[PATCH 1/5] dma-buf: cleanup dma_fence_unwrap selftest

[PATCH 1/5] dma-buf: cleanup dma_fence_unwrap selftest

[Christian König]

The selftests, fix the error handling, remove unused functions and stop
leaking memory in failed tests.

Signed-off-by: Christian König <christian.koenig@amd.com>
---
 drivers/dma-buf/st-dma-fence-unwrap.c | 40 +++++++++++----------------
 1 file changed, 16 insertions(+), 24 deletions(-)

diff --git a/drivers/dma-buf/st-dma-fence-unwrap.c b/drivers/dma-buf/st-dma-fence-unwrap.c
index 039f016b57be..59628add93f5 100644
--- a/drivers/dma-buf/st-dma-fence-unwrap.c
+++ b/drivers/dma-buf/st-dma-fence-unwrap.c
@@ -4,27 +4,19 @@
  * Copyright (C) 2022 Advanced Micro Devices, Inc.
  */
 
+#include <linux/dma-fence.h>
+#include <linux/dma-fence-array.h>
+#include <linux/dma-fence-chain.h>
 #include <linux/dma-fence-unwrap.h>
-#if 0
-#include <linux/kernel.h>
-#include <linux/kthread.h>
-#include <linux/mm.h>
-#include <linux/sched/signal.h>
-#include <linux/slab.h>
-#include <linux/spinlock.h>
-#include <linux/random.h>
-#endif
 
 #include "selftest.h"
 
 #define CHAIN_SZ (4 << 10)
 
-static inline struct mock_fence {
+struct mock_fence {
 	struct dma_fence base;
 	spinlock_t lock;
-} *to_mock_fence(struct dma_fence *f) {
-	return container_of(f, struct mock_fence, base);
-}
+};
 
 static const char *mock_name(struct dma_fence *f)
 {
@@ -45,7 +37,8 @@ static struct dma_fence *mock_fence(void)
 		return NULL;
 
 	spin_lock_init(&f->lock);
-	dma_fence_init(&f->base, &mock_ops, &f->lock, 0, 0);
+	dma_fence_init(&f->base, &mock_ops, &f->lock,
+		       dma_fence_context_alloc(1), 1);
 
 	return &f->base;
 }
@@ -113,7 +106,6 @@ static int sanitycheck(void *arg)
 	if (!chain)
 		return -ENOMEM;
 
-	dma_fence_signal(f);
 	dma_fence_put(chain);
 	return err;
 }
@@ -154,10 +146,10 @@ static int unwrap_array(void *arg)
 		err = -EINVAL;
 	}
 
-	dma_fence_signal(f1);
-	dma_fence_signal(f2);
+	dma_fence_put(f1);
+	dma_fence_put(f2);
 	dma_fence_put(array);
-	return 0;
+	return err;
 }
 
 static int unwrap_chain(void *arg)
@@ -196,10 +188,10 @@ static int unwrap_chain(void *arg)
 		err = -EINVAL;
 	}
 
-	dma_fence_signal(f1);
-	dma_fence_signal(f2);
+	dma_fence_put(f1);
+	dma_fence_put(f2);
 	dma_fence_put(chain);
-	return 0;
+	return err;
 }
 
 static int unwrap_chain_array(void *arg)
@@ -242,10 +234,10 @@ static int unwrap_chain_array(void *arg)
 		err = -EINVAL;
 	}
 
-	dma_fence_signal(f1);
-	dma_fence_signal(f2);
+	dma_fence_put(f1);
+	dma_fence_put(f2);
 	dma_fence_put(chain);
-	return 0;
+	return err;
 }
 
 int dma_fence_unwrap(void)
-- 
2.25.1

[PATCH 2/5] dma-buf: cleanup dma_fence_unwrap implementation

[Christian König]

Move the code from the inline functions into exported functions.

Signed-off-by: Christian König <christian.koenig@amd.com>
---
 drivers/dma-buf/Makefile           |  2 +-
 drivers/dma-buf/dma-fence-unwrap.c | 59 ++++++++++++++++++++++++++++++
 include/linux/dma-fence-unwrap.h   | 52 ++------------------------
 3 files changed, 64 insertions(+), 49 deletions(-)
 create mode 100644 drivers/dma-buf/dma-fence-unwrap.c

diff --git a/drivers/dma-buf/Makefile b/drivers/dma-buf/Makefile
index 4c9eb53ba3f8..70ec901edf2c 100644
--- a/drivers/dma-buf/Makefile
+++ b/drivers/dma-buf/Makefile
@@ -1,6 +1,6 @@
 # SPDX-License-Identifier: GPL-2.0-only
 obj-y := dma-buf.o dma-fence.o dma-fence-array.o dma-fence-chain.o \
-	 dma-resv.o
+	 dma-fence-unwrap.o dma-resv.o
 obj-$(CONFIG_DMABUF_HEAPS)	+= dma-heap.o
 obj-$(CONFIG_DMABUF_HEAPS)	+= heaps/
 obj-$(CONFIG_SYNC_FILE)		+= sync_file.o
diff --git a/drivers/dma-buf/dma-fence-unwrap.c b/drivers/dma-buf/dma-fence-unwrap.c
new file mode 100644
index 000000000000..711be125428c
--- /dev/null
+++ b/drivers/dma-buf/dma-fence-unwrap.c
@@ -0,0 +1,59 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * dma-fence-util: misc functions for dma_fence objects
+ *
+ * Copyright (C) 2022 Advanced Micro Devices, Inc.
+ * Authors:
+ *	Christian König <christian.koenig@amd.com>
+ */
+
+#include <linux/dma-fence.h>
+#include <linux/dma-fence-array.h>
+#include <linux/dma-fence-chain.h>
+#include <linux/dma-fence-unwrap.h>
+
+/* Internal helper to start new array iteration, don't use directly */
+static struct dma_fence *
+__dma_fence_unwrap_array(struct dma_fence_unwrap *cursor)
+{
+	cursor->array = dma_fence_chain_contained(cursor->chain);
+	cursor->index = 0;
+	return dma_fence_array_first(cursor->array);
+}
+
+/**
+ * dma_fence_unwrap_first - return the first fence from fence containers
+ * @head: the entrypoint into the containers
+ * @cursor: current position inside the containers
+ *
+ * Unwraps potential dma_fence_chain/dma_fence_array containers and return the
+ * first fence.
+ */
+struct dma_fence *dma_fence_unwrap_first(struct dma_fence *head,
+					 struct dma_fence_unwrap *cursor)
+{
+	cursor->chain = dma_fence_get(head);
+	return __dma_fence_unwrap_array(cursor);
+}
+EXPORT_SYMBOL_GPL(dma_fence_unwrap_first);
+
+/**
+ * dma_fence_unwrap_next - return the next fence from a fence containers
+ * @cursor: current position inside the containers
+ *
+ * Continue unwrapping the dma_fence_chain/dma_fence_array containers and return
+ * the next fence from them.
+ */
+struct dma_fence *dma_fence_unwrap_next(struct dma_fence_unwrap *cursor)
+{
+	struct dma_fence *tmp;
+
+	++cursor->index;
+	tmp = dma_fence_array_next(cursor->array, cursor->index);
+	if (tmp)
+		return tmp;
+
+	cursor->chain = dma_fence_chain_walk(cursor->chain);
+	return __dma_fence_unwrap_array(cursor);
+}
+EXPORT_SYMBOL_GPL(dma_fence_unwrap_next);
diff --git a/include/linux/dma-fence-unwrap.h b/include/linux/dma-fence-unwrap.h
index 77e335a1bcac..e7c219da4ed7 100644
--- a/include/linux/dma-fence-unwrap.h
+++ b/include/linux/dma-fence-unwrap.h
@@ -1,7 +1,5 @@
 /* SPDX-License-Identifier: GPL-2.0-only */
 /*
- * fence-chain: chain fences together in a timeline
- *
  * Copyright (C) 2022 Advanced Micro Devices, Inc.
  * Authors:
  *	Christian König <christian.koenig@amd.com>
@@ -10,8 +8,7 @@
 #ifndef __LINUX_DMA_FENCE_UNWRAP_H
 #define __LINUX_DMA_FENCE_UNWRAP_H
 
-#include <linux/dma-fence-chain.h>
-#include <linux/dma-fence-array.h>
+struct dma_fence;
 
 /**
  * struct dma_fence_unwrap - cursor into the container structure
@@ -33,50 +30,9 @@ struct dma_fence_unwrap {
 	unsigned int index;
 };
 
-/* Internal helper to start new array iteration, don't use directly */
-static inline struct dma_fence *
-__dma_fence_unwrap_array(struct dma_fence_unwrap * cursor)
-{
-	cursor->array = dma_fence_chain_contained(cursor->chain);
-	cursor->index = 0;
-	return dma_fence_array_first(cursor->array);
-}
-
-/**
- * dma_fence_unwrap_first - return the first fence from fence containers
- * @head: the entrypoint into the containers
- * @cursor: current position inside the containers
- *
- * Unwraps potential dma_fence_chain/dma_fence_array containers and return the
- * first fence.
- */
-static inline struct dma_fence *
-dma_fence_unwrap_first(struct dma_fence *head, struct dma_fence_unwrap *cursor)
-{
-	cursor->chain = dma_fence_get(head);
-	return __dma_fence_unwrap_array(cursor);
-}
-
-/**
- * dma_fence_unwrap_next - return the next fence from a fence containers
- * @cursor: current position inside the containers
- *
- * Continue unwrapping the dma_fence_chain/dma_fence_array containers and return
- * the next fence from them.
- */
-static inline struct dma_fence *
-dma_fence_unwrap_next(struct dma_fence_unwrap *cursor)
-{
-	struct dma_fence *tmp;
-
-	++cursor->index;
-	tmp = dma_fence_array_next(cursor->array, cursor->index);
-	if (tmp)
-		return tmp;
-
-	cursor->chain = dma_fence_chain_walk(cursor->chain);
-	return __dma_fence_unwrap_array(cursor);
-}
+struct dma_fence *dma_fence_unwrap_first(struct dma_fence *head,
+					 struct dma_fence_unwrap *cursor);
+struct dma_fence *dma_fence_unwrap_next(struct dma_fence_unwrap *cursor);
 
 /**
  * dma_fence_unwrap_for_each - iterate over all fences in containers
-- 
2.25.1

[PATCH 3/5] dma-buf: return only unsignaled fences in dma_fence_unwrap_for_each

[Christian König]

dma_fence_chain containers cleanup signaled fences automatically, so
filter those out from arrays as well.

Signed-off-by: Christian König <christian.koenig@amd.com>
---
 drivers/dma-buf/dma-fence-unwrap.c | 23 ++++++++++++++++-------
 include/linux/dma-fence-unwrap.h   |  4 ++--
 2 files changed, 18 insertions(+), 9 deletions(-)

diff --git a/drivers/dma-buf/dma-fence-unwrap.c b/drivers/dma-buf/dma-fence-unwrap.c
index 711be125428c..7b0b91086ded 100644
--- a/drivers/dma-buf/dma-fence-unwrap.c
+++ b/drivers/dma-buf/dma-fence-unwrap.c
@@ -32,8 +32,13 @@ __dma_fence_unwrap_array(struct dma_fence_unwrap *cursor)
 struct dma_fence *dma_fence_unwrap_first(struct dma_fence *head,
 					 struct dma_fence_unwrap *cursor)
 {
+	struct dma_fence *tmp;
+
 	cursor->chain = dma_fence_get(head);
-	return __dma_fence_unwrap_array(cursor);
+	tmp = __dma_fence_unwrap_array(cursor);
+	if (tmp && dma_fence_is_signaled(tmp))
+		tmp = dma_fence_unwrap_next(cursor);
+	return tmp;
 }
 EXPORT_SYMBOL_GPL(dma_fence_unwrap_first);
 
@@ -48,12 +53,16 @@ struct dma_fence *dma_fence_unwrap_next(struct dma_fence_unwrap *cursor)
 {
 	struct dma_fence *tmp;
 
-	++cursor->index;
-	tmp = dma_fence_array_next(cursor->array, cursor->index);
-	if (tmp)
-		return tmp;
+	do {
+		++cursor->index;
+		tmp = dma_fence_array_next(cursor->array, cursor->index);
+		if (tmp && !dma_fence_is_signaled(tmp))
+			return tmp;
+
+		cursor->chain = dma_fence_chain_walk(cursor->chain);
+		tmp = __dma_fence_unwrap_array(cursor);
+	} while (tmp && dma_fence_is_signaled(tmp));
 
-	cursor->chain = dma_fence_chain_walk(cursor->chain);
-	return __dma_fence_unwrap_array(cursor);
+	return tmp;
 }
 EXPORT_SYMBOL_GPL(dma_fence_unwrap_next);
diff --git a/include/linux/dma-fence-unwrap.h b/include/linux/dma-fence-unwrap.h
index e7c219da4ed7..e9d114637294 100644
--- a/include/linux/dma-fence-unwrap.h
+++ b/include/linux/dma-fence-unwrap.h
@@ -41,8 +41,8 @@ struct dma_fence *dma_fence_unwrap_next(struct dma_fence_unwrap *cursor);
  * @head: starting point for the iterator
  *
  * Unwrap dma_fence_chain and dma_fence_array containers and deep dive into all
- * potential fences in them. If @head is just a normal fence only that one is
- * returned.
+ * potential none signaled fences in them. If @head is just a normal fence only
+ * that one is returned.
  */
 #define dma_fence_unwrap_for_each(fence, cursor, head)			\
 	for (fence = dma_fence_unwrap_first(head, cursor); fence;	\
-- 
2.25.1

[PATCH 4/5] dma-buf: generalize dma_fence unwrap & merging v2

[Christian König]

Introduce a dma_fence_unwrap_merge() macro which allows to unwrap fences
which potentially can be containers as well and then merge them back
together into a flat dma_fence_array.

v2: rename the function, add some more comments about how the wrapper is
    used, move filtering of signaled fences into the unwrap iterator,
    add complex selftest which covers more cases.

Signed-off-by: Christian König <christian.koenig@amd.com>
---
 drivers/dma-buf/dma-fence-unwrap.c    |  99 +++++++++++++++++++++
 drivers/dma-buf/st-dma-fence-unwrap.c | 109 +++++++++++++++++++++++
 drivers/dma-buf/sync_file.c           | 119 ++------------------------
 include/linux/dma-fence-unwrap.h      |  24 ++++++
 4 files changed, 238 insertions(+), 113 deletions(-)

diff --git a/drivers/dma-buf/dma-fence-unwrap.c b/drivers/dma-buf/dma-fence-unwrap.c
index 7b0b91086ded..4ed5ea8807d7 100644
--- a/drivers/dma-buf/dma-fence-unwrap.c
+++ b/drivers/dma-buf/dma-fence-unwrap.c
@@ -11,6 +11,7 @@
 #include <linux/dma-fence-array.h>
 #include <linux/dma-fence-chain.h>
 #include <linux/dma-fence-unwrap.h>
+#include <linux/slab.h>
 
 /* Internal helper to start new array iteration, don't use directly */
 static struct dma_fence *
@@ -66,3 +67,101 @@ struct dma_fence *dma_fence_unwrap_next(struct dma_fence_unwrap *cursor)
 	return tmp;
 }
 EXPORT_SYMBOL_GPL(dma_fence_unwrap_next);
+
+/* Implementation for the dma_fence_merge() marco, don't use directly */
+struct dma_fence *__dma_fence_unwrap_merge(unsigned int num_fences,
+					   struct dma_fence **fences,
+					   struct dma_fence_unwrap *iter)
+{
+	struct dma_fence_array *result;
+	struct dma_fence *tmp, **array;
+	unsigned int i;
+	size_t count;
+
+	count = 0;
+	for (i = 0; i < num_fences; ++i) {
+		dma_fence_unwrap_for_each(tmp, &iter[i], fences[i])
+			++count;
+	}
+
+	if (count == 0)
+		return dma_fence_get_stub();
+
+	array = kmalloc_array(count, sizeof(*array), GFP_KERNEL);
+	if (!array)
+		return NULL;
+
+	/*
+	 * This trashes the input fence array and uses it as position for the
+	 * following merge loop. This works because the dma_fence_merge()
+	 * wrapper macro is creating this temporary array on the stack together
+	 * with the iterators.
+	 */
+	for (i = 0; i < num_fences; ++i)
+		fences[i] = dma_fence_unwrap_first(fences[i], &iter[i]);
+
+	count = 0;
+	do {
+		unsigned int sel;
+
+restart:
+		tmp = NULL;
+		for (i = 0; i < num_fences; ++i) {
+			struct dma_fence *next = fences[i];
+
+			if (!next)
+				continue;
+
+			/*
+			 * We can't guarantee that inpute fences are ordered by
+			 * context, but it is still quite likely when this
+			 * function is used multiple times. So attempt to order
+			 * the fences by context as we pass over them and merge
+			 * fences with the same context.
+			 */
+			if (!tmp || tmp->context > next->context) {
+				tmp = next;
+				sel = i;
+
+			} else if (tmp->context < next->context) {
+				continue;
+
+			} else if (dma_fence_is_later(tmp, next)) {
+				fences[i] = dma_fence_unwrap_next(&iter[i]);
+				goto restart;
+			} else {
+				fences[sel] = dma_fence_unwrap_next(&iter[sel]);
+				goto restart;
+			}
+		}
+
+		if (tmp) {
+			array[count++] = dma_fence_get(tmp);
+			fences[sel] = dma_fence_unwrap_next(&iter[sel]);
+		}
+	} while (tmp);
+
+	if (count == 0) {
+		tmp = dma_fence_get_stub();
+		goto return_tmp;
+	}
+
+	if (count == 1) {
+		tmp = array[0];
+		goto return_tmp;
+	}
+
+	result = dma_fence_array_create(count, array,
+					dma_fence_context_alloc(1),
+					1, false);
+	if (!result) {
+		tmp = NULL;
+		goto return_tmp;
+	}
+	return &result->base;
+
+return_tmp:
+	kfree(array);
+	return tmp;
+}
+EXPORT_SYMBOL_GPL(__dma_fence_unwrap_merge);
diff --git a/drivers/dma-buf/st-dma-fence-unwrap.c b/drivers/dma-buf/st-dma-fence-unwrap.c
index 59628add93f5..3a8aca651938 100644
--- a/drivers/dma-buf/st-dma-fence-unwrap.c
+++ b/drivers/dma-buf/st-dma-fence-unwrap.c
@@ -240,6 +240,113 @@ static int unwrap_chain_array(void *arg)
 	return err;
 }
 
+static int unwrap_merge(void *arg)
+{
+	struct dma_fence *fence, *f1, *f2, *f3;
+	struct dma_fence_unwrap iter;
+	int err = 0;
+
+	f1 = mock_fence();
+	if (!f1)
+		return -ENOMEM;
+
+	f2 = mock_fence();
+	if (!f2) {
+		err = -ENOMEM;
+		goto error_put_f1;
+	}
+
+	f3 = dma_fence_unwrap_merge(f1, f2);
+	if (!f3) {
+		err = -ENOMEM;
+		goto error_put_f2;
+	}
+
+	dma_fence_unwrap_for_each(fence, &iter, f3) {
+		if (fence == f1) {
+			dma_fence_put(f1);
+			f1 = NULL;
+		} else if (fence == f2) {
+			dma_fence_put(f2);
+			f2 = NULL;
+		} else {
+			pr_err("Unexpected fence!\n");
+			err = -EINVAL;
+		}
+	}
+
+	if (f1 || f2) {
+		pr_err("Not all fences seen!\n");
+		err = -EINVAL;
+	}
+
+	dma_fence_put(f3);
+error_put_f2:
+	dma_fence_put(f2);
+error_put_f1:
+	dma_fence_put(f1);
+	return err;
+}
+
+static int unwrap_merge_complex(void *arg)
+{
+	struct dma_fence *fence, *f1, *f2, *f3, *f4, *f5;
+	struct dma_fence_unwrap iter;
+	int err = -ENOMEM;
+
+	f1 = mock_fence();
+	if (!f1)
+		return -ENOMEM;
+
+	f2 = mock_fence();
+	if (!f2)
+		goto error_put_f1;
+
+	f3 = dma_fence_unwrap_merge(f1, f2);
+	if (!f3)
+		goto error_put_f2;
+
+	/* The resulting array has the fences in reverse */
+	f4 = dma_fence_unwrap_merge(f2, f1);
+	if (!f4)
+		goto error_put_f3;
+
+	/* Signaled fences should be filtered, the two arrays merged. */
+	f5 = dma_fence_unwrap_merge(f3, f4, dma_fence_get_stub());
+	if (!f5)
+		goto error_put_f4;
+
+	err = 0;
+	dma_fence_unwrap_for_each(fence, &iter, f5) {
+		if (fence == f1) {
+			dma_fence_put(f1);
+			f1 = NULL;
+		} else if (fence == f2) {
+			dma_fence_put(f2);
+			f2 = NULL;
+		} else {
+			pr_err("Unexpected fence!\n");
+			err = -EINVAL;
+		}
+	}
+
+	if (f1 || f2) {
+		pr_err("Not all fences seen!\n");
+		err = -EINVAL;
+	}
+
+	dma_fence_put(f5);
+error_put_f4:
+	dma_fence_put(f4);
+error_put_f3:
+	dma_fence_put(f3);
+error_put_f2:
+	dma_fence_put(f2);
+error_put_f1:
+	dma_fence_put(f1);
+	return err;
+}
+
 int dma_fence_unwrap(void)
 {
 	static const struct subtest tests[] = {
@@ -247,6 +354,8 @@ int dma_fence_unwrap(void)
 		SUBTEST(unwrap_array),
 		SUBTEST(unwrap_chain),
 		SUBTEST(unwrap_chain_array),
+		SUBTEST(unwrap_merge),
+		SUBTEST(unwrap_merge_complex),
 	};
 
 	return subtests(tests, NULL);
diff --git a/drivers/dma-buf/sync_file.c b/drivers/dma-buf/sync_file.c
index 0fe564539166..3ebec19a8e02 100644
--- a/drivers/dma-buf/sync_file.c
+++ b/drivers/dma-buf/sync_file.c
@@ -146,50 +146,6 @@ char *sync_file_get_name(struct sync_file *sync_file, char *buf, int len)
 	return buf;
 }
 
-static int sync_file_set_fence(struct sync_file *sync_file,
-			       struct dma_fence **fences, int num_fences)
-{
-	struct dma_fence_array *array;
-
-	/*
-	 * The reference for the fences in the new sync_file and held
-	 * in add_fence() during the merge procedure, so for num_fences == 1
-	 * we already own a new reference to the fence. For num_fence > 1
-	 * we own the reference of the dma_fence_array creation.
-	 */
-
-	if (num_fences == 0) {
-		sync_file->fence = dma_fence_get_stub();
-		kfree(fences);
-
-	} else if (num_fences == 1) {
-		sync_file->fence = fences[0];
-		kfree(fences);
-
-	} else {
-		array = dma_fence_array_create(num_fences, fences,
-					       dma_fence_context_alloc(1),
-					       1, false);
-		if (!array)
-			return -ENOMEM;
-
-		sync_file->fence = &array->base;
-	}
-
-	return 0;
-}
-
-static void add_fence(struct dma_fence **fences,
-		      int *i, struct dma_fence *fence)
-{
-	fences[*i] = fence;
-
-	if (!dma_fence_is_signaled(fence)) {
-		dma_fence_get(fence);
-		(*i)++;
-	}
-}
-
 /**
  * sync_file_merge() - merge two sync_files
  * @name:	name of new fence
@@ -203,84 +159,21 @@ static void add_fence(struct dma_fence **fences,
 static struct sync_file *sync_file_merge(const char *name, struct sync_file *a,
 					 struct sync_file *b)
 {
-	struct dma_fence *a_fence, *b_fence, **fences;
-	struct dma_fence_unwrap a_iter, b_iter;
-	unsigned int index, num_fences;
 	struct sync_file *sync_file;
+	struct dma_fence *fence;
 
 	sync_file = sync_file_alloc();
 	if (!sync_file)
 		return NULL;
 
-	num_fences = 0;
-	dma_fence_unwrap_for_each(a_fence, &a_iter, a->fence)
-		++num_fences;
-	dma_fence_unwrap_for_each(b_fence, &b_iter, b->fence)
-		++num_fences;
-
-	if (num_fences > INT_MAX)
-		goto err_free_sync_file;
-
-	fences = kcalloc(num_fences, sizeof(*fences), GFP_KERNEL);
-	if (!fences)
-		goto err_free_sync_file;
-
-	/*
-	 * We can't guarantee that fences in both a and b are ordered, but it is
-	 * still quite likely.
-	 *
-	 * So attempt to order the fences as we pass over them and merge fences
-	 * with the same context.
-	 */
-
-	index = 0;
-	for (a_fence = dma_fence_unwrap_first(a->fence, &a_iter),
-	     b_fence = dma_fence_unwrap_first(b->fence, &b_iter);
-	     a_fence || b_fence; ) {
-
-		if (!b_fence) {
-			add_fence(fences, &index, a_fence);
-			a_fence = dma_fence_unwrap_next(&a_iter);
-
-		} else if (!a_fence) {
-			add_fence(fences, &index, b_fence);
-			b_fence = dma_fence_unwrap_next(&b_iter);
-
-		} else if (a_fence->context < b_fence->context) {
-			add_fence(fences, &index, a_fence);
-			a_fence = dma_fence_unwrap_next(&a_iter);
-
-		} else if (b_fence->context < a_fence->context) {
-			add_fence(fences, &index, b_fence);
-			b_fence = dma_fence_unwrap_next(&b_iter);
-
-		} else if (__dma_fence_is_later(a_fence->seqno, b_fence->seqno,
-						a_fence->ops)) {
-			add_fence(fences, &index, a_fence);
-			a_fence = dma_fence_unwrap_next(&a_iter);
-			b_fence = dma_fence_unwrap_next(&b_iter);
-
-		} else {
-			add_fence(fences, &index, b_fence);
-			a_fence = dma_fence_unwrap_next(&a_iter);
-			b_fence = dma_fence_unwrap_next(&b_iter);
-		}
+	fence = dma_fence_unwrap_merge(a->fence, b->fence);
+	if (!fence) {
+		fput(sync_file->file);
+		return NULL;
 	}
-
-	if (sync_file_set_fence(sync_file, fences, index) < 0)
-		goto err_put_fences;
-
+	sync_file->fence = fence;
 	strlcpy(sync_file->user_name, name, sizeof(sync_file->user_name));
 	return sync_file;
-
-err_put_fences:
-	while (index)
-		dma_fence_put(fences[--index]);
-	kfree(fences);
-
-err_free_sync_file:
-	fput(sync_file->file);
-	return NULL;
 }
 
 static int sync_file_release(struct inode *inode, struct file *file)
diff --git a/include/linux/dma-fence-unwrap.h b/include/linux/dma-fence-unwrap.h
index e9d114637294..43c8a9bbee88 100644
--- a/include/linux/dma-fence-unwrap.h
+++ b/include/linux/dma-fence-unwrap.h
@@ -48,4 +48,28 @@ struct dma_fence *dma_fence_unwrap_next(struct dma_fence_unwrap *cursor);
 	for (fence = dma_fence_unwrap_first(head, cursor); fence;	\
 	     fence = dma_fence_unwrap_next(cursor))
 
+struct dma_fence *__dma_fence_unwrap_merge(unsigned int num_fences,
+					   struct dma_fence **fences,
+					   struct dma_fence_unwrap *cursors);
+
+/**
+ * dma_fence_unwrap_merge - unwrap and merge fences
+ *
+ * All fences given as parameters are unwrapped and merged back together as flat
+ * dma_fence_array. Useful if multiple containers need to be merged together.
+ *
+ * Implemented as a macro to allocate the necessary arrays on the stack and
+ * account the stack frame size to the caller.
+ *
+ * Returns NULL on memory allocation failure, a dma_fence object representing
+ * all the given fences otherwise.
+ */
+#define dma_fence_unwrap_merge(...)					\
+	({								\
+		struct dma_fence *__f[] = { __VA_ARGS__ };		\
+		struct dma_fence_unwrap __c[ARRAY_SIZE(__f)];		\
+									\
+		__dma_fence_unwrap_merge(ARRAY_SIZE(__f), __f, __c);	\
+	})
+
 #endif
-- 
2.25.1

[PATCH 5/5] drm: use dma_fence_unwrap_merge() in drm_syncobj

[Christian König]

The unwrap merge function is now intended for this use case.

Signed-off-by: Christian König <christian.koenig@amd.com>
---
 drivers/gpu/drm/drm_syncobj.c | 57 +++++------------------------------
 1 file changed, 7 insertions(+), 50 deletions(-)

diff --git a/drivers/gpu/drm/drm_syncobj.c b/drivers/gpu/drm/drm_syncobj.c
index 7e48dcd1bee4..bbad9e4696e7 100644
--- a/drivers/gpu/drm/drm_syncobj.c
+++ b/drivers/gpu/drm/drm_syncobj.c
@@ -184,6 +184,7 @@
  */
 
 #include <linux/anon_inodes.h>
+#include <linux/dma-fence-unwrap.h>
 #include <linux/file.h>
 #include <linux/fs.h>
 #include <linux/sched/signal.h>
@@ -853,57 +854,12 @@ drm_syncobj_fd_to_handle_ioctl(struct drm_device *dev, void *data,
 					&args->handle);
 }
 
-
-/*
- * Try to flatten a dma_fence_chain into a dma_fence_array so that it can be
- * added as timeline fence to a chain again.
- */
-static int drm_syncobj_flatten_chain(struct dma_fence **f)
-{
-	struct dma_fence_chain *chain = to_dma_fence_chain(*f);
-	struct dma_fence *tmp, **fences;
-	struct dma_fence_array *array;
-	unsigned int count;
-
-	if (!chain)
-		return 0;
-
-	count = 0;
-	dma_fence_chain_for_each(tmp, &chain->base)
-		++count;
-
-	fences = kmalloc_array(count, sizeof(*fences), GFP_KERNEL);
-	if (!fences)
-		return -ENOMEM;
-
-	count = 0;
-	dma_fence_chain_for_each(tmp, &chain->base)
-		fences[count++] = dma_fence_get(tmp);
-
-	array = dma_fence_array_create(count, fences,
-				       dma_fence_context_alloc(1),
-				       1, false);
-	if (!array)
-		goto free_fences;
-
-	dma_fence_put(*f);
-	*f = &array->base;
-	return 0;
-
-free_fences:
-	while (count--)
-		dma_fence_put(fences[count]);
-
-	kfree(fences);
-	return -ENOMEM;
-}
-
 static int drm_syncobj_transfer_to_timeline(struct drm_file *file_private,
 					    struct drm_syncobj_transfer *args)
 {
 	struct drm_syncobj *timeline_syncobj = NULL;
+	struct dma_fence *fence, *tmp;
 	struct dma_fence_chain *chain;
-	struct dma_fence *fence;
 	int ret;
 
 	timeline_syncobj = drm_syncobj_find(file_private, args->dst_handle);
@@ -912,13 +868,14 @@ static int drm_syncobj_transfer_to_timeline(struct drm_file *file_private,
 	}
 	ret = drm_syncobj_find_fence(file_private, args->src_handle,
 				     args->src_point, args->flags,
-				     &fence);
+				     &tmp);
 	if (ret)
 		goto err_put_timeline;
 
-	ret = drm_syncobj_flatten_chain(&fence);
-	if (ret)
-		goto err_free_fence;
+	fence = dma_fence_unwrap_merge(tmp);
+	dma_fence_put(tmp);
+	if (!fence)
+		goto err_put_timeline;
 
 	chain = dma_fence_chain_alloc();
 	if (!chain) {
-- 
2.25.1

Re: [PATCH 1/5] dma-buf: cleanup dma_fence_unwrap selftest

[Daniel Vetter]

On Wed, May 04, 2022 at 02:22:52PM +0200, Christian König wrote:
> The selftests, fix the error handling, remove unused functions and stop
> leaking memory in failed tests.
> 
> Signed-off-by: Christian König <christian.koenig@amd.com>
> ---
>  drivers/dma-buf/st-dma-fence-unwrap.c | 40 +++++++++++----------------
>  1 file changed, 16 insertions(+), 24 deletions(-)
> 
> diff --git a/drivers/dma-buf/st-dma-fence-unwrap.c b/drivers/dma-buf/st-dma-fence-unwrap.c
> index 039f016b57be..59628add93f5 100644
> --- a/drivers/dma-buf/st-dma-fence-unwrap.c
> +++ b/drivers/dma-buf/st-dma-fence-unwrap.c
> @@ -4,27 +4,19 @@
>   * Copyright (C) 2022 Advanced Micro Devices, Inc.
>   */
>  
> +#include <linux/dma-fence.h>
> +#include <linux/dma-fence-array.h>
> +#include <linux/dma-fence-chain.h>
>  #include <linux/dma-fence-unwrap.h>
> -#if 0
> -#include <linux/kernel.h>
> -#include <linux/kthread.h>
> -#include <linux/mm.h>
> -#include <linux/sched/signal.h>
> -#include <linux/slab.h>
> -#include <linux/spinlock.h>
> -#include <linux/random.h>
> -#endif
>  
>  #include "selftest.h"
>  
>  #define CHAIN_SZ (4 << 10)
>  
> -static inline struct mock_fence {
> +struct mock_fence {
>  	struct dma_fence base;
>  	spinlock_t lock;
> -} *to_mock_fence(struct dma_fence *f) {
> -	return container_of(f, struct mock_fence, base);
> -}
> +};
>  
>  static const char *mock_name(struct dma_fence *f)
>  {
> @@ -45,7 +37,8 @@ static struct dma_fence *mock_fence(void)
>  		return NULL;
>  
>  	spin_lock_init(&f->lock);
> -	dma_fence_init(&f->base, &mock_ops, &f->lock, 0, 0);
> +	dma_fence_init(&f->base, &mock_ops, &f->lock,
> +		       dma_fence_context_alloc(1), 1);
>  
>  	return &f->base;
>  }
> @@ -113,7 +106,6 @@ static int sanitycheck(void *arg)
>  	if (!chain)
>  		return -ENOMEM;
>  
> -	dma_fence_signal(f);
>  	dma_fence_put(chain);
>  	return err;
>  }
> @@ -154,10 +146,10 @@ static int unwrap_array(void *arg)
>  		err = -EINVAL;
>  	}
>  
> -	dma_fence_signal(f1);
> -	dma_fence_signal(f2);
> +	dma_fence_put(f1);
> +	dma_fence_put(f2);

I'm completely lost on why you add these _put() calls? The reference we
create all get transferred over to the container object, and that takes
care of releasing them.

The other bits with error handling and code cleanup all look good, and
dropping dma_fence_signal calls also makes sense. But this one I don't
get.
-Daniel

>  	dma_fence_put(array);
> -	return 0;
> +	return err;
>  }
>  
>  static int unwrap_chain(void *arg)
> @@ -196,10 +188,10 @@ static int unwrap_chain(void *arg)
>  		err = -EINVAL;
>  	}
>  
> -	dma_fence_signal(f1);
> -	dma_fence_signal(f2);
> +	dma_fence_put(f1);
> +	dma_fence_put(f2);
>  	dma_fence_put(chain);
> -	return 0;
> +	return err;
>  }
>  
>  static int unwrap_chain_array(void *arg)
> @@ -242,10 +234,10 @@ static int unwrap_chain_array(void *arg)
>  		err = -EINVAL;
>  	}
>  
> -	dma_fence_signal(f1);
> -	dma_fence_signal(f2);
> +	dma_fence_put(f1);
> +	dma_fence_put(f2);
>  	dma_fence_put(chain);
> -	return 0;
> +	return err;
>  }
>  
>  int dma_fence_unwrap(void)
> -- 
> 2.25.1
> 

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch

Re: [PATCH 1/5] dma-buf: cleanup dma_fence_unwrap selftest

[Daniel Vetter]

On Wed, May 04, 2022 at 02:22:52PM +0200, Christian König wrote:
> The selftests, fix the error handling, remove unused functions and stop
> leaking memory in failed tests.
> 
> Signed-off-by: Christian König <christian.koenig@amd.com>
> ---
>  drivers/dma-buf/st-dma-fence-unwrap.c | 40 +++++++++++----------------
>  1 file changed, 16 insertions(+), 24 deletions(-)
> 
> diff --git a/drivers/dma-buf/st-dma-fence-unwrap.c b/drivers/dma-buf/st-dma-fence-unwrap.c
> index 039f016b57be..59628add93f5 100644
> --- a/drivers/dma-buf/st-dma-fence-unwrap.c
> +++ b/drivers/dma-buf/st-dma-fence-unwrap.c
> @@ -4,27 +4,19 @@
>   * Copyright (C) 2022 Advanced Micro Devices, Inc.
>   */
>  
> +#include <linux/dma-fence.h>
> +#include <linux/dma-fence-array.h>
> +#include <linux/dma-fence-chain.h>
>  #include <linux/dma-fence-unwrap.h>
> -#if 0
> -#include <linux/kernel.h>
> -#include <linux/kthread.h>
> -#include <linux/mm.h>
> -#include <linux/sched/signal.h>
> -#include <linux/slab.h>
> -#include <linux/spinlock.h>
> -#include <linux/random.h>
> -#endif
>  
>  #include "selftest.h"
>  
>  #define CHAIN_SZ (4 << 10)
>  
> -static inline struct mock_fence {
> +struct mock_fence {
>  	struct dma_fence base;
>  	spinlock_t lock;
> -} *to_mock_fence(struct dma_fence *f) {
> -	return container_of(f, struct mock_fence, base);
> -}
> +};
>  
>  static const char *mock_name(struct dma_fence *f)
>  {
> @@ -45,7 +37,8 @@ static struct dma_fence *mock_fence(void)
>  		return NULL;
>  
>  	spin_lock_init(&f->lock);
> -	dma_fence_init(&f->base, &mock_ops, &f->lock, 0, 0);
> +	dma_fence_init(&f->base, &mock_ops, &f->lock,
> +		       dma_fence_context_alloc(1), 1);
>  
>  	return &f->base;
>  }
> @@ -113,7 +106,6 @@ static int sanitycheck(void *arg)
>  	if (!chain)
>  		return -ENOMEM;
>  
> -	dma_fence_signal(f);
>  	dma_fence_put(chain);
>  	return err;
>  }
> @@ -154,10 +146,10 @@ static int unwrap_array(void *arg)
>  		err = -EINVAL;
>  	}
>  
> -	dma_fence_signal(f1);
> -	dma_fence_signal(f2);
> +	dma_fence_put(f1);
> +	dma_fence_put(f2);

I'm completely lost on why you add these _put() calls? The reference we
create all get transferred over to the container object, and that takes
care of releasing them.

The other bits with error handling and code cleanup all look good, and
dropping dma_fence_signal calls also makes sense. But this one I don't
get.
-Daniel

>  	dma_fence_put(array);
> -	return 0;
> +	return err;
>  }
>  
>  static int unwrap_chain(void *arg)
> @@ -196,10 +188,10 @@ static int unwrap_chain(void *arg)
>  		err = -EINVAL;
>  	}
>  
> -	dma_fence_signal(f1);
> -	dma_fence_signal(f2);
> +	dma_fence_put(f1);
> +	dma_fence_put(f2);
>  	dma_fence_put(chain);
> -	return 0;
> +	return err;
>  }
>  
>  static int unwrap_chain_array(void *arg)
> @@ -242,10 +234,10 @@ static int unwrap_chain_array(void *arg)
>  		err = -EINVAL;
>  	}
>  
> -	dma_fence_signal(f1);
> -	dma_fence_signal(f2);
> +	dma_fence_put(f1);
> +	dma_fence_put(f2);
>  	dma_fence_put(chain);
> -	return 0;
> +	return err;
>  }
>  
>  int dma_fence_unwrap(void)
> -- 
> 2.25.1
> 

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch

Re: [PATCH 2/5] dma-buf: cleanup dma_fence_unwrap implementation

[Daniel Vetter]

On Wed, May 04, 2022 at 02:22:53PM +0200, Christian König wrote:
> Move the code from the inline functions into exported functions.
> 
> Signed-off-by: Christian König <christian.koenig@amd.com>

Didn't check you didn't slip in a typo or so :-)

Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>

> ---
>  drivers/dma-buf/Makefile           |  2 +-
>  drivers/dma-buf/dma-fence-unwrap.c | 59 ++++++++++++++++++++++++++++++
>  include/linux/dma-fence-unwrap.h   | 52 ++------------------------
>  3 files changed, 64 insertions(+), 49 deletions(-)
>  create mode 100644 drivers/dma-buf/dma-fence-unwrap.c
> 
> diff --git a/drivers/dma-buf/Makefile b/drivers/dma-buf/Makefile
> index 4c9eb53ba3f8..70ec901edf2c 100644
> --- a/drivers/dma-buf/Makefile
> +++ b/drivers/dma-buf/Makefile
> @@ -1,6 +1,6 @@
>  # SPDX-License-Identifier: GPL-2.0-only
>  obj-y := dma-buf.o dma-fence.o dma-fence-array.o dma-fence-chain.o \
> -	 dma-resv.o
> +	 dma-fence-unwrap.o dma-resv.o
>  obj-$(CONFIG_DMABUF_HEAPS)	+= dma-heap.o
>  obj-$(CONFIG_DMABUF_HEAPS)	+= heaps/
>  obj-$(CONFIG_SYNC_FILE)		+= sync_file.o
> diff --git a/drivers/dma-buf/dma-fence-unwrap.c b/drivers/dma-buf/dma-fence-unwrap.c
> new file mode 100644
> index 000000000000..711be125428c
> --- /dev/null
> +++ b/drivers/dma-buf/dma-fence-unwrap.c
> @@ -0,0 +1,59 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * dma-fence-util: misc functions for dma_fence objects
> + *
> + * Copyright (C) 2022 Advanced Micro Devices, Inc.
> + * Authors:
> + *	Christian König <christian.koenig@amd.com>
> + */
> +
> +#include <linux/dma-fence.h>
> +#include <linux/dma-fence-array.h>
> +#include <linux/dma-fence-chain.h>
> +#include <linux/dma-fence-unwrap.h>
> +
> +/* Internal helper to start new array iteration, don't use directly */
> +static struct dma_fence *
> +__dma_fence_unwrap_array(struct dma_fence_unwrap *cursor)
> +{
> +	cursor->array = dma_fence_chain_contained(cursor->chain);
> +	cursor->index = 0;
> +	return dma_fence_array_first(cursor->array);
> +}
> +
> +/**
> + * dma_fence_unwrap_first - return the first fence from fence containers
> + * @head: the entrypoint into the containers
> + * @cursor: current position inside the containers
> + *
> + * Unwraps potential dma_fence_chain/dma_fence_array containers and return the
> + * first fence.
> + */
> +struct dma_fence *dma_fence_unwrap_first(struct dma_fence *head,
> +					 struct dma_fence_unwrap *cursor)
> +{
> +	cursor->chain = dma_fence_get(head);
> +	return __dma_fence_unwrap_array(cursor);
> +}
> +EXPORT_SYMBOL_GPL(dma_fence_unwrap_first);
> +
> +/**
> + * dma_fence_unwrap_next - return the next fence from a fence containers
> + * @cursor: current position inside the containers
> + *
> + * Continue unwrapping the dma_fence_chain/dma_fence_array containers and return
> + * the next fence from them.
> + */
> +struct dma_fence *dma_fence_unwrap_next(struct dma_fence_unwrap *cursor)
> +{
> +	struct dma_fence *tmp;
> +
> +	++cursor->index;
> +	tmp = dma_fence_array_next(cursor->array, cursor->index);
> +	if (tmp)
> +		return tmp;
> +
> +	cursor->chain = dma_fence_chain_walk(cursor->chain);
> +	return __dma_fence_unwrap_array(cursor);
> +}
> +EXPORT_SYMBOL_GPL(dma_fence_unwrap_next);
> diff --git a/include/linux/dma-fence-unwrap.h b/include/linux/dma-fence-unwrap.h
> index 77e335a1bcac..e7c219da4ed7 100644
> --- a/include/linux/dma-fence-unwrap.h
> +++ b/include/linux/dma-fence-unwrap.h
> @@ -1,7 +1,5 @@
>  /* SPDX-License-Identifier: GPL-2.0-only */
>  /*
> - * fence-chain: chain fences together in a timeline
> - *
>   * Copyright (C) 2022 Advanced Micro Devices, Inc.
>   * Authors:
>   *	Christian König <christian.koenig@amd.com>
> @@ -10,8 +8,7 @@
>  #ifndef __LINUX_DMA_FENCE_UNWRAP_H
>  #define __LINUX_DMA_FENCE_UNWRAP_H
>  
> -#include <linux/dma-fence-chain.h>
> -#include <linux/dma-fence-array.h>
> +struct dma_fence;
>  
>  /**
>   * struct dma_fence_unwrap - cursor into the container structure
> @@ -33,50 +30,9 @@ struct dma_fence_unwrap {
>  	unsigned int index;
>  };
>  
> -/* Internal helper to start new array iteration, don't use directly */
> -static inline struct dma_fence *
> -__dma_fence_unwrap_array(struct dma_fence_unwrap * cursor)
> -{
> -	cursor->array = dma_fence_chain_contained(cursor->chain);
> -	cursor->index = 0;
> -	return dma_fence_array_first(cursor->array);
> -}
> -
> -/**
> - * dma_fence_unwrap_first - return the first fence from fence containers
> - * @head: the entrypoint into the containers
> - * @cursor: current position inside the containers
> - *
> - * Unwraps potential dma_fence_chain/dma_fence_array containers and return the
> - * first fence.
> - */
> -static inline struct dma_fence *
> -dma_fence_unwrap_first(struct dma_fence *head, struct dma_fence_unwrap *cursor)
> -{
> -	cursor->chain = dma_fence_get(head);
> -	return __dma_fence_unwrap_array(cursor);
> -}
> -
> -/**
> - * dma_fence_unwrap_next - return the next fence from a fence containers
> - * @cursor: current position inside the containers
> - *
> - * Continue unwrapping the dma_fence_chain/dma_fence_array containers and return
> - * the next fence from them.
> - */
> -static inline struct dma_fence *
> -dma_fence_unwrap_next(struct dma_fence_unwrap *cursor)
> -{
> -	struct dma_fence *tmp;
> -
> -	++cursor->index;
> -	tmp = dma_fence_array_next(cursor->array, cursor->index);
> -	if (tmp)
> -		return tmp;
> -
> -	cursor->chain = dma_fence_chain_walk(cursor->chain);
> -	return __dma_fence_unwrap_array(cursor);
> -}
> +struct dma_fence *dma_fence_unwrap_first(struct dma_fence *head,
> +					 struct dma_fence_unwrap *cursor);
> +struct dma_fence *dma_fence_unwrap_next(struct dma_fence_unwrap *cursor);
>  
>  /**
>   * dma_fence_unwrap_for_each - iterate over all fences in containers
> -- 
> 2.25.1
> 

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch

Re: [PATCH 2/5] dma-buf: cleanup dma_fence_unwrap implementation

[Daniel Vetter]

On Wed, May 04, 2022 at 02:22:53PM +0200, Christian König wrote:
> Move the code from the inline functions into exported functions.
> 
> Signed-off-by: Christian König <christian.koenig@amd.com>

Didn't check you didn't slip in a typo or so :-)

Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>

> ---
>  drivers/dma-buf/Makefile           |  2 +-
>  drivers/dma-buf/dma-fence-unwrap.c | 59 ++++++++++++++++++++++++++++++
>  include/linux/dma-fence-unwrap.h   | 52 ++------------------------
>  3 files changed, 64 insertions(+), 49 deletions(-)
>  create mode 100644 drivers/dma-buf/dma-fence-unwrap.c
> 
> diff --git a/drivers/dma-buf/Makefile b/drivers/dma-buf/Makefile
> index 4c9eb53ba3f8..70ec901edf2c 100644
> --- a/drivers/dma-buf/Makefile
> +++ b/drivers/dma-buf/Makefile
> @@ -1,6 +1,6 @@
>  # SPDX-License-Identifier: GPL-2.0-only
>  obj-y := dma-buf.o dma-fence.o dma-fence-array.o dma-fence-chain.o \
> -	 dma-resv.o
> +	 dma-fence-unwrap.o dma-resv.o
>  obj-$(CONFIG_DMABUF_HEAPS)	+= dma-heap.o
>  obj-$(CONFIG_DMABUF_HEAPS)	+= heaps/
>  obj-$(CONFIG_SYNC_FILE)		+= sync_file.o
> diff --git a/drivers/dma-buf/dma-fence-unwrap.c b/drivers/dma-buf/dma-fence-unwrap.c
> new file mode 100644
> index 000000000000..711be125428c
> --- /dev/null
> +++ b/drivers/dma-buf/dma-fence-unwrap.c
> @@ -0,0 +1,59 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * dma-fence-util: misc functions for dma_fence objects
> + *
> + * Copyright (C) 2022 Advanced Micro Devices, Inc.
> + * Authors:
> + *	Christian König <christian.koenig@amd.com>
> + */
> +
> +#include <linux/dma-fence.h>
> +#include <linux/dma-fence-array.h>
> +#include <linux/dma-fence-chain.h>
> +#include <linux/dma-fence-unwrap.h>
> +
> +/* Internal helper to start new array iteration, don't use directly */
> +static struct dma_fence *
> +__dma_fence_unwrap_array(struct dma_fence_unwrap *cursor)
> +{
> +	cursor->array = dma_fence_chain_contained(cursor->chain);
> +	cursor->index = 0;
> +	return dma_fence_array_first(cursor->array);
> +}
> +
> +/**
> + * dma_fence_unwrap_first - return the first fence from fence containers
> + * @head: the entrypoint into the containers
> + * @cursor: current position inside the containers
> + *
> + * Unwraps potential dma_fence_chain/dma_fence_array containers and return the
> + * first fence.
> + */
> +struct dma_fence *dma_fence_unwrap_first(struct dma_fence *head,
> +					 struct dma_fence_unwrap *cursor)
> +{
> +	cursor->chain = dma_fence_get(head);
> +	return __dma_fence_unwrap_array(cursor);
> +}
> +EXPORT_SYMBOL_GPL(dma_fence_unwrap_first);
> +
> +/**
> + * dma_fence_unwrap_next - return the next fence from a fence containers
> + * @cursor: current position inside the containers
> + *
> + * Continue unwrapping the dma_fence_chain/dma_fence_array containers and return
> + * the next fence from them.
> + */
> +struct dma_fence *dma_fence_unwrap_next(struct dma_fence_unwrap *cursor)
> +{
> +	struct dma_fence *tmp;
> +
> +	++cursor->index;
> +	tmp = dma_fence_array_next(cursor->array, cursor->index);
> +	if (tmp)
> +		return tmp;
> +
> +	cursor->chain = dma_fence_chain_walk(cursor->chain);
> +	return __dma_fence_unwrap_array(cursor);
> +}
> +EXPORT_SYMBOL_GPL(dma_fence_unwrap_next);
> diff --git a/include/linux/dma-fence-unwrap.h b/include/linux/dma-fence-unwrap.h
> index 77e335a1bcac..e7c219da4ed7 100644
> --- a/include/linux/dma-fence-unwrap.h
> +++ b/include/linux/dma-fence-unwrap.h
> @@ -1,7 +1,5 @@
>  /* SPDX-License-Identifier: GPL-2.0-only */
>  /*
> - * fence-chain: chain fences together in a timeline
> - *
>   * Copyright (C) 2022 Advanced Micro Devices, Inc.
>   * Authors:
>   *	Christian König <christian.koenig@amd.com>
> @@ -10,8 +8,7 @@
>  #ifndef __LINUX_DMA_FENCE_UNWRAP_H
>  #define __LINUX_DMA_FENCE_UNWRAP_H
>  
> -#include <linux/dma-fence-chain.h>
> -#include <linux/dma-fence-array.h>
> +struct dma_fence;
>  
>  /**
>   * struct dma_fence_unwrap - cursor into the container structure
> @@ -33,50 +30,9 @@ struct dma_fence_unwrap {
>  	unsigned int index;
>  };
>  
> -/* Internal helper to start new array iteration, don't use directly */
> -static inline struct dma_fence *
> -__dma_fence_unwrap_array(struct dma_fence_unwrap * cursor)
> -{
> -	cursor->array = dma_fence_chain_contained(cursor->chain);
> -	cursor->index = 0;
> -	return dma_fence_array_first(cursor->array);
> -}
> -
> -/**
> - * dma_fence_unwrap_first - return the first fence from fence containers
> - * @head: the entrypoint into the containers
> - * @cursor: current position inside the containers
> - *
> - * Unwraps potential dma_fence_chain/dma_fence_array containers and return the
> - * first fence.
> - */
> -static inline struct dma_fence *
> -dma_fence_unwrap_first(struct dma_fence *head, struct dma_fence_unwrap *cursor)
> -{
> -	cursor->chain = dma_fence_get(head);
> -	return __dma_fence_unwrap_array(cursor);
> -}
> -
> -/**
> - * dma_fence_unwrap_next - return the next fence from a fence containers
> - * @cursor: current position inside the containers
> - *
> - * Continue unwrapping the dma_fence_chain/dma_fence_array containers and return
> - * the next fence from them.
> - */
> -static inline struct dma_fence *
> -dma_fence_unwrap_next(struct dma_fence_unwrap *cursor)
> -{
> -	struct dma_fence *tmp;
> -
> -	++cursor->index;
> -	tmp = dma_fence_array_next(cursor->array, cursor->index);
> -	if (tmp)
> -		return tmp;
> -
> -	cursor->chain = dma_fence_chain_walk(cursor->chain);
> -	return __dma_fence_unwrap_array(cursor);
> -}
> +struct dma_fence *dma_fence_unwrap_first(struct dma_fence *head,
> +					 struct dma_fence_unwrap *cursor);
> +struct dma_fence *dma_fence_unwrap_next(struct dma_fence_unwrap *cursor);
>  
>  /**
>   * dma_fence_unwrap_for_each - iterate over all fences in containers
> -- 
> 2.25.1
> 

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch

Re: [PATCH 3/5] dma-buf: return only unsignaled fences in dma_fence_unwrap_for_each

[Daniel Vetter]

On Wed, May 04, 2022 at 02:22:54PM +0200, Christian König wrote:
> dma_fence_chain containers cleanup signaled fences automatically, so
> filter those out from arrays as well.
> 
> Signed-off-by: Christian König <christian.koenig@amd.com>
> ---
>  drivers/dma-buf/dma-fence-unwrap.c | 23 ++++++++++++++++-------
>  include/linux/dma-fence-unwrap.h   |  4 ++--
>  2 files changed, 18 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/dma-buf/dma-fence-unwrap.c b/drivers/dma-buf/dma-fence-unwrap.c
> index 711be125428c..7b0b91086ded 100644
> --- a/drivers/dma-buf/dma-fence-unwrap.c
> +++ b/drivers/dma-buf/dma-fence-unwrap.c
> @@ -32,8 +32,13 @@ __dma_fence_unwrap_array(struct dma_fence_unwrap *cursor)
>  struct dma_fence *dma_fence_unwrap_first(struct dma_fence *head,
>  					 struct dma_fence_unwrap *cursor)
>  {
> +	struct dma_fence *tmp;
> +
>  	cursor->chain = dma_fence_get(head);
> -	return __dma_fence_unwrap_array(cursor);
> +	tmp = __dma_fence_unwrap_array(cursor);
> +	if (tmp && dma_fence_is_signaled(tmp))
> +		tmp = dma_fence_unwrap_next(cursor);
> +	return tmp;
>  }
>  EXPORT_SYMBOL_GPL(dma_fence_unwrap_first);
>  
> @@ -48,12 +53,16 @@ struct dma_fence *dma_fence_unwrap_next(struct dma_fence_unwrap *cursor)
>  {
>  	struct dma_fence *tmp;
>  
> -	++cursor->index;
> -	tmp = dma_fence_array_next(cursor->array, cursor->index);
> -	if (tmp)
> -		return tmp;
> +	do {
> +		++cursor->index;
> +		tmp = dma_fence_array_next(cursor->array, cursor->index);
> +		if (tmp && !dma_fence_is_signaled(tmp))
> +			return tmp;

Don't do need a do {} while here too to first walk through the array
before going to the next one in the chain? Maybe add a testcase for this?

> +
> +		cursor->chain = dma_fence_chain_walk(cursor->chain);
> +		tmp = __dma_fence_unwrap_array(cursor);
> +	} while (tmp && dma_fence_is_signaled(tmp));
>  
> -	cursor->chain = dma_fence_chain_walk(cursor->chain);
> -	return __dma_fence_unwrap_array(cursor);
> +	return tmp;
>  }
>  EXPORT_SYMBOL_GPL(dma_fence_unwrap_next);
> diff --git a/include/linux/dma-fence-unwrap.h b/include/linux/dma-fence-unwrap.h
> index e7c219da4ed7..e9d114637294 100644
> --- a/include/linux/dma-fence-unwrap.h
> +++ b/include/linux/dma-fence-unwrap.h
> @@ -41,8 +41,8 @@ struct dma_fence *dma_fence_unwrap_next(struct dma_fence_unwrap *cursor);
>   * @head: starting point for the iterator
>   *
>   * Unwrap dma_fence_chain and dma_fence_array containers and deep dive into all
> - * potential fences in them. If @head is just a normal fence only that one is
> - * returned.
> + * potential none signaled fences in them. If @head is just a normal fence only
> + * that one is returned.

I think I get what you want to say, but it reads garbled. What about
leaving the current text as-is and adding something like

"Note that signalled fences are opportunistically filtered out, which
means the iteration is potentially over no fence at all"

Or something like that? I think smashing this all into one sentence
doesn't work well.

Then please also add this same sentence to unwrap_first/next() for
completeness.
-Daniel

>   */
>  #define dma_fence_unwrap_for_each(fence, cursor, head)			\
>  	for (fence = dma_fence_unwrap_first(head, cursor); fence;	\
> -- 
> 2.25.1
> 

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch

Re: [PATCH 3/5] dma-buf: return only unsignaled fences in dma_fence_unwrap_for_each

[Daniel Vetter]

On Wed, May 04, 2022 at 02:22:54PM +0200, Christian König wrote:
> dma_fence_chain containers cleanup signaled fences automatically, so
> filter those out from arrays as well.
> 
> Signed-off-by: Christian König <christian.koenig@amd.com>
> ---
>  drivers/dma-buf/dma-fence-unwrap.c | 23 ++++++++++++++++-------
>  include/linux/dma-fence-unwrap.h   |  4 ++--
>  2 files changed, 18 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/dma-buf/dma-fence-unwrap.c b/drivers/dma-buf/dma-fence-unwrap.c
> index 711be125428c..7b0b91086ded 100644
> --- a/drivers/dma-buf/dma-fence-unwrap.c
> +++ b/drivers/dma-buf/dma-fence-unwrap.c
> @@ -32,8 +32,13 @@ __dma_fence_unwrap_array(struct dma_fence_unwrap *cursor)
>  struct dma_fence *dma_fence_unwrap_first(struct dma_fence *head,
>  					 struct dma_fence_unwrap *cursor)
>  {
> +	struct dma_fence *tmp;
> +
>  	cursor->chain = dma_fence_get(head);
> -	return __dma_fence_unwrap_array(cursor);
> +	tmp = __dma_fence_unwrap_array(cursor);
> +	if (tmp && dma_fence_is_signaled(tmp))
> +		tmp = dma_fence_unwrap_next(cursor);
> +	return tmp;
>  }
>  EXPORT_SYMBOL_GPL(dma_fence_unwrap_first);
>  
> @@ -48,12 +53,16 @@ struct dma_fence *dma_fence_unwrap_next(struct dma_fence_unwrap *cursor)
>  {
>  	struct dma_fence *tmp;
>  
> -	++cursor->index;
> -	tmp = dma_fence_array_next(cursor->array, cursor->index);
> -	if (tmp)
> -		return tmp;
> +	do {
> +		++cursor->index;
> +		tmp = dma_fence_array_next(cursor->array, cursor->index);
> +		if (tmp && !dma_fence_is_signaled(tmp))
> +			return tmp;

Don't do need a do {} while here too to first walk through the array
before going to the next one in the chain? Maybe add a testcase for this?

> +
> +		cursor->chain = dma_fence_chain_walk(cursor->chain);
> +		tmp = __dma_fence_unwrap_array(cursor);
> +	} while (tmp && dma_fence_is_signaled(tmp));
>  
> -	cursor->chain = dma_fence_chain_walk(cursor->chain);
> -	return __dma_fence_unwrap_array(cursor);
> +	return tmp;
>  }
>  EXPORT_SYMBOL_GPL(dma_fence_unwrap_next);
> diff --git a/include/linux/dma-fence-unwrap.h b/include/linux/dma-fence-unwrap.h
> index e7c219da4ed7..e9d114637294 100644
> --- a/include/linux/dma-fence-unwrap.h
> +++ b/include/linux/dma-fence-unwrap.h
> @@ -41,8 +41,8 @@ struct dma_fence *dma_fence_unwrap_next(struct dma_fence_unwrap *cursor);
>   * @head: starting point for the iterator
>   *
>   * Unwrap dma_fence_chain and dma_fence_array containers and deep dive into all
> - * potential fences in them. If @head is just a normal fence only that one is
> - * returned.
> + * potential none signaled fences in them. If @head is just a normal fence only
> + * that one is returned.

I think I get what you want to say, but it reads garbled. What about
leaving the current text as-is and adding something like

"Note that signalled fences are opportunistically filtered out, which
means the iteration is potentially over no fence at all"

Or something like that? I think smashing this all into one sentence
doesn't work well.

Then please also add this same sentence to unwrap_first/next() for
completeness.
-Daniel

>   */
>  #define dma_fence_unwrap_for_each(fence, cursor, head)			\
>  	for (fence = dma_fence_unwrap_first(head, cursor); fence;	\
> -- 
> 2.25.1
> 

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch

Re: [PATCH 4/5] dma-buf: generalize dma_fence unwrap & merging v2

[Daniel Vetter]

On Wed, May 04, 2022 at 02:22:55PM +0200, Christian König wrote:
> Introduce a dma_fence_unwrap_merge() macro which allows to unwrap fences
> which potentially can be containers as well and then merge them back
> together into a flat dma_fence_array.
> 
> v2: rename the function, add some more comments about how the wrapper is
>     used, move filtering of signaled fences into the unwrap iterator,
>     add complex selftest which covers more cases.

Yeah this addresses everything. The only thing that leaves me puzzled is
the unconditional dma_fence_put() in the testcases for the fences we stuff
into containers, I thought we only need that for error cases but not the
success. But I'm confused about that already in a previous patch.

Aside from that Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>


> 
> Signed-off-by: Christian König <christian.koenig@amd.com>
> ---
>  drivers/dma-buf/dma-fence-unwrap.c    |  99 +++++++++++++++++++++
>  drivers/dma-buf/st-dma-fence-unwrap.c | 109 +++++++++++++++++++++++
>  drivers/dma-buf/sync_file.c           | 119 ++------------------------
>  include/linux/dma-fence-unwrap.h      |  24 ++++++
>  4 files changed, 238 insertions(+), 113 deletions(-)
> 
> diff --git a/drivers/dma-buf/dma-fence-unwrap.c b/drivers/dma-buf/dma-fence-unwrap.c
> index 7b0b91086ded..4ed5ea8807d7 100644
> --- a/drivers/dma-buf/dma-fence-unwrap.c
> +++ b/drivers/dma-buf/dma-fence-unwrap.c
> @@ -11,6 +11,7 @@
>  #include <linux/dma-fence-array.h>
>  #include <linux/dma-fence-chain.h>
>  #include <linux/dma-fence-unwrap.h>
> +#include <linux/slab.h>
>  
>  /* Internal helper to start new array iteration, don't use directly */
>  static struct dma_fence *
> @@ -66,3 +67,101 @@ struct dma_fence *dma_fence_unwrap_next(struct dma_fence_unwrap *cursor)
>  	return tmp;
>  }
>  EXPORT_SYMBOL_GPL(dma_fence_unwrap_next);
> +
> +/* Implementation for the dma_fence_merge() marco, don't use directly */
> +struct dma_fence *__dma_fence_unwrap_merge(unsigned int num_fences,
> +					   struct dma_fence **fences,
> +					   struct dma_fence_unwrap *iter)
> +{
> +	struct dma_fence_array *result;
> +	struct dma_fence *tmp, **array;
> +	unsigned int i;
> +	size_t count;
> +
> +	count = 0;
> +	for (i = 0; i < num_fences; ++i) {
> +		dma_fence_unwrap_for_each(tmp, &iter[i], fences[i])
> +			++count;
> +	}
> +
> +	if (count == 0)
> +		return dma_fence_get_stub();
> +
> +	array = kmalloc_array(count, sizeof(*array), GFP_KERNEL);
> +	if (!array)
> +		return NULL;
> +
> +	/*
> +	 * This trashes the input fence array and uses it as position for the
> +	 * following merge loop. This works because the dma_fence_merge()
> +	 * wrapper macro is creating this temporary array on the stack together
> +	 * with the iterators.
> +	 */
> +	for (i = 0; i < num_fences; ++i)
> +		fences[i] = dma_fence_unwrap_first(fences[i], &iter[i]);
> +
> +	count = 0;
> +	do {
> +		unsigned int sel;
> +
> +restart:
> +		tmp = NULL;
> +		for (i = 0; i < num_fences; ++i) {
> +			struct dma_fence *next = fences[i];
> +
> +			if (!next)
> +				continue;
> +
> +			/*
> +			 * We can't guarantee that inpute fences are ordered by
> +			 * context, but it is still quite likely when this
> +			 * function is used multiple times. So attempt to order
> +			 * the fences by context as we pass over them and merge
> +			 * fences with the same context.
> +			 */
> +			if (!tmp || tmp->context > next->context) {
> +				tmp = next;
> +				sel = i;
> +
> +			} else if (tmp->context < next->context) {
> +				continue;
> +
> +			} else if (dma_fence_is_later(tmp, next)) {
> +				fences[i] = dma_fence_unwrap_next(&iter[i]);
> +				goto restart;
> +			} else {
> +				fences[sel] = dma_fence_unwrap_next(&iter[sel]);
> +				goto restart;
> +			}
> +		}
> +
> +		if (tmp) {
> +			array[count++] = dma_fence_get(tmp);
> +			fences[sel] = dma_fence_unwrap_next(&iter[sel]);
> +		}
> +	} while (tmp);
> +
> +	if (count == 0) {
> +		tmp = dma_fence_get_stub();
> +		goto return_tmp;
> +	}
> +
> +	if (count == 1) {
> +		tmp = array[0];
> +		goto return_tmp;
> +	}
> +
> +	result = dma_fence_array_create(count, array,
> +					dma_fence_context_alloc(1),
> +					1, false);
> +	if (!result) {
> +		tmp = NULL;
> +		goto return_tmp;
> +	}
> +	return &result->base;
> +
> +return_tmp:
> +	kfree(array);
> +	return tmp;
> +}
> +EXPORT_SYMBOL_GPL(__dma_fence_unwrap_merge);
> diff --git a/drivers/dma-buf/st-dma-fence-unwrap.c b/drivers/dma-buf/st-dma-fence-unwrap.c
> index 59628add93f5..3a8aca651938 100644
> --- a/drivers/dma-buf/st-dma-fence-unwrap.c
> +++ b/drivers/dma-buf/st-dma-fence-unwrap.c
> @@ -240,6 +240,113 @@ static int unwrap_chain_array(void *arg)
>  	return err;
>  }
>  
> +static int unwrap_merge(void *arg)
> +{
> +	struct dma_fence *fence, *f1, *f2, *f3;
> +	struct dma_fence_unwrap iter;
> +	int err = 0;
> +
> +	f1 = mock_fence();
> +	if (!f1)
> +		return -ENOMEM;
> +
> +	f2 = mock_fence();
> +	if (!f2) {
> +		err = -ENOMEM;
> +		goto error_put_f1;
> +	}
> +
> +	f3 = dma_fence_unwrap_merge(f1, f2);
> +	if (!f3) {
> +		err = -ENOMEM;
> +		goto error_put_f2;
> +	}
> +
> +	dma_fence_unwrap_for_each(fence, &iter, f3) {
> +		if (fence == f1) {
> +			dma_fence_put(f1);
> +			f1 = NULL;
> +		} else if (fence == f2) {
> +			dma_fence_put(f2);
> +			f2 = NULL;
> +		} else {
> +			pr_err("Unexpected fence!\n");
> +			err = -EINVAL;
> +		}
> +	}
> +
> +	if (f1 || f2) {
> +		pr_err("Not all fences seen!\n");
> +		err = -EINVAL;
> +	}
> +
> +	dma_fence_put(f3);
> +error_put_f2:
> +	dma_fence_put(f2);
> +error_put_f1:
> +	dma_fence_put(f1);
> +	return err;
> +}
> +
> +static int unwrap_merge_complex(void *arg)
> +{
> +	struct dma_fence *fence, *f1, *f2, *f3, *f4, *f5;
> +	struct dma_fence_unwrap iter;
> +	int err = -ENOMEM;
> +
> +	f1 = mock_fence();
> +	if (!f1)
> +		return -ENOMEM;
> +
> +	f2 = mock_fence();
> +	if (!f2)
> +		goto error_put_f1;
> +
> +	f3 = dma_fence_unwrap_merge(f1, f2);
> +	if (!f3)
> +		goto error_put_f2;
> +
> +	/* The resulting array has the fences in reverse */
> +	f4 = dma_fence_unwrap_merge(f2, f1);
> +	if (!f4)
> +		goto error_put_f3;
> +
> +	/* Signaled fences should be filtered, the two arrays merged. */
> +	f5 = dma_fence_unwrap_merge(f3, f4, dma_fence_get_stub());
> +	if (!f5)
> +		goto error_put_f4;
> +
> +	err = 0;
> +	dma_fence_unwrap_for_each(fence, &iter, f5) {
> +		if (fence == f1) {
> +			dma_fence_put(f1);
> +			f1 = NULL;
> +		} else if (fence == f2) {
> +			dma_fence_put(f2);
> +			f2 = NULL;
> +		} else {
> +			pr_err("Unexpected fence!\n");
> +			err = -EINVAL;
> +		}
> +	}
> +
> +	if (f1 || f2) {
> +		pr_err("Not all fences seen!\n");
> +		err = -EINVAL;
> +	}
> +
> +	dma_fence_put(f5);
> +error_put_f4:
> +	dma_fence_put(f4);
> +error_put_f3:
> +	dma_fence_put(f3);
> +error_put_f2:
> +	dma_fence_put(f2);
> +error_put_f1:
> +	dma_fence_put(f1);
> +	return err;
> +}
> +
>  int dma_fence_unwrap(void)
>  {
>  	static const struct subtest tests[] = {
> @@ -247,6 +354,8 @@ int dma_fence_unwrap(void)
>  		SUBTEST(unwrap_array),
>  		SUBTEST(unwrap_chain),
>  		SUBTEST(unwrap_chain_array),
> +		SUBTEST(unwrap_merge),
> +		SUBTEST(unwrap_merge_complex),
>  	};
>  
>  	return subtests(tests, NULL);
> diff --git a/drivers/dma-buf/sync_file.c b/drivers/dma-buf/sync_file.c
> index 0fe564539166..3ebec19a8e02 100644
> --- a/drivers/dma-buf/sync_file.c
> +++ b/drivers/dma-buf/sync_file.c
> @@ -146,50 +146,6 @@ char *sync_file_get_name(struct sync_file *sync_file, char *buf, int len)
>  	return buf;
>  }
>  
> -static int sync_file_set_fence(struct sync_file *sync_file,
> -			       struct dma_fence **fences, int num_fences)
> -{
> -	struct dma_fence_array *array;
> -
> -	/*
> -	 * The reference for the fences in the new sync_file and held
> -	 * in add_fence() during the merge procedure, so for num_fences == 1
> -	 * we already own a new reference to the fence. For num_fence > 1
> -	 * we own the reference of the dma_fence_array creation.
> -	 */
> -
> -	if (num_fences == 0) {
> -		sync_file->fence = dma_fence_get_stub();
> -		kfree(fences);
> -
> -	} else if (num_fences == 1) {
> -		sync_file->fence = fences[0];
> -		kfree(fences);
> -
> -	} else {
> -		array = dma_fence_array_create(num_fences, fences,
> -					       dma_fence_context_alloc(1),
> -					       1, false);
> -		if (!array)
> -			return -ENOMEM;
> -
> -		sync_file->fence = &array->base;
> -	}
> -
> -	return 0;
> -}
> -
> -static void add_fence(struct dma_fence **fences,
> -		      int *i, struct dma_fence *fence)
> -{
> -	fences[*i] = fence;
> -
> -	if (!dma_fence_is_signaled(fence)) {
> -		dma_fence_get(fence);
> -		(*i)++;
> -	}
> -}
> -
>  /**
>   * sync_file_merge() - merge two sync_files
>   * @name:	name of new fence
> @@ -203,84 +159,21 @@ static void add_fence(struct dma_fence **fences,
>  static struct sync_file *sync_file_merge(const char *name, struct sync_file *a,
>  					 struct sync_file *b)
>  {
> -	struct dma_fence *a_fence, *b_fence, **fences;
> -	struct dma_fence_unwrap a_iter, b_iter;
> -	unsigned int index, num_fences;
>  	struct sync_file *sync_file;
> +	struct dma_fence *fence;
>  
>  	sync_file = sync_file_alloc();
>  	if (!sync_file)
>  		return NULL;
>  
> -	num_fences = 0;
> -	dma_fence_unwrap_for_each(a_fence, &a_iter, a->fence)
> -		++num_fences;
> -	dma_fence_unwrap_for_each(b_fence, &b_iter, b->fence)
> -		++num_fences;
> -
> -	if (num_fences > INT_MAX)
> -		goto err_free_sync_file;
> -
> -	fences = kcalloc(num_fences, sizeof(*fences), GFP_KERNEL);
> -	if (!fences)
> -		goto err_free_sync_file;
> -
> -	/*
> -	 * We can't guarantee that fences in both a and b are ordered, but it is
> -	 * still quite likely.
> -	 *
> -	 * So attempt to order the fences as we pass over them and merge fences
> -	 * with the same context.
> -	 */
> -
> -	index = 0;
> -	for (a_fence = dma_fence_unwrap_first(a->fence, &a_iter),
> -	     b_fence = dma_fence_unwrap_first(b->fence, &b_iter);
> -	     a_fence || b_fence; ) {
> -
> -		if (!b_fence) {
> -			add_fence(fences, &index, a_fence);
> -			a_fence = dma_fence_unwrap_next(&a_iter);
> -
> -		} else if (!a_fence) {
> -			add_fence(fences, &index, b_fence);
> -			b_fence = dma_fence_unwrap_next(&b_iter);
> -
> -		} else if (a_fence->context < b_fence->context) {
> -			add_fence(fences, &index, a_fence);
> -			a_fence = dma_fence_unwrap_next(&a_iter);
> -
> -		} else if (b_fence->context < a_fence->context) {
> -			add_fence(fences, &index, b_fence);
> -			b_fence = dma_fence_unwrap_next(&b_iter);
> -
> -		} else if (__dma_fence_is_later(a_fence->seqno, b_fence->seqno,
> -						a_fence->ops)) {
> -			add_fence(fences, &index, a_fence);
> -			a_fence = dma_fence_unwrap_next(&a_iter);
> -			b_fence = dma_fence_unwrap_next(&b_iter);
> -
> -		} else {
> -			add_fence(fences, &index, b_fence);
> -			a_fence = dma_fence_unwrap_next(&a_iter);
> -			b_fence = dma_fence_unwrap_next(&b_iter);
> -		}
> +	fence = dma_fence_unwrap_merge(a->fence, b->fence);
> +	if (!fence) {
> +		fput(sync_file->file);
> +		return NULL;
>  	}
> -
> -	if (sync_file_set_fence(sync_file, fences, index) < 0)
> -		goto err_put_fences;
> -
> +	sync_file->fence = fence;
>  	strlcpy(sync_file->user_name, name, sizeof(sync_file->user_name));
>  	return sync_file;
> -
> -err_put_fences:
> -	while (index)
> -		dma_fence_put(fences[--index]);
> -	kfree(fences);
> -
> -err_free_sync_file:
> -	fput(sync_file->file);
> -	return NULL;
>  }
>  
>  static int sync_file_release(struct inode *inode, struct file *file)
> diff --git a/include/linux/dma-fence-unwrap.h b/include/linux/dma-fence-unwrap.h
> index e9d114637294..43c8a9bbee88 100644
> --- a/include/linux/dma-fence-unwrap.h
> +++ b/include/linux/dma-fence-unwrap.h
> @@ -48,4 +48,28 @@ struct dma_fence *dma_fence_unwrap_next(struct dma_fence_unwrap *cursor);
>  	for (fence = dma_fence_unwrap_first(head, cursor); fence;	\
>  	     fence = dma_fence_unwrap_next(cursor))
>  
> +struct dma_fence *__dma_fence_unwrap_merge(unsigned int num_fences,
> +					   struct dma_fence **fences,
> +					   struct dma_fence_unwrap *cursors);
> +
> +/**
> + * dma_fence_unwrap_merge - unwrap and merge fences
> + *
> + * All fences given as parameters are unwrapped and merged back together as flat
> + * dma_fence_array. Useful if multiple containers need to be merged together.
> + *
> + * Implemented as a macro to allocate the necessary arrays on the stack and
> + * account the stack frame size to the caller.
> + *
> + * Returns NULL on memory allocation failure, a dma_fence object representing
> + * all the given fences otherwise.
> + */
> +#define dma_fence_unwrap_merge(...)					\
> +	({								\
> +		struct dma_fence *__f[] = { __VA_ARGS__ };		\
> +		struct dma_fence_unwrap __c[ARRAY_SIZE(__f)];		\
> +									\
> +		__dma_fence_unwrap_merge(ARRAY_SIZE(__f), __f, __c);	\
> +	})
> +
>  #endif
> -- 
> 2.25.1
> 

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch

Re: [PATCH 4/5] dma-buf: generalize dma_fence unwrap & merging v2

[Daniel Vetter]

On Wed, May 04, 2022 at 02:22:55PM +0200, Christian König wrote:
> Introduce a dma_fence_unwrap_merge() macro which allows to unwrap fences
> which potentially can be containers as well and then merge them back
> together into a flat dma_fence_array.
> 
> v2: rename the function, add some more comments about how the wrapper is
>     used, move filtering of signaled fences into the unwrap iterator,
>     add complex selftest which covers more cases.

Yeah this addresses everything. The only thing that leaves me puzzled is
the unconditional dma_fence_put() in the testcases for the fences we stuff
into containers, I thought we only need that for error cases but not the
success. But I'm confused about that already in a previous patch.

Aside from that Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>


> 
> Signed-off-by: Christian König <christian.koenig@amd.com>
> ---
>  drivers/dma-buf/dma-fence-unwrap.c    |  99 +++++++++++++++++++++
>  drivers/dma-buf/st-dma-fence-unwrap.c | 109 +++++++++++++++++++++++
>  drivers/dma-buf/sync_file.c           | 119 ++------------------------
>  include/linux/dma-fence-unwrap.h      |  24 ++++++
>  4 files changed, 238 insertions(+), 113 deletions(-)
> 
> diff --git a/drivers/dma-buf/dma-fence-unwrap.c b/drivers/dma-buf/dma-fence-unwrap.c
> index 7b0b91086ded..4ed5ea8807d7 100644
> --- a/drivers/dma-buf/dma-fence-unwrap.c
> +++ b/drivers/dma-buf/dma-fence-unwrap.c
> @@ -11,6 +11,7 @@
>  #include <linux/dma-fence-array.h>
>  #include <linux/dma-fence-chain.h>
>  #include <linux/dma-fence-unwrap.h>
> +#include <linux/slab.h>
>  
>  /* Internal helper to start new array iteration, don't use directly */
>  static struct dma_fence *
> @@ -66,3 +67,101 @@ struct dma_fence *dma_fence_unwrap_next(struct dma_fence_unwrap *cursor)
>  	return tmp;
>  }
>  EXPORT_SYMBOL_GPL(dma_fence_unwrap_next);
> +
> +/* Implementation for the dma_fence_merge() marco, don't use directly */
> +struct dma_fence *__dma_fence_unwrap_merge(unsigned int num_fences,
> +					   struct dma_fence **fences,
> +					   struct dma_fence_unwrap *iter)
> +{
> +	struct dma_fence_array *result;
> +	struct dma_fence *tmp, **array;
> +	unsigned int i;
> +	size_t count;
> +
> +	count = 0;
> +	for (i = 0; i < num_fences; ++i) {
> +		dma_fence_unwrap_for_each(tmp, &iter[i], fences[i])
> +			++count;
> +	}
> +
> +	if (count == 0)
> +		return dma_fence_get_stub();
> +
> +	array = kmalloc_array(count, sizeof(*array), GFP_KERNEL);
> +	if (!array)
> +		return NULL;
> +
> +	/*
> +	 * This trashes the input fence array and uses it as position for the
> +	 * following merge loop. This works because the dma_fence_merge()
> +	 * wrapper macro is creating this temporary array on the stack together
> +	 * with the iterators.
> +	 */
> +	for (i = 0; i < num_fences; ++i)
> +		fences[i] = dma_fence_unwrap_first(fences[i], &iter[i]);
> +
> +	count = 0;
> +	do {
> +		unsigned int sel;
> +
> +restart:
> +		tmp = NULL;
> +		for (i = 0; i < num_fences; ++i) {
> +			struct dma_fence *next = fences[i];
> +
> +			if (!next)
> +				continue;
> +
> +			/*
> +			 * We can't guarantee that inpute fences are ordered by
> +			 * context, but it is still quite likely when this
> +			 * function is used multiple times. So attempt to order
> +			 * the fences by context as we pass over them and merge
> +			 * fences with the same context.
> +			 */
> +			if (!tmp || tmp->context > next->context) {
> +				tmp = next;
> +				sel = i;
> +
> +			} else if (tmp->context < next->context) {
> +				continue;
> +
> +			} else if (dma_fence_is_later(tmp, next)) {
> +				fences[i] = dma_fence_unwrap_next(&iter[i]);
> +				goto restart;
> +			} else {
> +				fences[sel] = dma_fence_unwrap_next(&iter[sel]);
> +				goto restart;
> +			}
> +		}
> +
> +		if (tmp) {
> +			array[count++] = dma_fence_get(tmp);
> +			fences[sel] = dma_fence_unwrap_next(&iter[sel]);
> +		}
> +	} while (tmp);
> +
> +	if (count == 0) {
> +		tmp = dma_fence_get_stub();
> +		goto return_tmp;
> +	}
> +
> +	if (count == 1) {
> +		tmp = array[0];
> +		goto return_tmp;
> +	}
> +
> +	result = dma_fence_array_create(count, array,
> +					dma_fence_context_alloc(1),
> +					1, false);
> +	if (!result) {
> +		tmp = NULL;
> +		goto return_tmp;
> +	}
> +	return &result->base;
> +
> +return_tmp:
> +	kfree(array);
> +	return tmp;
> +}
> +EXPORT_SYMBOL_GPL(__dma_fence_unwrap_merge);
> diff --git a/drivers/dma-buf/st-dma-fence-unwrap.c b/drivers/dma-buf/st-dma-fence-unwrap.c
> index 59628add93f5..3a8aca651938 100644
> --- a/drivers/dma-buf/st-dma-fence-unwrap.c
> +++ b/drivers/dma-buf/st-dma-fence-unwrap.c
> @@ -240,6 +240,113 @@ static int unwrap_chain_array(void *arg)
>  	return err;
>  }
>  
> +static int unwrap_merge(void *arg)
> +{
> +	struct dma_fence *fence, *f1, *f2, *f3;
> +	struct dma_fence_unwrap iter;
> +	int err = 0;
> +
> +	f1 = mock_fence();
> +	if (!f1)
> +		return -ENOMEM;
> +
> +	f2 = mock_fence();
> +	if (!f2) {
> +		err = -ENOMEM;
> +		goto error_put_f1;
> +	}
> +
> +	f3 = dma_fence_unwrap_merge(f1, f2);
> +	if (!f3) {
> +		err = -ENOMEM;
> +		goto error_put_f2;
> +	}
> +
> +	dma_fence_unwrap_for_each(fence, &iter, f3) {
> +		if (fence == f1) {
> +			dma_fence_put(f1);
> +			f1 = NULL;
> +		} else if (fence == f2) {
> +			dma_fence_put(f2);
> +			f2 = NULL;
> +		} else {
> +			pr_err("Unexpected fence!\n");
> +			err = -EINVAL;
> +		}
> +	}
> +
> +	if (f1 || f2) {
> +		pr_err("Not all fences seen!\n");
> +		err = -EINVAL;
> +	}
> +
> +	dma_fence_put(f3);
> +error_put_f2:
> +	dma_fence_put(f2);
> +error_put_f1:
> +	dma_fence_put(f1);
> +	return err;
> +}
> +
> +static int unwrap_merge_complex(void *arg)
> +{
> +	struct dma_fence *fence, *f1, *f2, *f3, *f4, *f5;
> +	struct dma_fence_unwrap iter;
> +	int err = -ENOMEM;
> +
> +	f1 = mock_fence();
> +	if (!f1)
> +		return -ENOMEM;
> +
> +	f2 = mock_fence();
> +	if (!f2)
> +		goto error_put_f1;
> +
> +	f3 = dma_fence_unwrap_merge(f1, f2);
> +	if (!f3)
> +		goto error_put_f2;
> +
> +	/* The resulting array has the fences in reverse */
> +	f4 = dma_fence_unwrap_merge(f2, f1);
> +	if (!f4)
> +		goto error_put_f3;
> +
> +	/* Signaled fences should be filtered, the two arrays merged. */
> +	f5 = dma_fence_unwrap_merge(f3, f4, dma_fence_get_stub());
> +	if (!f5)
> +		goto error_put_f4;
> +
> +	err = 0;
> +	dma_fence_unwrap_for_each(fence, &iter, f5) {
> +		if (fence == f1) {
> +			dma_fence_put(f1);
> +			f1 = NULL;
> +		} else if (fence == f2) {
> +			dma_fence_put(f2);
> +			f2 = NULL;
> +		} else {
> +			pr_err("Unexpected fence!\n");
> +			err = -EINVAL;
> +		}
> +	}
> +
> +	if (f1 || f2) {
> +		pr_err("Not all fences seen!\n");
> +		err = -EINVAL;
> +	}
> +
> +	dma_fence_put(f5);
> +error_put_f4:
> +	dma_fence_put(f4);
> +error_put_f3:
> +	dma_fence_put(f3);
> +error_put_f2:
> +	dma_fence_put(f2);
> +error_put_f1:
> +	dma_fence_put(f1);
> +	return err;
> +}
> +
>  int dma_fence_unwrap(void)
>  {
>  	static const struct subtest tests[] = {
> @@ -247,6 +354,8 @@ int dma_fence_unwrap(void)
>  		SUBTEST(unwrap_array),
>  		SUBTEST(unwrap_chain),
>  		SUBTEST(unwrap_chain_array),
> +		SUBTEST(unwrap_merge),
> +		SUBTEST(unwrap_merge_complex),
>  	};
>  
>  	return subtests(tests, NULL);
> diff --git a/drivers/dma-buf/sync_file.c b/drivers/dma-buf/sync_file.c
> index 0fe564539166..3ebec19a8e02 100644
> --- a/drivers/dma-buf/sync_file.c
> +++ b/drivers/dma-buf/sync_file.c
> @@ -146,50 +146,6 @@ char *sync_file_get_name(struct sync_file *sync_file, char *buf, int len)
>  	return buf;
>  }
>  
> -static int sync_file_set_fence(struct sync_file *sync_file,
> -			       struct dma_fence **fences, int num_fences)
> -{
> -	struct dma_fence_array *array;
> -
> -	/*
> -	 * The reference for the fences in the new sync_file and held
> -	 * in add_fence() during the merge procedure, so for num_fences == 1
> -	 * we already own a new reference to the fence. For num_fence > 1
> -	 * we own the reference of the dma_fence_array creation.
> -	 */
> -
> -	if (num_fences == 0) {
> -		sync_file->fence = dma_fence_get_stub();
> -		kfree(fences);
> -
> -	} else if (num_fences == 1) {
> -		sync_file->fence = fences[0];
> -		kfree(fences);
> -
> -	} else {
> -		array = dma_fence_array_create(num_fences, fences,
> -					       dma_fence_context_alloc(1),
> -					       1, false);
> -		if (!array)
> -			return -ENOMEM;
> -
> -		sync_file->fence = &array->base;
> -	}
> -
> -	return 0;
> -}
> -
> -static void add_fence(struct dma_fence **fences,
> -		      int *i, struct dma_fence *fence)
> -{
> -	fences[*i] = fence;
> -
> -	if (!dma_fence_is_signaled(fence)) {
> -		dma_fence_get(fence);
> -		(*i)++;
> -	}
> -}
> -
>  /**
>   * sync_file_merge() - merge two sync_files
>   * @name:	name of new fence
> @@ -203,84 +159,21 @@ static void add_fence(struct dma_fence **fences,
>  static struct sync_file *sync_file_merge(const char *name, struct sync_file *a,
>  					 struct sync_file *b)
>  {
> -	struct dma_fence *a_fence, *b_fence, **fences;
> -	struct dma_fence_unwrap a_iter, b_iter;
> -	unsigned int index, num_fences;
>  	struct sync_file *sync_file;
> +	struct dma_fence *fence;
>  
>  	sync_file = sync_file_alloc();
>  	if (!sync_file)
>  		return NULL;
>  
> -	num_fences = 0;
> -	dma_fence_unwrap_for_each(a_fence, &a_iter, a->fence)
> -		++num_fences;
> -	dma_fence_unwrap_for_each(b_fence, &b_iter, b->fence)
> -		++num_fences;
> -
> -	if (num_fences > INT_MAX)
> -		goto err_free_sync_file;
> -
> -	fences = kcalloc(num_fences, sizeof(*fences), GFP_KERNEL);
> -	if (!fences)
> -		goto err_free_sync_file;
> -
> -	/*
> -	 * We can't guarantee that fences in both a and b are ordered, but it is
> -	 * still quite likely.
> -	 *
> -	 * So attempt to order the fences as we pass over them and merge fences
> -	 * with the same context.
> -	 */
> -
> -	index = 0;
> -	for (a_fence = dma_fence_unwrap_first(a->fence, &a_iter),
> -	     b_fence = dma_fence_unwrap_first(b->fence, &b_iter);
> -	     a_fence || b_fence; ) {
> -
> -		if (!b_fence) {
> -			add_fence(fences, &index, a_fence);
> -			a_fence = dma_fence_unwrap_next(&a_iter);
> -
> -		} else if (!a_fence) {
> -			add_fence(fences, &index, b_fence);
> -			b_fence = dma_fence_unwrap_next(&b_iter);
> -
> -		} else if (a_fence->context < b_fence->context) {
> -			add_fence(fences, &index, a_fence);
> -			a_fence = dma_fence_unwrap_next(&a_iter);
> -
> -		} else if (b_fence->context < a_fence->context) {
> -			add_fence(fences, &index, b_fence);
> -			b_fence = dma_fence_unwrap_next(&b_iter);
> -
> -		} else if (__dma_fence_is_later(a_fence->seqno, b_fence->seqno,
> -						a_fence->ops)) {
> -			add_fence(fences, &index, a_fence);
> -			a_fence = dma_fence_unwrap_next(&a_iter);
> -			b_fence = dma_fence_unwrap_next(&b_iter);
> -
> -		} else {
> -			add_fence(fences, &index, b_fence);
> -			a_fence = dma_fence_unwrap_next(&a_iter);
> -			b_fence = dma_fence_unwrap_next(&b_iter);
> -		}
> +	fence = dma_fence_unwrap_merge(a->fence, b->fence);
> +	if (!fence) {
> +		fput(sync_file->file);
> +		return NULL;
>  	}
> -
> -	if (sync_file_set_fence(sync_file, fences, index) < 0)
> -		goto err_put_fences;
> -
> +	sync_file->fence = fence;
>  	strlcpy(sync_file->user_name, name, sizeof(sync_file->user_name));
>  	return sync_file;
> -
> -err_put_fences:
> -	while (index)
> -		dma_fence_put(fences[--index]);
> -	kfree(fences);
> -
> -err_free_sync_file:
> -	fput(sync_file->file);
> -	return NULL;
>  }
>  
>  static int sync_file_release(struct inode *inode, struct file *file)
> diff --git a/include/linux/dma-fence-unwrap.h b/include/linux/dma-fence-unwrap.h
> index e9d114637294..43c8a9bbee88 100644
> --- a/include/linux/dma-fence-unwrap.h
> +++ b/include/linux/dma-fence-unwrap.h
> @@ -48,4 +48,28 @@ struct dma_fence *dma_fence_unwrap_next(struct dma_fence_unwrap *cursor);
>  	for (fence = dma_fence_unwrap_first(head, cursor); fence;	\
>  	     fence = dma_fence_unwrap_next(cursor))
>  
> +struct dma_fence *__dma_fence_unwrap_merge(unsigned int num_fences,
> +					   struct dma_fence **fences,
> +					   struct dma_fence_unwrap *cursors);
> +
> +/**
> + * dma_fence_unwrap_merge - unwrap and merge fences
> + *
> + * All fences given as parameters are unwrapped and merged back together as flat
> + * dma_fence_array. Useful if multiple containers need to be merged together.
> + *
> + * Implemented as a macro to allocate the necessary arrays on the stack and
> + * account the stack frame size to the caller.
> + *
> + * Returns NULL on memory allocation failure, a dma_fence object representing
> + * all the given fences otherwise.
> + */
> +#define dma_fence_unwrap_merge(...)					\
> +	({								\
> +		struct dma_fence *__f[] = { __VA_ARGS__ };		\
> +		struct dma_fence_unwrap __c[ARRAY_SIZE(__f)];		\
> +									\
> +		__dma_fence_unwrap_merge(ARRAY_SIZE(__f), __f, __c);	\
> +	})
> +
>  #endif
> -- 
> 2.25.1
> 

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch

Re: [PATCH 5/5] drm: use dma_fence_unwrap_merge() in drm_syncobj

[Daniel Vetter]

On Wed, May 04, 2022 at 02:22:56PM +0200, Christian König wrote:
> The unwrap merge function is now intended for this use case.
> 
> Signed-off-by: Christian König <christian.koenig@amd.com>

Yeah this starts to make sense now as refactor.

Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>

> ---
>  drivers/gpu/drm/drm_syncobj.c | 57 +++++------------------------------
>  1 file changed, 7 insertions(+), 50 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_syncobj.c b/drivers/gpu/drm/drm_syncobj.c
> index 7e48dcd1bee4..bbad9e4696e7 100644
> --- a/drivers/gpu/drm/drm_syncobj.c
> +++ b/drivers/gpu/drm/drm_syncobj.c
> @@ -184,6 +184,7 @@
>   */
>  
>  #include <linux/anon_inodes.h>
> +#include <linux/dma-fence-unwrap.h>
>  #include <linux/file.h>
>  #include <linux/fs.h>
>  #include <linux/sched/signal.h>
> @@ -853,57 +854,12 @@ drm_syncobj_fd_to_handle_ioctl(struct drm_device *dev, void *data,
>  					&args->handle);
>  }
>  
> -
> -/*
> - * Try to flatten a dma_fence_chain into a dma_fence_array so that it can be
> - * added as timeline fence to a chain again.
> - */
> -static int drm_syncobj_flatten_chain(struct dma_fence **f)
> -{
> -	struct dma_fence_chain *chain = to_dma_fence_chain(*f);
> -	struct dma_fence *tmp, **fences;
> -	struct dma_fence_array *array;
> -	unsigned int count;
> -
> -	if (!chain)
> -		return 0;
> -
> -	count = 0;
> -	dma_fence_chain_for_each(tmp, &chain->base)
> -		++count;
> -
> -	fences = kmalloc_array(count, sizeof(*fences), GFP_KERNEL);
> -	if (!fences)
> -		return -ENOMEM;
> -
> -	count = 0;
> -	dma_fence_chain_for_each(tmp, &chain->base)
> -		fences[count++] = dma_fence_get(tmp);
> -
> -	array = dma_fence_array_create(count, fences,
> -				       dma_fence_context_alloc(1),
> -				       1, false);
> -	if (!array)
> -		goto free_fences;
> -
> -	dma_fence_put(*f);
> -	*f = &array->base;
> -	return 0;
> -
> -free_fences:
> -	while (count--)
> -		dma_fence_put(fences[count]);
> -
> -	kfree(fences);
> -	return -ENOMEM;
> -}
> -
>  static int drm_syncobj_transfer_to_timeline(struct drm_file *file_private,
>  					    struct drm_syncobj_transfer *args)
>  {
>  	struct drm_syncobj *timeline_syncobj = NULL;
> +	struct dma_fence *fence, *tmp;
>  	struct dma_fence_chain *chain;
> -	struct dma_fence *fence;
>  	int ret;
>  
>  	timeline_syncobj = drm_syncobj_find(file_private, args->dst_handle);
> @@ -912,13 +868,14 @@ static int drm_syncobj_transfer_to_timeline(struct drm_file *file_private,
>  	}
>  	ret = drm_syncobj_find_fence(file_private, args->src_handle,
>  				     args->src_point, args->flags,
> -				     &fence);
> +				     &tmp);
>  	if (ret)
>  		goto err_put_timeline;
>  
> -	ret = drm_syncobj_flatten_chain(&fence);
> -	if (ret)
> -		goto err_free_fence;
> +	fence = dma_fence_unwrap_merge(tmp);
> +	dma_fence_put(tmp);
> +	if (!fence)
> +		goto err_put_timeline;
>  
>  	chain = dma_fence_chain_alloc();
>  	if (!chain) {
> -- 
> 2.25.1
> 

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch

Re: [PATCH 5/5] drm: use dma_fence_unwrap_merge() in drm_syncobj

[Daniel Vetter]

On Wed, May 04, 2022 at 02:22:56PM +0200, Christian König wrote:
> The unwrap merge function is now intended for this use case.
> 
> Signed-off-by: Christian König <christian.koenig@amd.com>

Yeah this starts to make sense now as refactor.

Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>

> ---
>  drivers/gpu/drm/drm_syncobj.c | 57 +++++------------------------------
>  1 file changed, 7 insertions(+), 50 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_syncobj.c b/drivers/gpu/drm/drm_syncobj.c
> index 7e48dcd1bee4..bbad9e4696e7 100644
> --- a/drivers/gpu/drm/drm_syncobj.c
> +++ b/drivers/gpu/drm/drm_syncobj.c
> @@ -184,6 +184,7 @@
>   */
>  
>  #include <linux/anon_inodes.h>
> +#include <linux/dma-fence-unwrap.h>
>  #include <linux/file.h>
>  #include <linux/fs.h>
>  #include <linux/sched/signal.h>
> @@ -853,57 +854,12 @@ drm_syncobj_fd_to_handle_ioctl(struct drm_device *dev, void *data,
>  					&args->handle);
>  }
>  
> -
> -/*
> - * Try to flatten a dma_fence_chain into a dma_fence_array so that it can be
> - * added as timeline fence to a chain again.
> - */
> -static int drm_syncobj_flatten_chain(struct dma_fence **f)
> -{
> -	struct dma_fence_chain *chain = to_dma_fence_chain(*f);
> -	struct dma_fence *tmp, **fences;
> -	struct dma_fence_array *array;
> -	unsigned int count;
> -
> -	if (!chain)
> -		return 0;
> -
> -	count = 0;
> -	dma_fence_chain_for_each(tmp, &chain->base)
> -		++count;
> -
> -	fences = kmalloc_array(count, sizeof(*fences), GFP_KERNEL);
> -	if (!fences)
> -		return -ENOMEM;
> -
> -	count = 0;
> -	dma_fence_chain_for_each(tmp, &chain->base)
> -		fences[count++] = dma_fence_get(tmp);
> -
> -	array = dma_fence_array_create(count, fences,
> -				       dma_fence_context_alloc(1),
> -				       1, false);
> -	if (!array)
> -		goto free_fences;
> -
> -	dma_fence_put(*f);
> -	*f = &array->base;
> -	return 0;
> -
> -free_fences:
> -	while (count--)
> -		dma_fence_put(fences[count]);
> -
> -	kfree(fences);
> -	return -ENOMEM;
> -}
> -
>  static int drm_syncobj_transfer_to_timeline(struct drm_file *file_private,
>  					    struct drm_syncobj_transfer *args)
>  {
>  	struct drm_syncobj *timeline_syncobj = NULL;
> +	struct dma_fence *fence, *tmp;
>  	struct dma_fence_chain *chain;
> -	struct dma_fence *fence;
>  	int ret;
>  
>  	timeline_syncobj = drm_syncobj_find(file_private, args->dst_handle);
> @@ -912,13 +868,14 @@ static int drm_syncobj_transfer_to_timeline(struct drm_file *file_private,
>  	}
>  	ret = drm_syncobj_find_fence(file_private, args->src_handle,
>  				     args->src_point, args->flags,
> -				     &fence);
> +				     &tmp);
>  	if (ret)
>  		goto err_put_timeline;
>  
> -	ret = drm_syncobj_flatten_chain(&fence);
> -	if (ret)
> -		goto err_free_fence;
> +	fence = dma_fence_unwrap_merge(tmp);
> +	dma_fence_put(tmp);
> +	if (!fence)
> +		goto err_put_timeline;
>  
>  	chain = dma_fence_chain_alloc();
>  	if (!chain) {
> -- 
> 2.25.1
> 

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch

Re: [PATCH 1/5] dma-buf: cleanup dma_fence_unwrap selftest

[Christian König]

Am 05.05.22 um 15:29 schrieb Daniel Vetter:
> On Wed, May 04, 2022 at 02:22:52PM +0200, Christian König wrote:
>> The selftests, fix the error handling, remove unused functions and stop
>> leaking memory in failed tests.
>>
>> Signed-off-by: Christian König <christian.koenig@amd.com>
>> ---
>>   drivers/dma-buf/st-dma-fence-unwrap.c | 40 +++++++++++----------------
>>   1 file changed, 16 insertions(+), 24 deletions(-)
>>
>> diff --git a/drivers/dma-buf/st-dma-fence-unwrap.c b/drivers/dma-buf/st-dma-fence-unwrap.c
>> index 039f016b57be..59628add93f5 100644
>> --- a/drivers/dma-buf/st-dma-fence-unwrap.c
>> +++ b/drivers/dma-buf/st-dma-fence-unwrap.c
>> @@ -4,27 +4,19 @@
>>    * Copyright (C) 2022 Advanced Micro Devices, Inc.
>>    */
>>   
>> +#include <linux/dma-fence.h>
>> +#include <linux/dma-fence-array.h>
>> +#include <linux/dma-fence-chain.h>
>>   #include <linux/dma-fence-unwrap.h>
>> -#if 0
>> -#include <linux/kernel.h>
>> -#include <linux/kthread.h>
>> -#include <linux/mm.h>
>> -#include <linux/sched/signal.h>
>> -#include <linux/slab.h>
>> -#include <linux/spinlock.h>
>> -#include <linux/random.h>
>> -#endif
>>   
>>   #include "selftest.h"
>>   
>>   #define CHAIN_SZ (4 << 10)
>>   
>> -static inline struct mock_fence {
>> +struct mock_fence {
>>   	struct dma_fence base;
>>   	spinlock_t lock;
>> -} *to_mock_fence(struct dma_fence *f) {
>> -	return container_of(f, struct mock_fence, base);
>> -}
>> +};
>>   
>>   static const char *mock_name(struct dma_fence *f)
>>   {
>> @@ -45,7 +37,8 @@ static struct dma_fence *mock_fence(void)
>>   		return NULL;
>>   
>>   	spin_lock_init(&f->lock);
>> -	dma_fence_init(&f->base, &mock_ops, &f->lock, 0, 0);
>> +	dma_fence_init(&f->base, &mock_ops, &f->lock,
>> +		       dma_fence_context_alloc(1), 1);
>>   
>>   	return &f->base;
>>   }
>> @@ -113,7 +106,6 @@ static int sanitycheck(void *arg)
>>   	if (!chain)
>>   		return -ENOMEM;
>>   
>> -	dma_fence_signal(f);
>>   	dma_fence_put(chain);
>>   	return err;
>>   }
>> @@ -154,10 +146,10 @@ static int unwrap_array(void *arg)
>>   		err = -EINVAL;
>>   	}
>>   
>> -	dma_fence_signal(f1);
>> -	dma_fence_signal(f2);
>> +	dma_fence_put(f1);
>> +	dma_fence_put(f2);
> I'm completely lost on why you add these _put() calls?

Because my five year old had a nightmare and I had not enough caffeine 
in my blood stream on the next morning.

Fixed in the next round.

Thanks,
Christian.

>   The reference we
> create all get transferred over to the container object, and that takes
> care of releasing them.
>
> The other bits with error handling and code cleanup all look good, and
> dropping dma_fence_signal calls also makes sense. But this one I don't
> get.
> -Daniel
>
>>   	dma_fence_put(array);
>> -	return 0;
>> +	return err;
>>   }
>>   
>>   static int unwrap_chain(void *arg)
>> @@ -196,10 +188,10 @@ static int unwrap_chain(void *arg)
>>   		err = -EINVAL;
>>   	}
>>   
>> -	dma_fence_signal(f1);
>> -	dma_fence_signal(f2);
>> +	dma_fence_put(f1);
>> +	dma_fence_put(f2);
>>   	dma_fence_put(chain);
>> -	return 0;
>> +	return err;
>>   }
>>   
>>   static int unwrap_chain_array(void *arg)
>> @@ -242,10 +234,10 @@ static int unwrap_chain_array(void *arg)
>>   		err = -EINVAL;
>>   	}
>>   
>> -	dma_fence_signal(f1);
>> -	dma_fence_signal(f2);
>> +	dma_fence_put(f1);
>> +	dma_fence_put(f2);
>>   	dma_fence_put(chain);
>> -	return 0;
>> +	return err;
>>   }
>>   
>>   int dma_fence_unwrap(void)
>> -- 
>> 2.25.1
>>

Re: [PATCH 1/5] dma-buf: cleanup dma_fence_unwrap selftest

[Christian König]

Am 05.05.22 um 15:29 schrieb Daniel Vetter:
> On Wed, May 04, 2022 at 02:22:52PM +0200, Christian König wrote:
>> The selftests, fix the error handling, remove unused functions and stop
>> leaking memory in failed tests.
>>
>> Signed-off-by: Christian König <christian.koenig@amd.com>
>> ---
>>   drivers/dma-buf/st-dma-fence-unwrap.c | 40 +++++++++++----------------
>>   1 file changed, 16 insertions(+), 24 deletions(-)
>>
>> diff --git a/drivers/dma-buf/st-dma-fence-unwrap.c b/drivers/dma-buf/st-dma-fence-unwrap.c
>> index 039f016b57be..59628add93f5 100644
>> --- a/drivers/dma-buf/st-dma-fence-unwrap.c
>> +++ b/drivers/dma-buf/st-dma-fence-unwrap.c
>> @@ -4,27 +4,19 @@
>>    * Copyright (C) 2022 Advanced Micro Devices, Inc.
>>    */
>>   
>> +#include <linux/dma-fence.h>
>> +#include <linux/dma-fence-array.h>
>> +#include <linux/dma-fence-chain.h>
>>   #include <linux/dma-fence-unwrap.h>
>> -#if 0
>> -#include <linux/kernel.h>
>> -#include <linux/kthread.h>
>> -#include <linux/mm.h>
>> -#include <linux/sched/signal.h>
>> -#include <linux/slab.h>
>> -#include <linux/spinlock.h>
>> -#include <linux/random.h>
>> -#endif
>>   
>>   #include "selftest.h"
>>   
>>   #define CHAIN_SZ (4 << 10)
>>   
>> -static inline struct mock_fence {
>> +struct mock_fence {
>>   	struct dma_fence base;
>>   	spinlock_t lock;
>> -} *to_mock_fence(struct dma_fence *f) {
>> -	return container_of(f, struct mock_fence, base);
>> -}
>> +};
>>   
>>   static const char *mock_name(struct dma_fence *f)
>>   {
>> @@ -45,7 +37,8 @@ static struct dma_fence *mock_fence(void)
>>   		return NULL;
>>   
>>   	spin_lock_init(&f->lock);
>> -	dma_fence_init(&f->base, &mock_ops, &f->lock, 0, 0);
>> +	dma_fence_init(&f->base, &mock_ops, &f->lock,
>> +		       dma_fence_context_alloc(1), 1);
>>   
>>   	return &f->base;
>>   }
>> @@ -113,7 +106,6 @@ static int sanitycheck(void *arg)
>>   	if (!chain)
>>   		return -ENOMEM;
>>   
>> -	dma_fence_signal(f);
>>   	dma_fence_put(chain);
>>   	return err;
>>   }
>> @@ -154,10 +146,10 @@ static int unwrap_array(void *arg)
>>   		err = -EINVAL;
>>   	}
>>   
>> -	dma_fence_signal(f1);
>> -	dma_fence_signal(f2);
>> +	dma_fence_put(f1);
>> +	dma_fence_put(f2);
> I'm completely lost on why you add these _put() calls?

Because my five year old had a nightmare and I had not enough caffeine 
in my blood stream on the next morning.

Fixed in the next round.

Thanks,
Christian.

>   The reference we
> create all get transferred over to the container object, and that takes
> care of releasing them.
>
> The other bits with error handling and code cleanup all look good, and
> dropping dma_fence_signal calls also makes sense. But this one I don't
> get.
> -Daniel
>
>>   	dma_fence_put(array);
>> -	return 0;
>> +	return err;
>>   }
>>   
>>   static int unwrap_chain(void *arg)
>> @@ -196,10 +188,10 @@ static int unwrap_chain(void *arg)
>>   		err = -EINVAL;
>>   	}
>>   
>> -	dma_fence_signal(f1);
>> -	dma_fence_signal(f2);
>> +	dma_fence_put(f1);
>> +	dma_fence_put(f2);
>>   	dma_fence_put(chain);
>> -	return 0;
>> +	return err;
>>   }
>>   
>>   static int unwrap_chain_array(void *arg)
>> @@ -242,10 +234,10 @@ static int unwrap_chain_array(void *arg)
>>   		err = -EINVAL;
>>   	}
>>   
>> -	dma_fence_signal(f1);
>> -	dma_fence_signal(f2);
>> +	dma_fence_put(f1);
>> +	dma_fence_put(f2);
>>   	dma_fence_put(chain);
>> -	return 0;
>> +	return err;
>>   }
>>   
>>   int dma_fence_unwrap(void)
>> -- 
>> 2.25.1
>>