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| author | Kuniyuki Iwashima <kuniyu@amazon.com> | 2024-04-12 19:19:28 -0700 |
|---|---|---|
| committer | Paolo Abeni <pabeni@redhat.com> | 2024-04-16 13:50:57 +0200 |
| commit | fd86344823b521149bb31d91eba900ba3525efa6 (patch) | |
| tree | ae1de297b7ddfc6eeb4ceaf8224934611d25e8d9 /net/unix/af_unix.c | |
| parent | e918c7bbc0df0eec447017c5064797b6072b7b0d (diff) | |
| download | linux-fd86344823b521149bb31d91eba900ba3525efa6.tar.gz linux-fd86344823b521149bb31d91eba900ba3525efa6.tar.bz2 linux-fd86344823b521149bb31d91eba900ba3525efa6.zip | |
af_unix: Try not to hold unix_gc_lock during accept().
Commit dcf70df2048d ("af_unix: Fix up unix_edge.successor for embryo
socket.") added spin_lock(&unix_gc_lock) in accept() path, and it
caused regression in a stress test as reported by kernel test robot.
If the embryo socket is not part of the inflight graph, we need not
hold the lock.
To decide that in O(1) time and avoid the regression in the normal
use case,
1. add a new stat unix_sk(sk)->scm_stat.nr_unix_fds
2. count the number of inflight AF_UNIX sockets in the receive
queue under unix_state_lock()
3. move unix_update_edges() call under unix_state_lock()
4. avoid locking if nr_unix_fds is 0 in unix_update_edges()
Reported-by: kernel test robot <oliver.sang@intel.com>
Closes: https://lore.kernel.org/oe-lkp/202404101427.92a08551-oliver.sang@intel.com
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Link: https://lore.kernel.org/r/20240413021928.20946-1-kuniyu@amazon.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Diffstat (limited to 'net/unix/af_unix.c')
| -rw-r--r-- | net/unix/af_unix.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c index 142d210b5b03..ed16d5f66df8 100644 --- a/net/unix/af_unix.c +++ b/net/unix/af_unix.c @@ -1719,12 +1719,12 @@ static int unix_accept(struct socket *sock, struct socket *newsock, int flags, } tsk = skb->sk; - unix_update_edges(unix_sk(tsk)); skb_free_datagram(sk, skb); wake_up_interruptible(&unix_sk(sk)->peer_wait); /* attach accepted sock to socket */ unix_state_lock(tsk); + unix_update_edges(unix_sk(tsk)); newsock->state = SS_CONNECTED; unix_sock_inherit_flags(sock, newsock); sock_graft(tsk, newsock); |