BUG: when using 'brctl stp'

BUG: when using 'brctl stp'

[Daniel K.]

I get this on the latest GIT, it was also present shortly after -rc1.
I have not tested with earlier kernels.

# brctl stp br0 on
[  169.672008] BUG: sleeping function called from invalid context at kernel/mutex.c:86
[  169.672532] in_atomic():1, irqs_disabled():0
[  169.672832] 
[  169.672832] Call Trace:
[  169.673406]  [<ffffffff8125db3a>] mutex_lock+0x19/0x2f
[  169.673696]  [<ffffffff81067135>] __alloc_pages+0x71/0x2d3
[  169.673996]  [<ffffffff881e0abc>] :bridge:set_stp_state+0x12/0x37
[  169.674293]  [<ffffffff881e0a0a>] :bridge:store_bridge_parm+0x5f/0x79
[  169.674587]  [<ffffffff810ceb24>] sysfs_write_file+0xf2/0x134
[  169.674879]  [<ffffffff8108b3ad>] vfs_write+0xce/0x177
[  169.675170]  [<ffffffff8108b970>] sys_write+0x45/0x6e
[  169.675463]  [<ffffffff8100bc8e>] system_call+0x7e/0x83
[  169.675769] 
[  169.676139] br0: starting userspace STP failed, staring kernel STP

# brctl stp br0 off
[  171.774500] BUG: sleeping function called from invalid context at kernel/mutex.c:86
[  171.775040] in_atomic():1, irqs_disabled():0
[  171.775327] 
[  171.775328] Call Trace:
[  171.775906]  [<ffffffff8125db3a>] mutex_lock+0x19/0x2f
[  171.776195]  [<ffffffff81067135>] __alloc_pages+0x71/0x2d3
[  171.776496]  [<ffffffff881e0abc>] :bridge:set_stp_state+0x12/0x37
[  171.776792]  [<ffffffff881e0a0a>] :bridge:store_bridge_parm+0x5f/0x79
[  171.777086]  [<ffffffff810ceb24>] sysfs_write_file+0xf2/0x134
[  171.777378]  [<ffffffff8108b3ad>] vfs_write+0xce/0x177
[  171.777669]  [<ffffffff8108b970>] sys_write+0x45/0x6e
[  171.777958]  [<ffffffff8100bc8e>] system_call+0x7e/0x83
[  171.778250] 


Daniel K.

Re: BUG: when using 'brctl stp'

[Stephen Hemminger]

Bridge locking for /sys/class/net/br0/bridge/stp_enabled
was wrong.  Another bug in bridge utilities makes it such that
this interface, meant it wasn't being used.  The locking needs to be removed
from set_stp_state(), the lock is already acquired down in
br_stp_start()/br_stp_stop.

Signed-off-by: Stephen Hemminger <shemminger@linux-foundation.org>


--- a/net/bridge/br_sysfs_br.c	2007-07-16 14:24:18.000000000 +0100
+++ b/net/bridge/br_sysfs_br.c	2007-08-14 13:44:23.000000000 +0100
@@ -150,9 +150,7 @@ static ssize_t show_stp_state(struct dev
 static void set_stp_state(struct net_bridge *br, unsigned long val)
 {
 	rtnl_lock();
-	spin_unlock_bh(&br->lock);
 	br_stp_set_enabled(br, val);
-	spin_lock_bh(&br->lock);
 	rtnl_unlock();
 }
 

Re: BUG: when using 'brctl stp'

[Lennert Buytenhek]

On Tue, Aug 14, 2007 at 02:11:05PM +0100, Stephen Hemminger wrote:

> Bridge locking for /sys/class/net/br0/bridge/stp_enabled
> was wrong.  Another bug in bridge utilities makes it such that
> this interface, meant it wasn't being used.  The locking needs
> to be removed from set_stp_state(), the lock is already acquired
> down in br_stp_start()/br_stp_stop.

The 'locking' in set_stp_state() is actually dropping the lock
around the br_stp_set_enabled() invocation, not acquiring it:


> @@ -150,9 +150,7 @@ static ssize_t show_stp_state(struct dev
>  static void set_stp_state(struct net_bridge *br, unsigned long val)
>  {
>  	rtnl_lock();
> -	spin_unlock_bh(&br->lock);
>  	br_stp_set_enabled(br, val);
> -	spin_lock_bh(&br->lock);
>  	rtnl_unlock();
>  }

[PATCH] bridge: sysfs locking fix.

[Stephen Hemminger]

Forget earlier patch, it is wrong...

The stp change code generates "sleeping function called from invalid context"
because rtnl_lock() called with BH disabled. This fixes it by not acquiring then
dropping the bridge lock.

Signed-off-by: Stephen Hemminger <shemminger@linux-foundation.org>

--- a/net/bridge/br_sysfs_br.c	2007-08-06 09:26:48.000000000 +0100
+++ b/net/bridge/br_sysfs_br.c	2007-08-14 14:29:52.000000000 +0100
@@ -147,20 +147,26 @@ static ssize_t show_stp_state(struct dev
 	return sprintf(buf, "%d\n", br->stp_enabled);
 }
 
-static void set_stp_state(struct net_bridge *br, unsigned long val)
-{
-	rtnl_lock();
-	spin_unlock_bh(&br->lock);
-	br_stp_set_enabled(br, val);
-	spin_lock_bh(&br->lock);
-	rtnl_unlock();
-}
 
 static ssize_t store_stp_state(struct device *d,
 			       struct device_attribute *attr, const char *buf,
 			       size_t len)
 {
-	return store_bridge_parm(d, buf, len, set_stp_state);
+	struct net_bridge *br = to_bridge(d);
+	char *endp;
+	unsigned long val;
+
+	if (!capable(CAP_NET_ADMIN))
+		return -EPERM;
+
+	val = simple_strtoul(buf, &endp, 0);
+	if (endp == buf)
+		return -EINVAL;
+
+	rtnl_lock();
+	br_stp_set_enabled(br, val);
+	rtnl_unlock();
+
 }
 static DEVICE_ATTR(stp_state, S_IRUGO | S_IWUSR, show_stp_state,
 		   store_stp_state);

Re: [PATCH] bridge: sysfs locking fix.

[David Miller]

From: Stephen Hemminger <shemminger@linux-foundation.org>
Date: Tue, 14 Aug 2007 14:50:52 +0100

> Forget earlier patch, it is wrong...
> 
> The stp change code generates "sleeping function called from invalid context"
> because rtnl_lock() called with BH disabled. This fixes it by not acquiring then
> dropping the bridge lock.
> 
> Signed-off-by: Stephen Hemminger <shemminger@linux-foundation.org>

Applied, thanks Stephen.

Re: [PATCH] bridge: sysfs locking fix.

[Daniel Lezcano]

Stephen Hemminger wrote:
> Forget earlier patch, it is wrong...
> 
> The stp change code generates "sleeping function called from invalid context"
> because rtnl_lock() called with BH disabled. This fixes it by not acquiring then
> dropping the bridge lock.
> 
> Signed-off-by: Stephen Hemminger <shemminger@linux-foundation.org>
> 
> --- a/net/bridge/br_sysfs_br.c	2007-08-06 09:26:48.000000000 +0100
> +++ b/net/bridge/br_sysfs_br.c	2007-08-14 14:29:52.000000000 +0100
> @@ -147,20 +147,26 @@ static ssize_t show_stp_state(struct dev
>  	return sprintf(buf, "%d\n", br->stp_enabled);
>  }
> 
> -static void set_stp_state(struct net_bridge *br, unsigned long val)
> -{
> -	rtnl_lock();
> -	spin_unlock_bh(&br->lock);
> -	br_stp_set_enabled(br, val);
> -	spin_lock_bh(&br->lock);
> -	rtnl_unlock();
> -}
> 
>  static ssize_t store_stp_state(struct device *d,
>  			       struct device_attribute *attr, const char *buf,
>  			       size_t len)
>  {
> -	return store_bridge_parm(d, buf, len, set_stp_state);
> +	struct net_bridge *br = to_bridge(d);
> +	char *endp;
> +	unsigned long val;
> +
> +	if (!capable(CAP_NET_ADMIN))
> +		return -EPERM;
> +
> +	val = simple_strtoul(buf, &endp, 0);
> +	if (endp == buf)
> +		return -EINVAL;
> +
> +	rtnl_lock();
> +	br_stp_set_enabled(br, val);
> +	rtnl_unlock();
> +

Shouldn't len value be returned at the end of the function ?

>  }
>  static DEVICE_ATTR(stp_state, S_IRUGO | S_IWUSR, show_stp_state,
>  		   store_stp_state);
> -