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

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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: Wei Wang <weiwan@google.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Wei Wang 2017-06-17 10:42:39 -07:00 committed by David S. Miller
parent 52df157f17
commit 560fd93bca
1 changed files with 19 additions and 17 deletions
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36
net/decnet/dn_route.c
View File

@ -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) ||
(now - rt->dst.lastuse) < expire) {
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) ||
(now - rt->dst.lastuse) < expire) {
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 @@ make_route:
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 @@ make_route:
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 @@ e_nobufs:
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 @@ make_route:
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 @@ e_nobufs:
goto done;
e_neighbour:
dst_free(&rt->dst);
dst_release_immediate(&rt->dst);
goto done;
}