summaryrefslogtreecommitdiffstats
path: root/net/unix
diff options
context:
space:
mode:
authorKirill Tkhai <tkhai@ya.ru>2023-01-14 12:35:02 +0300
committerDavid S. Miller <davem@davemloft.net>2023-01-16 11:21:11 +0000
commitb27401a30ee466c4476b035487be0580767ba1fb (patch)
treed2e97d34aecaddbddb5fe2cc4c5f7449c09a07db /net/unix
parent40ea3ee2ced1a6eb3d6b22ecda40f5f6179fd990 (diff)
downloadlinux-stable-b27401a30ee466c4476b035487be0580767ba1fb.tar.gz
linux-stable-b27401a30ee466c4476b035487be0580767ba1fb.tar.bz2
linux-stable-b27401a30ee466c4476b035487be0580767ba1fb.zip
unix: Improve locking scheme in unix_show_fdinfo()
After switching to TCP_ESTABLISHED or TCP_LISTEN sk_state, alive SOCK_STREAM and SOCK_SEQPACKET sockets can't change it anymore (since commit 3ff8bff704f4 "unix: Fix race in SOCK_SEQPACKET's unix_dgram_sendmsg()"). Thus, we do not need to take lock here. Signed-off-by: Kirill Tkhai <tkhai@ya.ru> Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/unix')
-rw-r--r--net/unix/af_unix.c20
1 files changed, 10 insertions, 10 deletions
diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
index f0c2293f1d3b..009616fa0256 100644
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -807,23 +807,23 @@ static int unix_count_nr_fds(struct sock *sk)
static void unix_show_fdinfo(struct seq_file *m, struct socket *sock)
{
struct sock *sk = sock->sk;
+ unsigned char s_state;
struct unix_sock *u;
- int nr_fds;
+ int nr_fds = 0;
if (sk) {
+ s_state = READ_ONCE(sk->sk_state);
u = unix_sk(sk);
- if (sock->type == SOCK_DGRAM) {
- nr_fds = atomic_read(&u->scm_stat.nr_fds);
- goto out_print;
- }
- unix_state_lock(sk);
- if (sk->sk_state != TCP_LISTEN)
+ /* SOCK_STREAM and SOCK_SEQPACKET sockets never change their
+ * sk_state after switching to TCP_ESTABLISHED or TCP_LISTEN.
+ * SOCK_DGRAM is ordinary. So, no lock is needed.
+ */
+ if (sock->type == SOCK_DGRAM || s_state == TCP_ESTABLISHED)
nr_fds = atomic_read(&u->scm_stat.nr_fds);
- else
+ else if (s_state == TCP_LISTEN)
nr_fds = unix_count_nr_fds(sk);
- unix_state_unlock(sk);
-out_print:
+
seq_printf(m, "scm_fds: %u\n", nr_fds);
}
}