Re: [Qemu-devel] [PATCH for-3.0 ?] tests/libqtest: Improve kill_qemu() assert

["Alex Bennée" <alex.bennee@linaro.org>]

Peter Maydell <peter.maydell@linaro.org> writes:

> In kill_qemu() we have an assert that checks that the QEMU process
> didn't dump core:
>             assert(!WCOREDUMP(wstatus));
>
> Unfortunately the WCOREDUMP macro here means the resulting message
> is not very easy to comprehend on at least some systems:
>
> ahci-test: tests/libqtest.c:113: kill_qemu: Assertion `!(((__extension__ (((union { __typeof(wstatus) __in; int __i; }) { .__in = (wstatus) }).__i))) & 0x80)' failed.
>
> and it doesn't identify what signal the process took.
>
> Instead of using a raw assert, print the information in an
> easier to understand way:
>
> /i386/ahci/sanity: libqtest.c: kill_qemu() tried to terminate QEMU process but it dumped core with signal 11
> ahci-test: tests/libqtest.c:118: kill_qemu: Assertion `0' failed.
> Aborted (core dumped)
>
> (Of course, the really useful information would be why the QEMU
> process dumped core in the first place, but we don't have that
> by the time the test program has picked up the exit status.)
>
> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
> ---
> In particular, the travis test config that enables gprof
> seems to (a) run into this every so often and (b) have the
> really unhelpful assertion text quoted above:
>  https://travis-ci.org/qemu/qemu/jobs/406192798
>
> Maybe for 3.0 since it's only test code.
>
>  tests/libqtest.c | 8 +++++++-
>  1 file changed, 7 insertions(+), 1 deletion(-)
>
> diff --git a/tests/libqtest.c b/tests/libqtest.c
> index 098af6aec44..99341e1b47d 100644
> --- a/tests/libqtest.c
> +++ b/tests/libqtest.c
> @@ -110,7 +110,13 @@ static void kill_qemu(QTestState *s)
>          pid = waitpid(s->qemu_pid, &wstatus, 0);
>
>          if (pid == s->qemu_pid && WIFSIGNALED(wstatus)) {
> -            assert(!WCOREDUMP(wstatus));
> +            if (WCOREDUMP(wstatus)) {
> +                fprintf(stderr,
> +                        "libqtest.c: kill_qemu() tried to terminate QEMU "
> +                        "process but it dumped core with signal %d\n",
> +                        WTERMSIG(wstatus));
> +                assert(0);
> +            }

I had something similar but I added a:

+            if (WCOREDUMP(wstatus)) {
+                   fprintf(stderr, "Child QEMU (%s) dumped core\n", getenv("QTEST_QEMU_BINARY"));
+                   abort();
+            }

So I could tell which QEMU was the one that was crashing. As you are
asserting you can drop the filename/function stuff or use __file__ and
__func__ instead. Anyway it is an improvement on what we have now so:

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>


>          }
>      }
>  }


--
Alex Bennée