From: Olivier Houchard <ohouchard@haproxy.com>
Date: Fri, 18 Jan 2019 16:21:32 +0000 (+0100)
Subject: MINOR: xref: Add missing barriers.
X-Git-Tag: v2.0-dev1~85
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=ff5dd74e25e1069d74635dba9e8215a6093c481e;p=thirdparty%2Fhaproxy.git

MINOR: xref: Add missing barriers.

Add a few missing barriers in the xref code, it's unlikely to be a problem
for x86, but may be on architectures with weak memory ordering.
---

diff --git a/include/common/xref.h b/include/common/xref.h
index 6dfa7b6275..a6291f52f5 100644
--- a/include/common/xref.h
+++ b/include/common/xref.h
@@ -32,6 +32,7 @@ static inline struct xref *xref_get_peer_and_lock(struct xref *xref)
 
 		/* Get the local pointer to the peer. */
 		local = HA_ATOMIC_XCHG(&xref->peer, XREF_BUSY);
+		__ha_barrier_store();
 
 		/* If the local pointer is NULL, the peer no longer exists. */
 		if (local == NULL) {
@@ -53,6 +54,7 @@ static inline struct xref *xref_get_peer_and_lock(struct xref *xref)
 		/* The remote lock is BUSY, We retry the process. */
 		if (remote == XREF_BUSY) {
 			xref->peer = local;
+			__ha_barrier_store();
 			continue;
 		}
 
@@ -66,6 +68,8 @@ static inline void xref_unlock(struct xref *xref, struct xref *peer)
 	/* Release the peer. */
 	peer->peer = xref;
 
+	__ha_barrier_store();
+
 	/* Release myself. */
 	xref->peer = peer;
 }
@@ -73,6 +77,7 @@ static inline void xref_unlock(struct xref *xref, struct xref *peer)
 static inline void xref_disconnect(struct xref *xref, struct xref *peer)
 {
 	peer->peer = NULL;
+	__ha_barrier_store();
 	xref->peer = NULL;
 }