inet: simplify timewait refcounting
timewait sockets have a complex refcounting logic.
Once we realize it should be similar to established and
syn_recv sockets, we can use sk_nulls_del_node_init_rcu()
and remove inet_twsk_unhash()
In particular, deferred inet_twsk_put() added in commit
13475a30b66cd ("tcp: connect() race with timewait reuse")
looks unecessary : When removing a timewait socket from
ehash or bhash, caller must own a reference on the socket
anyway.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/inet_timewait_sock.c b/net/ipv4/inet_timewait_sock.c
index 2ffbd16..92cd4d5 100644
--- a/net/ipv4/inet_timewait_sock.c
+++ b/net/ipv4/inet_timewait_sock.c
@@ -18,28 +18,6 @@
/**
- * inet_twsk_unhash - unhash a timewait socket from established hash
- * @tw: timewait socket
- *
- * unhash a timewait socket from established hash, if hashed.
- * ehash lock must be held by caller.
- * Returns 1 if caller should call inet_twsk_put() after lock release.
- */
-int inet_twsk_unhash(struct inet_timewait_sock *tw)
-{
- if (hlist_nulls_unhashed(&tw->tw_node))
- return 0;
-
- hlist_nulls_del_rcu(&tw->tw_node);
- sk_nulls_node_init(&tw->tw_node);
- /*
- * We cannot call inet_twsk_put() ourself under lock,
- * caller must call it for us.
- */
- return 1;
-}
-
-/**
* inet_twsk_bind_unhash - unhash a timewait socket from bind hash
* @tw: timewait socket
* @hashinfo: hashinfo pointer
@@ -48,35 +26,29 @@
* bind hash lock must be held by caller.
* Returns 1 if caller should call inet_twsk_put() after lock release.
*/
-int inet_twsk_bind_unhash(struct inet_timewait_sock *tw,
+void inet_twsk_bind_unhash(struct inet_timewait_sock *tw,
struct inet_hashinfo *hashinfo)
{
struct inet_bind_bucket *tb = tw->tw_tb;
if (!tb)
- return 0;
+ return;
__hlist_del(&tw->tw_bind_node);
tw->tw_tb = NULL;
inet_bind_bucket_destroy(hashinfo->bind_bucket_cachep, tb);
- /*
- * We cannot call inet_twsk_put() ourself under lock,
- * caller must call it for us.
- */
- return 1;
+ __sock_put((struct sock *)tw);
}
/* Must be called with locally disabled BHs. */
static void inet_twsk_kill(struct inet_timewait_sock *tw)
{
struct inet_hashinfo *hashinfo = tw->tw_dr->hashinfo;
- struct inet_bind_hashbucket *bhead;
- int refcnt;
- /* Unlink from established hashes. */
spinlock_t *lock = inet_ehash_lockp(hashinfo, tw->tw_hash);
+ struct inet_bind_hashbucket *bhead;
spin_lock(lock);
- refcnt = inet_twsk_unhash(tw);
+ sk_nulls_del_node_init_rcu((struct sock *)tw);
spin_unlock(lock);
/* Disassociate with bind bucket. */
@@ -84,11 +56,9 @@
hashinfo->bhash_size)];
spin_lock(&bhead->lock);
- refcnt += inet_twsk_bind_unhash(tw, hashinfo);
+ inet_twsk_bind_unhash(tw, hashinfo);
spin_unlock(&bhead->lock);
- BUG_ON(refcnt >= atomic_read(&tw->tw_refcnt));
- atomic_sub(refcnt, &tw->tw_refcnt);
atomic_dec(&tw->tw_dr->tw_count);
inet_twsk_put(tw);
}