Re: [PATCH v2 1/2] platform/x86: Add new Dell UART backlight driver

[Andy Shevchenko <andy@kernel.org>]

On Mon, May 13, 2024 at 06:54:25PM +0300, Ilpo Järvinen wrote:
> On Mon, 13 May 2024, Andy Shevchenko wrote:
> > On Mon, May 13, 2024 at 05:33:10PM +0200, Hans de Goede wrote:
> > > On 5/13/24 5:19 PM, Andy Shevchenko wrote:
> > > > On Mon, May 13, 2024 at 03:18:10PM +0200, Hans de Goede wrote:
> > > >> On 5/13/24 2:58 PM, Andy Shevchenko wrote:
> > > >>> On Mon, May 13, 2024 at 01:15:50PM +0200, Hans de Goede wrote:
> > 
> > > >>>> +static int dell_uart_bl_command(struct dell_uart_backlight *dell_bl,
> > > >>>> +				const u8 *cmd, int cmd_len,
> > > >>>> +				u8 *resp, int resp_max_len)
> > > >>>> +{
> > > >>>> +	int ret;
> > > >>>> +
> > > >>>> +	ret = mutex_lock_killable(&dell_bl->mutex);
> > > >>>
> > > >>> Can't be called via cleanup.h?
> > > >>
> > > >> I prefer to have the locking explicit rather then use cleanup.h .
> > > > 
> > > > Hmm... interesting, so you push-back the cleanup.h usage?
> > > 
> > > I'm in favor of the guard(mutex)(&smne_mutex); syntax, but this
> > > is a mutex_lock_killable() for which that does not work AFAIK.
> > > 
> > > So in this case AFAICT we would need to use the cleanup stuff manually
> > > and in that case I believe that in that case just sticking with
> > > the current code is better.
> > 
> > There is scoped_cond_guard().
> > But there is no DEFINE_GUARD_COND() for mutex_lock_killable().
> 
> Is there a way to return the original error code with scoped_cond_guard() 
> or does that it force overriding the original return value with a 
> hard-coded one provided by the caller which seems a step backwards?

Yeah, that's also a downside. Perhaps you can reply to the original thread
about this. But it seems it was developed for boolean type of functions w/o
thinking a lot about returned values.

-- 
With Best Regards,
Andy Shevchenko