Subject: [PATCH net-next] bridge: avoid unnecessary read of jiffies

From: Stephen Hemminger <[email-masked]>
Date: Tue, 7 Feb 2017 08:46:46 -0800

Jiffies is volatile so read it once.

Signed-off-by: Stephen Hemminger <[email-masked]>
---
 net/bridge/br_fdb.c   | 6 ++++--
 net/bridge/br_input.c | 6 ++++--
 2 files changed, 8 insertions(+), 4 deletions(-)

diff --git a/net/bridge/br_fdb.c b/net/bridge/br_fdb.c
index 5028691fa68a..5693168e88b6 100644
--- a/net/bridge/br_fdb.c
+++ b/net/bridge/br_fdb.c
@@ -592,13 +592,15 @@ void br_fdb_update(struct net_bridge *br, struct net_bridge_port *source,
 				br_warn(br, "received packet on %s with own address as source address (addr:%pM, vlan:%u)\n",
 					source->dev->name, addr, vid);
 		} else {
+			unsigned long now = jiffies;
+
 			/* fastpath: update of existing entry */
 			if (unlikely(source != fdb->dst)) {
 				fdb->dst = source;
 				fdb_modified = true;
 			}
-			if (jiffies != fdb->updated)
-				fdb->updated = jiffies;
+			if (now != fdb->updated)
+				fdb->updated = now;
 			if (unlikely(added_by_user))
 				fdb->added_by_user = 1;
 			if (unlikely(fdb_modified))
diff --git a/net/bridge/br_input.c b/net/bridge/br_input.c
index 220943f920d2..4615a9b3e26c 100644
--- a/net/bridge/br_input.c
+++ b/net/bridge/br_input.c
@@ -195,11 +195,13 @@ int br_handle_frame_finish(struct net *net, struct sock *sk, struct sk_buff *skb
 	}
 
 	if (dst) {
+		unsigned long now = jiffies;
+
 		if (dst->is_local)
 			return br_pass_frame_up(skb);
 
-		if (jiffies != dst->used)
-			dst->used = jiffies;
+		if (now != dst->used)
+			dst->used = now;
 		br_forward(dst->dst, skb, local_rcv, false);
 	} else {
 		if (!mcast_hit)
-- 
2.11.0