selftests/bpf: Print log buffer for exceptions test only on failure

Alexei reported seeing log messages for some test cases even though we
just wanted to match the error string from the verifier. Move the
printing of the log buffer to a guarded condition so that we only print
it when we fail to match on the expected string in the log buffer,
preventing unneeded output when running the test.

Reported-by: Alexei Starovoitov <ast@kernel.org>
Fixes: d2a93715bfb0 ("selftests/bpf: Add tests for BPF exceptions")
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20230918155233.297024-2-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

diff --git a/tools/testing/selftests/bpf/prog_tests/exceptions.c b/tools/testing/selftests/bpf/prog_tests/exceptions.c
index 5663e427dc00daf0204e24050452fb0ec8d0d7d3..516f4a13013cca26f9e416a75e6774b3090f64ea 100644 (file)
--- a/tools/testing/selftests/bpf/prog_tests/exceptions.c
+++ b/tools/testing/selftests/bpf/prog_tests/exceptions.c
@@ -103,9 +103,10 @@ static void test_exceptions_success(void)
                        goto done;                                                \
                }                                                                 \
                if (load_ret != 0) {                                              \
-                       printf("%s\n", log_buf);                                  \
-                       if (!ASSERT_OK_PTR(strstr(log_buf, msg), "strstr"))       \
+                       if (!ASSERT_OK_PTR(strstr(log_buf, msg), "strstr")) {     \
+                               printf("%s\n", log_buf);                          \
                                goto done;                                        \
+                       }                                                         \
                }                                                                 \
                if (!load_ret && attach_err) {                                    \
                        if (!ASSERT_ERR_PTR(link = bpf_program__attach(prog), "attach err")) \