[PATCH 1/2] dma-buf: add dma_resv_for_each_fence v3

[PATCH 1/2] dma-buf: add dma_resv_for_each_fence v3

[Christian König]

A simpler version of the iterator to be used when the dma_resv object is
locked.

v2: fix index check here as well
v3: minor coding improvement, some documentation cleanup

Signed-off-by: Christian König <christian.koenig@amd.com>
---
 drivers/dma-buf/dma-resv.c | 51 ++++++++++++++++++++++++++++++++++++++
 include/linux/dma-resv.h   | 20 +++++++++++++++
 2 files changed, 71 insertions(+)

diff --git a/drivers/dma-buf/dma-resv.c b/drivers/dma-buf/dma-resv.c
index a480af9581bd..2f98caa68ae5 100644
--- a/drivers/dma-buf/dma-resv.c
+++ b/drivers/dma-buf/dma-resv.c
@@ -423,6 +423,57 @@ struct dma_fence *dma_resv_iter_next_unlocked(struct dma_resv_iter *cursor)
 }
 EXPORT_SYMBOL(dma_resv_iter_next_unlocked);
 
+/**
+ * dma_resv_iter_first - first fence from a locked dma_resv object
+ * @cursor: cursor to record the current position
+ *
+ * Return the first fence in the dma_resv object while holding the
+ * &dma_resv.lock.
+ */
+struct dma_fence *dma_resv_iter_first(struct dma_resv_iter *cursor)
+{
+	struct dma_fence *fence;
+
+	dma_resv_assert_held(cursor->obj);
+
+	cursor->index = 0;
+	if (cursor->all_fences)
+		cursor->fences = dma_resv_shared_list(cursor->obj);
+	else
+		cursor->fences = NULL;
+
+	fence = dma_resv_excl_fence(cursor->obj);
+	if (!fence)
+		fence = dma_resv_iter_next(cursor);
+
+	cursor->is_restarted = true;
+	return fence;
+}
+EXPORT_SYMBOL_GPL(dma_resv_iter_first);
+
+/**
+ * dma_resv_iter_next - next fence from a locked dma_resv object
+ * @cursor: cursor to record the current position
+ *
+ * Return the next fences from the dma_resv object while holding the
+ * &dma_resv.lock.
+ */
+struct dma_fence *dma_resv_iter_next(struct dma_resv_iter *cursor)
+{
+	unsigned int idx;
+
+	dma_resv_assert_held(cursor->obj);
+
+	cursor->is_restarted = false;
+	if (!cursor->fences || cursor->index >= cursor->fences->shared_count)
+		return NULL;
+
+	idx = cursor->index++;
+	return rcu_dereference_protected(cursor->fences->shared[idx],
+					 dma_resv_held(cursor->obj));
+}
+EXPORT_SYMBOL_GPL(dma_resv_iter_next);
+
 /**
  * dma_resv_copy_fences - Copy all fences from src to dst.
  * @dst: the destination reservation object
diff --git a/include/linux/dma-resv.h b/include/linux/dma-resv.h
index 764138ad8583..491359cea54c 100644
--- a/include/linux/dma-resv.h
+++ b/include/linux/dma-resv.h
@@ -179,6 +179,8 @@ struct dma_resv_iter {
 
 struct dma_fence *dma_resv_iter_first_unlocked(struct dma_resv_iter *cursor);
 struct dma_fence *dma_resv_iter_next_unlocked(struct dma_resv_iter *cursor);
+struct dma_fence *dma_resv_iter_first(struct dma_resv_iter *cursor);
+struct dma_fence *dma_resv_iter_next(struct dma_resv_iter *cursor);
 
 /**
  * dma_resv_iter_begin - initialize a dma_resv_iter object
@@ -244,6 +246,24 @@ static inline bool dma_resv_iter_is_restarted(struct dma_resv_iter *cursor)
 	for (fence = dma_resv_iter_first_unlocked(cursor);		\
 	     fence; fence = dma_resv_iter_next_unlocked(cursor))
 
+/**
+ * dma_resv_for_each_fence - fence iterator
+ * @cursor: a struct dma_resv_iter pointer
+ * @obj: a dma_resv object pointer
+ * @all_fences: true if all fences should be returned
+ * @fence: the current fence
+ *
+ * Iterate over the fences in a struct dma_resv object while holding the
+ * &dma_resv.lock. @all_fences controls if the shared fences are returned as
+ * well. The cursor initialisation is part of the iterator and the fence stays
+ * valid as long as the lock is held and so no extra reference to the fence is
+ * taken.
+ */
+#define dma_resv_for_each_fence(cursor, obj, all_fences, fence)	\
+	for (dma_resv_iter_begin(cursor, obj, all_fences),	\
+	     fence = dma_resv_iter_first(cursor); fence;	\
+	     fence = dma_resv_iter_next(cursor))
+
 #define dma_resv_held(obj) lockdep_is_held(&(obj)->lock.base)
 #define dma_resv_assert_held(obj) lockdep_assert_held(&(obj)->lock.base)
 
-- 
2.25.1

[PATCH 2/2] dma-buf: add dma_resv selftest v3

[Christian König]

Just exercising a very minor subset of the functionality, but already
proven useful.

v2: add missing locking
v3: some more cleanup and consolidation, add unlocked test as well

Signed-off-by: Christian König <christian.koenig@amd.com>
---
 drivers/dma-buf/Makefile      |   3 +-
 drivers/dma-buf/selftests.h   |   1 +
 drivers/dma-buf/st-dma-resv.c | 282 ++++++++++++++++++++++++++++++++++
 3 files changed, 285 insertions(+), 1 deletion(-)
 create mode 100644 drivers/dma-buf/st-dma-resv.c

diff --git a/drivers/dma-buf/Makefile b/drivers/dma-buf/Makefile
index 1ef021273a06..511805dbeb75 100644
--- a/drivers/dma-buf/Makefile
+++ b/drivers/dma-buf/Makefile
@@ -11,6 +11,7 @@ obj-$(CONFIG_DMABUF_SYSFS_STATS) += dma-buf-sysfs-stats.o
 dmabuf_selftests-y := \
 	selftest.o \
 	st-dma-fence.o \
-	st-dma-fence-chain.o
+	st-dma-fence-chain.o \
+	st-dma-resv.o
 
 obj-$(CONFIG_DMABUF_SELFTESTS)	+= dmabuf_selftests.o
diff --git a/drivers/dma-buf/selftests.h b/drivers/dma-buf/selftests.h
index bc8cea67bf1e..97d73aaa31da 100644
--- a/drivers/dma-buf/selftests.h
+++ b/drivers/dma-buf/selftests.h
@@ -12,3 +12,4 @@
 selftest(sanitycheck, __sanitycheck__) /* keep first (igt selfcheck) */
 selftest(dma_fence, dma_fence)
 selftest(dma_fence_chain, dma_fence_chain)
+selftest(dma_resv, dma_resv)
diff --git a/drivers/dma-buf/st-dma-resv.c b/drivers/dma-buf/st-dma-resv.c
new file mode 100644
index 000000000000..50d3791ccb8c
--- /dev/null
+++ b/drivers/dma-buf/st-dma-resv.c
@@ -0,0 +1,282 @@
+/* SPDX-License-Identifier: MIT */
+
+/*
+* Copyright © 2019 Intel Corporation
+* Copyright © 2021 Advanced Micro Devices, Inc.
+*/
+
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+#include <linux/dma-resv.h>
+
+#include "selftest.h"
+
+static struct spinlock fence_lock;
+
+static const char *fence_name(struct dma_fence *f)
+{
+	return "selftest";
+}
+
+static const struct dma_fence_ops fence_ops = {
+	.get_driver_name = fence_name,
+	.get_timeline_name = fence_name,
+};
+
+static struct dma_fence *alloc_fence(void)
+{
+	struct dma_fence *f;
+
+	f = kmalloc(sizeof(*f), GFP_KERNEL);
+	if (!f)
+		return NULL;
+
+	dma_fence_init(f, &fence_ops, &fence_lock, 0, 0);
+	return f;
+}
+
+static int sanitycheck(void *arg)
+{
+	struct dma_resv resv;
+	struct dma_fence *f;
+	int r;
+
+	f = alloc_fence();
+	if (!f)
+		return -ENOMEM;
+
+	dma_fence_signal(f);
+	dma_fence_put(f);
+
+	dma_resv_init(&resv);
+	r = dma_resv_lock(&resv, NULL);
+	if (r)
+		pr_err("Resv locking failed\n");
+	else
+		dma_resv_unlock(&resv);
+	dma_resv_fini(&resv);
+	return r;
+}
+
+static int test_signaling(void *arg, bool shared)
+{
+	struct dma_resv resv;
+	struct dma_fence *f;
+	int r;
+
+	f = alloc_fence();
+	if (!f)
+		return -ENOMEM;
+
+	dma_resv_init(&resv);
+	r = dma_resv_lock(&resv, NULL);
+	if (r) {
+		pr_err("Resv locking failed\n");
+		goto err_free;
+	}
+
+	if (shared) {
+		r = dma_resv_reserve_shared(&resv, 1);
+		if (r) {
+			pr_err("Resv shared slot allocation failed\n");
+			goto err_unlock;
+		}
+
+		dma_resv_add_shared_fence(&resv, f);
+	} else {
+		dma_resv_add_excl_fence(&resv, f);
+	}
+
+	if (dma_resv_test_signaled(&resv, shared)) {
+		pr_err("Resv unexpectedly signaled\n");
+		r = -EINVAL;
+		goto err_unlock;
+	}
+	dma_fence_signal(f);
+	if (!dma_resv_test_signaled(&resv, shared)) {
+		pr_err("Resv not reporting signaled\n");
+		r = -EINVAL;
+		goto err_unlock;
+	}
+err_unlock:
+	dma_resv_unlock(&resv);
+err_free:
+	dma_resv_fini(&resv);
+	dma_fence_put(f);
+	return r;
+}
+
+static int test_excl_signaling(void *arg)
+{
+	return test_signaling(arg, false);
+}
+
+static int test_shared_signaling(void *arg)
+{
+	return test_signaling(arg, true);
+}
+
+static int test_for_each(void *arg, bool shared)
+{
+	struct dma_resv_iter cursor;
+	struct dma_fence *f, *fence;
+	struct dma_resv resv;
+	int r;
+
+	f = alloc_fence();
+	if (!f)
+		return -ENOMEM;
+
+	dma_resv_init(&resv);
+	r = dma_resv_lock(&resv, NULL);
+	if (r) {
+		pr_err("Resv locking failed\n");
+		goto err_free;
+	}
+
+	if (shared) {
+		r = dma_resv_reserve_shared(&resv, 1);
+		if (r) {
+			pr_err("Resv shared slot allocation failed\n");
+			goto err_unlock;
+		}
+
+		dma_resv_add_shared_fence(&resv, f);
+	} else {
+		dma_resv_add_excl_fence(&resv, f);
+	}
+
+	r = -ENOENT;
+	dma_resv_for_each_fence(&cursor, &resv, shared, fence) {
+		if (!r) {
+			pr_err("More than one fence found\n");
+			r = -EINVAL;
+			goto err_unlock;
+		}
+		if (f != fence) {
+			pr_err("Unexpected fence\n");
+			r = -EINVAL;
+			goto err_unlock;
+		}
+		if (dma_resv_iter_is_exclusive(&cursor) != !shared) {
+			pr_err("Unexpected fence usage\n");
+			r = -EINVAL;
+			goto err_unlock;
+		}
+		r = 0;
+	}
+	if (r) {
+		pr_err("No fence found\n");
+		goto err_unlock;
+	}
+	dma_fence_signal(f);
+err_unlock:
+	dma_resv_unlock(&resv);
+err_free:
+	dma_resv_fini(&resv);
+	dma_fence_put(f);
+	return r;
+}
+
+static int test_excl_for_each(void *arg)
+{
+	return test_for_each(arg, false);
+}
+
+static int test_shared_for_each(void *arg)
+{
+	return test_for_each(arg, false);
+}
+
+static int test_for_each_unlocked(void *arg, bool shared)
+{
+	struct dma_resv_iter cursor;
+	struct dma_fence *f, *fence;
+	struct dma_resv resv;
+	int r;
+
+	f = alloc_fence();
+	if (!f)
+		return -ENOMEM;
+
+	dma_resv_init(&resv);
+	r = dma_resv_lock(&resv, NULL);
+	if (r) {
+		pr_err("Resv locking failed\n");
+		goto err_free;
+	}
+
+	if (shared) {
+		r = dma_resv_reserve_shared(&resv, 1);
+		if (r) {
+			pr_err("Resv shared slot allocation failed\n");
+			dma_resv_unlock(&resv);
+			goto err_free;
+		}
+
+		dma_resv_add_shared_fence(&resv, f);
+	} else {
+		dma_resv_add_excl_fence(&resv, f);
+	}
+	dma_resv_unlock(&resv);
+
+	r = -ENOENT;
+	dma_resv_iter_begin(&cursor, &resv, shared);
+	dma_resv_for_each_fence_unlocked(&cursor, fence) {
+		if (!r) {
+			dma_resv_iter_end(&cursor);
+			pr_err("More than one fence found\n");
+			r = -EINVAL;
+			goto err_free;
+		}
+		if (f != fence) {
+			dma_resv_iter_end(&cursor);
+			pr_err("Unexpected fence\n");
+			r = -EINVAL;
+			goto err_free;
+		}
+		if (dma_resv_iter_is_exclusive(&cursor) != !shared) {
+			dma_resv_iter_end(&cursor);
+			pr_err("Unexpected fence usage\n");
+			r = -EINVAL;
+			goto err_free;
+		}
+		r = 0;
+	}
+	dma_resv_iter_end(&cursor);
+	if (r) {
+		pr_err("No fence found\n");
+		goto err_free;
+	}
+	dma_fence_signal(f);
+err_free:
+	dma_resv_fini(&resv);
+	dma_fence_put(f);
+	return r;
+}
+
+static int test_excl_for_each_unlocked(void *arg)
+{
+	return test_for_each_unlocked(arg, false);
+}
+
+static int test_shared_for_each_unlocked(void *arg)
+{
+	return test_for_each_unlocked(arg, true);
+}
+
+int dma_resv(void)
+{
+	static const struct subtest tests[] = {
+		SUBTEST(sanitycheck),
+		SUBTEST(test_excl_signaling),
+		SUBTEST(test_shared_signaling),
+		SUBTEST(test_excl_for_each),
+		SUBTEST(test_shared_for_each),
+		SUBTEST(test_excl_for_each_unlocked),
+		SUBTEST(test_shared_for_each_unlocked),
+	};
+
+	spin_lock_init(&fence_lock);
+	return subtests(tests, NULL);
+}
-- 
2.25.1

Re: [PATCH 2/2] dma-buf: add dma_resv selftest v3

[Tvrtko Ursulin]

On 06/10/2021 13:36, Christian König wrote:
> Just exercising a very minor subset of the functionality, but already
> proven useful.
> 
> v2: add missing locking
> v3: some more cleanup and consolidation, add unlocked test as well
> 
> Signed-off-by: Christian König <christian.koenig@amd.com>
> ---
>   drivers/dma-buf/Makefile      |   3 +-
>   drivers/dma-buf/selftests.h   |   1 +
>   drivers/dma-buf/st-dma-resv.c | 282 ++++++++++++++++++++++++++++++++++
>   3 files changed, 285 insertions(+), 1 deletion(-)
>   create mode 100644 drivers/dma-buf/st-dma-resv.c
> 
> diff --git a/drivers/dma-buf/Makefile b/drivers/dma-buf/Makefile
> index 1ef021273a06..511805dbeb75 100644
> --- a/drivers/dma-buf/Makefile
> +++ b/drivers/dma-buf/Makefile
> @@ -11,6 +11,7 @@ obj-$(CONFIG_DMABUF_SYSFS_STATS) += dma-buf-sysfs-stats.o
>   dmabuf_selftests-y := \
>   	selftest.o \
>   	st-dma-fence.o \
> -	st-dma-fence-chain.o
> +	st-dma-fence-chain.o \
> +	st-dma-resv.o
>   
>   obj-$(CONFIG_DMABUF_SELFTESTS)	+= dmabuf_selftests.o
> diff --git a/drivers/dma-buf/selftests.h b/drivers/dma-buf/selftests.h
> index bc8cea67bf1e..97d73aaa31da 100644
> --- a/drivers/dma-buf/selftests.h
> +++ b/drivers/dma-buf/selftests.h
> @@ -12,3 +12,4 @@
>   selftest(sanitycheck, __sanitycheck__) /* keep first (igt selfcheck) */
>   selftest(dma_fence, dma_fence)
>   selftest(dma_fence_chain, dma_fence_chain)
> +selftest(dma_resv, dma_resv)
> diff --git a/drivers/dma-buf/st-dma-resv.c b/drivers/dma-buf/st-dma-resv.c
> new file mode 100644
> index 000000000000..50d3791ccb8c
> --- /dev/null
> +++ b/drivers/dma-buf/st-dma-resv.c
> @@ -0,0 +1,282 @@
> +/* SPDX-License-Identifier: MIT */
> +
> +/*
> +* Copyright © 2019 Intel Corporation
> +* Copyright © 2021 Advanced Micro Devices, Inc.
> +*/
> +
> +#include <linux/slab.h>
> +#include <linux/spinlock.h>
> +#include <linux/dma-resv.h>
> +
> +#include "selftest.h"
> +
> +static struct spinlock fence_lock;
> +
> +static const char *fence_name(struct dma_fence *f)
> +{
> +	return "selftest";
> +}
> +
> +static const struct dma_fence_ops fence_ops = {
> +	.get_driver_name = fence_name,
> +	.get_timeline_name = fence_name,
> +};
> +
> +static struct dma_fence *alloc_fence(void)
> +{
> +	struct dma_fence *f;
> +
> +	f = kmalloc(sizeof(*f), GFP_KERNEL);
> +	if (!f)
> +		return NULL;
> +
> +	dma_fence_init(f, &fence_ops, &fence_lock, 0, 0);
> +	return f;
> +}
> +
> +static int sanitycheck(void *arg)
> +{
> +	struct dma_resv resv;
> +	struct dma_fence *f;
> +	int r;
> +
> +	f = alloc_fence();
> +	if (!f)
> +		return -ENOMEM;
> +
> +	dma_fence_signal(f);
> +	dma_fence_put(f);
> +
> +	dma_resv_init(&resv);
> +	r = dma_resv_lock(&resv, NULL);
> +	if (r)
> +		pr_err("Resv locking failed\n");
> +	else
> +		dma_resv_unlock(&resv);
> +	dma_resv_fini(&resv);
> +	return r;
> +}
> +
> +static int test_signaling(void *arg, bool shared)
> +{
> +	struct dma_resv resv;
> +	struct dma_fence *f;
> +	int r;
> +
> +	f = alloc_fence();
> +	if (!f)
> +		return -ENOMEM;
> +
> +	dma_resv_init(&resv);
> +	r = dma_resv_lock(&resv, NULL);
> +	if (r) {
> +		pr_err("Resv locking failed\n");
> +		goto err_free;
> +	}
> +
> +	if (shared) {
> +		r = dma_resv_reserve_shared(&resv, 1);
> +		if (r) {
> +			pr_err("Resv shared slot allocation failed\n");
> +			goto err_unlock;
> +		}
> +
> +		dma_resv_add_shared_fence(&resv, f);
> +	} else {
> +		dma_resv_add_excl_fence(&resv, f);
> +	}
> +
> +	if (dma_resv_test_signaled(&resv, shared)) {
> +		pr_err("Resv unexpectedly signaled\n");
> +		r = -EINVAL;
> +		goto err_unlock;
> +	}
> +	dma_fence_signal(f);
> +	if (!dma_resv_test_signaled(&resv, shared)) {
> +		pr_err("Resv not reporting signaled\n");
> +		r = -EINVAL;
> +		goto err_unlock;
> +	}
> +err_unlock:
> +	dma_resv_unlock(&resv);
> +err_free:
> +	dma_resv_fini(&resv);
> +	dma_fence_put(f);
> +	return r;
> +}
> +
> +static int test_excl_signaling(void *arg)
> +{
> +	return test_signaling(arg, false);
> +}
> +
> +static int test_shared_signaling(void *arg)
> +{
> +	return test_signaling(arg, true);
> +}
> +
> +static int test_for_each(void *arg, bool shared)
> +{
> +	struct dma_resv_iter cursor;
> +	struct dma_fence *f, *fence;
> +	struct dma_resv resv;
> +	int r;
> +
> +	f = alloc_fence();
> +	if (!f)
> +		return -ENOMEM;
> +
> +	dma_resv_init(&resv);
> +	r = dma_resv_lock(&resv, NULL);
> +	if (r) {
> +		pr_err("Resv locking failed\n");
> +		goto err_free;
> +	}
> +
> +	if (shared) {
> +		r = dma_resv_reserve_shared(&resv, 1);
> +		if (r) {
> +			pr_err("Resv shared slot allocation failed\n");
> +			goto err_unlock;
> +		}
> +
> +		dma_resv_add_shared_fence(&resv, f);
> +	} else {
> +		dma_resv_add_excl_fence(&resv, f);
> +	}

This block repeates three times so could be consolidated but it doesn't 
matter hugely.

> +
> +	r = -ENOENT;
> +	dma_resv_for_each_fence(&cursor, &resv, shared, fence) {
> +		if (!r) {
> +			pr_err("More than one fence found\n");
> +			r = -EINVAL;
> +			goto err_unlock;
> +		}
> +		if (f != fence) {
> +			pr_err("Unexpected fence\n");
> +			r = -EINVAL;
> +			goto err_unlock;
> +		}
> +		if (dma_resv_iter_is_exclusive(&cursor) != !shared) {
> +			pr_err("Unexpected fence usage\n");
> +			r = -EINVAL;
> +			goto err_unlock;
> +		}
> +		r = 0;
> +	}
> +	if (r) {
> +		pr_err("No fence found\n");
> +		goto err_unlock;
> +	}
> +	dma_fence_signal(f);

This would warn if the loop jumps to err_unlock but I guess there are 
bigger problems in that case.

> +err_unlock:
> +	dma_resv_unlock(&resv);
> +err_free:
> +	dma_resv_fini(&resv);
> +	dma_fence_put(f);
> +	return r;
> +}
> +
> +static int test_excl_for_each(void *arg)
> +{
> +	return test_for_each(arg, false);
> +}
> +
> +static int test_shared_for_each(void *arg)
> +{
> +	return test_for_each(arg, false);

true

With that:

Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>

Regards,

Tvrtko

> +}
> +
> +static int test_for_each_unlocked(void *arg, bool shared)
> +{
> +	struct dma_resv_iter cursor;
> +	struct dma_fence *f, *fence;
> +	struct dma_resv resv;
> +	int r;
> +
> +	f = alloc_fence();
> +	if (!f)
> +		return -ENOMEM;
> +
> +	dma_resv_init(&resv);
> +	r = dma_resv_lock(&resv, NULL);
> +	if (r) {
> +		pr_err("Resv locking failed\n");
> +		goto err_free;
> +	}
> +
> +	if (shared) {
> +		r = dma_resv_reserve_shared(&resv, 1);
> +		if (r) {
> +			pr_err("Resv shared slot allocation failed\n");
> +			dma_resv_unlock(&resv);
> +			goto err_free;
> +		}
> +
> +		dma_resv_add_shared_fence(&resv, f);
> +	} else {
> +		dma_resv_add_excl_fence(&resv, f);
> +	}
> +	dma_resv_unlock(&resv);
> +
> +	r = -ENOENT;
> +	dma_resv_iter_begin(&cursor, &resv, shared);
> +	dma_resv_for_each_fence_unlocked(&cursor, fence) {
> +		if (!r) {
> +			dma_resv_iter_end(&cursor);
> +			pr_err("More than one fence found\n");
> +			r = -EINVAL;
> +			goto err_free;
> +		}
> +		if (f != fence) {
> +			dma_resv_iter_end(&cursor);
> +			pr_err("Unexpected fence\n");
> +			r = -EINVAL;
> +			goto err_free;
> +		}
> +		if (dma_resv_iter_is_exclusive(&cursor) != !shared) {
> +			dma_resv_iter_end(&cursor);
> +			pr_err("Unexpected fence usage\n");
> +			r = -EINVAL;
> +			goto err_free;
> +		}
> +		r = 0;
> +	}
> +	dma_resv_iter_end(&cursor);
> +	if (r) {
> +		pr_err("No fence found\n");
> +		goto err_free;
> +	}
> +	dma_fence_signal(f);
> +err_free:
> +	dma_resv_fini(&resv);
> +	dma_fence_put(f);
> +	return r;
> +}
> +
> +static int test_excl_for_each_unlocked(void *arg)
> +{
> +	return test_for_each_unlocked(arg, false);
> +}
> +
> +static int test_shared_for_each_unlocked(void *arg)
> +{
> +	return test_for_each_unlocked(arg, true);
> +}
> +
> +int dma_resv(void)
> +{
> +	static const struct subtest tests[] = {
> +		SUBTEST(sanitycheck),
> +		SUBTEST(test_excl_signaling),
> +		SUBTEST(test_shared_signaling),
> +		SUBTEST(test_excl_for_each),
> +		SUBTEST(test_shared_for_each),
> +		SUBTEST(test_excl_for_each_unlocked),
> +		SUBTEST(test_shared_for_each_unlocked),
> +	};
> +
> +	spin_lock_init(&fence_lock);
> +	return subtests(tests, NULL);
> +}
> 

Re: [PATCH 1/2] dma-buf: add dma_resv_for_each_fence v3

[Tvrtko Ursulin]

On 06/10/2021 13:36, Christian König wrote:
> A simpler version of the iterator to be used when the dma_resv object is
> locked.
> 
> v2: fix index check here as well
> v3: minor coding improvement, some documentation cleanup
> 
> Signed-off-by: Christian König <christian.koenig@amd.com>
> ---
>   drivers/dma-buf/dma-resv.c | 51 ++++++++++++++++++++++++++++++++++++++
>   include/linux/dma-resv.h   | 20 +++++++++++++++
>   2 files changed, 71 insertions(+)
> 
> diff --git a/drivers/dma-buf/dma-resv.c b/drivers/dma-buf/dma-resv.c
> index a480af9581bd..2f98caa68ae5 100644
> --- a/drivers/dma-buf/dma-resv.c
> +++ b/drivers/dma-buf/dma-resv.c
> @@ -423,6 +423,57 @@ struct dma_fence *dma_resv_iter_next_unlocked(struct dma_resv_iter *cursor)
>   }
>   EXPORT_SYMBOL(dma_resv_iter_next_unlocked);
>   
> +/**
> + * dma_resv_iter_first - first fence from a locked dma_resv object
> + * @cursor: cursor to record the current position
> + *
> + * Return the first fence in the dma_resv object while holding the
> + * &dma_resv.lock.
> + */
> +struct dma_fence *dma_resv_iter_first(struct dma_resv_iter *cursor)
> +{
> +	struct dma_fence *fence;
> +
> +	dma_resv_assert_held(cursor->obj);
> +
> +	cursor->index = 0;
> +	if (cursor->all_fences)
> +		cursor->fences = dma_resv_shared_list(cursor->obj);
> +	else
> +		cursor->fences = NULL;
> +
> +	fence = dma_resv_excl_fence(cursor->obj);
> +	if (!fence)
> +		fence = dma_resv_iter_next(cursor);
> +
> +	cursor->is_restarted = true;
> +	return fence;
> +}
> +EXPORT_SYMBOL_GPL(dma_resv_iter_first);
> +
> +/**
> + * dma_resv_iter_next - next fence from a locked dma_resv object
> + * @cursor: cursor to record the current position
> + *
> + * Return the next fences from the dma_resv object while holding the
> + * &dma_resv.lock.
> + */
> +struct dma_fence *dma_resv_iter_next(struct dma_resv_iter *cursor)
> +{
> +	unsigned int idx;
> +
> +	dma_resv_assert_held(cursor->obj);
> +
> +	cursor->is_restarted = false;
> +	if (!cursor->fences || cursor->index >= cursor->fences->shared_count)
> +		return NULL;
> +
> +	idx = cursor->index++;
> +	return rcu_dereference_protected(cursor->fences->shared[idx],
> +					 dma_resv_held(cursor->obj));
> +}
> +EXPORT_SYMBOL_GPL(dma_resv_iter_next);
> +
>   /**
>    * dma_resv_copy_fences - Copy all fences from src to dst.
>    * @dst: the destination reservation object
> diff --git a/include/linux/dma-resv.h b/include/linux/dma-resv.h
> index 764138ad8583..491359cea54c 100644
> --- a/include/linux/dma-resv.h
> +++ b/include/linux/dma-resv.h
> @@ -179,6 +179,8 @@ struct dma_resv_iter {
>   
>   struct dma_fence *dma_resv_iter_first_unlocked(struct dma_resv_iter *cursor);
>   struct dma_fence *dma_resv_iter_next_unlocked(struct dma_resv_iter *cursor);
> +struct dma_fence *dma_resv_iter_first(struct dma_resv_iter *cursor);
> +struct dma_fence *dma_resv_iter_next(struct dma_resv_iter *cursor);
>   
>   /**
>    * dma_resv_iter_begin - initialize a dma_resv_iter object
> @@ -244,6 +246,24 @@ static inline bool dma_resv_iter_is_restarted(struct dma_resv_iter *cursor)
>   	for (fence = dma_resv_iter_first_unlocked(cursor);		\
>   	     fence; fence = dma_resv_iter_next_unlocked(cursor))
>   
> +/**
> + * dma_resv_for_each_fence - fence iterator
> + * @cursor: a struct dma_resv_iter pointer
> + * @obj: a dma_resv object pointer
> + * @all_fences: true if all fences should be returned
> + * @fence: the current fence
> + *
> + * Iterate over the fences in a struct dma_resv object while holding the
> + * &dma_resv.lock. @all_fences controls if the shared fences are returned as
> + * well. The cursor initialisation is part of the iterator and the fence stays
> + * valid as long as the lock is held and so no extra reference to the fence is
> + * taken.
> + */
> +#define dma_resv_for_each_fence(cursor, obj, all_fences, fence)	\
> +	for (dma_resv_iter_begin(cursor, obj, all_fences),	\
> +	     fence = dma_resv_iter_first(cursor); fence;	\
> +	     fence = dma_resv_iter_next(cursor))
> +
>   #define dma_resv_held(obj) lockdep_is_held(&(obj)->lock.base)
>   #define dma_resv_assert_held(obj) lockdep_assert_held(&(obj)->lock.base)
>   
> 

Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>

Regards,

Tvrtko