[PATCH v2 net-next 1/5] bridge: use atomic ops to read/change p->flags in sysfs

[Eric Dumazet <edumazet@google.com>]

Change net/bridge/br_sysfs_if.c to use atomic operations
to read/change bits n p->flags.

Signed-off-by: Eric Dumazet <edumazet@google.com>
---
 net/bridge/br_sysfs_if.c | 61 ++++++++++++++++++++++------------------
 1 file changed, 33 insertions(+), 28 deletions(-)

diff --git a/net/bridge/br_sysfs_if.c b/net/bridge/br_sysfs_if.c
index 1923c004f0d2b746902f5b6de1bbb72f7f824125..738544901563f570355554f49b2b80cf962f8e71 100644
--- a/net/bridge/br_sysfs_if.c
+++ b/net/bridge/br_sysfs_if.c
@@ -44,40 +44,45 @@ const struct brport_attribute brport_attr_##_name = { 	        \
 	.store	= _store,					\
 };
 
-#define BRPORT_ATTR_FLAG(_name, _mask)				\
+#define BRPORT_ATTR_FLAG(_name, _bitnr)				\
 static ssize_t show_##_name(struct net_bridge_port *p, char *buf) \
 {								\
-	return sysfs_emit(buf, "%d\n", !!(p->flags & _mask));	\
+	return sysfs_emit(buf, "%d\n", test_bit(_bitnr, &p->flags));	\
 }								\
 static int store_##_name(struct net_bridge_port *p, unsigned long v) \
 {								\
-	return store_flag(p, v, _mask);				\
+	return store_flag(p, v, _bitnr);				\
 }								\
 static BRPORT_ATTR(_name, 0644,					\
 		   show_##_name, store_##_name)
 
 static int store_flag(struct net_bridge_port *p, unsigned long v,
-		      unsigned long mask)
+		      unsigned long bitnr)
 {
+	unsigned long oflags, flags = READ_ONCE(p->flags);
 	struct netlink_ext_ack extack = {0};
-	unsigned long flags = p->flags;
 	int err;
 
+
+	oflags = flags;
 	if (v)
-		flags |= mask;
+		__set_bit(bitnr, &flags);
 	else
-		flags &= ~mask;
+		__clear_bit(bitnr, &flags);
 
-	if (flags != p->flags) {
-		err = br_switchdev_set_port_flag(p, flags, mask, &extack);
-		if (err) {
-			netdev_err(p->dev, "%s\n", extack._msg);
-			return err;
-		}
+	if (flags == oflags)
+		return 0;
 
-		p->flags = flags;
-		br_port_flags_change(p, mask);
+	err = br_switchdev_set_port_flag(p, flags, BIT(bitnr), &extack);
+	if (err) {
+		netdev_err(p->dev, "%s\n", extack._msg);
+		return err;
 	}
+	if (v)
+		set_bit(bitnr, &p->flags);
+	else
+		clear_bit(bitnr, &p->flags);
+	br_port_flags_change(p, BIT(bitnr));
 	return 0;
 }
 
@@ -247,17 +252,17 @@ static int store_backup_port(struct net_bridge_port *p, char *buf)
 }
 static BRPORT_ATTR_RAW(backup_port, 0644, show_backup_port, store_backup_port);
 
-BRPORT_ATTR_FLAG(hairpin_mode, BR_HAIRPIN_MODE);
-BRPORT_ATTR_FLAG(bpdu_guard, BR_BPDU_GUARD);
-BRPORT_ATTR_FLAG(root_block, BR_ROOT_BLOCK);
-BRPORT_ATTR_FLAG(learning, BR_LEARNING);
-BRPORT_ATTR_FLAG(unicast_flood, BR_FLOOD);
-BRPORT_ATTR_FLAG(proxyarp, BR_PROXYARP);
-BRPORT_ATTR_FLAG(proxyarp_wifi, BR_PROXYARP_WIFI);
-BRPORT_ATTR_FLAG(multicast_flood, BR_MCAST_FLOOD);
-BRPORT_ATTR_FLAG(broadcast_flood, BR_BCAST_FLOOD);
-BRPORT_ATTR_FLAG(neigh_suppress, BR_NEIGH_SUPPRESS);
-BRPORT_ATTR_FLAG(isolated, BR_ISOLATED);
+BRPORT_ATTR_FLAG(hairpin_mode, BR_HAIRPIN_MODE_BIT);
+BRPORT_ATTR_FLAG(bpdu_guard, BR_BPDU_GUARD_BIT);
+BRPORT_ATTR_FLAG(root_block, BR_ROOT_BLOCK_BIT);
+BRPORT_ATTR_FLAG(learning, BR_LEARNING_BIT);
+BRPORT_ATTR_FLAG(unicast_flood, BR_FLOOD_BIT);
+BRPORT_ATTR_FLAG(proxyarp, BR_PROXYARP_BIT);
+BRPORT_ATTR_FLAG(proxyarp_wifi, BR_PROXYARP_WIFI_BIT);
+BRPORT_ATTR_FLAG(multicast_flood, BR_MCAST_FLOOD_BIT);
+BRPORT_ATTR_FLAG(broadcast_flood, BR_BCAST_FLOOD_BIT);
+BRPORT_ATTR_FLAG(neigh_suppress, BR_NEIGH_SUPPRESS_BIT);
+BRPORT_ATTR_FLAG(isolated, BR_ISOLATED_BIT);
 
 #ifdef CONFIG_BRIDGE_IGMP_SNOOPING
 static ssize_t show_multicast_router(struct net_bridge_port *p, char *buf)
@@ -273,8 +278,8 @@ static int store_multicast_router(struct net_bridge_port *p,
 static BRPORT_ATTR(multicast_router, 0644, show_multicast_router,
 		   store_multicast_router);
 
-BRPORT_ATTR_FLAG(multicast_fast_leave, BR_MULTICAST_FAST_LEAVE);
-BRPORT_ATTR_FLAG(multicast_to_unicast, BR_MULTICAST_TO_UNICAST);
+BRPORT_ATTR_FLAG(multicast_fast_leave, BR_MULTICAST_FAST_LEAVE_BIT);
+BRPORT_ATTR_FLAG(multicast_to_unicast, BR_MULTICAST_TO_UNICAST_BIT);
 #endif
 
 static const struct brport_attribute *brport_attrs[] = {
-- 
2.54.0.1099.g489fc7bff1-goog