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

[Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>]

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);
> +}
>