Commit f67ad87a authored by Stanislav Fomichev's avatar Stanislav Fomichev Committed by Daniel Borkmann
Browse files

selftests/bpf: retry tests that expect build-id 



While running test_progs in a loop I found out that I'm sometimes hitting
"Didn't find expected build ID from the map" error.

Looking at stack_map_get_build_id_offset() it seems that it is racy (by
design) and can sometimes return BPF_STACK_BUILD_ID_IP (i.e. can't trylock
current->mm->mmap_sem).

Let's retry this test a single time.

Fixes: 13790d1c ("bpf: add selftest for stackmap with build_id in NMI context")
Acked-by: default avatarSong Liu <songliubraving@fb.com>
Signed-off-by: default avatarStanislav Fomichev <sdf@google.com>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
parent 4af396ae

tools/testing/selftests/bpf/test_progs.c

+30 −0
Original line number Diff line number Diff line
@@ -1188,7 +1188,9 @@ static void test_stacktrace_build_id(void) 
	int i, j;

	struct bpf_stack_build_id id_offs[PERF_MAX_STACK_DEPTH];

	int build_id_matches = 0;

	int retry = 1;



retry:

	err = bpf_prog_load(file, BPF_PROG_TYPE_TRACEPOINT, &obj, &prog_fd);

	if (CHECK(err, "prog_load", "err %d errno %d\n", err, errno))

		goto out;
@@ -1301,6 +1303,19 @@ static void test_stacktrace_build_id(void) 
		previous_key = key;

	} while (bpf_map_get_next_key(stackmap_fd, &previous_key, &key) == 0);



	/* stack_map_get_build_id_offset() is racy and sometimes can return

	 * BPF_STACK_BUILD_ID_IP instead of BPF_STACK_BUILD_ID_VALID;

	 * try it one more time.

	 */

	if (build_id_matches < 1 && retry--) {

		ioctl(pmu_fd, PERF_EVENT_IOC_DISABLE);

		close(pmu_fd);

		bpf_object__close(obj);

		printf("%s:WARN:Didn't find expected build ID from the map, retrying\n",

		       __func__);

		goto retry;

	}



	if (CHECK(build_id_matches < 1, "build id match",

		  "Didn't find expected build ID from the map\n"))

		goto disable_pmu;
@@ -1341,7 +1356,9 @@ static void test_stacktrace_build_id_nmi(void) 
	int i, j;

	struct bpf_stack_build_id id_offs[PERF_MAX_STACK_DEPTH];

	int build_id_matches = 0;

	int retry = 1;



retry:

	err = bpf_prog_load(file, BPF_PROG_TYPE_PERF_EVENT, &obj, &prog_fd);

	if (CHECK(err, "prog_load", "err %d errno %d\n", err, errno))

		return;
@@ -1436,6 +1453,19 @@ static void test_stacktrace_build_id_nmi(void) 
		previous_key = key;

	} while (bpf_map_get_next_key(stackmap_fd, &previous_key, &key) == 0);



	/* stack_map_get_build_id_offset() is racy and sometimes can return

	 * BPF_STACK_BUILD_ID_IP instead of BPF_STACK_BUILD_ID_VALID;

	 * try it one more time.

	 */

	if (build_id_matches < 1 && retry--) {

		ioctl(pmu_fd, PERF_EVENT_IOC_DISABLE);

		close(pmu_fd);

		bpf_object__close(obj);

		printf("%s:WARN:Didn't find expected build ID from the map, retrying\n",

		       __func__);

		goto retry;

	}



	if (CHECK(build_id_matches < 1, "build id match",

		  "Didn't find expected build ID from the map\n"))

		goto disable_pmu;