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Commit 8d4698f7 authored by Stephen Hemminger's avatar Stephen Hemminger Committed by David S. Miller
Browse files

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: default avatarStephen Hemminger <shemminger@vyatta.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent d315492b

net/bridge/br_ioctl.c

+7 −1
Original line number Diff line number Diff line
@@ -188,15 +188,21 @@ static int old_dev_ioctl(struct net_device *dev, struct ifreq *rq, int cmd) 
		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))

net/bridge/br_sysfs_br.c

+18 −8
Original line number Diff line number Diff line
@@ -29,11 +29,12 @@ 
 */

static ssize_t store_bridge_parm(struct device *d,

				 const char *buf, size_t len,

				 void (*set)(struct net_bridge *, unsigned long))

				 int (*set)(struct net_bridge *, unsigned long))

{

	struct net_bridge *br = to_bridge(d);

	char *endp;

	unsigned long val;

	int err;



	if (!capable(CAP_NET_ADMIN))

		return -EPERM;
@@ -43,9 +44,9 @@ static ssize_t store_bridge_parm(struct device *d, 
		return -EINVAL;



	spin_lock_bh(&br->lock);

	(*set)(br, val);

	err = (*set)(br, val);

	spin_unlock_bh(&br->lock);

	return len;

	return err ? err : len;

}
@@ -56,12 +57,13 @@ static ssize_t show_forward_delay(struct device *d, 
	return sprintf(buf, "%lu\n", jiffies_to_clock_t(br->forward_delay));

}



static void set_forward_delay(struct net_bridge *br, unsigned long val)

static int set_forward_delay(struct net_bridge *br, unsigned long val)

{

	unsigned long delay = clock_t_to_jiffies(val);

	br->forward_delay = delay;

	if (br_is_root_bridge(br))

		br->bridge_forward_delay = delay;

	return 0;

}



static ssize_t store_forward_delay(struct device *d,
@@ -80,12 +82,17 @@ static ssize_t show_hello_time(struct device *d, struct device_attribute *attr, 
		       jiffies_to_clock_t(to_bridge(d)->hello_time));

}



static void set_hello_time(struct net_bridge *br, unsigned long val)

static int set_hello_time(struct net_bridge *br, unsigned long val)

{

	unsigned long t = clock_t_to_jiffies(val);



	if (t < HZ)

		return -EINVAL;



	br->hello_time = t;

	if (br_is_root_bridge(br))

		br->bridge_hello_time = t;

	return 0;

}



static ssize_t store_hello_time(struct device *d,
@@ -104,12 +111,13 @@ static ssize_t show_max_age(struct device *d, struct device_attribute *attr, 
		       jiffies_to_clock_t(to_bridge(d)->max_age));

}



static void set_max_age(struct net_bridge *br, unsigned long val)

static int set_max_age(struct net_bridge *br, unsigned long val)

{

	unsigned long t = clock_t_to_jiffies(val);

	br->max_age = t;

	if (br_is_root_bridge(br))

		br->bridge_max_age = t;

	return 0;

}



static ssize_t store_max_age(struct device *d, struct device_attribute *attr,
@@ -126,9 +134,10 @@ static ssize_t show_ageing_time(struct device *d, 
	return sprintf(buf, "%lu\n", jiffies_to_clock_t(br->ageing_time));

}



static void set_ageing_time(struct net_bridge *br, unsigned long val)

static int set_ageing_time(struct net_bridge *br, unsigned long val)

{

	br->ageing_time = clock_t_to_jiffies(val);

	return 0;

}



static ssize_t store_ageing_time(struct device *d,
@@ -180,9 +189,10 @@ static ssize_t show_priority(struct device *d, struct device_attribute *attr, 
		       (br->bridge_id.prio[0] << 8) | br->bridge_id.prio[1]);

}



static void set_priority(struct net_bridge *br, unsigned long val)

static int set_priority(struct net_bridge *br, unsigned long val)

{

	br_stp_set_bridge_priority(br, (u16) val);

	return 0;

}



static ssize_t store_priority(struct device *d, struct device_attribute *attr,