p2p: use safe atomic operations when changing connFlags (#17325)

eef65b20 · Felföldi Zsolt · Péter Szilágyi · c4df6746 · eef65b20
Commit eef65b20 authored Aug 06, 2018 by Felföldi Zsolt Committed by Péter Szilágyi Aug 06, 2018
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Showing with 11 additions and 6 deletions

server.go p2p/server.go +11 -6

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--- a/p2p/server.go
+++ b/p2p/server.go
@@ -258,13 +258,18 @@ func (c *conn) is(f connFlag) bool {
 }
 func (c *conn) set(f connFlag, val bool) {
-	flags := connFlag(atomic.LoadInt32((*int32)(&c.flags)))
+	for {
-	if val {
+		oldFlags := connFlag(atomic.LoadInt32((*int32)(&c.flags)))
-		flags |= f
+		flags := oldFlags
-	} else {
+		if val {
-		flags &= ^f
+			flags |= f
+		} else {
+			flags &= ^f
+		}
+		if atomic.CompareAndSwapInt32((*int32)(&c.flags), int32(oldFlags), int32(flags)) {
+			return
+		}
 	}
-	atomic.StoreInt32((*int32)(&c.flags), int32(flags))
 }
 // Peers returns all connected peers.