Re: [PATCH] mac80211: use BUG_ON and return -EINVAL if rate_lowest_index() fails

["Arend van Spriel" <arend@broadcom.com>]

On 06/16/2011 12:02 AM, Pavel Roskin wrote:
> WARN_ON is not enough, as we cannot return a valid index, and the
> callers will use whatever we return, causing a cascade of oopses and
> eventually a panic.
>
> Signed-off-by: Pavel Roskin<proski@gnu.org>
> ---
>   0 files changed, 0 insertions(+), 0 deletions(-)
>
> diff --git a/include/net/mac80211.h b/include/net/mac80211.h
> index e33fe79..d117019 100644
> --- a/include/net/mac80211.h
> +++ b/include/net/mac80211.h
> @@ -3108,10 +3108,10 @@ rate_lowest_index(struct ieee80211_supported_band *sband,
>   		if (rate_supported(sta, sband->band, i))
>   			return i;
>
> -	/* warn when we cannot find a rate. */
> -	WARN_ON(1);
> +	/* If we cannot find any rate, we are in trouble. */
> +	BUG_ON(1);
>
> -	return 0;
> +	return -EINVAL;
>   }

I would expect some description what the caller should do when -EINVAL 
is returned. Could even argue whether you want a BUG_ON or allow the 
caller (driver) to reset the hardware, reassociate, etc. upon -EINVAL. I 
am not sure under which circumstances this could happen so there may 
really be no way out.

Gr. AvS

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