diff mbox series

[v2,net,05/15] af_unix: Annotate data-race of sk->sk_state in unix_stream_connect().

Message ID 20240604165241.44758-6-kuniyu@amazon.com (mailing list archive)
State Accepted
Commit a9bf9c7dc6a5899c01cb8f6e773a66315a5cd4b7
Delegated to: Netdev Maintainers
Headers show
Series af_unix: Fix lockless access of sk->sk_state and others fields. | expand

Checks

Context Check Description
netdev/series_format success Posting correctly formatted
netdev/tree_selection success Clearly marked for net
netdev/ynl success Generated files up to date; no warnings/errors; no diff in generated;
netdev/fixes_present success Fixes tag present in non-next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 906 this patch: 906
netdev/build_tools success No tools touched, skip
netdev/cc_maintainers success CCed 5 of 5 maintainers
netdev/build_clang success Errors and warnings before: 904 this patch: 904
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/deprecated_api success None detected
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success Fixes tag looks correct
netdev/build_allmodconfig_warn success Errors and warnings before: 910 this patch: 910
netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 25 lines checked
netdev/build_clang_rust success No Rust files in patch. Skipping build
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0
netdev/contest success net-next-2024-06-05--00-00 (tests: 1045)

Commit Message

Kuniyuki Iwashima June 4, 2024, 4:52 p.m. UTC 
As small optimisation, unix_stream_connect() prefetches the client's
sk->sk_state without unix_state_lock() and checks if it's TCP_CLOSE.

Later, sk->sk_state is checked again under unix_state_lock().

Let's use READ_ONCE() for the first check and TCP_CLOSE directly for
the second check.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
---
 net/unix/af_unix.c | 7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)
diff mbox series

Patch

diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
index 3bacf47cb94d..84552826530d 100644
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -1481,7 +1481,6 @@  static int unix_stream_connect(struct socket *sock, struct sockaddr *uaddr,
 	struct sk_buff *skb = NULL;
 	long timeo;
 	int err;
-	int st;
 
 	err = unix_validate_addr(sunaddr, addr_len);
 	if (err)
@@ -1571,9 +1570,7 @@  static int unix_stream_connect(struct socket *sock, struct sockaddr *uaddr,
 
 	   Well, and we have to recheck the state after socket locked.
 	 */
-	st = sk->sk_state;
-
-	switch (st) {
+	switch (READ_ONCE(sk->sk_state)) {
 	case TCP_CLOSE:
 		/* This is ok... continue with connect */
 		break;
@@ -1588,7 +1585,7 @@  static int unix_stream_connect(struct socket *sock, struct sockaddr *uaddr,
 
 	unix_state_lock_nested(sk, U_LOCK_SECOND);
 
-	if (sk->sk_state != st) {
+	if (sk->sk_state != TCP_CLOSE) {
 		unix_state_unlock(sk);
 		unix_state_unlock(other);
 		sock_put(other);