Re: [PATCH] therm_throt.c: Fix error handling in thermal_throttle_add_dev

[Ingo Molnar <mingo@elte.hu>]

* Fenghua Yu <fenghua.yu@intel.com> wrote:

> From: Fenghua Yu <fenghua.yu@intel.com>
> 
> Warn when sysfs_add_file_to_group fails.
> 
> Also add missing curly braces.
> 
> Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
> ---
>  arch/x86/kernel/cpu/mcheck/therm_throt.c |   14 ++++++++++----
>  1 files changed, 10 insertions(+), 4 deletions(-)

> +               WARN_ON(err);

Hm, we tend to use WARN_ON_ONCE(), to avoid repeat spamming of the 
syslog. Also, and perhaps more importantly, WARN_ON() is not a 
particularly smart way to handle errors. How do other drivers handle 
sysfs registration failures?

Also, that's not the only thing the patch does:

> @@ -211,20 +211,26 @@ static __cpuinit int thermal_throttle_add_dev(struct sys_device *sys_dev)

> -	return err;
> +	return 0;

How is the ignoring of an error and turning it into a WARN_ON() a fix? 
Either it makes no sense to return errors - in which case the whole 
add_dev method needs to be fixed in all drivers - or it makes sense, in 
which case the behavior here is inconsistent.

At minimum more explanation is needed in the changelog.

Thanks,

	Ingo