All of lore.kernel.org
 help / color / mirror / Atom feed
* Deploying new iterator interface for dma-buf
@ 2021-09-16 11:30 ` Christian König
  0 siblings, 0 replies; 62+ messages in thread
From: Christian König @ 2021-09-16 11:30 UTC (permalink / raw)
  To: linaro-mm-sig, dri-devel, linux-media, intel-gfx; +Cc: daniel, tvrtko.ursulin

Next round for that one here, maybe the CI systems are now more
gracefully with me :)

I'm pretty sure that a couple of those dma_resv_for_each_fence_unlocked
should actually be replaced with lock+dma_resv_for_each_fence, but that
needs more auditing.

Please review and comment.

Thanks,
Christian.



^ permalink raw reply	[flat|nested] 62+ messages in thread
* Deploying new iterator interface for dma-buf
@ 2021-09-17 12:34 Christian König
  2021-09-17 12:35 ` [PATCH 15/26] drm/i915: use the new iterator in i915_request_await_object v2 Christian König
  0 siblings, 1 reply; 62+ messages in thread
From: Christian König @ 2021-09-17 12:34 UTC (permalink / raw)
  To: linaro-mm-sig, dri-devel, linux-media, intel-gfx; +Cc: daniel

Hopefully the last round for this.

Added dma_resv_iter_begin/end as requested by Daniel. Fixed a bunch of
problems pointed out by the CI systems and found a few more myselve.

Please review and/or comment,
Christian.



^ permalink raw reply	[flat|nested] 62+ messages in thread
* [PATCH 01/26] dma-buf: add dma_resv_for_each_fence_unlocked v3
@ 2021-09-21 17:36 Christian König
  2021-09-21 17:36 ` [PATCH 15/26] drm/i915: use the new iterator in i915_request_await_object v2 Christian König
  0 siblings, 1 reply; 62+ messages in thread
From: Christian König @ 2021-09-21 17:36 UTC (permalink / raw)
  To: ckoenig.leichtzumerken, linaro-mm-sig, dri-devel, linux-media, intel-gfx
  Cc: daniel, tvrtko.ursulin

Abstract the complexity of iterating over all the fences
in a dma_resv object.

The new loop handles the whole RCU and retry dance and
returns only fences where we can be sure we grabbed the
right one.

v2: fix accessing the shared fences while they might be freed,
    improve kerneldoc, rename _cursor to _iter, add
    dma_resv_iter_is_exclusive, add dma_resv_iter_begin/end

v3: restructor the code, move rcu_read_lock()/unlock() into the
    iterator, add dma_resv_iter_is_restarted()

Signed-off-by: Christian König <christian.koenig@amd.com>
---
 drivers/dma-buf/dma-resv.c | 98 ++++++++++++++++++++++++++++++++++++++
 include/linux/dma-resv.h   | 95 ++++++++++++++++++++++++++++++++++++
 2 files changed, 193 insertions(+)

diff --git a/drivers/dma-buf/dma-resv.c b/drivers/dma-buf/dma-resv.c
index 84fbe60629e3..11b5399f4bd3 100644
--- a/drivers/dma-buf/dma-resv.c
+++ b/drivers/dma-buf/dma-resv.c
@@ -323,6 +323,104 @@ void dma_resv_add_excl_fence(struct dma_resv *obj, struct dma_fence *fence)
 }
 EXPORT_SYMBOL(dma_resv_add_excl_fence);
 
+/**
+ * dma_resv_iter_restart_unlocked - restart the unlocked iterator
+ * @cursor: The dma_resv_iter object to restart
+ *
+ * Restart the unlocked iteration by initializing the cursor object.
+ */
+static void dma_resv_iter_restart_unlocked(struct dma_resv_iter *cursor)
+{
+	cursor->seq = read_seqcount_begin(&cursor->obj->seq);
+	cursor->index = -1;
+	if (cursor->all_fences) {
+		rcu_read_lock();
+		cursor->fences = dma_resv_shared_list(cursor->obj);
+		rcu_read_unlock();
+	} else {
+		cursor->fences = NULL;
+	}
+	cursor->is_restarted = true;
+}
+
+/**
+ * dma_resv_iter_walk_unlocked - walk over fences in a dma_resv obj
+ * @cursor: cursor to record the current position
+ *
+ * Return all the fences in the dma_resv object which are not yet signaled.
+ * The returned fence has an extra local reference so will stay alive.
+ * If a concurrent modify is detected the whole iterration is started over again.
+ */
+static void dma_resv_iter_walk_unlocked(struct dma_resv_iter *cursor)
+{
+	struct dma_resv *obj = cursor->obj;
+
+	do {
+		/* Drop the reference from the previous round */
+		dma_fence_put(cursor->fence);
+
+		if (cursor->index++ == -1) {
+			cursor->fence = dma_resv_excl_fence(obj);
+			cursor->fence = dma_fence_get_rcu(cursor->fence);
+
+		} else if (!cursor->fences ||
+			   cursor->index >= cursor->fences->shared_count) {
+			cursor->fence = NULL;
+
+		} else {
+			struct dma_resv_list *fences = cursor->fences;
+			unsigned int idx = cursor->index;
+
+			cursor->fence = rcu_dereference(fences->shared[idx]);
+			cursor->fence = dma_fence_get_rcu(cursor->fence);
+		}
+	} while (cursor->fence && dma_fence_is_signaled(cursor->fence));
+}
+
+/**
+ * dma_resv_iter_first_unlocked - first fence in an unlocked dma_resv obj.
+ * @cursor: the cursor with the current position
+ *
+ * Returns the first fence from an unlocked dma_resv obj.
+ */
+struct dma_fence *dma_resv_iter_first_unlocked(struct dma_resv_iter *cursor)
+{
+	rcu_read_lock();
+	do {
+		dma_resv_iter_restart_unlocked(cursor);
+		dma_resv_iter_walk_unlocked(cursor);
+	} while (read_seqcount_retry(&cursor->obj->seq, cursor->seq));
+	rcu_read_unlock();
+
+	return cursor->fence;
+}
+EXPORT_SYMBOL(dma_resv_iter_first_unlocked);
+
+/**
+ * dma_resv_iter_next_unlocked - next fence in an unlocked dma_resv obj.
+ * @cursor: the cursor with the current position
+ *
+ * Returns the next fence from an unlocked dma_resv obj.
+ */
+struct dma_fence *dma_resv_iter_next_unlocked(struct dma_resv_iter *cursor)
+{
+	bool restart;
+
+	rcu_read_lock();
+	cursor->is_restarted = false;
+	restart = read_seqcount_retry(&cursor->obj->seq, cursor->seq);
+	do {
+		if (restart)
+			dma_resv_iter_restart_unlocked(cursor);
+		dma_resv_iter_walk_unlocked(cursor);
+		restart = true;
+	} while (read_seqcount_retry(&cursor->obj->seq, cursor->seq));
+	rcu_read_unlock();
+
+	return cursor->fence;
+}
+EXPORT_SYMBOL(dma_resv_iter_next_unlocked);
+
 /**
  * dma_resv_copy_fences - Copy all fences from src to dst.
  * @dst: the destination reservation object
diff --git a/include/linux/dma-resv.h b/include/linux/dma-resv.h
index 9100dd3dc21f..baf77a542392 100644
--- a/include/linux/dma-resv.h
+++ b/include/linux/dma-resv.h
@@ -149,6 +149,101 @@ struct dma_resv {
 	struct dma_resv_list __rcu *fence;
 };
 
+/**
+ * struct dma_resv_iter - current position into the dma_resv fences
+ *
+ * Don't touch this directly in the driver, use the accessor function instead.
+ */
+struct dma_resv_iter {
+	/** @obj: The dma_resv object we iterate over */
+	struct dma_resv *obj;
+
+	/** @all_fences: If all fences should be returned */
+	bool all_fences;
+
+	/** @fence: the currently handled fence */
+	struct dma_fence *fence;
+
+	/** @seq: sequence number to check for modifications */
+	unsigned int seq;
+
+	/** @index: index into the shared fences */
+	unsigned int index;
+
+	/** @fences: the shared fences */
+	struct dma_resv_list *fences;
+
+	/** @is_restarted: true if this is the first returned fence */
+	bool is_restarted;
+};
+
+struct dma_fence *dma_resv_iter_first_unlocked(struct dma_resv_iter *cursor);
+struct dma_fence *dma_resv_iter_next_unlocked(struct dma_resv_iter *cursor);
+
+/**
+ * dma_resv_iter_begin - initialize a dma_resv_iter object
+ * @cursor: The dma_resv_iter object to initialize
+ * @obj: The dma_resv object which we want to iterator over
+ * @all_fences: If all fences should be returned or just the exclusive one
+ */
+static inline void dma_resv_iter_begin(struct dma_resv_iter *cursor,
+				       struct dma_resv *obj,
+				       bool all_fences)
+{
+	cursor->obj = obj;
+	cursor->all_fences = all_fences;
+	cursor->fence = NULL;
+}
+
+/**
+ * dma_resv_iter_end - cleanup a dma_resv_iter object
+ * @cursor: the dma_resv_iter object which should be cleaned up
+ *
+ * Make sure that the reference to the fence in the cursor is properly
+ * dropped.
+ */
+static inline void dma_resv_iter_end(struct dma_resv_iter *cursor)
+{
+	dma_fence_put(cursor->fence);
+}
+
+/**
+ * dma_resv_iter_is_exclusive - test if the current fence is the exclusive one
+ * @cursor: the cursor of the current position
+ *
+ * Returns true if the currently returned fence is the exclusive one.
+ */
+static inline bool dma_resv_iter_is_exclusive(struct dma_resv_iter *cursor)
+{
+	return cursor->index == -1;
+}
+
+/**
+ * dma_resv_iter_is_restarted - test if this is the first fence after a restart
+ * @cursor: the cursor with the current position
+ *
+ * Return true if this is the first fence in an interation after a restart.
+ */
+static inline bool dma_resv_iter_is_restarted(struct dma_resv_iter *cursor)
+{
+	return cursor->is_restarted;
+}
+
+/**
+ * dma_resv_for_each_fence_unlocked - unlocked fence iterator
+ * @cursor: a struct dma_resv_iter pointer
+ * @fence: the current fence
+ *
+ * Iterate over the fences in a struct dma_resv object without holding the
+ * &dma_resv.lock and using RCU instead. The cursor needs to be initialized
+ * with dma_resv_iter_begin() and cleaned up with dma_resv_iter_end(). Inside
+ * the iterator a reference to the dma_fence is hold and the RCU lock dropped.
+ * When the dma_resv is modified the iteration starts over again.
+ */
+#define dma_resv_for_each_fence_unlocked(cursor, fence)			\
+	for (fence = dma_resv_iter_first_unlocked(cursor);		\
+	     fence; fence = dma_resv_iter_next_unlocked(cursor))
+
 #define dma_resv_held(obj) lockdep_is_held(&(obj)->lock.base)
 #define dma_resv_assert_held(obj) lockdep_assert_held(&(obj)->lock.base)
 
-- 
2.25.1


^ permalink raw reply related	[flat|nested] 62+ messages in thread
* Deploying new iterator interface for dma-buf
@ 2021-09-22  9:10 Christian König
  2021-09-22  9:10 ` [PATCH 15/26] drm/i915: use the new iterator in i915_request_await_object v2 Christian König
  0 siblings, 1 reply; 62+ messages in thread
From: Christian König @ 2021-09-22  9:10 UTC (permalink / raw)
  To: linaro-mm-sig, dri-devel, linux-media, intel-gfx; +Cc: daniel, tvrtko.ursulin

Hi guys,

The version I've send out yesterday had a rather obvious coding error and I honestly forgot the cover letter.

This one here is better tested and will now hopefully not be torn apart from the CI system immediately.

I tried to address all review and documentation comments as best as I could, so I'm hoping that we can now considering pushing this.

Cheers,
Christian.



^ permalink raw reply	[flat|nested] 62+ messages in thread

end of thread, other threads:[~2021-09-22 10:35 UTC | newest]

Thread overview: 62+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2021-09-16 11:30 Deploying new iterator interface for dma-buf Christian König
2021-09-16 11:30 ` [Intel-gfx] " Christian König
2021-09-16 11:30 ` [PATCH 01/26] dma-buf: add dma_resv_for_each_fence_unlocked v2 Christian König
2021-09-16 11:30   ` [Intel-gfx] " Christian König
2021-09-16 12:15   ` Daniel Vetter
2021-09-16 12:15     ` [Intel-gfx] " Daniel Vetter
2021-09-16 11:30 ` [PATCH 02/26] dma-buf: add dma_resv_for_each_fence Christian König
2021-09-16 11:30   ` [Intel-gfx] " Christian König
2021-09-16 11:30 ` [PATCH 03/26] dma-buf: use new iterator in dma_resv_copy_fences Christian König
2021-09-16 11:30   ` [Intel-gfx] " Christian König
2021-09-16 11:30 ` [PATCH 04/26] dma-buf: use new iterator in dma_resv_get_fences v2 Christian König
2021-09-16 11:30   ` [Intel-gfx] " Christian König
2021-09-16 11:30 ` [PATCH 05/26] dma-buf: use new iterator in dma_resv_wait_timeout Christian König
2021-09-16 11:30   ` [Intel-gfx] " Christian König
2021-09-16 11:30 ` [PATCH 06/26] dma-buf: use new iterator in dma_resv_test_signaled Christian König
2021-09-16 11:30   ` [Intel-gfx] " Christian König
2021-09-16 11:30 ` [PATCH 07/26] drm/ttm: use the new iterator in ttm_bo_flush_all_fences Christian König
2021-09-16 11:30   ` [Intel-gfx] " Christian König
2021-09-16 11:30 ` [PATCH 08/26] drm/amdgpu: use the new iterator in amdgpu_sync_resv Christian König
2021-09-16 11:30   ` [Intel-gfx] " Christian König
2021-09-16 11:30 ` [PATCH 09/26] drm/amdgpu: use new iterator in amdgpu_ttm_bo_eviction_valuable Christian König
2021-09-16 11:30   ` [Intel-gfx] " Christian König
2021-09-16 11:30 ` [PATCH 10/26] drm/msm: use new iterator in msm_gem_describe Christian König
2021-09-16 11:30   ` [Intel-gfx] " Christian König
2021-09-16 11:30 ` [PATCH 11/26] drm/radeon: use new iterator in radeon_sync_resv Christian König
2021-09-16 11:30   ` [Intel-gfx] " Christian König
2021-09-16 11:30 ` [PATCH 12/26] drm/scheduler: use new iterator in drm_sched_job_add_implicit_dependencies v2 Christian König
2021-09-16 11:30   ` [Intel-gfx] " Christian König
2021-09-16 11:30 ` [PATCH 13/26] drm/i915: use the new iterator in i915_gem_busy_ioctl Christian König
2021-09-16 11:30   ` [Intel-gfx] " Christian König
2021-09-16 11:30 ` [PATCH 14/26] drm/i915: use the new iterator in i915_sw_fence_await_reservation v2 Christian König
2021-09-16 11:30   ` [Intel-gfx] " Christian König
2021-09-16 11:30 ` [PATCH 15/26] drm/i915: use the new iterator in i915_request_await_object v2 Christian König
2021-09-16 11:30   ` [Intel-gfx] " Christian König
2021-09-16 11:30 ` [PATCH 16/26] drm/i915: use new iterator in i915_gem_object_wait_reservation v2 Christian König
2021-09-16 11:30   ` [Intel-gfx] " Christian König
2021-09-16 11:30 ` [PATCH 17/26] drm/i915: use new iterator in i915_gem_object_wait_priority v2 Christian König
2021-09-16 11:30   ` [Intel-gfx] " Christian König
2021-09-16 11:30 ` [PATCH 18/26] drm/i915: use new iterator in i915_gem_object_last_write_engine v2 Christian König
2021-09-16 11:30   ` [Intel-gfx] " Christian König
2021-09-16 11:30 ` [PATCH 19/26] drm/i915: use new cursor in intel_prepare_plane_fb v2 Christian König
2021-09-16 11:30   ` [Intel-gfx] " Christian König
2021-09-16 11:30 ` [PATCH 20/26] drm: use new iterator in drm_gem_fence_array_add_implicit v2 Christian König
2021-09-16 11:30   ` [Intel-gfx] " Christian König
2021-09-16 11:30 ` [PATCH 21/26] drm: use new iterator in drm_gem_plane_helper_prepare_fb v2 Christian König
2021-09-16 11:30   ` [Intel-gfx] " Christian König
2021-09-16 11:30 ` [PATCH 22/26] drm/nouveau: use the new iterator in nouveau_fence_sync Christian König
2021-09-16 11:30   ` [Intel-gfx] " Christian König
2021-09-16 11:30 ` [PATCH 23/26] drm/nouveau: use the new interator in nv50_wndw_prepare_fb v2 Christian König
2021-09-16 11:30   ` [Intel-gfx] " Christian König
2021-09-16 11:30 ` [PATCH 24/26] drm/etnaviv: use new iterator in etnaviv_gem_describe Christian König
2021-09-16 11:30   ` [Intel-gfx] " Christian König
2021-09-16 11:30 ` [PATCH 25/26] drm/etnaviv: replace dma_resv_get_excl_unlocked Christian König
2021-09-16 11:30   ` [Intel-gfx] " Christian König
2021-09-16 11:30 ` [PATCH 26/26] dma-buf: nuke dma_resv_get_excl_unlocked Christian König
2021-09-16 11:30   ` [Intel-gfx] " Christian König
2021-09-16 12:28 ` [Intel-gfx] ✗ Fi.CI.CHECKPATCH: warning for series starting with [01/26] dma-buf: add dma_resv_for_each_fence_unlocked v2 Patchwork
2021-09-16 12:50 ` [Intel-gfx] ✗ Fi.CI.BAT: failure " Patchwork
2021-09-17 12:34 Deploying new iterator interface for dma-buf Christian König
2021-09-17 12:35 ` [PATCH 15/26] drm/i915: use the new iterator in i915_request_await_object v2 Christian König
2021-09-21 17:36 [PATCH 01/26] dma-buf: add dma_resv_for_each_fence_unlocked v3 Christian König
2021-09-21 17:36 ` [PATCH 15/26] drm/i915: use the new iterator in i915_request_await_object v2 Christian König
2021-09-22  9:10 Deploying new iterator interface for dma-buf Christian König
2021-09-22  9:10 ` [PATCH 15/26] drm/i915: use the new iterator in i915_request_await_object v2 Christian König
2021-09-22 10:34   ` Tvrtko Ursulin

This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.