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: tests/libqtest.c:119: kill_qemu() tried to terminate QEMU process but it dumped core with signal 11 (Segmentation fault)
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>
---
changes v1->v2: addressed some of the bikeshedding with:
 * print file-and-line in the fprintf message, and then
   just abort(), rather than assert(0)
 * print the signal name via strsignal() as well

 tests/libqtest.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/tests/libqtest.c b/tests/libqtest.c
index 098af6aec44..bfc86a15f4b 100644
--- a/tests/libqtest.c
+++ b/tests/libqtest.c
@@ -110,7 +110,16 @@ 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)) {
+                int sig = WTERMSIG(wstatus);
+                const char *signame = strsignal(sig) ?: "unknown ???";
+
+                fprintf(stderr,
+                        "%s:%d: kill_qemu() tried to terminate QEMU "
+                        "process but it dumped core with signal %d (%s)\n",
+                        __FILE__, __LINE__, sig, signame);
+                abort();
+            }
         }
     }
 }
-- 
2.17.1

On 07/23/2018 01:47 PM, Peter Maydell wrote:
> 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: tests/libqtest.c:119: kill_qemu() tried to terminate QEMU process but it dumped core with signal 11 (Segmentation fault)
> 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.)

Last time we bike-shedded this, I suggested that we fix things to call 
waitpid() in a loop, and that we just assert that exit status is 0:

https://lists.gnu.org/archive/html/qemu-devel/2018-05/msg05610.html

In other words, why are we special-casing death-by-coredump, when ALL 
non-zero exit status (whether or not a core dump was involved) is 
contrary to the assumptions of the testsuite?

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org

On 23 July 2018 at 19:59, Eric Blake <eblake@redhat.com> wrote:
> In other words, why are we special-casing death-by-coredump, when ALL
> non-zero exit status (whether or not a core dump was involved) is contrary
> to the assumptions of the testsuite?

Because we're trying to get as much actual information
as we have out into the logs, not merely "die so the test
fails"...

thanks
-- PMM

On 07/23/2018 02:02 PM, Peter Maydell wrote:
> On 23 July 2018 at 19:59, Eric Blake <eblake@redhat.com> wrote:
>> In other words, why are we special-casing death-by-coredump, when ALL
>> non-zero exit status (whether or not a core dump was involved) is contrary
>> to the assumptions of the testsuite?
> 
> Because we're trying to get as much actual information
> as we have out into the logs, not merely "die so the test
> fails"...

Fair enough; so I posted a v2 based on your starting point:

https://lists.gnu.org/archive/html/qemu-devel/2018-07/msg04438.html

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org