selftests/bpf: Use read_perf_max_sample_freq() in perf_event_stackmap

Currently, perf_event sample period in perf_event_stackmap is set too low
that the test fails randomly. Fix this by using the max sample frequency,
from read_perf_max_sample_freq().

Move read_perf_max_sample_freq() to testing_helpers.c. Replace the CHECK()
with if-printf, as CHECK is not available in testing_helpers.c.

Fixes: 1da4864c2b20 ("selftests/bpf: Add callchain_stackid")
Signed-off-by: Song Liu <song@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20230412210423.900851-2-song@kernel.org

1 files changed, 0 insertions, 15 deletions

diff --git a/tools/testing/selftests/bpf/prog_tests/stacktrace_build_id_nmi.c b/tools/testing/selftests/bpf/prog_tests/stacktrace_build_id_nmi.c
index 47558b0d7f66..5db9eec24b5b 100644
--- a/tools/testing/selftests/bpf/prog_tests/stacktrace_build_id_nmi.c
+++ b/tools/testing/selftests/bpf/prog_tests/stacktrace_build_id_nmi.c
@@ -2,21 +2,6 @@
 #include <test_progs.h>
 #include "test_stacktrace_build_id.skel.h"
 
-static __u64 read_perf_max_sample_freq(void)
-{
-	__u64 sample_freq = 5000; /* fallback to 5000 on error */
-	FILE *f;
-	__u32 duration = 0;
-
-	f = fopen("/proc/sys/kernel/perf_event_max_sample_rate", "r");
-	if (f == NULL)
-		return sample_freq;
-	CHECK(fscanf(f, "%llu", &sample_freq) != 1, "Get max sample rate",
-		  "return default value: 5000,err %d\n", -errno);
-	fclose(f);
-	return sample_freq;
-}
-
 void test_stacktrace_build_id_nmi(void)
 {
 	int control_map_fd, stackid_hmap_fd, stackmap_fd;