From: Ihor Solodrai ihor.solodrai@pm.me

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-YwCT10eFF...

Signed-off-by: Ihor Solodrai ihor.solodrai@pm.me Signed-off-by: Andrii Nakryiko andrii@kernel.org Link: https://lore.kernel.org/bpf/20241011153104.249800-1-ihor.solodrai@pm.me Signed-off-by: Shung-Hsi Yu shung-hsi.yu@suse.com --- .../testing/selftests/bpf/prog_tests/perf_link.c | 15 +++++++++++++-- 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/bpf/prog_tests/perf_link.c b/tools/testing/selftests/bpf/prog_tests/perf_link.c index 3a25f1c743a1..d940ff87fa08 100644 --- a/tools/testing/selftests/bpf/prog_tests/perf_link.c +++ b/tools/testing/selftests/bpf/prog_tests/perf_link.c @@ -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 */ - burn_cpu(); - ASSERT_GT(skel->bss->run_cnt, 0, "run_cnt"); + timeout_time_ns = get_time_ns() + BURN_TIMEOUT_NS; + while (true) { + burn_cpu(); + 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