diff options
| author | Ricardo B. Marlière <rbm@suse.com> | 2026-07-20 08:13:08 -0300 |
|---|---|---|
| committer | Kumar Kartikeya Dwivedi <memxor@gmail.com> | 2026-07-21 19:27:13 +0200 |
| commit | 71cf3f3275e5f4d7f31bd540608c80535343b427 (patch) | |
| tree | 607173326efa1b1db578de4b72ebe9bbace1bad4 /tools | |
| parent | 0b236ac75d04a235f3574a2208941b22c1e7a965 (diff) | |
selftests/bpf: Fix lsm_bdev dev_t encoding mismatch
progs/lsm_bdev.c keys its verity_devices hashmap with the raw kernel dev_t
read straight off bdev->bd_dev, i.e. MKDEV(major, minor) = (major << 20) |
minor. prog_tests/lsm_bdev.c instead builds its lookup key with dev_key =
(__u32)st.st_rdev from stat(2), but the stat(2) syscall fills st_rdev via
the kernel's new_encode_dev(), a different bit layout: (minor & 0xff) |
(major << 8) | ((minor & ~0xff) << 12).
For any device with a non-trivial major these two values differ, so the
lookup can never find what the BPF program stored, and test_lsm_bdev()
always fails with:
test_lsm_bdev:FAIL:map lookup unexpected error: -2 (errno 2)
Reconstruct the raw kernel dev_t from the decoded major/minor instead of
casting st_rdev directly, restoring the layout the BPF program actually
reads.
Fixes: 96f4c251a087 ("selftests/bpf: add block device management selftests")
Signed-off-by: Ricardo B. Marlière <rbm@suse.com>
Acked-by: Ihor Solodrai <ihor.solodrai@linux.dev>
Link: https://lore.kernel.org/bpf/20260720-selftests-bpf_fixes-v2-2-b450eda93dfe@suse.com
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Diffstat (limited to 'tools')
| -rw-r--r-- | tools/testing/selftests/bpf/prog_tests/lsm_bdev.c | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/tools/testing/selftests/bpf/prog_tests/lsm_bdev.c b/tools/testing/selftests/bpf/prog_tests/lsm_bdev.c index a970798e1173..28bc4b117f41 100644 --- a/tools/testing/selftests/bpf/prog_tests/lsm_bdev.c +++ b/tools/testing/selftests/bpf/prog_tests/lsm_bdev.c @@ -17,6 +17,7 @@ #include <stdlib.h> #include <string.h> #include <sys/stat.h> +#include <sys/sysmacros.h> #include <sys/types.h> #include <unistd.h> #include "lsm_bdev.skel.h" @@ -172,7 +173,7 @@ void test_lsm_bdev(void) if (!ASSERT_OK(stat(DM_DEV_PATH, &st), "stat dm dev")) goto remove_dm; - dev_key = (__u32)st.st_rdev; + dev_key = (major(st.st_rdev) << 20) | minor(st.st_rdev); /* Look up the device in the BPF map and verify. */ err = bpf_map__lookup_elem(skel->maps.verity_devices, |