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Subject: Re: [B.A.T.M.A.N.] [PATCH] batman-adv: silence smatch errors in
 multicast compat code
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On Mon, Nov 11, 2013 at 05:33:09PM +0100, Simon Wunderlich wrote:
> diff --git a/compat.h b/compat.h
> index 186547b..a99c9d5 100644
> --- a/compat.h
> +++ b/compat.h
> @@ -160,14 +160,12 @@ static inline int batadv_param_set_copystring(const char *val,
>  #define NET_ADDR_RANDOM 0
>  
>  #define netdev_master_upper_dev_get_rcu(dev) \
> -	upper; \
> -	rcu_read_unlock(); \
> +	NULL; \
>  	if (dev->br_port ? 1 : 0) { \
> +		rcu_read_unlock(); \
>  		dev_hold(dev); \
>  		return dev; \
>  	} \
> -\
> -	return NULL\
>

This approach unfortunately doesn't work and leads to crashes
because we assign NULL to upper and therefore dev, too, leading to
a null pointer exception when trying to access dev->br-port.

As the smatch warning is just a compat warning not leading to any
issues despite that, could we simply silence the build system to
ignore this instead?