Re: [B.A.T.M.A.N.] [PATCH maint] batman-adv: wait for rtnl in batadv_store_mesh_iface instead of failing if it is taken

[Simon Wunderlich <simon.wunderlich@s2003.tu-chemnitz.de>]

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On Tue, May 28, 2013 at 05:32:32PM +0200, Matthias Schiffer wrote:
> The rtnl_lock in batadv_store_mesh_iface has been converted to a rtnl_trylock
> some time ago to avoid a possible deadlock between rtnl and s_active on removal
> of the sysfs nodes.
> 
> The behaviour introduced by that was quite confusing as it could lead to the
> sysfs store to fail, making batman-adv setup scripts unreliable. As recently the
> sysfs removal was postponed to a worker not running with the rtnl taken, the
> deadlock can't occur any more and it is safe to change the trylock back to a
> lock to make the sysfs store reliable again.
> 
> Signed-off-by: Matthias Schiffer <mschiffer@universe-factory.net>

Reviewed-by: Simon Wunderlich <siwu@hrz.tu-chemnitz.de>

Thanks for posting,
	Simon

> ---
>  sysfs.c | 5 +----
>  1 file changed, 1 insertion(+), 4 deletions(-)
> 
> diff --git a/sysfs.c b/sysfs.c
> index 15a22ef..929e304 100644
> --- a/sysfs.c
> +++ b/sysfs.c
> @@ -582,10 +582,7 @@ static ssize_t batadv_store_mesh_iface(struct kobject *kobj,
>  	    (strncmp(hard_iface->soft_iface->name, buff, IFNAMSIZ) == 0))
>  		goto out;
>  
> -	if (!rtnl_trylock()) {
> -		ret = -ERESTARTSYS;
> -		goto out;
> -	}
> +	rtnl_lock();
>  
>  	if (status_tmp == BATADV_IF_NOT_IN_USE) {
>  		batadv_hardif_disable_interface(hard_iface,
> -- 
> 1.8.3
> 

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