| Message ID | 20210927145941.1383001-12-memxor@gmail.com (mailing list archive) |
|---|---|
| State | Superseded |
| Delegated to: | BPF |
| Headers | show |
| Series | Support kernel module function calls from eBPF | expand |
| Context | Check | Description |
|---|---|---|
| netdev/cover_letter | success | Link |
| netdev/fixes_present | success | Link |
| netdev/patch_count | success | Link |
| netdev/tree_selection | success | Clearly marked for bpf-next |
| netdev/subject_prefix | success | Link |
| netdev/cc_maintainers | fail | 1 blamed authors not CCed: john.fastabend@gmail.com; 4 maintainers not CCed: kpsingh@kernel.org shuah@kernel.org linux-kselftest@vger.kernel.org john.fastabend@gmail.com |
| netdev/source_inline | success | Was 0 now: 0 |
| netdev/verify_signedoff | success | Link |
| netdev/module_param | success | Was 0 now: 0 |
| netdev/build_32bit | success | Errors and warnings before: 0 this patch: 0 |
| netdev/kdoc | success | Errors and warnings before: 0 this patch: 0 |
| netdev/verify_fixes | success | Link |
| netdev/checkpatch | success | total: 0 errors, 0 warnings, 0 checks, 12 lines checked |
| netdev/build_allmodconfig_warn | success | Errors and warnings before: 0 this patch: 0 |
| netdev/header_inline | success | Link |
| bpf/vmtest-bpf-next | success | VM_Test |
| bpf/vmtest-bpf-next-PR | success | PR summary |
> On Sep 27, 2021, at 7:59 AM, Kumar Kartikeya Dwivedi <memxor@gmail.com> wrote: > > Cleanup code uses while (cpu++ < cpu_cnt) for closing fds, which means > it starts iterating from 1 for closing fds. If the first fd is -1, it > skips over it and closes garbage fds (typically zero) in the remaining > array. This leads to test failures for future tests when they end up > storing fd 0 (as the slot becomes free due to close(0)) in ldimm64's BTF > fd, ending up trying to match module BTF id with vmlinux. > > This was observed as spurious CI failure for the ksym_module_libbpf and > module_attach tests. The test ends up closing fd 0 and breaking libbpf's > assumption that module BTF fd will always be > 0, which leads to the > kernel thinking that we are pointing to a BTF ID in vmlinux BTF. > > Cc: Song Liu <songliubraving@fb.com> > Fixes: 025bd7c753aa (selftests/bpf: Add test for bpf_get_branch_snapshot) > Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com> Thanks for the fix! Acked-by: Song Liu <songliubraving@fb.com> > --- > tools/testing/selftests/bpf/prog_tests/get_branch_snapshot.c | 5 ++--- > 1 file changed, 2 insertions(+), 3 deletions(-) > > diff --git a/tools/testing/selftests/bpf/prog_tests/get_branch_snapshot.c b/tools/testing/selftests/bpf/prog_tests/get_branch_snapshot.c > index f81db9135ae4..67e86f8d8677 100644 > --- a/tools/testing/selftests/bpf/prog_tests/get_branch_snapshot.c > +++ b/tools/testing/selftests/bpf/prog_tests/get_branch_snapshot.c > @@ -38,10 +38,9 @@ static int create_perf_events(void) > > static void close_perf_events(void) > { > - int cpu = 0; > - int fd; > + int cpu, fd; > > - while (cpu++ < cpu_cnt) { > + for (cpu = 0; cpu < cpu_cnt; cpu++) { > fd = pfd_array[cpu]; > if (fd < 0) > break; > -- > 2.33.0 >
On Tue, Sep 28, 2021 at 4:58 PM Song Liu <songliubraving@fb.com> wrote: > > > > > On Sep 27, 2021, at 7:59 AM, Kumar Kartikeya Dwivedi <memxor@gmail.com> wrote: > > > > Cleanup code uses while (cpu++ < cpu_cnt) for closing fds, which means > > it starts iterating from 1 for closing fds. If the first fd is -1, it > > skips over it and closes garbage fds (typically zero) in the remaining > > array. This leads to test failures for future tests when they end up > > storing fd 0 (as the slot becomes free due to close(0)) in ldimm64's BTF > > fd, ending up trying to match module BTF id with vmlinux. > > > > This was observed as spurious CI failure for the ksym_module_libbpf and > > module_attach tests. The test ends up closing fd 0 and breaking libbpf's > > assumption that module BTF fd will always be > 0, which leads to the > > kernel thinking that we are pointing to a BTF ID in vmlinux BTF. > > > > Cc: Song Liu <songliubraving@fb.com> > > Fixes: 025bd7c753aa (selftests/bpf: Add test for bpf_get_branch_snapshot) > > Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com> > > Thanks for the fix! > > Acked-by: Song Liu <songliubraving@fb.com> Applied this fix to bpf-next.
diff --git a/tools/testing/selftests/bpf/prog_tests/get_branch_snapshot.c b/tools/testing/selftests/bpf/prog_tests/get_branch_snapshot.c index f81db9135ae4..67e86f8d8677 100644 --- a/tools/testing/selftests/bpf/prog_tests/get_branch_snapshot.c +++ b/tools/testing/selftests/bpf/prog_tests/get_branch_snapshot.c @@ -38,10 +38,9 @@ static int create_perf_events(void) static void close_perf_events(void) { - int cpu = 0; - int fd; + int cpu, fd; - while (cpu++ < cpu_cnt) { + for (cpu = 0; cpu < cpu_cnt; cpu++) { fd = pfd_array[cpu]; if (fd < 0) break;
Cleanup code uses while (cpu++ < cpu_cnt) for closing fds, which means it starts iterating from 1 for closing fds. If the first fd is -1, it skips over it and closes garbage fds (typically zero) in the remaining array. This leads to test failures for future tests when they end up storing fd 0 (as the slot becomes free due to close(0)) in ldimm64's BTF fd, ending up trying to match module BTF id with vmlinux. This was observed as spurious CI failure for the ksym_module_libbpf and module_attach tests. The test ends up closing fd 0 and breaking libbpf's assumption that module BTF fd will always be > 0, which leads to the kernel thinking that we are pointing to a BTF ID in vmlinux BTF. Cc: Song Liu <songliubraving@fb.com> Fixes: 025bd7c753aa (selftests/bpf: Add test for bpf_get_branch_snapshot) Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com> --- tools/testing/selftests/bpf/prog_tests/get_branch_snapshot.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-)