[Intel-gfx] [PATCH] drm/i915: Add might_sleep() check to wait_for()

[Mika Kuoppala]

Chris Wilson <chris at chris-wilson.co.uk> writes:

> We should long past the time of trying to use wait_for() from inside
> atomic contexts, so add a might_sleep() check to prevent misuse.
>
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> Cc: Tvrtko Ursulin <tvrtko.ursulin at intel.com>

Reviewed-by: Mika Kuoppala <mika.kuoppala at linux.intel.com>

> ---
>  drivers/gpu/drm/i915/intel_drv.h | 11 ++---------
>  1 file changed, 2 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
> index fd64a5e8ea12..a898ded7efe9 100644
> --- a/drivers/gpu/drm/i915/intel_drv.h
> +++ b/drivers/gpu/drm/i915/intel_drv.h
> @@ -47,14 +47,11 @@
>   * contexts. Note that it's important that we check the condition again after
>   * having timed out, since the timeout could be due to preemption or similar and
>   * we've never had a chance to check the condition before the timeout.
> - *
> - * TODO: When modesetting has fully transitioned to atomic, the below
> - * drm_can_sleep() can be removed and in_atomic()/!in_atomic() asserts
> - * added.
>   */
>  #define _wait_for(COND, US, W) ({ \
>  	unsigned long timeout__ = jiffies + usecs_to_jiffies(US) + 1;	\
>  	int ret__;							\
> +	might_sleep();							\
>  	for (;;) {							\
>  		bool expired__ = time_after(jiffies, timeout__);	\
>  		if (COND) {						\
> @@ -65,11 +62,7 @@
>  			ret__ = -ETIMEDOUT;				\
>  			break;						\
>  		}							\
> -		if ((W) && drm_can_sleep()) {				\
> -			usleep_range((W), (W)*2);			\
> -		} else {						\
> -			cpu_relax();					\
> -		}							\
> +		usleep_range((W), (W)*2);				\
>  	}								\
>  	ret__;								\
>  })
> -- 
> 2.15.0
>
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