From: "Christian König" <ckoenig.leichtzumerken@gmail.com> To: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>, linaro-mm-sig@lists.linaro.org, dri-devel@lists.freedesktop.org, linux-media@vger.kernel.org, intel-gfx@lists.freedesktop.org Cc: daniel@ffwll.ch Subject: Re: [Intel-gfx] [PATCH 16/26] drm/i915: use new iterator in i915_gem_object_wait_reservation v2 Date: Tue, 21 Sep 2021 19:35:53 +0200 [thread overview] Message-ID: <e66dd0dc-02a6-7437-ab98-dff4e8ff8de3@gmail.com> (raw) In-Reply-To: <e0954bdd-2183-f662-8192-c44f931c602b@linux.intel.com> Am 20.09.21 um 12:00 schrieb Tvrtko Ursulin: > > On 17/09/2021 13:35, Christian König wrote: >> Simplifying the code a bit. >> >> v2: add missing rcu read unlock. >> >> Signed-off-by: Christian König <christian.koenig@amd.com> >> --- >> drivers/gpu/drm/i915/gem/i915_gem_wait.c | 57 ++++++------------------ >> 1 file changed, 14 insertions(+), 43 deletions(-) >> >> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_wait.c >> b/drivers/gpu/drm/i915/gem/i915_gem_wait.c >> index f909aaa09d9c..e416cf528635 100644 >> --- a/drivers/gpu/drm/i915/gem/i915_gem_wait.c >> +++ b/drivers/gpu/drm/i915/gem/i915_gem_wait.c >> @@ -37,55 +37,26 @@ 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; >> - >> - 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_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); >> + struct dma_resv_iter cursor; >> + struct dma_fence *fence; >> + >> + rcu_read_lock(); >> + dma_resv_iter_begin(&cursor, resv, flags & I915_WAIT_ALL); >> + dma_resv_for_each_fence_unlocked(&cursor, fence) { >> + rcu_read_unlock(); >> + timeout = i915_gem_object_wait_fence(fence, flags, timeout); > > Converting this one could be problematic. It's the wait ioctl which > used to grab an atomic snapshot and wait for that rendering to > complete. With this change I think it has the potential to run forever > keeps catching new activity against the same object. > > I am not sure whether or not the difference is relevant for how > userspace uses it but I think needs discussion. It was years ago, but IIRC we had the same discussion for the dma_resv_wait_timeout() function and the result was that this is not a valid use case and waiting forever if you see new work over and over again is a valid result. Let me double check the history of this code here as well. > Hm actually there are internal callers as well, and at least some of > those have the object locked. Would a wider refactoring to separate > those into buckets (locked vs unlocked) make sense? Yes definitely. Regards, Christian. > > Regards, > > Tvrtko > > >> + rcu_read_lock(); >> + if (timeout < 0) >> + break; >> } >> - >> - if (excl && timeout >= 0) >> - timeout = i915_gem_object_wait_fence(excl, flags, timeout); >> - >> - dma_fence_put(excl); >> + dma_resv_iter_end(&cursor); >> + rcu_read_unlock(); >> /* >> * Opportunistically prune the fences iff we know they have >> *all* been >> * signaled. >> */ >> - if (prune_fences) >> + if (timeout > 0) >> dma_resv_prune(resv); >> return timeout; >>
next prev parent reply other threads:[~2021-09-21 17:36 UTC|newest] Thread overview: 115+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-09-17 12:34 Deploying new iterator interface for dma-buf Christian König 2021-09-17 12:34 ` [Intel-gfx] " Christian König 2021-09-17 12:34 ` [PATCH 01/26] dma-buf: add dma_resv_for_each_fence_unlocked v2 Christian König 2021-09-17 12:34 ` [Intel-gfx] " Christian König 2021-09-17 13:23 ` Daniel Vetter 2021-09-17 13:23 ` [Intel-gfx] " Daniel Vetter 2021-09-20 8:43 ` Tvrtko Ursulin 2021-09-20 10:09 ` Christian König 2021-09-20 10:26 ` Tvrtko Ursulin 2021-09-17 12:34 ` [PATCH 02/26] dma-buf: add dma_resv_for_each_fence Christian König 2021-09-17 12:34 ` [Intel-gfx] " Christian König 2021-09-17 13:27 ` Daniel Vetter 2021-09-17 13:27 ` [Intel-gfx] " Daniel Vetter 2021-09-17 14:30 ` Daniel Vetter 2021-09-17 14:30 ` Daniel Vetter 2021-09-17 12:34 ` [PATCH 03/26] dma-buf: use new iterator in dma_resv_copy_fences Christian König 2021-09-17 12:34 ` [Intel-gfx] " Christian König 2021-09-17 14:35 ` Daniel Vetter 2021-09-17 14:35 ` [Intel-gfx] " Daniel Vetter 2021-09-20 7:23 ` Christian König 2021-09-20 7:23 ` [Intel-gfx] " Christian König 2021-09-17 12:34 ` [PATCH 04/26] dma-buf: use new iterator in dma_resv_get_fences v2 Christian König 2021-09-17 12:34 ` [Intel-gfx] " Christian König 2021-09-17 14:39 ` Daniel Vetter 2021-09-17 14:39 ` [Intel-gfx] " Daniel Vetter 2021-09-17 12:34 ` [PATCH 05/26] dma-buf: use new iterator in dma_resv_wait_timeout Christian König 2021-09-17 12:34 ` [Intel-gfx] " Christian König 2021-09-17 14:43 ` Daniel Vetter 2021-09-17 14:43 ` [Intel-gfx] " Daniel Vetter 2021-09-20 7:27 ` Christian König 2021-09-20 7:27 ` [Intel-gfx] " Christian König 2021-09-17 12:34 ` [PATCH 06/26] dma-buf: use new iterator in dma_resv_test_signaled Christian König 2021-09-17 12:34 ` [Intel-gfx] " Christian König 2021-09-17 14:45 ` Daniel Vetter 2021-09-17 14:45 ` [Intel-gfx] " Daniel Vetter 2021-09-17 12:34 ` [PATCH 07/26] drm/ttm: use the new iterator in ttm_bo_flush_all_fences Christian König 2021-09-17 12:34 ` [Intel-gfx] " Christian König 2021-09-17 14:50 ` Daniel Vetter 2021-09-17 14:50 ` [Intel-gfx] " Daniel Vetter 2021-09-17 12:34 ` [PATCH 08/26] drm/amdgpu: use the new iterator in amdgpu_sync_resv Christian König 2021-09-17 12:34 ` [Intel-gfx] " Christian König 2021-09-17 12:34 ` [PATCH 09/26] drm/amdgpu: use new iterator in amdgpu_ttm_bo_eviction_valuable Christian König 2021-09-17 12:34 ` [Intel-gfx] " Christian König 2021-09-17 12:34 ` [PATCH 10/26] drm/msm: use new iterator in msm_gem_describe Christian König 2021-09-17 12:34 ` [Intel-gfx] " Christian König 2021-09-17 12:34 ` [PATCH 11/26] drm/radeon: use new iterator in radeon_sync_resv Christian König 2021-09-17 12:34 ` [Intel-gfx] " Christian König 2021-09-17 12:34 ` [PATCH 12/26] drm/scheduler: use new iterator in drm_sched_job_add_implicit_dependencies v2 Christian König 2021-09-17 12:34 ` [Intel-gfx] " Christian König 2021-09-17 14:52 ` Daniel Vetter 2021-09-17 14:52 ` [Intel-gfx] " Daniel Vetter 2021-11-15 14:03 ` Sascha Hauer 2021-11-15 14:03 ` Sascha Hauer 2021-11-15 14:03 ` [Intel-gfx] " Sascha Hauer 2021-11-15 14:08 ` Daniel Vetter 2021-11-15 14:08 ` [Intel-gfx] " Daniel Vetter 2021-11-15 14:08 ` Daniel Vetter 2021-11-15 20:32 ` Christian König 2021-11-15 20:32 ` Christian König 2021-11-15 20:32 ` [Intel-gfx] " Christian König 2021-11-16 7:56 ` Sascha Hauer 2021-11-16 7:56 ` [Intel-gfx] " Sascha Hauer 2021-11-16 7:56 ` Sascha Hauer 2021-09-17 12:35 ` [PATCH 13/26] drm/i915: use the new iterator in i915_gem_busy_ioctl Christian König 2021-09-17 12:35 ` [Intel-gfx] " Christian König 2021-09-20 8:45 ` Tvrtko Ursulin 2021-09-20 10:13 ` Christian König 2021-09-20 10:33 ` Tvrtko Ursulin 2021-09-21 9:41 ` Christian König 2021-09-21 13:10 ` Tvrtko Ursulin 2021-09-17 12:35 ` [PATCH 14/26] drm/i915: use the new iterator in i915_sw_fence_await_reservation v3 Christian König 2021-09-17 12:35 ` [Intel-gfx] " Christian König 2021-09-20 8:45 ` Tvrtko Ursulin 2021-09-20 8:47 ` Tvrtko Ursulin 2021-09-20 10:14 ` Christian König 2021-09-17 12:35 ` [PATCH 15/26] drm/i915: use the new iterator in i915_request_await_object v2 Christian König 2021-09-17 12:35 ` [Intel-gfx] " Christian König 2021-09-17 12:35 ` [PATCH 16/26] drm/i915: use new iterator in i915_gem_object_wait_reservation v2 Christian König 2021-09-17 12:35 ` [Intel-gfx] " Christian König 2021-09-20 10:00 ` Tvrtko Ursulin 2021-09-21 17:35 ` Christian König [this message] 2021-09-17 12:35 ` [PATCH 17/26] drm/i915: use new iterator in i915_gem_object_wait_priority v2 Christian König 2021-09-17 12:35 ` [Intel-gfx] " Christian König 2021-09-17 12:35 ` [PATCH 18/26] drm/i915: use new iterator in i915_gem_object_last_write_engine v2 Christian König 2021-09-17 12:35 ` [Intel-gfx] " Christian König 2021-09-17 12:35 ` [PATCH 19/26] drm/i915: use new cursor in intel_prepare_plane_fb v2 Christian König 2021-09-17 12:35 ` [Intel-gfx] " Christian König 2021-09-17 12:35 ` [PATCH 20/26] drm: use new iterator in drm_gem_fence_array_add_implicit v2 Christian König 2021-09-17 12:35 ` [Intel-gfx] " Christian König 2021-09-17 14:53 ` Daniel Vetter 2021-09-17 14:53 ` [Intel-gfx] " Daniel Vetter 2021-09-20 7:31 ` Christian König 2021-09-20 7:31 ` [Intel-gfx] " Christian König 2021-09-17 12:35 ` [PATCH 21/26] drm: use new iterator in drm_gem_plane_helper_prepare_fb v2 Christian König 2021-09-17 12:35 ` [Intel-gfx] " Christian König 2021-09-17 14:55 ` Daniel Vetter 2021-09-17 14:55 ` [Intel-gfx] " Daniel Vetter 2021-09-20 7:35 ` Christian König 2021-09-20 7:35 ` [Intel-gfx] " Christian König 2021-09-17 12:35 ` [PATCH 22/26] drm/nouveau: use the new iterator in nouveau_fence_sync Christian König 2021-09-17 12:35 ` [Intel-gfx] " Christian König 2021-09-17 12:35 ` [PATCH 23/26] drm/nouveau: use the new interator in nv50_wndw_prepare_fb v2 Christian König 2021-09-17 12:35 ` [Intel-gfx] " Christian König 2021-09-17 12:35 ` [PATCH 24/26] drm/etnaviv: use new iterator in etnaviv_gem_describe Christian König 2021-09-17 12:35 ` [Intel-gfx] " Christian König 2021-09-17 12:35 ` [PATCH 25/26] drm/etnaviv: replace dma_resv_get_excl_unlocked Christian König 2021-09-17 12:35 ` [Intel-gfx] " Christian König 2021-09-17 12:35 ` [PATCH 26/26] dma-buf: nuke dma_resv_get_excl_unlocked Christian König 2021-09-17 12:35 ` [Intel-gfx] " Christian König 2021-09-17 14:56 ` Daniel Vetter 2021-09-17 14:56 ` [Intel-gfx] " Daniel Vetter 2021-09-17 14:01 ` [Intel-gfx] ✗ Fi.CI.CHECKPATCH: warning for series starting with [01/26] dma-buf: add dma_resv_for_each_fence_unlocked v2 Patchwork 2021-09-17 14:29 ` [Intel-gfx] ✓ Fi.CI.BAT: success " Patchwork 2021-09-17 15:43 ` [Intel-gfx] ✗ Fi.CI.IGT: failure " Patchwork -- strict thread matches above, loose matches on Subject: below -- 2021-09-16 11:30 Deploying new iterator interface for dma-buf Christian König 2021-09-16 11:30 ` [Intel-gfx] [PATCH 16/26] drm/i915: use new iterator in i915_gem_object_wait_reservation v2 Christian König
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