Re: [PATCH v5 5/5] kselftests: Add dma-heap test

[Brian Starkey]

Hi John,

I haven't looked at any selftests before, but is there any advantage
to using the test harness?
https://www.kernel.org/doc/html/v5.1/dev-tools/kselftest.html#test-harness

Couple of minor things below

On Fri, Jun 07, 2019 at 03:07:19AM +0000, John Stultz wrote:
> Add very trivial allocation and import test for dma-heaps,
> utilizing the vgem driver as a test importer.
> 
> A good chunk of this code taken from:
>   tools/testing/selftests/android/ion/ionmap_test.c
>   Originally by Laura Abbott <labbott@xxxxxxxxxx>
> 
> Cc: Benjamin Gaignard <benjamin.gaignard@xxxxxxxxxx>
> Cc: Sumit Semwal <sumit.semwal@xxxxxxxxxx>
> Cc: Liam Mark <lmark@xxxxxxxxxxxxxx>
> Cc: Pratik Patel <pratikp@xxxxxxxxxxxxxx>
> Cc: Brian Starkey <Brian.Starkey@xxxxxxx>
> Cc: Vincent Donnefort <Vincent.Donnefort@xxxxxxx>
> Cc: Sudipto Paul <Sudipto.Paul@xxxxxxx>
> Cc: Andrew F. Davis <afd@xxxxxx>
> Cc: Christoph Hellwig <hch@xxxxxxxxxxxxx>
> Cc: Chenbo Feng <fengc@xxxxxxxxxx>
> Cc: Alistair Strachan <astrachan@xxxxxxxxxx>
> Cc: dri-devel@xxxxxxxxxxxxxxxxxxxxx
> Reviewed-by: Benjamin Gaignard <benjamin.gaignard@xxxxxxxxxx>
> Signed-off-by: John Stultz <john.stultz@xxxxxxxxxx>
> Change-Id: Ib98569fdda6378eb086b8092fb5d6bd419b8d431
> ---
> v2:
> * Switched to use reworked dma-heap apis
> v3:
> * Add simple mmap
> * Utilize dma-buf testdev to test importing
> v4:
> * Rework to use vgem
> * Pass in fd_flags to match interface changes
> * Skip . and .. dirs
> ---
>  tools/testing/selftests/dmabuf-heaps/Makefile |  11 +
>  .../selftests/dmabuf-heaps/dmabuf-heap.c      | 232 ++++++++++++++++++
>  2 files changed, 243 insertions(+)
>  create mode 100644 tools/testing/selftests/dmabuf-heaps/Makefile
>  create mode 100644 tools/testing/selftests/dmabuf-heaps/dmabuf-heap.c
> 
> diff --git a/tools/testing/selftests/dmabuf-heaps/Makefile b/tools/testing/selftests/dmabuf-heaps/Makefile
> new file mode 100644
> index 000000000000..c414ad36b4bf
> --- /dev/null
> +++ b/tools/testing/selftests/dmabuf-heaps/Makefile
> @@ -0,0 +1,11 @@
> +# SPDX-License-Identifier: GPL-2.0
> +CFLAGS += -static -O3 -Wl,-no-as-needed -Wall
> +#LDLIBS += -lrt -lpthread -lm
> +
> +# these are all "safe" tests that don't modify
> +# system time or require escalated privileges
> +TEST_GEN_PROGS = dmabuf-heap
> +

newline

> +
> +include ../lib.mk
> +
> diff --git a/tools/testing/selftests/dmabuf-heaps/dmabuf-heap.c b/tools/testing/selftests/dmabuf-heaps/dmabuf-heap.c
> new file mode 100644
> index 000000000000..33d4b105c673
> --- /dev/null
> +++ b/tools/testing/selftests/dmabuf-heaps/dmabuf-heap.c
> @@ -0,0 +1,232 @@
> +// SPDX-License-Identifier: GPL-2.0
> +
> +#include <dirent.h>
> +#include <errno.h>
> +#include <fcntl.h>
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <stdint.h>
> +#include <string.h>
> +#include <unistd.h>
> +#include <sys/ioctl.h>
> +#include <sys/mman.h>
> +#include <sys/types.h>
> +
> +#include <linux/dma-buf.h>
> +#include <drm/drm.h>
> +
> +
> +#include "../../../../include/uapi/linux/dma-heap.h"
> +
> +#define DEVPATH "/dev/dma_heap"
> +
> +int check_vgem(int fd)

Functions can be static

> +{
> +	drm_version_t version = { 0 };
> +	char name[5];
> +	int ret;
> +
> +	version.name_len = 4;
> +	version.name = name;
> +
> +	ret = ioctl(fd, DRM_IOCTL_VERSION, &version);
> +	if (ret)
> +		return 1;
> +
> +	return strcmp(name, "vgem");
> +}
> +
> +int open_vgem(void)
> +{
> +	int i, fd;
> +	const char *drmstr = "/dev/dri/card";
> +
> +	fd = -1;
> +	for (i = 0; i < 16; i++) {
> +		char name[80];
> +
> +		sprintf(name, "%s%u", drmstr, i);
> +
> +		fd = open(name, O_RDWR);
> +		if (fd < 0)
> +			continue;
> +
> +		if (check_vgem(fd)) {

It's a minor thing, but the naming vs the logic reads backwards to me
here. I'd expect check_vgem() to return true for vgem.

> +			close(fd);
> +			continue;
> +		} else {
> +			break;
> +		}
> +
> +	}
> +	return fd;
> +}
> +
> +int import_vgem_fd(int vgem_fd, int dma_buf_fd, uint32_t *handle)
> +{
> +	struct drm_prime_handle import_handle = { 0 };
> +	int ret;
> +
> +	import_handle.fd = dma_buf_fd;
> +	import_handle.flags = 0;
> +	import_handle.handle = 0;

You could just initialise import_handle directly. Same for the other
functions

> +
> +	ret = ioctl(vgem_fd, DRM_IOCTL_PRIME_FD_TO_HANDLE, &import_handle);
> +	if (ret == 0)
> +		*handle = import_handle.handle;
> +	return ret;
> +}
> +
> +void close_handle(int vgem_fd, uint32_t handle)
> +{
> +	struct drm_gem_close close = { 0 };
> +
> +	close.handle = handle;
> +	ioctl(vgem_fd, DRM_IOCTL_GEM_CLOSE, &close);
> +}
> +
> +
> +int dmabuf_heap_open(char *name)
> +{
> +	int ret, fd;
> +	char buf[256];
> +
> +	ret = sprintf(buf, "%s/%s", DEVPATH, name);
> +	if (ret < 0) {
> +		printf("sprintf failed!\n");
> +		return ret;
> +	}
> +
> +	fd = open(buf, O_RDWR);
> +	if (fd < 0)
> +		printf("open %s failed!\n", buf);
> +	return fd;
> +}
> +
> +int dmabuf_heap_alloc(int fd, size_t len, unsigned int flags, int *dmabuf_fd)
> +{
> +	struct dma_heap_allocation_data data = {
> +		.len = len,
> +		.fd_flags = O_RDWR | O_CLOEXEC,
> +		.heap_flags = flags,
> +	};

Like this :-)

> +	int ret;
> +
> +	if (dmabuf_fd == NULL)
> +		return -EINVAL;
> +
> +	ret = ioctl(fd, DMA_HEAP_IOC_ALLOC, &data);
> +	if (ret < 0)
> +		return ret;
> +	*dmabuf_fd = (int)data.fd;
> +	return ret;
> +}
> +
> +void dmabuf_sync(int fd, int start_stop)
> +{
> +	struct dma_buf_sync sync = { 0 };
> +	int ret;
> +
> +	sync.flags = start_stop | DMA_BUF_SYNC_RW;
> +	ret = ioctl(fd, DMA_BUF_IOCTL_SYNC, &sync);
> +	if (ret)
> +		printf("sync failed %d\n", errno);
> +

newline

> +}
> +
> +#define ONE_MEG (1024*1024)
> +
> +void do_test(char *heap_name)
> +{
> +	int heap_fd = -1, dmabuf_fd = -1, importer_fd = -1;
> +	uint32_t handle = 0;
> +	void *p = NULL;
> +	int ret;
> +
> +	printf("Testing heap: %s\n", heap_name);
> +
> +	heap_fd = dmabuf_heap_open(heap_name);
> +	if (heap_fd < 0)
> +		return;
> +
> +	printf("Allocating 1 MEG\n");
> +	ret = dmabuf_heap_alloc(heap_fd, ONE_MEG, 0, &dmabuf_fd);
> +	if (ret)

It'd be good to print something here so you can easily tell if
allocations are failing.

> +		goto out;
> +
> +	/* mmap and write a simple pattern */
> +	p = mmap(NULL,
> +		 ONE_MEG,
> +		 PROT_READ | PROT_WRITE,
> +		 MAP_SHARED,
> +		 dmabuf_fd,
> +		 0);
> +	if (p == MAP_FAILED) {
> +		printf("mmap() failed: %m\n");
> +		goto out;
> +	}
> +	printf("mmap passed\n");
> +
> +
> +	dmabuf_sync(dmabuf_fd, DMA_BUF_SYNC_START);
> +
> +	memset(p, 1, ONE_MEG/2);
> +	memset((char *)p+ONE_MEG/2, 0, ONE_MEG/2);

Are the selftests using the kernel coding style? If so, there's some
spaces missing.

> +	dmabuf_sync(dmabuf_fd, DMA_BUF_SYNC_END);
> +
> +	importer_fd = open_vgem();
> +	if (importer_fd < 0) {
> +		ret = importer_fd;
> +		printf("Failed to open vgem\n");
> +		goto out;
> +	}
> +
> +	ret = import_vgem_fd(importer_fd, dmabuf_fd, &handle);
> +	if (ret < 0) {
> +		printf("Failed to import buffer\n");
> +		goto out;
> +	}
> +	printf("import passed\n");
> +
> +	dmabuf_sync(dmabuf_fd, DMA_BUF_SYNC_START);
> +	memset(p, 0xff, ONE_MEG);
> +	dmabuf_sync(dmabuf_fd, DMA_BUF_SYNC_END);
> +	printf("syncs passed\n");
> +
> +	close_handle(importer_fd, handle);
> +	ret = 0;

No need for this

> +
> +out:
> +	if (p)
> +		munmap(p, ONE_MEG);
> +	if (importer_fd >= 0)
> +		close(importer_fd);
> +	if (dmabuf_fd >= 0)
> +		close(dmabuf_fd);
> +	if (heap_fd >= 0)
> +		close(heap_fd);
> +}
> +
> +
> +int main(void)
> +{
> +	DIR *d;
> +	struct dirent *dir;
> +
> +	d = opendir(DEVPATH);
> +	if (!d) {
> +		printf("No %s directory?\n", DEVPATH);
> +		return -1;
> +	}
> +
> +	while ((dir = readdir(d)) != NULL) {
> +		if (!strncmp(dir->d_name, ".", 2))
> +			continue;
> +		if (!strncmp(dir->d_name, "..", 3))
> +			continue;
> +
> +		do_test(dir->d_name);
> +	}
> +

I know it's only a test, and you're about to exit, but you should
probably still closedir() in case someone copies this code.

Cheers,
-Brian

> +	return 0;
> +}
> -- 
> 2.17.1
>