netdev - Re: [PATCH] bridge: sysfs locking fix.

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Date:	Fri, 24 Aug 2007 10:18:07 +0200
From:	Daniel Lezcano <dlezcano@...osys.com>
To:	Stephen Hemminger <shemminger@...ux-foundation.org>
CC:	Lennert Buytenhek <buytenh@...tstofly.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	"David S. Miller" <davem@...emloft.net>, netdev@...r.kernel.org,
	bridge@...ux-foundation.org
Subject: Re: [PATCH] bridge: sysfs locking fix.

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@...ux-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);
> -

-
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