Re: [PATCH bpf-next v2 2/2] selftests/bpf: Unmount the bpffs that cgroup_hierarchical_stats mounted

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Low] bpf: unconditional rmdir in cleanup_bpffs triggers spurious assertion failures
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commit 34f23b53e236bfae8b2ad74d5d89f8806c601dbb
Author: Qiliang Yuan <odys.yuan@gmail.com>

selftests/bpf: Unmount the bpffs that cgroup_hierarchical_stats mounted

This commit fixes a logic error in cleanup_bpffs() where a locally mounted
bpffs was not correctly unmounted. By inverting the check on mounted_bpffs,
the test ensures it cleans up its own mounts rather than leaking them.

> diff --git a/tools/testing/selftests/bpf/prog_tests/cgroup_hierarchical_stats.c b/tools/testing/selftests/bpf/prog_tests/cgroup_hierarchical_stats.c
> index ad19d6d41918a..cc6ab2c263da1 100644
> --- a/tools/testing/selftests/bpf/prog_tests/cgroup_hierarchical_stats.c
> +++ b/tools/testing/selftests/bpf/prog_tests/cgroup_hierarchical_stats.c
> @@ -110,7 +110,7 @@ static void cleanup_bpffs(void)
>  	ASSERT_OK(rmdir(BPFFS_ATTACH_COUNTERS), "rmdir "BPFFS_ATTACH_COUNTERS);

[Severity: Low]
In cleanup_bpffs() within
tools/testing/selftests/bpf/prog_tests/cgroup_hierarchical_stats.c, does this
unconditional rmdir() trigger spurious assertion failures during early setup
error paths?

When setup fails (e.g., in setup_cgroups() or the initial mount() call), the
BPFFS_ATTACH_COUNTERS directory is never created. During the teardown path
(hierarchy_cleanup() -> destroy_hierarchy() -> cleanup_bpffs()), rmdir() is
unconditionally called and wrapped in ASSERT_OK().

If the directory does not exist, rmdir() returns -ENOENT, triggering a
secondary assertion failure. This clutters the test output and masks the
original setup failure.

>  
>  	/* Unmount bpffs, if it wasn't already mounted when we started */
> -	if (mounted_bpffs)
> +	if (!mounted_bpffs)
>  		return;
>  
>  	ASSERT_OK(umount(BPFFS_ROOT), "unmount bpffs");

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20261009-selftests-bpf-cgroup-stats-bpffs-v2-0-f93a111da992@gmail.com?part=2