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af_unix: Define locking order for U_LOCK_SECOND in unix_state_double_lock().

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unix_dgram_connect() and unix_dgram_{send,recv}msg() lock the socket
and peer in ascending order of the socket address.

Let's define the order as unix_state_lock_cmp_fn() instead of using
unix_state_lock_nested().

Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Reviewed-by: Kent Overstreet <kent.overstreet@linux.dev>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
This commit is contained in:
Kuniyuki Iwashima 2024-06-20 13:56:14 -07:00 committed by Paolo Abeni
parent 3955802f16
commit ed99822817
1 changed files with 15 additions and 1 deletions
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16
net/unix/af_unix.c
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@ -134,6 +134,18 @@ static int unix_table_lock_cmp_fn(const struct lockdep_map *a,
{
return cmp_ptr(a, b);
}
static int unix_state_lock_cmp_fn(const struct lockdep_map *_a,
const struct lockdep_map *_b)
{
const struct unix_sock *a, *b;
a = container_of(_a, struct unix_sock, lock.dep_map);
b = container_of(_b, struct unix_sock, lock.dep_map);
/* unix_state_double_lock(): ascending address order. */
return cmp_ptr(a, b);
}
#endif
static unsigned int unix_unbound_hash(struct sock *sk)
@ -987,6 +999,7 @@ static struct sock *unix_create1(struct net *net, struct socket *sock, int kern,
u->path.dentry = NULL;
u->path.mnt = NULL;
spin_lock_init(&u->lock);
lock_set_cmp_fn(&u->lock, unix_state_lock_cmp_fn, NULL);
mutex_init(&u->iolock); /* single task reading lock */
mutex_init(&u->bindlock); /* single task binding lock */
init_waitqueue_head(&u->peer_wait);
@ -1335,11 +1348,12 @@ static void unix_state_double_lock(struct sock *sk1, struct sock *sk2)
unix_state_lock(sk1);
return;
}
if (sk1 > sk2)
swap(sk1, sk2);
unix_state_lock(sk1);
unix_state_lock_nested(sk2, U_LOCK_SECOND);
unix_state_lock(sk2);
}
static void unix_state_double_unlock(struct sock *sk1, struct sock *sk2)