From: "Christian König" <ckoenig.leichtzumerken@gmail.com>
To: 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, tvrtko.ursulin@linux.intel.com
Subject: [PATCH 01/26] dma-buf: add dma_resv_for_each_fence_unlocked v2
Date: Thu, 16 Sep 2021 13:30:17 +0200 [thread overview]
Message-ID: <20210916113042.3631-2-christian.koenig@amd.com> (raw)
In-Reply-To: <20210916113042.3631-1-christian.koenig@amd.com>
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
Signed-off-by: Christian König <christian.koenig@amd.com>
---
drivers/dma-buf/dma-resv.c | 62 ++++++++++++++++++++++++++++++++++++++
include/linux/dma-resv.h | 50 ++++++++++++++++++++++++++++++
2 files changed, 112 insertions(+)
diff --git a/drivers/dma-buf/dma-resv.c b/drivers/dma-buf/dma-resv.c
index 84fbe60629e3..77083170ec3b 100644
--- a/drivers/dma-buf/dma-resv.c
+++ b/drivers/dma-buf/dma-resv.c
@@ -323,6 +323,68 @@ void dma_resv_add_excl_fence(struct dma_resv *obj, struct dma_fence *fence)
}
EXPORT_SYMBOL(dma_resv_add_excl_fence);
+/**
+ * dma_resv_walk_unlocked - walk over fences in a dma_resv obj
+ * @obj: the dma_resv object
+ * @cursor: cursor to record the current position
+ * @all_fences: true returns also the shared fences
+ * @first: if we should start over
+ *
+ * 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 iterator is started over again.
+ */
+struct dma_fence *dma_resv_walk_unlocked(struct dma_resv *obj,
+ struct dma_resv_iter *cursor,
+ bool all_fences, bool first)
+{
+ struct dma_fence *fence = NULL;
+
+ first |= read_seqcount_retry(&obj->seq, cursor->seq);
+ do {
+ /* Drop the reference from the previous round */
+ dma_fence_put(fence);
+
+ cursor->is_first = first;
+ if (first) {
+ cursor->seq = read_seqcount_begin(&obj->seq);
+ cursor->index = -1;
+ cursor->fences = dma_resv_shared_list(obj);
+
+ fence = dma_resv_excl_fence(obj);
+ if (fence && test_bit(DMA_FENCE_FLAG_SIGNALED_BIT,
+ &fence->flags))
+ fence = NULL;
+ } else {
+ fence = NULL;
+ }
+
+ if (fence) {
+ fence = dma_fence_get_rcu(fence);
+ } else if (all_fences && cursor->fences) {
+ struct dma_resv_list *fences = cursor->fences;
+
+ while (++cursor->index < fences->shared_count) {
+ fence = rcu_dereference(
+ fences->shared[cursor->index]);
+ if (!test_bit(DMA_FENCE_FLAG_SIGNALED_BIT,
+ &fence->flags))
+ break;
+ }
+ if (cursor->index < fences->shared_count)
+ fence = dma_fence_get_rcu(fence);
+ else
+ fence = NULL;
+ }
+
+ /* For the eventually next round */
+ first = true;
+ } while (read_seqcount_retry(&obj->seq, cursor->seq));
+
+ return fence;
+}
+EXPORT_SYMBOL_GPL(dma_resv_walk_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..1cd686384c71 100644
--- a/include/linux/dma-resv.h
+++ b/include/linux/dma-resv.h
@@ -149,6 +149,53 @@ 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 {
+ /** @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_first: true if this is the first returned fence */
+ bool is_first;
+};
+
+/**
+ * dma_resv_for_each_fence_unlocked - fence iterator
+ * @obj: a dma_resv object pointer
+ * @cursor: a struct dma_resv_iter pointer
+ * @all_fences: true if all fences should be returned
+ * @fence: the current fence
+ *
+ * Iterate over the fences in a struct dma_resv object without holding the
+ * dma_resv::lock. The RCU read side lock must be hold when using this, but can
+ * be dropped and re-taken as necessary inside the loop. @all_fences controls
+ * if the shared fences are returned as well.
+ */
+#define dma_resv_for_each_fence_unlocked(obj, cursor, all_fences, fence) \
+ for (fence = dma_resv_walk_unlocked(obj, cursor, all_fences, true); \
+ fence; dma_fence_put(fence), \
+ fence = dma_resv_walk_unlocked(obj, cursor, all_fences, false))
+
+/**
+ * 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;
+}
+
#define dma_resv_held(obj) lockdep_is_held(&(obj)->lock.base)
#define dma_resv_assert_held(obj) lockdep_assert_held(&(obj)->lock.base)
@@ -366,6 +413,9 @@ void dma_resv_fini(struct dma_resv *obj);
int dma_resv_reserve_shared(struct dma_resv *obj, unsigned int num_fences);
void dma_resv_add_shared_fence(struct dma_resv *obj, struct dma_fence *fence);
void dma_resv_add_excl_fence(struct dma_resv *obj, struct dma_fence *fence);
+struct dma_fence *dma_resv_walk_unlocked(struct dma_resv *obj,
+ struct dma_resv_iter *cursor,
+ bool first, bool all_fences);
int dma_resv_get_fences(struct dma_resv *obj, struct dma_fence **pfence_excl,
unsigned *pshared_count, struct dma_fence ***pshared);
int dma_resv_copy_fences(struct dma_resv *dst, struct dma_resv *src);
--
2.25.1
next prev parent reply other threads:[~2021-09-16 11:30 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-16 11:30 Deploying new iterator interface for dma-buf Christian König
2021-09-16 11:30 ` Christian König [this message]
2021-09-16 12:15 ` [PATCH 01/26] dma-buf: add dma_resv_for_each_fence_unlocked v2 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 ` [PATCH 03/26] dma-buf: use new iterator in dma_resv_copy_fences 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 ` [PATCH 05/26] dma-buf: use new iterator in dma_resv_wait_timeout 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 ` [PATCH 07/26] drm/ttm: use the new iterator in ttm_bo_flush_all_fences 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 ` [PATCH 09/26] drm/amdgpu: use new iterator in amdgpu_ttm_bo_eviction_valuable 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 ` [PATCH 11/26] drm/radeon: use new iterator in radeon_sync_resv 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 ` [PATCH 13/26] drm/i915: use the new iterator in i915_gem_busy_ioctl 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 ` [PATCH 15/26] drm/i915: use the new iterator in i915_request_await_object v2 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 ` [PATCH 17/26] drm/i915: use new iterator in i915_gem_object_wait_priority v2 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 ` [PATCH 19/26] drm/i915: use new cursor in intel_prepare_plane_fb v2 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 ` [PATCH 21/26] drm: use new iterator in drm_gem_plane_helper_prepare_fb v2 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 ` [PATCH 23/26] drm/nouveau: use the new interator in nv50_wndw_prepare_fb v2 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 ` [PATCH 25/26] drm/etnaviv: replace dma_resv_get_excl_unlocked Christian König
2021-09-16 11:30 ` [PATCH 26/26] dma-buf: nuke dma_resv_get_excl_unlocked Christian König
2021-09-17 12:34 Deploying new iterator interface for dma-buf 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 13:23 ` Daniel Vetter
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20210916113042.3631-2-christian.koenig@amd.com \
--to=ckoenig.leichtzumerken@gmail.com \
--cc=daniel@ffwll.ch \
--cc=dri-devel@lists.freedesktop.org \
--cc=intel-gfx@lists.freedesktop.org \
--cc=linaro-mm-sig@lists.linaro.org \
--cc=linux-media@vger.kernel.org \
--cc=tvrtko.ursulin@linux.intel.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).