On 13/10/2021 11:41, Maarten Lankhorst wrote:
No memory should be allocated when calling i915_gem_object_wait, because it may be called to idle a BO when evicting memory. Fix this by using dma_resv_iter helpers to call i915_gem_object_wait_fence() on each fence, which cleans up the code a lot. Also remove dma_resv_prune, it's questionably. This will result in the following lockdep splat.
<snip>
@@ -37,56 +36,17 @@ i915_gem_object_wait_reservation(struct dma_resv *resv, unsigned int flags, long timeout) { - struct dma_fence *excl; - bool prune_fences = false; - - if (flags & I915_WAIT_ALL) { - struct dma_fence **shared; - unsigned int count, i; - int ret; + struct dma_resv_iter cursor; + struct dma_fence *fence;- ret = dma_resv_get_fences(resv, &excl, &count, &shared);- if (ret) - return ret; - - for (i = 0; i < count; i++) { - timeout = i915_gem_object_wait_fence(shared[i], - flags, timeout); - if (timeout < 0) - break; + dma_resv_iter_begin(&cursor, resv, flags & I915_WAIT_ALL); + dma_resv_for_each_fence_unlocked(&cursor, fence) {- dma_fence_put(shared[i]);- } - - for (; i < count; i++) - dma_fence_put(shared[i]); - kfree(shared); - - /* - * If both shared fences and an exclusive fence exist, - * then by construction the shared fences must be later - * than the exclusive fence. If we successfully wait for - * all the shared fences, we know that the exclusive fence - * must all be signaled. If all the shared fences are - * signaled, we can prune the array and recover the - * floating references on the fences/requests. - */ - prune_fences = count && timeout >= 0; - } else { - excl = dma_resv_get_excl_unlocked(resv); + timeout = i915_gem_object_wait_fence(fence, flags, timeout); + if (timeout <= 0) + break;
You have another change in behaviour here, well a bug really. When userspace passes in zero timeout you fail to report activity in other than the first fence.
Regards, Tvrtko
