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

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20170207084646.70dc888a@xeon-e3>
Date:   Tue, 7 Feb 2017 08:46:46 -0800
From:   Stephen Hemminger <stephen@...workplumber.org>
To:     Nikolay Aleksandrov <nikolay@...ulusnetworks.com>
Cc:     netdev@...r.kernel.org, roopa@...ulusnetworks.com,
        davem@...emloft.net, bridge@...ts.linux-foundation.org
Subject: [PATCH net-next] bridge: avoid unnecessary read of jiffies


Jiffies is volatile so read it once.

Signed-off-by: Stephen Hemminger <sthemmin@...rosoft.com>
---
 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