It's follow-up for discussion [1] CHECK and CHECK_FAIL macros in test_progs.h can affect errno in some circumstances, e.g. if some code accidentally closes stdout. It makes checking errno in patterns like this unreliable: if (CHECK(!bpf_prog_attach_xattr(...), "tag", "msg")) goto err; CHECK_FAIL(errno != ENOENT); , since by CHECK_FAIL time errno could be affected not only by bpf_prog_attach_xattr but by CHECK as well. Fix it by saving and restoring errno in the macros. There is no "Fixes" tag since no problems were discovered yet and it's rather precaution. test_progs was run with this change and no difference was identified. [1] https://lore.kernel.org/bpf/20191219210907.GD16266@xxxxxxxxxxxxxxxxxxxxxxxxxxxxx/ Signed-off-by: Andrey Ignatov <rdna@xxxxxx> --- tools/testing/selftests/bpf/test_progs.h | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/tools/testing/selftests/bpf/test_progs.h b/tools/testing/selftests/bpf/test_progs.h index 8477df835979..de1fdaa4e7b4 100644 --- a/tools/testing/selftests/bpf/test_progs.h +++ b/tools/testing/selftests/bpf/test_progs.h @@ -100,6 +100,7 @@ extern struct ipv6_packet pkt_v6; #define _CHECK(condition, tag, duration, format...) ({ \ int __ret = !!(condition); \ + int __save_errno = errno; \ if (__ret) { \ test__fail(); \ printf("%s:FAIL:%s ", __func__, tag); \ @@ -108,15 +109,18 @@ extern struct ipv6_packet pkt_v6; printf("%s:PASS:%s %d nsec\n", \ __func__, tag, duration); \ } \ + errno = __save_errno; \ __ret; \ }) #define CHECK_FAIL(condition) ({ \ int __ret = !!(condition); \ + int __save_errno = errno; \ if (__ret) { \ test__fail(); \ printf("%s:FAIL:%d\n", __func__, __LINE__); \ } \ + errno = __save_errno; \ __ret; \ }) -- 2.17.1
