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

Tvrtko Ursulin
2021-09-20T08:46:04Z

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;
> }
>
>