Re: [PATCH 05/19] drm/i915: Be irqsafe inside reset

[Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>]

On 17/05/2018 08:40, Chris Wilson wrote:
> As we want to be able to call i915_reset_engine and co from a softirq or

Just by glancing i915_reset_engine looks to heavy weight to ever be 
callable from softirq/timer context. There is even a flush_workqueue in 
there.

> timer context, we need to be irqsafe at all timers. So we have to forgo
> the simple spin_lock_irq for the full spin_lock_irqsave.
> 
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> ---
>   drivers/gpu/drm/i915/i915_gem.c | 6 ++++--
>   1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
> index 03874b50ada9..a3885adec78a 100644
> --- a/drivers/gpu/drm/i915/i915_gem.c
> +++ b/drivers/gpu/drm/i915/i915_gem.c
> @@ -3137,15 +3137,17 @@ i915_gem_reset_request(struct intel_engine_cs *engine,

Or you meant to write i915_gem_reset_request / i915_gem_reset_engine in 
the commit message?

Regards,

Tvrtko

>   		 */
>   		request = i915_gem_find_active_request(engine);
>   		if (request) {
> +			unsigned long flags;
> +
>   			i915_gem_context_mark_innocent(request->gem_context);
>   			dma_fence_set_error(&request->fence, -EAGAIN);
>   
>   			/* Rewind the engine to replay the incomplete rq */
> -			spin_lock_irq(&engine->timeline.lock);
> +			spin_lock_irqsave(&engine->timeline.lock, flags);
>   			request = list_prev_entry(request, link);
>   			if (&request->link == &engine->timeline.requests)
>   				request = NULL;
> -			spin_unlock_irq(&engine->timeline.lock);
> +			spin_unlock_irqrestore(&engine->timeline.lock, flags);
>   		}
>   	}
>   
> 
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