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Commit 3fbfadce authored by Martin KaFai Lau's avatar Martin KaFai Lau Committed by David S. Miller
Browse files

bpf: Fix test_lru_sanity5() in test_lru_map.c 



test_lru_sanity5() fails when the number of online cpus
is fewer than the number of possible cpus.  It can be
reproduced with qemu by using cmd args "--smp cpus=2,maxcpus=8".

The problem is the loop in test_lru_sanity5() is testing
'i' which is incorrect.

This patch:
1. Make sched_next_online() always return -1 if it cannot
   find a next cpu to schedule the process.
2. In test_lru_sanity5(), the parent process does
   sched_setaffinity() first (through sched_next_online())
   and the forked process will inherit it according to
   the 'man sched_setaffinity'.

Fixes: 5db58faf ("bpf: Add tests for the LRU bpf_htab")
Reported-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
Signed-off-by: default avatarMartin KaFai Lau <kafai@fb.com>
Acked-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
Acked-by: default avatarAlexei Starovoitov <ast@kernel.org>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent d5ff72d9

tools/testing/selftests/bpf/test_lru_map.c

+27 −26
Original line number Diff line number Diff line
@@ -67,21 +67,23 @@ static int map_equal(int lru_map, int expected) 
	return map_subset(lru_map, expected) && map_subset(expected, lru_map);

}



static int sched_next_online(int pid, int next_to_try)

static int sched_next_online(int pid, int *next_to_try)

{

	cpu_set_t cpuset;

	int next = *next_to_try;

	int ret = -1;



	if (next_to_try == nr_cpus)

		return -1;



	while (next_to_try < nr_cpus) {

	while (next < nr_cpus) {

		CPU_ZERO(&cpuset);

		CPU_SET(next_to_try++, &cpuset);

		if (!sched_setaffinity(pid, sizeof(cpuset), &cpuset))

		CPU_SET(next++, &cpuset);

		if (!sched_setaffinity(pid, sizeof(cpuset), &cpuset)) {

			ret = 0;

			break;

		}

	}



	return next_to_try;

	*next_to_try = next;

	return ret;

}



/* Size of the LRU amp is 2
@@ -96,11 +98,12 @@ static void test_lru_sanity0(int map_type, int map_flags) 
{

	unsigned long long key, value[nr_cpus];

	int lru_map_fd, expected_map_fd;

	int next_cpu = 0;



	printf("%s (map_type:%d map_flags:0x%X): ", __func__, map_type,

	       map_flags);



	assert(sched_next_online(0, 0) != -1);

	assert(sched_next_online(0, &next_cpu) != -1);



	if (map_flags & BPF_F_NO_COMMON_LRU)

		lru_map_fd = create_map(map_type, map_flags, 2 * nr_cpus);
@@ -183,6 +186,7 @@ static void test_lru_sanity1(int map_type, int map_flags, unsigned int tgt_free) 
	int lru_map_fd, expected_map_fd;

	unsigned int batch_size;

	unsigned int map_size;

	int next_cpu = 0;



	if (map_flags & BPF_F_NO_COMMON_LRU)

		/* Ther percpu lru list (i.e each cpu has its own LRU
@@ -196,7 +200,7 @@ static void test_lru_sanity1(int map_type, int map_flags, unsigned int tgt_free) 
	printf("%s (map_type:%d map_flags:0x%X): ", __func__, map_type,

	       map_flags);



	assert(sched_next_online(0, 0) != -1);

	assert(sched_next_online(0, &next_cpu) != -1);



	batch_size = tgt_free / 2;

	assert(batch_size * 2 == tgt_free);
@@ -262,6 +266,7 @@ static void test_lru_sanity2(int map_type, int map_flags, unsigned int tgt_free) 
	int lru_map_fd, expected_map_fd;

	unsigned int batch_size;

	unsigned int map_size;

	int next_cpu = 0;



	if (map_flags & BPF_F_NO_COMMON_LRU)

		/* Ther percpu lru list (i.e each cpu has its own LRU
@@ -275,7 +280,7 @@ static void test_lru_sanity2(int map_type, int map_flags, unsigned int tgt_free) 
	printf("%s (map_type:%d map_flags:0x%X): ", __func__, map_type,

	       map_flags);



	assert(sched_next_online(0, 0) != -1);

	assert(sched_next_online(0, &next_cpu) != -1);



	batch_size = tgt_free / 2;

	assert(batch_size * 2 == tgt_free);
@@ -370,11 +375,12 @@ static void test_lru_sanity3(int map_type, int map_flags, unsigned int tgt_free) 
	int lru_map_fd, expected_map_fd;

	unsigned int batch_size;

	unsigned int map_size;

	int next_cpu = 0;



	printf("%s (map_type:%d map_flags:0x%X): ", __func__, map_type,

	       map_flags);



	assert(sched_next_online(0, 0) != -1);

	assert(sched_next_online(0, &next_cpu) != -1);



	batch_size = tgt_free / 2;

	assert(batch_size * 2 == tgt_free);
@@ -430,11 +436,12 @@ static void test_lru_sanity4(int map_type, int map_flags, unsigned int tgt_free) 
	int lru_map_fd, expected_map_fd;

	unsigned long long key, value[nr_cpus];

	unsigned long long end_key;

	int next_cpu = 0;



	printf("%s (map_type:%d map_flags:0x%X): ", __func__, map_type,

	       map_flags);



	assert(sched_next_online(0, 0) != -1);

	assert(sched_next_online(0, &next_cpu) != -1);



	if (map_flags & BPF_F_NO_COMMON_LRU)

		lru_map_fd = create_map(map_type, map_flags,
@@ -502,9 +509,8 @@ static void do_test_lru_sanity5(unsigned long long last_key, int map_fd) 
static void test_lru_sanity5(int map_type, int map_flags)

{

	unsigned long long key, value[nr_cpus];

	int next_sched_cpu = 0;

	int next_cpu = 0;

	int map_fd;

	int i;



	if (map_flags & BPF_F_NO_COMMON_LRU)

		return;
@@ -519,27 +525,20 @@ static void test_lru_sanity5(int map_type, int map_flags) 
	key = 0;

	assert(!bpf_map_update(map_fd, &key, value, BPF_NOEXIST));



	for (i = 0; i < nr_cpus; i++) {

	while (sched_next_online(0, &next_cpu) != -1) {

		pid_t pid;



		pid = fork();

		if (pid == 0) {

			next_sched_cpu = sched_next_online(0, next_sched_cpu);

			if (next_sched_cpu != -1)

			do_test_lru_sanity5(key, map_fd);

			exit(0);

		} else if (pid == -1) {

			printf("couldn't spawn #%d process\n", i);

			printf("couldn't spawn process to test key:%llu\n",

			       key);

			exit(1);

		} else {

			int status;



			/* It is mostly redundant and just allow the parent

			 * process to update next_shced_cpu for the next child

			 * process

			 */

			next_sched_cpu = sched_next_online(pid, next_sched_cpu);



			assert(waitpid(pid, &status, 0) == pid);

			assert(status == 0);

			key++;
@@ -547,6 +546,8 @@ static void test_lru_sanity5(int map_type, int map_flags) 
	}



	close(map_fd);

	/* At least one key should be tested */

	assert(key > 0);



	printf("Pass\n");

}