diff mbox series

[v1,net-next,3/4] af_unix: Move spin_lock() in manage_oob().

Message ID 20240905193240.17565-4-kuniyu@amazon.com (mailing list archive)
State Accepted
Commit a0264a9f51fe0d196f22efd7538eb749e3448c2d
Delegated to: Netdev Maintainers
Headers show
Series af_unix: Correct manage_oob() when OOB follows a consumed OOB. | expand

Checks

Context Check Description
netdev/series_format success Posting correctly formatted
netdev/tree_selection success Clearly marked for net-next, async
netdev/ynl success Generated files up to date; no warnings/errors; no diff in generated;
netdev/fixes_present success Fixes tag not required for -next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 16 this patch: 16
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: 16 this patch: 16
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 No Fixes tag
netdev/build_allmodconfig_warn success Errors and warnings before: 20 this patch: 20
netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 36 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-2024-09-07--06-00 (tests: 722)

Commit Message

Kuniyuki Iwashima Sept. 5, 2024, 7:32 p.m. UTC 
When OOB skb has been already consumed, manage_oob() returns the next
skb if exists.  In such a case, we need to fall back to the else branch
below.

Then, we want to keep holding spin_lock(&sk->sk_receive_queue.lock).

Let's move it out of if-else branch and add lightweight check before
spin_lock() for major use cases without OOB skb.

Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
---
 net/unix/af_unix.c | 15 +++++++--------
 1 file changed, 7 insertions(+), 8 deletions(-)
diff mbox series

Patch

diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
index 91d7877a1079..159d78fc3d14 100644
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -2657,9 +2657,12 @@  static struct sk_buff *manage_oob(struct sk_buff *skb, struct sock *sk,
 	struct sk_buff *read_skb = NULL, *unread_skb = NULL;
 	struct unix_sock *u = unix_sk(sk);
 
-	if (!unix_skb_len(skb)) {
-		spin_lock(&sk->sk_receive_queue.lock);
+	if (likely(unix_skb_len(skb) && skb != READ_ONCE(u->oob_skb)))
+		return skb;
 
+	spin_lock(&sk->sk_receive_queue.lock);
+
+	if (!unix_skb_len(skb)) {
 		if (copied && (!u->oob_skb || skb == u->oob_skb)) {
 			skb = NULL;
 		} else if (flags & MSG_PEEK) {
@@ -2670,14 +2673,9 @@  static struct sk_buff *manage_oob(struct sk_buff *skb, struct sock *sk,
 			__skb_unlink(read_skb, &sk->sk_receive_queue);
 		}
 
-		spin_unlock(&sk->sk_receive_queue.lock);
-
-		consume_skb(read_skb);
-		return skb;
+		goto unlock;
 	}
 
-	spin_lock(&sk->sk_receive_queue.lock);
-
 	if (skb != u->oob_skb)
 		goto unlock;
 
@@ -2698,6 +2696,7 @@  static struct sk_buff *manage_oob(struct sk_buff *skb, struct sock *sk,
 unlock:
 	spin_unlock(&sk->sk_receive_queue.lock);
 
+	consume_skb(read_skb);
 	kfree_skb(unread_skb);
 
 	return skb;