Re: [PATCH 2/3] perf test: fix sys_enter_openat event test for musl

[sashiko-bot@kernel.org]

Sashiko AI review found 1 potential issue(s):
- [Medium] The updated bitwise check `(tp_flags & flags) != flags` fails to verify the `O_RDONLY` access mode and permits arbitrary unrelated flags, severely weakening the test.
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commit 0700122c98ba7f263a329cd8f9fbeef95b67603e
Author: Martin Kaiser <martin@kaiser.cx>

perf test: fix sys_enter_openat event test for musl

This commit updates the sys_enter_openat test to allow additional flags in the
captured event. It replaces the strict equality check with a bitwise mask check
to accommodate the O_LARGEFILE flag implicitly added by musl libc.

> diff --git a/tools/perf/tests/openat-syscall-tp-fields.c b/tools/perf/tests/openat-syscall-tp-fields.c
> --- a/tools/perf/tests/openat-syscall-tp-fields.c
> +++ b/tools/perf/tests/openat-syscall-tp-fields.c

[ ... ]

> @@ -120,7 +120,8 @@ static int test__syscall_openat_tp_fields(struct test_suite *test __maybe_unused
>  
>  				tp_flags = evsel__intval(evsel, &sample, "flags");
>  				perf_sample__exit(&sample);
> -				if (flags != tp_flags) {
> +				/* C library wrapper may set additional flags */
> +				if ((tp_flags & flags) != flags) {

Does this check still verify the O_RDONLY access mode?

Since O_RDONLY is defined as 0, the flags variable evaluates to exactly
O_DIRECTORY. This means the condition functionally becomes
(tp_flags & O_DIRECTORY) != O_DIRECTORY.

Does this unintentionally permit other access modes like O_WRONLY or O_RDWR,
and ignore other unrelated flags as long as O_DIRECTORY is set?

>  					pr_debug("%s: Expected flags=%#x, got %#x\n",
>  						 __func__, flags, tp_flags);
>  					goto out_delete_evlist;

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Sashiko AI review · https://sashiko.dev/#/patchset/20260427090225.794482-1-martin@kaiser.cx?part=2