Re: [Intel-gfx] [PATCH 13/26] drm/i915: use the new iterator in i915_gem_busy_ioctl

Tvrtko Ursulin
2021-09-20T08:45:17Z

On 17/09/2021 13:35, Christian König wrote:
> This makes the function much simpler since the complex
> retry logic is now handled else where.
>
> Signed-off-by: Christian König <christian.koenig@amd.com>
> ---
> drivers/gpu/drm/i915/gem/i915_gem_busy.c | 32 ++++++++----------------
> 1 file changed, 11 insertions(+), 21 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_busy.c b/drivers/gpu/drm/i915/gem/i915_gem_busy.c
> index 6234e17259c1..b1cb7ba688da 100644
> --- a/drivers/gpu/drm/i915/gem/i915_gem_busy.c
> +++ b/drivers/gpu/drm/i915/gem/i915_gem_busy.c
> @@ -82,8 +82,8 @@ i915_gem_busy_ioctl(struct drm_device *dev, void *data,
> {
> struct drm_i915_gem_busy *args = data;
> struct drm_i915_gem_object *obj;
> - struct dma_resv_list *list;
> - unsigned int seq;
> + struct dma_resv_iter cursor;
> + struct dma_fence *fence;
> int err;
>
> err = -ENOENT;
> @@ -109,27 +109,17 @@ i915_gem_busy_ioctl(struct drm_device *dev, void *data,
> * to report the overall busyness. This is what the wait-ioctl does.
> *
> */
> -retry:
> - seq = raw_read_seqcount(&obj->base.resv->seq);
> -
> - /* Translate the exclusive fence to the READ *and* WRITE engine */
> - args->busy = busy_check_writer(dma_resv_excl_fence(obj->base.resv));
> -
> - /* Translate shared fences to READ set of engines */
> - list = dma_resv_shared_list(obj->base.resv);
> - if (list) {
> - unsigned int shared_count = list->shared_count, i;
> -
> - for (i = 0; i < shared_count; ++i) {
> - struct dma_fence *fence =
> - rcu_dereference(list->shared[i]);
> -
> + args->busy = false;
> + dma_resv_iter_begin(&cursor, obj->base.resv, true);
> + dma_resv_for_each_fence_unlocked(&cursor, fence) {

You did not agree with my suggestion to reset args->busy on restart and
so preserve current behaviour?

Regards,

Tvrtko

> + if (dma_resv_iter_is_exclusive(&cursor))
> + /* Translate the exclusive fence to the READ *and* WRITE engine */
> + args->busy = busy_check_writer(fence);
> + else
> + /* Translate shared fences to READ set of engines */
> args->busy |= busy_check_reader(fence);
> - }
> }
> -
> - if (args->busy && read_seqcount_retry(&obj->base.resv->seq, seq))
> - goto retry;
> + dma_resv_iter_end(&cursor);
>
> err = 0;
> out:
>