On Mon, Sep 8, 2008 at 10:46 PM, David Miller <davem@xxxxxxxxxxxxx> wrote: > From: Stephen Hemminger <shemminger@xxxxxxxxxx> > Date: Thu, 4 Sep 2008 15:47:09 -0700 > >> 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@xxxxxxxxxx> > > Applied, thanks Stephen. > > I added more information to the commit message so that Dushan's > incredibly contribution to this bug getting fixed are mentioned. > I don't see how we would have figured out Bridging as even the > cause without his detective work. So it's definitely wrong not > to give him at least some mention in the commit message :-/ > I don't know what to say :) Thank you > 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. > A little nitpick: 200 times greater context switch rate :), like 100000 per second. > He then correlated this with a report by bdupree@xxxxxxxxxxxxxxx: > > 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. Btw. is there a way to make the command to turn STP off work too? brctl stp br0 off Because AFAIK if I shut down STP the hello timer should shut down too, but it still continues to work. Thank you for your time and effort Dushan Tcholich > > Signed-off-by: Stephen Hemminger <shemminger@xxxxxxxxxx> > Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx> > --- > net/bridge/br_ioctl.c | 8 +++++++- > net/bridge/br_sysfs_br.c | 26 ++++++++++++++++++-------- > 2 files changed, 25 insertions(+), 9 deletions(-) > > 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 @@ 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)) > diff --git a/net/bridge/br_sysfs_br.c b/net/bridge/br_sysfs_br.c > index 27d6a51..158dee8 100644 > --- a/net/bridge/br_sysfs_br.c > +++ b/net/bridge/br_sysfs_br.c > @@ -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, > -- > 1.5.6.5.GIT > > _______________________________________________ Bridge mailing list Bridge@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/bridge
