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

Ville Syrjälä
2022-08-26T11:08:31Z

On Fri, Aug 26, 2022 at 11:38:14AM +0300, 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[].
>
> 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 118598c9a809..8dd405553cfa 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->dpll.shared_dplls)))
> + break;

Shame we can't neatly use a BUILD_BUG_ON() when assigning .dpll_info.

For patches 2-5
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>

> +
> drm_WARN_ON(&dev_priv->drm, i != dpll_info[i].id);
> dev_priv->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->dpll.mgr = dpll_mgr;
> dev_priv->dpll.num_shared_dpll = i;
> mutex_init(&dev_priv->dpll.lock);
> -
> - BUG_ON(dev_priv->dpll.num_shared_dpll > I915_NUM_PLLS);
> }
>
> /**
> --
> 2.34.1

--
Ville Syrjälä
Intel