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From: Jason Ekstrand <jason@jlekstrand.net>
To: dri-devel@lists.freedesktop.org
Cc: Jason Ekstrand <jason@jlekstrand.net>
Subject: [PATCH 2/3] dma-buf: add dma_resv_get_singleton_rcu (v3)
Date: Mon, 15 Mar 2021 23:53:21 -0500	[thread overview]
Message-ID: <20210316045322.2020294-3-jason@jlekstrand.net> (raw)
In-Reply-To: <20210316045322.2020294-1-jason@jlekstrand.net>

Add a helper function to get a single fence representing
all fences in a dma_resv object.

This fence is either the only one in the object or all not
signaled fences of the object in a flatted out dma_fence_array.

v2 (Jason Ekstrand):
 - Take reference of fences both for creating the dma_fence_array and in
   the case where we return one fence.
 - Handle the case where dma_resv_get_list() returns NULL

v3 (Jason Ekstrand):
 - Add an _rcu suffix because it is read-only
 - Rewrite to use dma_resv_get_fences_rcu so it's RCU-safe
 - Add an EXPORT_SYMBOL_GPL declaration
 - Re-author the patch to Jason since very little is left of Christian
   König's original patch

Signed-off-by: Jason Ekstrand <jason@jlekstrand.net>
---
 drivers/dma-buf/dma-resv.c | 104 +++++++++++++++++++++++++++++++++++++
 include/linux/dma-resv.h   |   2 +
 2 files changed, 106 insertions(+)

diff --git a/drivers/dma-buf/dma-resv.c b/drivers/dma-buf/dma-resv.c
index 6ddbeb5dfbf65..5dd4c38bd9cb4 100644
--- a/drivers/dma-buf/dma-resv.c
+++ b/drivers/dma-buf/dma-resv.c
@@ -33,6 +33,8 @@
  */
 
 #include <linux/dma-resv.h>
+#include <linux/dma-fence-chain.h>
+#include <linux/dma-fence-array.h>
 #include <linux/export.h>
 #include <linux/mm.h>
 #include <linux/sched/mm.h>
@@ -49,6 +51,19 @@
  * write-side updates.
  */
 
+/**
+ * dma_fence_deep_dive_for_each - deep dive into the fence containers
+ * @fence: resulting fence
+ * @chain: variable for a dma_fence_chain
+ * @index: index into a dma_fence_array
+ * @head: starting point
+ *
+ * Helper to deep dive into the fence containers for flattening them.
+ */
+#define dma_fence_deep_dive_for_each(fence, chain, index, head)	\
+	dma_fence_chain_for_each(chain, head)			\
+		dma_fence_array_for_each(fence, index, chain)
+
 DEFINE_WD_CLASS(reservation_ww_class);
 EXPORT_SYMBOL(reservation_ww_class);
 
@@ -517,6 +532,95 @@ int dma_resv_get_fences_rcu(struct dma_resv *obj,
 }
 EXPORT_SYMBOL_GPL(dma_resv_get_fences_rcu);
 
+/**
+ * dma_resv_get_singleton - get a single fence for the dma_resv object
+ * @obj: the reservation object
+ * @extra: extra fence to add to the resulting array
+ * @result: resulting dma_fence
+ *
+ * Get a single fence representing all unsignaled fences in the dma_resv object
+ * plus the given extra fence. If we got only one fence return a new
+ * reference to that, otherwise return a dma_fence_array object.
+ *
+ * RETURNS
+ * Returns -NOMEM if allocations fail, zero otherwise.
+ */
+int dma_resv_get_singleton_rcu(struct dma_resv *obj, struct dma_fence **result)
+{
+	struct dma_fence **resv_fences, *fence, *chain, **fences;
+	struct dma_fence_array *array;
+	unsigned int num_resv_fences, num_fences;
+	unsigned int ret, i, j;
+
+	ret = dma_resv_get_fences_rcu(obj, NULL, &num_resv_fences, &resv_fences);
+	if (ret)
+		return ret;
+
+	num_fences = 0;
+	*result = NULL;
+
+	if (num_resv_fences == 0)
+		return 0;
+
+	for (i = 0; i < num_resv_fences; ++i) {
+		dma_fence_deep_dive_for_each(fence, chain, j, resv_fences[i]) {
+			if (dma_fence_is_signaled(fence))
+				continue;
+
+			*result = fence;
+			++num_fences;
+		}
+	}
+
+	if (num_fences <= 1) {
+		*result = dma_fence_get(*result);
+		goto put_resv_fences;
+	}
+
+	fences = kmalloc_array(num_fences, sizeof(struct dma_fence*),
+			       GFP_KERNEL);
+	if (!fences) {
+		*result = NULL;
+		ret = -ENOMEM;
+		goto put_resv_fences;
+	}
+
+	num_fences = 0;
+	for (i = 0; i < num_resv_fences; ++i) {
+		dma_fence_deep_dive_for_each(fence, chain, j, resv_fences[i]) {
+			if (!dma_fence_is_signaled(fence))
+				fences[num_fences++] = dma_fence_get(fence);
+		}
+	}
+
+	if (num_fences <= 1) {
+		*result = num_fences ? fences[0] : NULL;
+		kfree(fences);
+		goto put_resv_fences;
+	}
+
+	array = dma_fence_array_create(num_fences, fences,
+				       dma_fence_context_alloc(1),
+				       1, false);
+	if (array) {
+		*result = &array->base;
+	} else {
+		*result = NULL;
+		while (num_fences--)
+			dma_fence_put(fences[num_fences]);
+		kfree(fences);
+		ret = -ENOMEM;
+	}
+
+put_resv_fences:
+	while (num_resv_fences--)
+		dma_fence_put(resv_fences[num_resv_fences]);
+	kfree(resv_fences);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(dma_resv_get_singleton_rcu);
+
 /**
  * dma_resv_wait_timeout_rcu - Wait on reservation's objects
  * shared and/or exclusive fences.
diff --git a/include/linux/dma-resv.h b/include/linux/dma-resv.h
index d44a77e8a7e34..5f82894fed0b9 100644
--- a/include/linux/dma-resv.h
+++ b/include/linux/dma-resv.h
@@ -285,6 +285,8 @@ int dma_resv_get_fences_rcu(struct dma_resv *obj,
 
 int dma_resv_copy_fences(struct dma_resv *dst, struct dma_resv *src);
 
+int dma_resv_get_singleton_rcu(struct dma_resv *obj, struct dma_fence **result);
+
 long dma_resv_wait_timeout_rcu(struct dma_resv *obj, bool wait_all, bool intr,
 			       unsigned long timeout);
 
-- 
2.29.2

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  parent reply	other threads:[~2021-03-16  5:02 UTC|newest]

Thread overview: 53+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-25 23:58 [PATCH] RFC: dma-buf: Add an API for importing and exporting sync files Jason Ekstrand
2020-02-26  9:16 ` Christian König
2020-02-26 10:05   ` Daniel Vetter
2020-02-26 15:28     ` Jason Ekstrand
2020-02-26 16:46       ` Bas Nieuwenhuizen
2020-02-27  8:28         ` Christian König
2020-03-03 19:10           ` Jason Ekstrand
2020-03-04  8:34             ` Christian König
2020-03-04 16:27               ` Jason Ekstrand
2020-03-04 16:41                 ` Jason Ekstrand
2020-03-05 13:06                   ` Christian König
2020-03-05 15:54                     ` Jason Ekstrand
2020-03-09 16:21                       ` Christian König
2020-03-11  3:43                         ` Jason Ekstrand
2020-02-26 18:09 ` [PATCH] RFC: dma-buf: Add an API for importing and exporting sync files (v2) Jason Ekstrand
2020-03-03 19:03   ` [PATCH] RFC: dma-buf: Add an API for importing and exporting sync files (v3) Jason Ekstrand
2020-03-03 19:05     ` Jason Ekstrand
2020-03-11  3:43     ` [PATCH 1/3] dma-buf: add dma_fence_array_for_each (v2) Jason Ekstrand
2020-03-11  3:43       ` [PATCH 2/3] dma-buf: add dma_resv_get_singleton (v2) Jason Ekstrand
2020-03-11  3:43       ` [PATCH 3/3] RFC: dma-buf: Add an API for importing and exporting sync files (v4) Jason Ekstrand
2020-03-11 13:18         ` Christian König
2020-03-12 15:57           ` Jason Ekstrand
2020-03-13 10:33             ` Christian König
2020-03-17 21:21         ` [PATCH 3/3] RFC: dma-buf: Add an API for importing and exporting sync files (v5) Jason Ekstrand
2020-09-30  9:39           ` Michel Dänzer
2020-09-30  9:55             ` Daniel Vetter
2021-03-15 21:11               ` Jason Ekstrand
2021-03-15 21:30                 ` Daniel Vetter
2021-03-15 21:04           ` [PATCH 0/3] dma-buf: Add an API for exporting sync files (v6) Jason Ekstrand
2021-03-15 21:04             ` [PATCH 1/3] dma-buf: add dma_fence_array_for_each (v2) Jason Ekstrand
2021-03-15 21:04             ` [PATCH 2/3] dma-buf: add dma_resv_get_singleton (v2) Jason Ekstrand
2021-03-15 21:04             ` [PATCH 3/3] dma-buf: Add an API for exporting sync files (v6) Jason Ekstrand
2021-03-15 23:10               ` Jason Ekstrand
2021-03-16  8:51                 ` Michel Dänzer
2021-03-16 14:35                   ` Jason Ekstrand
2021-03-16  0:10               ` kernel test robot
2021-03-16  2:37               ` kernel test robot
2021-03-16  0:15             ` [PATCH 0/3] " Jason Ekstrand
2021-03-16  4:53             ` [PATCH 0/3] dma-buf: Add an API for exporting sync files (v7) Jason Ekstrand
2021-03-16  4:53               ` [PATCH 1/3] dma-buf: add dma_fence_array_for_each (v2) Jason Ekstrand
2021-03-16  4:53               ` Jason Ekstrand [this message]
2021-03-16  4:53               ` [PATCH 3/3] dma-buf: Add an API for exporting sync files (v7) Jason Ekstrand
2021-03-16  8:06                 ` kernel test robot
2021-03-17 22:19               ` [PATCH 0/3] dma-buf: Add an API for exporting sync files (v8) Jason Ekstrand
2021-03-17 22:19                 ` [PATCH 1/3] dma-buf: add dma_fence_array_for_each (v2) Jason Ekstrand
2021-03-18  9:38                   ` Christian König
2021-03-18 13:13                     ` Daniel Vetter
2021-03-19  1:40                       ` Jason Ekstrand
2021-03-17 22:19                 ` [PATCH 2/3] dma-buf: add dma_resv_get_singleton_rcu (v3) Jason Ekstrand
2021-03-17 22:19                 ` [PATCH 3/3] dma-buf: Add an API for exporting sync files (v8) Jason Ekstrand
2021-03-23 17:57                   ` Jason Ekstrand
2021-03-23 19:06                     ` Simon Ser
2021-03-23 19:34                       ` Jason Ekstrand

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