From 1602a7b7d33741d0490682e620bb29e96ad684d7 Mon Sep 17 00:00:00 2001
From: Trond Myklebust <trondmy@gmail.com>
Date: Thu, 3 Jan 2019 09:17:12 -0500
Subject: [PATCH] SUNRPC: Don't allow compiler optimisation of
 svc_xprt_release_slot()

Use READ_ONCE() to tell the compiler to not optimse away the read of
xprt->xpt_flags in svc_xprt_release_slot().

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
---
 net/sunrpc/svc_xprt.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/net/sunrpc/svc_xprt.c b/net/sunrpc/svc_xprt.c
index 4eb8fbf..c3af1aa 100644
--- a/net/sunrpc/svc_xprt.c
+++ b/net/sunrpc/svc_xprt.c
@@ -363,9 +363,13 @@ static void svc_xprt_release_slot(struct svc_rqst *rqstp)
 
 static bool svc_xprt_has_something_to_do(struct svc_xprt *xprt)
 {
-	if (xprt->xpt_flags & ((1<<XPT_CONN)|(1<<XPT_CLOSE)))
+	unsigned long xpt_flags;
+
+	xpt_flags = READ_ONCE(xprt->xpt_flags);
+
+	if (xpt_flags & (BIT(XPT_CONN) | BIT(XPT_CLOSE)))
 		return true;
-	if (xprt->xpt_flags & ((1<<XPT_DATA)|(1<<XPT_DEFERRED))) {
+	if (xpt_flags & (BIT(XPT_DATA) | BIT(XPT_DEFERRED))) {
 		if (xprt->xpt_ops->xpo_has_wspace(xprt) &&
 		    svc_xprt_slots_in_range(xprt))
 			return true;
-- 
2.7.4