Re: [PATCH v2] drm/i915: Initialise entry in intel_ppat_get() for older compilers

[Joonas Lahtinen <joonas.lahtinen@linux.intel.com>]

On Fri, 2017-11-17 at 13:32 +0000, Wang, Zhi A wrote:
> Thanks! Looks good to me.

An explicit Reviewed-by would probably be in place then? Then we get
the patch merged, too.

Regards, Joonas

> -----Original Message-----
> From: Chris Wilson [mailto:chris@chris-wilson.co.uk] 
> Sent: Wednesday, November 15, 2017 3:17 PM
> To: intel-gfx@lists.freedesktop.org
> Cc: Chris Wilson <chris@chris-wilson.co.uk>; Joonas Lahtinen <joonas.lahtinen@linux.intel.com>; Wang, Zhi A <zhi.a.wang@intel.com>; Ville Syrjälä <ville.syrjala@linux.intel.com>
> Subject: [PATCH v2] drm/i915: Initialise entry in intel_ppat_get() for older compilers
> 
> gcc-4.7.3 is confused by the guards inside intel_ppat_get() and reports:
> 
> drivers/gpu/drm/i915/i915_gem_gtt.c: In function ‘intel_ppat_get’:
> drivers/gpu/drm/i915/i915_gem_gtt.c:3044:27: warning: ‘entry’ may be used uninitialized in this function [-Wmaybe-uninitialized]
> 
> Forgive the compiler this once, and rearrange the code so that entry is always initialised.
> 
> v2: Flavour with a bit of NULL (instead of ERR_PTR(-ENOSPC).
> 
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
> Cc: Zhi Wang <zhi.a.wang@intel.com>
> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
> ---
>  drivers/gpu/drm/i915/i915_gem_gtt.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c b/drivers/gpu/drm/i915/i915_gem_gtt.c
> index 3c3a699436c9..f92a39fc511c 100644
> --- a/drivers/gpu/drm/i915/i915_gem_gtt.c
> +++ b/drivers/gpu/drm/i915/i915_gem_gtt.c
> @@ -3076,7 +3076,7 @@ const struct intel_ppat_entry *  intel_ppat_get(struct drm_i915_private *i915, u8 value)  {
>  	struct intel_ppat *ppat = &i915->ppat;
> -	struct intel_ppat_entry *entry;
> +	struct intel_ppat_entry *entry = NULL;
>  	unsigned int scanned, best_score;
>  	int i;
>  
> @@ -3099,7 +3099,7 @@ intel_ppat_get(struct drm_i915_private *i915, u8 value)
>  	}
>  
>  	if (scanned == ppat->max_entries) {
> -		if (!best_score)
> +		if (!entry)
>  			return ERR_PTR(-ENOSPC);
>  
>  		kref_get(&entry->ref);
> --
> 2.15.0
> 
-- 
Joonas Lahtinen
Open Source Technology Center
Intel Corporation
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