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

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

On Mon, 08 Dec 2014, Jani Nikula <jani.nikula@linux.intel.com> wrote:
> 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!

What I learned today: This holds for -O0.

>
> 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

-- 
Jani Nikula, Intel Open Source Technology Center
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