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| author | Yonghong Song <yonghong.song@linux.dev> | 2023-08-27 08:05:51 -0700 |
|---|---|---|
| committer | Daniel Borkmann <daniel@iogearbox.net> | 2023-08-30 08:45:05 +0200 |
| commit | 5439cfa7fe612e7d02d5a1234feda3fa6e483ba7 (patch) | |
| tree | daf1947a9403a37ccb72d22c9aeaec922c004061 /tools | |
| parent | 9d0a67b9d42c630d5013ef81587335d975a7a4a9 (diff) | |
| download | lwn-5439cfa7fe612e7d02d5a1234feda3fa6e483ba7.tar.gz lwn-5439cfa7fe612e7d02d5a1234feda3fa6e483ba7.zip | |
selftests/bpf: Fix flaky cgroup_iter_sleepable subtest
Occasionally, with './test_progs -j' on my vm, I will hit the
following failure:
test_cgrp_local_storage:PASS:join_cgroup /cgrp_local_storage 0 nsec
test_cgroup_iter_sleepable:PASS:skel_open 0 nsec
test_cgroup_iter_sleepable:PASS:skel_load 0 nsec
test_cgroup_iter_sleepable:PASS:attach_iter 0 nsec
test_cgroup_iter_sleepable:PASS:iter_create 0 nsec
test_cgroup_iter_sleepable:FAIL:cgroup_id unexpected cgroup_id: actual 1 != expected 2812
#48/5 cgrp_local_storage/cgroup_iter_sleepable:FAIL
#48 cgrp_local_storage:FAIL
Finally, I decided to do some investigation since the test is introduced
by myself. It turns out the reason is due to cgroup_fd with value 0.
In cgroup_iter, a cgroup_fd of value 0 means the root cgroup.
/* from cgroup_iter.c */
if (fd)
cgrp = cgroup_v1v2_get_from_fd(fd);
else if (id)
cgrp = cgroup_get_from_id(id);
else /* walk the entire hierarchy by default. */
cgrp = cgroup_get_from_path("/");
That is why we got cgroup_id 1 instead of expected 2812.
Why we got a cgroup_fd 0? Nobody should really touch 'stdin' (fd 0) in
test_progs. I traced 'close' syscall with stack trace and found the root
cause, which is a bug in bpf_obj_pinning.c. Basically, the code closed
fd 0 although it should not. Fixing the bug in bpf_obj_pinning.c also
resolved the above cgroup_iter_sleepable subtest failure.
Fixes: 3b22f98e5a05 ("selftests/bpf: Add path_fd-based BPF_OBJ_PIN and BPF_OBJ_GET tests")
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20230827150551.1743497-1-yonghong.song@linux.dev
Diffstat (limited to 'tools')
| -rw-r--r-- | tools/testing/selftests/bpf/prog_tests/bpf_obj_pinning.c | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/tools/testing/selftests/bpf/prog_tests/bpf_obj_pinning.c b/tools/testing/selftests/bpf/prog_tests/bpf_obj_pinning.c index 31f1e815f671..ee0458a5ce78 100644 --- a/tools/testing/selftests/bpf/prog_tests/bpf_obj_pinning.c +++ b/tools/testing/selftests/bpf/prog_tests/bpf_obj_pinning.c @@ -8,6 +8,7 @@ #include <linux/unistd.h> #include <linux/mount.h> #include <sys/syscall.h> +#include "bpf/libbpf_internal.h" static inline int sys_fsopen(const char *fsname, unsigned flags) { @@ -155,7 +156,7 @@ static void validate_pin(int map_fd, const char *map_name, int src_value, ASSERT_OK(err, "obj_pin"); /* cleanup */ - if (pin_opts.path_fd >= 0) + if (path_kind == PATH_FD_REL && pin_opts.path_fd >= 0) close(pin_opts.path_fd); if (old_cwd[0]) ASSERT_OK(chdir(old_cwd), "restore_cwd"); @@ -220,7 +221,7 @@ static void validate_get(int map_fd, const char *map_name, int src_value, goto cleanup; /* cleanup */ - if (get_opts.path_fd >= 0) + if (path_kind == PATH_FD_REL && get_opts.path_fd >= 0) close(get_opts.path_fd); if (old_cwd[0]) ASSERT_OK(chdir(old_cwd), "restore_cwd"); |