bridge: don't allow setting hello time to zero
Dushan Tcholich reports that on his system ksoftirqd can consume
between %6 to %10 of cpu time, and cause ~200 context switches per
second.
He then correlated this with a report by bdupree@techfinesse.com:
http://marc.info/?l=linux-kernel&m=119613299024398&w=2
and the culprit cause seems to be starting the bridge interface.
In particular, when starting the bridge interface, his scripts
are specifying a hello timer interval of "0".
The bridge hello time can't be safely set to values less than 1
second, otherwise it is possible to end up with a runaway timer.
Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/bridge/br_ioctl.c b/net/bridge/br_ioctl.c
index eeee218..5bbf073 100644
--- a/net/bridge/br_ioctl.c
+++ b/net/bridge/br_ioctl.c
@@ -188,15 +188,21 @@
return 0;
case BRCTL_SET_BRIDGE_HELLO_TIME:
+ {
+ unsigned long t = clock_t_to_jiffies(args[1]);
if (!capable(CAP_NET_ADMIN))
return -EPERM;
+ if (t < HZ)
+ return -EINVAL;
+
spin_lock_bh(&br->lock);
- br->bridge_hello_time = clock_t_to_jiffies(args[1]);
+ br->bridge_hello_time = t;
if (br_is_root_bridge(br))
br->hello_time = br->bridge_hello_time;
spin_unlock_bh(&br->lock);
return 0;
+ }
case BRCTL_SET_BRIDGE_MAX_AGE:
if (!capable(CAP_NET_ADMIN))