Commit c4da4661 authored by Kuniyuki Iwashima's avatar Kuniyuki Iwashima Committed by Paolo Abeni
Browse files

af_unix: Remove U_LOCK_DIAG. 



sk_diag_dump_icons() acquires embryo's lock by unix_state_lock_nested()
to fetch its peer.

The embryo's ->peer is set to NULL only when its parent listener is
close()d.  Then, unix_release_sock() is called for each embryo after
unlinking skb by skb_dequeue().

In sk_diag_dump_icons(), we hold the parent's recvq lock, so we need
not acquire unix_state_lock_nested(), and peer is always non-NULL.

Let's remove unnecessary unix_state_lock_nested() and non-NULL test
for peer.

Signed-off-by: default avatarKuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: default avatarPaolo Abeni <pabeni@redhat.com>
parent b380b181

include/net/af_unix.h

+0 −1
Original line number Diff line number Diff line
@@ -98,7 +98,6 @@ struct unix_sock { 
#define unix_state_unlock(s)	spin_unlock(&unix_sk(s)->lock)

enum unix_socket_lock_class {

	U_LOCK_NORMAL,

	U_LOCK_DIAG, /* used while dumping icons, see sk_diag_dump_icons(). */

	U_LOCK_GC_LISTENER, /* used for listening socket while determining gc

			     * candidates to close a small race window.

			     */

net/unix/diag.c

+3 −14
Original line number Diff line number Diff line
@@ -73,20 +73,9 @@ static int sk_diag_dump_icons(struct sock *sk, struct sk_buff *nlskb) 


		buf = nla_data(attr);

		i = 0;

		skb_queue_walk(&sk->sk_receive_queue, skb) {

			struct sock *req, *peer;



			req = skb->sk;

			/*

			 * The state lock is outer for the same sk's

			 * queue lock. With the other's queue locked it's

			 * OK to lock the state.

			 */

			unix_state_lock_nested(req, U_LOCK_DIAG);

			peer = unix_sk(req)->peer;

			buf[i++] = (peer ? sock_i_ino(peer) : 0);

			unix_state_unlock(req);

		}

		skb_queue_walk(&sk->sk_receive_queue, skb)

			buf[i++] = sock_i_ino(unix_peer(skb->sk));



		spin_unlock(&sk->sk_receive_queue.lock);

	}