Commit e6c209da authored by Ihor Solodrai's avatar Ihor Solodrai Committed by Andrii Nakryiko
Browse files

selftests/bpf: Check for timeout in perf_link test 

Recently perf_link test started unreliably failing on libbpf CI:
  * https://github.com/libbpf/libbpf/actions/runs/11260672407/job/31312405473
  * https://github.com/libbpf/libbpf/actions/runs/11260992334/job/31315514626
  * https://github.com/libbpf/libbpf/actions/runs/11263162459/job/31320458251

Part of the test is running a dummy loop for a while and then checking
for a counter incremented by the test program.

Instead of waiting for an arbitrary number of loop iterations once,
check for the test counter in a loop and use get_time_ns() helper to
enforce a 100ms timeout.

v1: https://lore.kernel.org/bpf/zuRd072x9tumn2iN4wDNs5av0nu5nekMNV4PkR-YwCT10eFFTrUtZBRkLWFbrcCe7guvLStGQlhibo8qWojCO7i2-NGajes5GYIyynexD-w=@pm.me/



Signed-off-by: default avatarIhor Solodrai <ihor.solodrai@pm.me>
Signed-off-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20241011153104.249800-1-ihor.solodrai@pm.me
parent 82370ed5

tools/testing/selftests/bpf/prog_tests/perf_link.c

+13 −2
Original line number Diff line number Diff line
@@ -4,8 +4,12 @@ 
#include <pthread.h>

#include <sched.h>

#include <test_progs.h>

#include "testing_helpers.h"

#include "test_perf_link.skel.h"



#define BURN_TIMEOUT_MS 100

#define BURN_TIMEOUT_NS BURN_TIMEOUT_MS * 1000000



static void burn_cpu(void)

{

	volatile int j = 0;
@@ -32,6 +36,7 @@ void serial_test_perf_link(void) 
	int run_cnt_before, run_cnt_after;

	struct bpf_link_info info;

	__u32 info_len = sizeof(info);

	__u64 timeout_time_ns;



	/* create perf event */

	memset(&attr, 0, sizeof(attr));
@@ -63,8 +68,14 @@ void serial_test_perf_link(void) 
	ASSERT_GT(info.prog_id, 0, "link_prog_id");



	/* ensure we get at least one perf_event prog execution */

	timeout_time_ns = get_time_ns() + BURN_TIMEOUT_NS;

	while (true) {

		burn_cpu();

	ASSERT_GT(skel->bss->run_cnt, 0, "run_cnt");

		if (skel->bss->run_cnt > 0)

			break;

	        if (!ASSERT_LT(get_time_ns(), timeout_time_ns, "run_cnt_timeout"))

			break;

	}



	/* perf_event is still active, but we close link and BPF program

	 * shouldn't be executed anymore