[Intel-gfx] [PATCH] drm/i915: Reword warning for missing cases

[Ville Syrjälä]

On Tue, Mar 13, 2018 at 12:17:13AM +0000, Chris Wilson wrote:
> Quoting Lucas De Marchi (2018-03-13 00:03:12)
> > In some places we end up converting switch statements to a series of
> > if/else, particularly when introducing helper functions to handle a
> > group of cases. It's tempting to either leave a wrong warning (since now
> > we don't have a switch case anymore) or to convert to WARN(1, ...),
> > losing what MISSING_CASE() provides: source location and id number.
> > 
> > Fix the message to allow reusing MISSING_CASE() - it may not always be
> > correct (e.g. if you are not checking an id anymore), but it avoids
> > useless conversions. A quick grep reveals at least a few users in
> > drivers/gpu/drm/i915/intel_csr.c and drivers/gpu/drm/i915/intel_ddi.c.
> > 
> > Signed-off-by: Lucas De Marchi <lucas.demarchi at intel.com>
> > ---
> >  drivers/gpu/drm/i915/i915_utils.h | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/i915_utils.h b/drivers/gpu/drm/i915/i915_utils.h
> > index 51dbfe5bb418..8cdc21b92f5f 100644
> > --- a/drivers/gpu/drm/i915/i915_utils.h
> > +++ b/drivers/gpu/drm/i915/i915_utils.h
> > @@ -40,7 +40,7 @@
> >  #undef WARN_ON_ONCE
> >  #define WARN_ON_ONCE(x) WARN_ONCE((x), "%s", "WARN_ON_ONCE(" __stringify(x) ")")
> >  
> > -#define MISSING_CASE(x) WARN(1, "Missing switch case (%lu) in %s\n", \
> > +#define MISSING_CASE(x) WARN(1, "Missing case (%lu) in %s\n", \
> >                              (long)(x), __func__)
> 
> Whilst here you could make this more informative by:
> "Missing case (%s = %lu) in %s\n", __stringify(x), (long)(x), __func__

The backtrace isn't enough?

> 
> Also these should only be compiled for dev/CI as we have a few pages
> worth of them.
> -Chris
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-- 
Ville Syrjälä
Intel OTC