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selftests/bpf: Fix flakiness of task_local_storage/sys_enter_exit

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The test_sys_enter_exit test was setting target_pid before attaching
the BPF programs, which causes syscalls made during the attach phase
to be counted. This is flaky because, apparently, there is no
guarantee that both on_enter and on_exit will trigger during the
attachment.

Move the target_pid assignment to after task_local_storage__attach()
so that only explicit sys_gettid() calls are counted.

Reported-by: BPF CI Bot (Claude Opus 4.6) <bot+bpf-ci@kernel.org>
Closes: https://github.com/kernel-patches/vmtest/issues/448
Signed-off-by: Ihor Solodrai <ihor.solodrai@linux.dev>
Reviewed-by: Emil Tsalapatis <emil@etsalapatis.com>
Link: https://lore.kernel.org/r/20260224211202.214325-1-ihor.solodrai@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Ihor Solodrai
2026-02-24 13:12:02 -08:00
committed by Alexei Starovoitov
parent e4094d56c5
commit c89b50cc6b
1 changed files with 11 additions and 5 deletions
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16
tools/testing/selftests/bpf/prog_tests/task_local_storage.c
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@@ -25,24 +25,30 @@
static void test_sys_enter_exit(void)
{
struct task_local_storage *skel;
pid_t pid = sys_gettid();
int err;
skel = task_local_storage__open_and_load();
if (!ASSERT_OK_PTR(skel, "skel_open_and_load"))
return;
skel->bss->target_pid = sys_gettid();
err = task_local_storage__attach(skel);
if (!ASSERT_OK(err, "skel_attach"))
goto out;
/* Set target_pid after attach so that syscalls made during
* attach are not counted.
*/
skel->bss->target_pid = pid;
sys_gettid();
sys_gettid();
/* 3x syscalls: 1x attach and 2x gettid */
ASSERT_EQ(skel->bss->enter_cnt, 3, "enter_cnt");
ASSERT_EQ(skel->bss->exit_cnt, 3, "exit_cnt");
skel->bss->target_pid = 0;
/* 2x gettid syscalls */
ASSERT_EQ(skel->bss->enter_cnt, 2, "enter_cnt");
ASSERT_EQ(skel->bss->exit_cnt, 2, "exit_cnt");
ASSERT_EQ(skel->bss->mismatch_cnt, 0, "mismatch_cnt");
out:
task_local_storage__destroy(skel);