Re: [PATCH] drm/i915: Check mask/bit helper functions

[Jani Nikula <jani.nikula@linux.intel.com>]

On Mon, 08 Dec 2014, Daniel Vetter <daniel.vetter@ffwll.ch> wrote:
> After a bit of irc discussion we've concluded that it would be prudent
> to check that callers use the mask/enable paramters correctly. So add
> a WARN_ON.
>
> Spurred by Damien's bugfix which added _MASKED_FIELD.
>
> v2: We use WARN_ON(1) a lot to catch default cases in switch blocks
> which should always be extended. So this doesn't work really. Dunno
> why gcc only started complaining when I've moved the WARN out of the
> static inline helper to address a feedback from Jani.

Ah, that would be precisely because of the static inline helper. The
function parameter is never a builtin constant!

BR,
Jani.


>
> Cc: Damien Lespiau <damien.lespiau@intel.com>
> Cc: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: Jani Nikula <jani.nikula@linux.intel.com>
> Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
> ---
>  drivers/gpu/drm/i915/i915_irq.c | 6 ++++++
>  1 file changed, 6 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
> index 08a5a4ba52ac..e6a1db36928e 100644
> --- a/drivers/gpu/drm/i915/i915_irq.c
> +++ b/drivers/gpu/drm/i915/i915_irq.c
> @@ -183,6 +183,8 @@ static void ilk_update_gt_irq(struct drm_i915_private *dev_priv,
>  {
>  	assert_spin_locked(&dev_priv->irq_lock);
>  
> +	WARN_ON(enabled_irq_mask & ~interrupt_mask);
> +
>  	if (WARN_ON(!intel_irqs_enabled(dev_priv)))
>  		return;
>  
> @@ -229,6 +231,8 @@ static void snb_update_pm_irq(struct drm_i915_private *dev_priv,
>  {
>  	uint32_t new_val;
>  
> +	WARN_ON(enabled_irq_mask & ~interrupt_mask);
> +
>  	assert_spin_locked(&dev_priv->irq_lock);
>  
>  	new_val = dev_priv->pm_irq_mask;
> @@ -328,6 +332,8 @@ void ibx_display_interrupt_update(struct drm_i915_private *dev_priv,
>  	sdeimr &= ~interrupt_mask;
>  	sdeimr |= (~enabled_irq_mask & interrupt_mask);
>  
> +	WARN_ON(enabled_irq_mask & ~interrupt_mask);
> +
>  	assert_spin_locked(&dev_priv->irq_lock);
>  
>  	if (WARN_ON(!intel_irqs_enabled(dev_priv)))
> -- 
> 2.1.1
>

-- 
Jani Nikula, Intel Open Source Technology Center
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