[Intel-gfx] [PATCH] drm/i915: Initialise subslice prior to potential zero-length loop

[Summers, Stuart]

On Tue, 2019-06-04 at 11:49 +0300, Lionel Landwerlin wrote:
> On 29/05/2019 14:24, Chris Wilson wrote:
> > Appease static analysers by making sure subslice always have a
> > value.
> > 
> > drivers/gpu/drm/i915//gt/intel_engine_cs.c:971
> > intel_sseu_fls_subslice() error: uninitialized symbol 'subslice'.
> > 
> > There's also the nagging question of whether that fls() is off-by-
> > one...
> > 
> > 
> > Fixes: 1ac159e23c2c ("drm/i915: Expand subslice mask")


Thanks for the patch! Given the above was reverted, I can incorporate
this in to the updates I push. I'll make sure to include you on that
review.

Thanks,
Stuart

> > Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> > Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio at intel.com>
> > Cc: Lionel Landwerlin <lionel.g.landwerlin at intel.com>
> > Cc: Stuart Summers <stuart.summers at intel.com>
> > Cc: Manasi Navare <manasi.d.navare at intel.com>
> 
> 
> Stuart should probably rb this too as he's been looking after this 
> topology stuff.
> 
> Looks good to me :
> 
> 
> Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin at intel.com>
> 
> 
> > ---
> >   drivers/gpu/drm/i915/gt/intel_engine_cs.c | 6 +++---
> >   1 file changed, 3 insertions(+), 3 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/gt/intel_engine_cs.c
> > b/drivers/gpu/drm/i915/gt/intel_engine_cs.c
> > index 158722b50691..fc880424be2f 100644
> > --- a/drivers/gpu/drm/i915/gt/intel_engine_cs.c
> > +++ b/drivers/gpu/drm/i915/gt/intel_engine_cs.c
> > @@ -956,12 +956,12 @@ const char *i915_cache_level_str(struct
> > drm_i915_private *i915, int type)
> >   static inline u32
> >   intel_sseu_fls_subslice(const struct sseu_dev_info *sseu, u32
> > slice)
> >   {
> > -	u32 subslice;
> > +	const u8 *subslice_mask = sseu->subslice_mask + slice * sseu-
> > >ss_stride;
> > +	u32 subslice = 0;
> >   	int i;
> >   
> >   	for (i = sseu->ss_stride - 1; i >= 0; i--) {
> > -		subslice = fls(sseu->subslice_mask[slice * sseu-
> > >ss_stride +
> > -						   i]);
> > +		subslice = fls(subslice_mask[i]);
> >   		if (subslice) {
> >   			subslice += i * BITS_PER_BYTE;
> >   			break;
> 
> 
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