[PATCH 3/3] SUNRPC: Fix a hang in xprt_switch_set_next_cursor()

[Trond Myklebust <trondmy@xxxxxxxxx>]

Apparently we do need the memory barrier.

Signed-off-by: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx>
---
 net/sunrpc/xprtmultipath.c | 12 ++++--------
 1 file changed, 4 insertions(+), 8 deletions(-)

diff --git a/net/sunrpc/xprtmultipath.c b/net/sunrpc/xprtmultipath.c
index c12778e1235e..852da66cdaec 100644
--- a/net/sunrpc/xprtmultipath.c
+++ b/net/sunrpc/xprtmultipath.c
@@ -293,18 +293,14 @@ struct rpc_xprt *xprt_switch_set_next_cursor(struct list_head *head,
 		struct rpc_xprt **cursor,
 		xprt_switch_find_xprt_t find_next)
 {
-	struct rpc_xprt *cur, *pos, *old;
+	struct rpc_xprt *pos, *old;
 
-	cur = READ_ONCE(*cursor);
-	for (;;) {
-		old = cur;
+	old = READ_ONCE(*cursor);
+	do {
 		pos = find_next(head, old);
 		if (pos == NULL)
 			break;
-		cur = cmpxchg_relaxed(cursor, old, pos);
-		if (cur == old)
-			break;
-	}
+	} while (!try_cmpxchg(cursor, &old, pos));
 	return pos;
 }
 
-- 
2.21.0