Commit d6a511de authored by Suresh K C's avatar Suresh K C Committed by Andrew Morton
Browse files

selftests: cachestat: add tests for mmap, refactor and enhance mmap test for cachestat validation 

Add a cohesive test case that verifies cachestat behavior with
memory-mapped files using mmap().  Also refactor the test logic to reduce
redundancy, improve error reporting, and clarify failure messages for both
shmem and mmap file types.

[akpm@linux-foundation.org: coding-style cleanups]
Link: https://lkml.kernel.org/r/20250709174657.6916-1-suresh.k.chandrappa@gmail.com


Signed-off-by: default avatarSuresh K C <suresh.k.chandrappa@gmail.com>
Reviewed-by: default avatarJoshua Hahn <joshua.hahnjy@gmail.com>
Tested-by: default avatarNhat Pham <nphamcs@gmail.com>
Acked-by: default avatarNhat Pham <nphamcs@gmail.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 881388f3

tools/testing/selftests/cachestat/test_cachestat.c

+54 −8
Original line number Diff line number Diff line
@@ -33,6 +33,11 @@ void print_cachestat(struct cachestat *cs) 
	cs->nr_evicted, cs->nr_recently_evicted);

}



enum file_type {

	FILE_MMAP,

	FILE_SHMEM

};



bool write_exactly(int fd, size_t filesize)

{

	int random_fd = open("/dev/urandom", O_RDONLY);
@@ -201,8 +206,20 @@ static int test_cachestat(const char *filename, bool write_random, bool create, 
out:

	return ret;

}

const char *file_type_str(enum file_type type)

{

	switch (type) {

	case FILE_SHMEM:

		return "shmem";

	case FILE_MMAP:

		return "mmap";

	default:

		return "unknown";

	}

}



bool test_cachestat_shmem(void)



bool run_cachestat_test(enum file_type type)

{

	size_t PS = sysconf(_SC_PAGESIZE);

	size_t filesize = PS * 512 * 2; /* 2 2MB huge pages */
@@ -212,27 +229,50 @@ bool test_cachestat_shmem(void) 
	char *filename = "tmpshmcstat";

	struct cachestat cs;

	bool ret = true;

	int fd;

	unsigned long num_pages = compute_len / PS;

	int fd = shm_open(filename, O_CREAT | O_RDWR, 0600);

	if (type == FILE_SHMEM)

		fd = shm_open(filename, O_CREAT | O_RDWR, 0600);

	else

		fd = open(filename, O_RDWR | O_CREAT | O_TRUNC, 0666);



	if (fd < 0) {

		ksft_print_msg("Unable to create shmem file.\n");

		ksft_print_msg("Unable to create %s file.\n",

				file_type_str(type));

		ret = false;

		goto out;

	}



	if (ftruncate(fd, filesize)) {

		ksft_print_msg("Unable to truncate shmem file.\n");

		ksft_print_msg("Unable to truncate %s file.\n",file_type_str(type));

		ret = false;

		goto close_fd;

	}



	switch (type) {

	case FILE_SHMEM:

		if (!write_exactly(fd, filesize)) {

		ksft_print_msg("Unable to write to shmem file.\n");

			ksft_print_msg("Unable to write to file.\n");

			ret = false;

			goto close_fd;

		}

		break;

	case FILE_MMAP:

		char *map = mmap(NULL, filesize, PROT_READ | PROT_WRITE,

				 MAP_SHARED, fd, 0);



		if (map == MAP_FAILED) {

			ksft_print_msg("mmap failed.\n");

			ret = false;

			goto close_fd;

		}

		for (int i = 0; i < filesize; i++)

			map[i] = 'A';

		break;

	default:

		ksft_print_msg("Unsupported file type.\n");

		ret = false;

		goto close_fd;

	}

	syscall_ret = syscall(__NR_cachestat, fd, &cs_range, &cs, 0);



	if (syscall_ret) {
@@ -308,12 +348,18 @@ int main(void) 
		break;

	}



	if (test_cachestat_shmem())

	if (run_cachestat_test(FILE_SHMEM))

		ksft_test_result_pass("cachestat works with a shmem file\n");

	else {

		ksft_test_result_fail("cachestat fails with a shmem file\n");

		ret = 1;

	}



	if (run_cachestat_test(FILE_MMAP))

		ksft_test_result_pass("cachestat works with a mmap file\n");

	else {

		ksft_test_result_fail("cachestat fails with a mmap file\n");

		ret = 1;

	}

	return ret;

}