Re: [Intel-gfx] [PATCH 14/26] drm/i915: use the new iterator in i915_sw_fence_await_reservation v3

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

On 17/09/2021 13:35, Christian König wrote:
> Simplifying the code a bit.
> 
> v2: use dma_resv_for_each_fence instead, according to Tvrtko the lock is
>      held here anyway.
> v3: back to using dma_resv_for_each_fence_unlocked.

It did not work out - what happened?

Regards,

Tvrtko

> Signed-off-by: Christian König <christian.koenig@amd.com>
> ---
>   drivers/gpu/drm/i915/i915_sw_fence.c | 57 ++++++++--------------------
>   1 file changed, 15 insertions(+), 42 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_sw_fence.c b/drivers/gpu/drm/i915/i915_sw_fence.c
> index c589a681da77..7635b0478ea5 100644
> --- a/drivers/gpu/drm/i915/i915_sw_fence.c
> +++ b/drivers/gpu/drm/i915/i915_sw_fence.c
> @@ -572,56 +572,29 @@ int i915_sw_fence_await_reservation(struct i915_sw_fence *fence,
>   				    unsigned long timeout,
>   				    gfp_t gfp)
>   {
> -	struct dma_fence *excl;
> +	struct dma_resv_iter cursor;
> +	struct dma_fence *f;
>   	int ret = 0, pending;
>   
>   	debug_fence_assert(fence);
>   	might_sleep_if(gfpflags_allow_blocking(gfp));
>   
> -	if (write) {
> -		struct dma_fence **shared;
> -		unsigned int count, i;
> -
> -		ret = dma_resv_get_fences(resv, &excl, &count, &shared);
> -		if (ret)
> -			return ret;
> -
> -		for (i = 0; i < count; i++) {
> -			if (shared[i]->ops == exclude)
> -				continue;
> -
> -			pending = i915_sw_fence_await_dma_fence(fence,
> -								shared[i],
> -								timeout,
> -								gfp);
> -			if (pending < 0) {
> -				ret = pending;
> -				break;
> -			}
> -
> -			ret |= pending;
> -		}
> -
> -		for (i = 0; i < count; i++)
> -			dma_fence_put(shared[i]);
> -		kfree(shared);
> -	} else {
> -		excl = dma_resv_get_excl_unlocked(resv);
> -	}
> -
> -	if (ret >= 0 && excl && excl->ops != exclude) {
> -		pending = i915_sw_fence_await_dma_fence(fence,
> -							excl,
> -							timeout,
> +	rcu_read_lock();
> +	dma_resv_iter_begin(&cursor, resv, write);
> +	dma_resv_for_each_fence_unlocked(&cursor, f) {
> +		rcu_read_unlock();
> +		pending = i915_sw_fence_await_dma_fence(fence, f, timeout,
>   							gfp);
> -		if (pending < 0)
> +		rcu_read_lock();
> +		if (pending < 0) {
>   			ret = pending;
> -		else
> -			ret |= pending;
> -	}
> -
> -	dma_fence_put(excl);
> +			break;
> +		}
>   
> +		ret |= pending;
> +	}
> +	dma_resv_iter_end(&cursor);
> +	rcu_read_unlock();
>   	return ret;
>   }
>   
>