[NETFILTER]: nf_conntrack: reduce timer updates in __nf_ct_refresh_acct()

Only update the conntrack timer if there's been at least HZ jiffies since
the last update. Reduces the number of del_timer/add_timer cycles from one
per packet to one per connection per second (plus once for each state change
of a connection)

Should handle timer wraparounds and connection timeout changes.

Signed-off-by: Martin Josefsson <gandalf@wlug.westbo.se>
Signed-off-by: Patrick McHardy <kaber@trash.net>

1 files changed, 8 insertions, 3 deletions

diff --git a/net/netfilter/nf_conntrack_core.c b/net/netfilter/nf_conntrack_core.c
index 355b330c214e..3e7c0a90003a 100644
--- a/net/netfilter/nf_conntrack_core.c
+++ b/net/netfilter/nf_conntrack_core.c
@@ -864,9 +864,14 @@ void __nf_ct_refresh_acct(struct nf_conn *ct,
                 ct->timeout.expires = extra_jiffies;
                 event = IPCT_REFRESH;
         } else {
-                /* Need del_timer for race avoidance (may already be dying). */
-                if (del_timer(&ct->timeout)) {
-                        ct->timeout.expires = jiffies + extra_jiffies;
+                unsigned long newtime = jiffies + extra_jiffies;
+
+                /* Only update the timeout if the new timeout is at least
+                   HZ jiffies from the old timeout. Need del_timer for race
+                   avoidance (may already be dying). */
+                if (newtime - ct->timeout.expires >= HZ
+                    && del_timer(&ct->timeout)) {
+                        ct->timeout.expires = newtime;
                         add_timer(&ct->timeout);
                         event = IPCT_REFRESH;
                 }