Re: [PATCH v11 5/5] ring-buffer/selftest: Add ring-buffer mapping test

[Google]

On Thu, 11 Jan 2024 16:17:12 +0000
Vincent Donnefort <vdonnefort@xxxxxxxxxx> wrote:

> This test maps a ring-buffer and validate the meta-page after reset and
> after emitting few events.
> 
> Cc: Shuah Khan <shuah@xxxxxxxxxx>
> Cc: Shuah Khan <skhan@xxxxxxxxxxxxxxxxxxx>
> Cc: linux-kselftest@xxxxxxxxxxxxxxx
> Signed-off-by: Vincent Donnefort <vdonnefort@xxxxxxxxxx>

Looks good to me and tested.

Reviewed-by: Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx>
Tested-by: Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx>

Thank you,

> 
> diff --git a/tools/testing/selftests/ring-buffer/Makefile b/tools/testing/selftests/ring-buffer/Makefile
> new file mode 100644
> index 000000000000..627c5fa6d1ab
> --- /dev/null
> +++ b/tools/testing/selftests/ring-buffer/Makefile
> @@ -0,0 +1,8 @@
> +# SPDX-License-Identifier: GPL-2.0
> +CFLAGS += -Wl,-no-as-needed -Wall
> +CFLAGS += $(KHDR_INCLUDES)
> +CFLAGS += -D_GNU_SOURCE
> +
> +TEST_GEN_PROGS = map_test
> +
> +include ../lib.mk
> diff --git a/tools/testing/selftests/ring-buffer/config b/tools/testing/selftests/ring-buffer/config
> new file mode 100644
> index 000000000000..ef8214661612
> --- /dev/null
> +++ b/tools/testing/selftests/ring-buffer/config
> @@ -0,0 +1 @@
> +CONFIG_FTRACE=y
> diff --git a/tools/testing/selftests/ring-buffer/map_test.c b/tools/testing/selftests/ring-buffer/map_test.c
> new file mode 100644
> index 000000000000..49107e8da5e9
> --- /dev/null
> +++ b/tools/testing/selftests/ring-buffer/map_test.c
> @@ -0,0 +1,188 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Ring-buffer memory mapping tests
> + *
> + * Copyright (c) 2024 Vincent Donnefort <vdonnefort@xxxxxxxxxx>
> + */
> +#include <fcntl.h>
> +#include <sched.h>
> +#include <stdbool.h>
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <unistd.h>
> +
> +#include <linux/trace_mmap.h>
> +
> +#include <sys/mman.h>
> +#include <sys/ioctl.h>
> +
> +#include "../user_events/user_events_selftests.h" /* share tracefs setup */
> +#include "../kselftest_harness.h"
> +
> +#define TRACEFS_ROOT "/sys/kernel/tracing"
> +
> +static int __tracefs_write(const char *path, const char *value)
> +{
> +	FILE *file;
> +
> +	file = fopen(path, "w");
> +	if (!file)
> +		return -1;
> +
> +	fputs(value, file);
> +	fclose(file);
> +
> +	return 0;
> +}
> +
> +static int __tracefs_write_int(const char *path, int value)
> +{
> +	char *str;
> +	int ret;
> +
> +	if (asprintf(&str, "%d", value) < 0)
> +		return -1;
> +
> +	ret = __tracefs_write(path, str);
> +
> +	free(str);
> +
> +	return ret;
> +}
> +
> +#define tracefs_write_int(path, value) \
> +	ASSERT_EQ(__tracefs_write_int((path), (value)), 0)
> +
> +static int tracefs_reset(void)
> +{
> +	if (__tracefs_write_int(TRACEFS_ROOT"/tracing_on", 0))
> +		return -1;
> +	if (__tracefs_write_int(TRACEFS_ROOT"/trace", 0))
> +		return -1;
> +	if (__tracefs_write(TRACEFS_ROOT"/set_event", ""))
> +		return -1;
> +
> +	return 0;
> +}
> +
> +FIXTURE(map) {
> +	struct trace_buffer_meta	*meta;
> +	void				*data;
> +	int				cpu_fd;
> +	bool				umount;
> +};
> +
> +FIXTURE_VARIANT(map) {
> +	int	subbuf_size;
> +};
> +
> +FIXTURE_VARIANT_ADD(map, subbuf_size_4k) {
> +	.subbuf_size = 4,
> +};
> +
> +FIXTURE_VARIANT_ADD(map, subbuf_size_8k) {
> +	.subbuf_size = 8,
> +};
> +
> +FIXTURE_SETUP(map)
> +{
> +	int cpu = sched_getcpu(), page_size = getpagesize();
> +	unsigned long meta_len, data_len;
> +	char *cpu_path, *message;
> +	bool fail, umount;
> +	cpu_set_t cpu_mask;
> +	void *map;
> +
> +	if (!tracefs_enabled(&message, &fail, &umount)) {
> +		if (fail) {
> +			TH_LOG("Tracefs setup failed: %s", message);
> +			ASSERT_FALSE(fail);
> +		}
> +		SKIP(return, "Skipping: %s", message);
> +	}
> +
> +	self->umount = umount;
> +
> +	ASSERT_GE(cpu, 0);
> +
> +	ASSERT_EQ(tracefs_reset(), 0);
> +
> +	tracefs_write_int(TRACEFS_ROOT"/buffer_subbuf_size_kb", variant->subbuf_size);
> +
> +	ASSERT_GE(asprintf(&cpu_path,
> +			   TRACEFS_ROOT"/per_cpu/cpu%d/trace_pipe_raw",
> +			   cpu), 0);
> +
> +	self->cpu_fd = open(cpu_path, O_RDONLY | O_NONBLOCK);
> +	ASSERT_GE(self->cpu_fd, 0);
> +	free(cpu_path);
> +
> +	map = mmap(NULL, page_size, PROT_READ, MAP_SHARED, self->cpu_fd, 0);
> +	ASSERT_NE(map, MAP_FAILED);
> +	self->meta = (struct trace_buffer_meta *)map;
> +
> +	meta_len = self->meta->meta_page_size;
> +	data_len = self->meta->subbuf_size * self->meta->nr_subbufs;
> +
> +	map = mmap(NULL, data_len, PROT_READ, MAP_SHARED, self->cpu_fd, meta_len);
> +	ASSERT_NE(map, MAP_FAILED);
> +	self->data = map;
> +
> +	/*
> +	 * Ensure generated events will be found on this very same ring-buffer.
> +	 */
> +	CPU_ZERO(&cpu_mask);
> +	CPU_SET(cpu, &cpu_mask);
> +	ASSERT_EQ(sched_setaffinity(0, sizeof(cpu_mask), &cpu_mask), 0);
> +}
> +
> +FIXTURE_TEARDOWN(map)
> +{
> +	tracefs_reset();
> +
> +	if (self->umount)
> +		tracefs_unmount();
> +
> +	munmap(self->data, self->meta->subbuf_size * self->meta->nr_subbufs);
> +	munmap(self->meta, self->meta->meta_page_size);
> +	close(self->cpu_fd);
> +}
> +
> +TEST_F(map, meta_page_check)
> +{
> +	int cnt = 0;
> +
> +	ASSERT_EQ(self->meta->entries, 0);
> +	ASSERT_EQ(self->meta->overrun, 0);
> +	ASSERT_EQ(self->meta->read, 0);
> +	ASSERT_EQ(self->meta->subbufs_touched, 0);
> +	ASSERT_EQ(self->meta->subbufs_lost, 0);
> +	ASSERT_EQ(self->meta->subbufs_read, 0);
> +
> +	ASSERT_EQ(self->meta->reader.id, 0);
> +	ASSERT_EQ(self->meta->reader.read, 0);
> +
> +	ASSERT_EQ(ioctl(self->cpu_fd, TRACE_MMAP_IOCTL_GET_READER), 0);
> +	ASSERT_EQ(self->meta->reader.id, 0);
> +
> +	tracefs_write_int(TRACEFS_ROOT"/tracing_on", 1);
> +	for (int i = 0; i < 16; i++)
> +		tracefs_write_int(TRACEFS_ROOT"/trace_marker", i);
> +again:
> +	ASSERT_EQ(ioctl(self->cpu_fd, TRACE_MMAP_IOCTL_GET_READER), 0);
> +
> +	ASSERT_EQ(self->meta->entries, 16);
> +	ASSERT_EQ(self->meta->overrun, 0);
> +	ASSERT_EQ(self->meta->read, 16);
> +	/* subbufs_touched doesn't take into account the commit page */
> +	ASSERT_EQ(self->meta->subbufs_touched, 0);
> +	ASSERT_EQ(self->meta->subbufs_lost, 0);
> +	ASSERT_EQ(self->meta->subbufs_read, 1);
> +
> +	ASSERT_EQ(self->meta->reader.id, 1);
> +
> +	if (!(cnt++))
> +		goto again;
> +}
> +
> +TEST_HARNESS_MAIN
> -- 
> 2.43.0.275.g3460e3d667-goog
> 


-- 
Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx>