Re: [Intel-gfx] [PATCH v2 2/5] drm/i915/dpll: replace BUG_ON() with drm_WARN_ON()

[Andrzej Hajda <andrzej.hajda@intel.com>]

On 30.08.2022 11:34, Jani Nikula wrote:
> Avoid BUG_ON(). Actually check the dpll count and bail out loudly with
> drm_WARN_ON() from the loop before overflowing
> i915->dpll.shared_dplls[].
> 
> v2: Rebase
> 
> Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> Signed-off-by: Jani Nikula <jani.nikula@intel.com>
> ---
>   drivers/gpu/drm/i915/display/intel_dpll_mgr.c | 6 ++++--
>   1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_dpll_mgr.c b/drivers/gpu/drm/i915/display/intel_dpll_mgr.c
> index bbe142056c7c..ed267c918009 100644
> --- a/drivers/gpu/drm/i915/display/intel_dpll_mgr.c
> +++ b/drivers/gpu/drm/i915/display/intel_dpll_mgr.c
> @@ -4199,6 +4199,10 @@ void intel_shared_dpll_init(struct drm_i915_private *dev_priv)
>   	dpll_info = dpll_mgr->dpll_info;
>   
>   	for (i = 0; dpll_info[i].name; i++) {
> +		if (drm_WARN_ON(&dev_priv->drm,
> +				i >= ARRAY_SIZE(dev_priv->display.dpll.shared_dplls)))
> +			break;
> +

Shouldn't this check be replaced by some compile time checker.
Anyway:
Reviewed-by: Andrzej Hajda <andrzej.hajda@intel.com>

Regards
Andrzej


>   		drm_WARN_ON(&dev_priv->drm, i != dpll_info[i].id);
>   		dev_priv->display.dpll.shared_dplls[i].info = &dpll_info[i];
>   	}
> @@ -4206,8 +4210,6 @@ void intel_shared_dpll_init(struct drm_i915_private *dev_priv)
>   	dev_priv->display.dpll.mgr = dpll_mgr;
>   	dev_priv->display.dpll.num_shared_dpll = i;
>   	mutex_init(&dev_priv->display.dpll.lock);
> -
> -	BUG_ON(dev_priv->display.dpll.num_shared_dpll > I915_NUM_PLLS);
>   }
>   
>   /**