On 14/09/2021 11:39, Christian König wrote:
Am 14.09.21 um 12:26 schrieb Tvrtko Ursulin:
On 13/09/2021 14:16, Christian König wrote:
Simplifying the code a bit.
Signed-off-by: Christian König christian.koenig@amd.com
drivers/gpu/drm/i915/i915_request.c | 36 ++++++----------------------- 1 file changed, 7 insertions(+), 29 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_request.c b/drivers/gpu/drm/i915/i915_request.c index 37aef1308573..b81045ceb619 100644 --- a/drivers/gpu/drm/i915/i915_request.c +++ b/drivers/gpu/drm/i915/i915_request.c @@ -1583,38 +1583,16 @@ i915_request_await_object(struct i915_request *to, struct drm_i915_gem_object *obj, bool write) { - struct dma_fence *excl; + struct dma_resv_cursor cursor; + struct dma_fence *fence; int ret = 0; - if (write) { - struct dma_fence **shared; - unsigned int count, i;
- ret = dma_resv_get_fences(obj->base.resv, &excl, &count, - &shared); - if (ret) - return ret;
- for (i = 0; i < count; i++) { - ret = i915_request_await_dma_fence(to, shared[i]); - if (ret) - break;
- dma_fence_put(shared[i]); + dma_resv_for_each_fence_unlocked(obj->base.resv, &cursor, write, fence) {
I think callers have the object locked for this one. At least if you haven't tried it it's worth asking CI (you have the assert already so it will tell you). But I think it's important to have an atomic snapshot here.
Thanks for the info. In this case I'm just going to use the locked variant of the iterator here for the next round.
Could you point me to the place where the lock is grabed/released for reference?
There is quite a few callers and I haven't audited all of them. But I think, given the function is used for setting up tracking of implicit dependencies, that it has to be true.
In the case of execbuf for instance the flow is relatively complicated:
i915_gem_do_execbuffer eb_relocate_parse eb_validate_vmas eb_lock_vmas i915_gem_object_lock eb_submit eb_move_to_gpu i915_request_await_object i915_gem_ww_ctx_fini i915_gem_ww_ctx_unlock_all i915_gem_object_unlock
Other call sites have simpler flows but there is a lot of them so I think using CI is easiest.
Regards,
Tvrtko
Thanks, Christian.
Regards,
Tvrtko
+ ret = i915_request_await_dma_fence(to, fence); + if (ret) { + dma_fence_put(fence); + break; }
- for (; i < count; i++) - dma_fence_put(shared[i]); - kfree(shared); - } else { - excl = dma_resv_get_excl_unlocked(obj->base.resv); - }
- if (excl) { - if (ret == 0) - ret = i915_request_await_dma_fence(to, excl);
- dma_fence_put(excl); } return ret;