[PATCH bpf v1 3/3] selftests/bpf: Avoid a clobbering of errno

[Krzesimir Nowak]

Save errno right after bpf_prog_test_run returns, so we later check
the error code actually set by bpf_prog_test_run, not by some libcap
function.

Cc: Jakub Kicinski <jakub.kicin...@netronome.com>
Fixes: 5a8d5209ac022 ("selftests: bpf: add trivial JSET tests")
Signed-off-by: Krzesimir Nowak <krzesi...@kinvolk.io>
---
 tools/testing/selftests/bpf/test_verifier.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/bpf/test_verifier.c 
b/tools/testing/selftests/bpf/test_verifier.c
index bf0da03f593b..514e17246396 100644
--- a/tools/testing/selftests/bpf/test_verifier.c
+++ b/tools/testing/selftests/bpf/test_verifier.c
@@ -818,15 +818,17 @@ static int do_prog_test_run(int fd_prog, bool unpriv, 
uint32_t expected_val,
        __u32 size_tmp = sizeof(tmp);
        uint32_t retval;
        int err;
+       int saved_errno;
 
        if (unpriv)
                set_admin(true);
        err = bpf_prog_test_run(fd_prog, 1, data, size_data,
                                tmp, &size_tmp, &retval, NULL);
+       saved_errno = errno;
        if (unpriv)
                set_admin(false);
        if (err) {
-               switch (errno) {
+               switch (saved_errno) {
                case 524/*ENOTSUPP*/:
                        printf("Did not run the program (not supported) ");
                        return 0;
-- 
2.20.1