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

[Qiliang Yuan]

setup_bpffs() mounts a bpffs on /sys/fs/bpf and records in mounted_bpffs
whether it did, so that cleanup_bpffs() unmounts only a bpffs that the
test mounted itself.

cleanup_bpffs() checks the flag the other way around. As mounting on
/sys/fs/bpf succeeds even when a bpffs is already there, the test never
unmounts the bpffs it mounted, and every run leaves another one stacked
on /sys/fs/bpf of the mount namespace that the test_progs worker keeps
running later tests in.

Unmount the bpffs only when setup_bpffs() mounted it.

Fixes: 88886309d2e8 ("selftests/bpf: add a selftest for cgroup hierarchical 
stats collection")
Signed-off-by: Qiliang Yuan <odys.y...@gmail.com>
Reviewed-by: Yosry Ahmed <yo...@kernel.org>
---
 tools/testing/selftests/bpf/prog_tests/cgroup_hierarchical_stats.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

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);
 
        /* 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");

-- 
2.43.0