

	goto done;

}