VisionFive2 Linux kernel

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

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author: Xuan Zhuo <xuanzhuo@linux.alibaba.com> 2021-09-18 16:52:32 +0800 committer: David S. Miller <davem@davemloft.net> 2021-09-20 09:41:29 +0100 commit: 3765996e4f0b8a755cab215a08df744490c76052 parent: e30cd812dffadc58241ae378e48728e6a161becd
Commit Summary:
napi: fix race inside napi_enable
Diffstat:
1 file changed, 8 insertions, 6 deletions
diff --git a/net/core/dev.c b/net/core/dev.c
index 74fd402d26dd..7ee9fecd3aff 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -6923,12 +6923,16 @@ EXPORT_SYMBOL(napi_disable);
  */
 void napi_enable(struct napi_struct *n)
 {
-	BUG_ON(!test_bit(NAPI_STATE_SCHED, &n->state));
-	smp_mb__before_atomic();
-	clear_bit(NAPI_STATE_SCHED, &n->state);
-	clear_bit(NAPI_STATE_NPSVC, &n->state);
-	if (n->dev->threaded && n->thread)
-		set_bit(NAPI_STATE_THREADED, &n->state);
+	unsigned long val, new;
+
+	do {
+		val = READ_ONCE(n->state);
+		BUG_ON(!test_bit(NAPI_STATE_SCHED, &val));
+
+		new = val & ~(NAPIF_STATE_SCHED | NAPIF_STATE_NPSVC);
+		if (n->dev->threaded && n->thread)
+			new |= NAPIF_STATE_THREADED;
+	} while (cmpxchg(&n->state, val, new) != val);
 }
 EXPORT_SYMBOL(napi_enable);