VisionFive2 Linux kernel

StarFive Tech Linux Kernel for VisionFive (JH7110) boards (mirror)

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author: Eric Dumazet <edumazet@google.com> 2023-06-29 16:41:50 +0000 committer: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 2023-07-19 16:36:47 +0200 commit: 5738c0c4eec970c2629efd827053336a4f8b1ca0 parent: 58f9e88eb247263c74383b4ee8858abac15cdbe0
Commit Summary:
tcp: annotate data races in __tcp_oow_rate_limited()
Diffstat:
1 file changed, 8 insertions, 3 deletions
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index bf8b22218dd4..57f1e4883b76 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -3590,8 +3590,11 @@ static int tcp_ack_update_window(struct sock *sk, const struct sk_buff *skb, u32
 static bool __tcp_oow_rate_limited(struct net *net, int mib_idx,
 				   u32 *last_oow_ack_time)
 {
-	if (*last_oow_ack_time) {
-		s32 elapsed = (s32)(tcp_jiffies32 - *last_oow_ack_time);
+	/* Paired with the WRITE_ONCE() in this function. */
+	u32 val = READ_ONCE(*last_oow_ack_time);
+
+	if (val) {
+		s32 elapsed = (s32)(tcp_jiffies32 - val);
 
 		if (0 <= elapsed &&
 		    elapsed < READ_ONCE(net->ipv4.sysctl_tcp_invalid_ratelimit)) {
@@ -3600,7 +3603,10 @@ static bool __tcp_oow_rate_limited(struct net *net, int mib_idx,
 		}
 	}
 
-	*last_oow_ack_time = tcp_jiffies32;
+	/* Paired with the prior READ_ONCE() and with itself,
+	 * as we might be lockless.
+	 */
+	WRITE_ONCE(*last_oow_ack_time, tcp_jiffies32);
 
 	return false;	/* not rate-limited: go ahead, send dupack now! */
 }