From: Trond Myklebust <trondmy@gmail.com>
Date: Thu, 3 Jan 2019 14:17:12 +0000 (-0500)
Subject: SUNRPC: Don't allow compiler optimisation of svc_xprt_release_slot()
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=1602a7b7d33741d0490682e620bb29e96ad684d7;p=linux.git

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>
---

diff --git a/net/sunrpc/svc_xprt.c b/net/sunrpc/svc_xprt.c
index 4eb8fbf2508dc..c3af1aaef551a 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;