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af_unix: Remove U_LOCK_DIAG.

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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: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
This commit is contained in:
Kuniyuki Iwashima 2024-06-20 13:56:18 -07:00 committed by Paolo Abeni
parent b380b18102
commit c4da4661d9
2 changed files with 2 additions and 14 deletions
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1
include/net/af_unix.h
View File

@ -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.
*/

15
net/unix/diag.c
View File

@ -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;
skb_queue_walk(&sk->sk_receive_queue, skb)
buf[i++] = sock_i_ino(unix_peer(skb->sk));
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);
}
spin_unlock(&sk->sk_receive_queue.lock);
}