[PATCH] SUNRPC: Don't allow compiler optimisation of svc_xprt_release_slot()

Trond Myklebust
2019-01-03T14:18:23Z

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>
---
net/sunrpc/svc_xprt.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/net/sunrpc/svc_xprt.c b/net/sunrpc/svc_xprt.c
index 51d36230b6e3..94d344325e22 100644
--- a/net/sunrpc/svc_xprt.c
+++ b/net/sunrpc/svc_xprt.c
@@ -363,9 +363,11 @@ 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 = 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;
--
2.20.1