| Message ID | 20220513154906.206715-3-berrange@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | tests/libqtest: fix cleanup of QEMU processes and add robustness | expand |
On 13/05/2022 17.49, Daniel P. Berrangé wrote: > Although we register a ABRT handler to kill off QEMU when g_assert() > triggers, we want an extra safety net. The QEMU process might be > non-functional and thus not have responded to SIGTERM. The test script > might also have crashed with SEGV, in which case the cleanup handlers > won't ever run. > > Using the Linux specific prctl(PR_SET_PDEATHSIG) syscall, we > can ensure that QEMU gets sent SIGKILL as soon as the controlling > qtest exits, if nothing else has correctly told it to quit. > > Note, technically the death signal is sent when the *thread* that > called fork() exits. IOW, if you are calling qtest_init() in one > thread, letting that thread exit, and then expecting to run > qtest_quit() in a different thread, things are not going to work > out. Fortunately that is not a scenario that exists in qtests, > as pairs of qtest_init and qtest_quit are always called from the > same thread. > > Signed-off-by: Daniel P. Berrangé <berrange@redhat.com> > --- > tests/qtest/libqtest.c | 17 +++++++++++++++++ > 1 file changed, 17 insertions(+) > > diff --git a/tests/qtest/libqtest.c b/tests/qtest/libqtest.c > index 4a4697c0d1..2e49618454 100644 > --- a/tests/qtest/libqtest.c > +++ b/tests/qtest/libqtest.c > @@ -19,6 +19,9 @@ > #include <sys/socket.h> > #include <sys/wait.h> > #include <sys/un.h> > +#ifdef __linux__ > +#include <sys/prctl.h> > +#endif /* __linux__ */ > > #include "libqtest.h" > #include "libqmp.h" > @@ -301,6 +304,20 @@ QTestState *qtest_init_without_qmp_handshake(const char *extra_args) > s->expected_status = 0; > s->qemu_pid = fork(); > if (s->qemu_pid == 0) { > +#ifdef __linux__ > + /* > + * Although we register a ABRT handler to kill off QEMU > + * when g_assert() triggers, we want an extra safety > + * net. The QEMU process might be non-functional and > + * thus not have responded to SIGTERM. The test script > + * might also have crashed with SEGV, in which case the > + * cleanup handlers won't ever run. > + * > + * This PR_SET_PDEATHSIG setup will ensure any remaining > + * QEMU will get terminated with SIGKILL in these cases. > + */ > + prctl(PR_SET_PDEATHSIG, SIGKILL, 0, 0, 0); > +#endif /* __linux__ */ > if (!g_setenv("QEMU_AUDIO_DRV", "none", true)) { > exit(1); > } Reviewed-by: Thomas Huth <thuth@redhat.com>
diff --git a/tests/qtest/libqtest.c b/tests/qtest/libqtest.c index 4a4697c0d1..2e49618454 100644 --- a/tests/qtest/libqtest.c +++ b/tests/qtest/libqtest.c @@ -19,6 +19,9 @@ #include <sys/socket.h> #include <sys/wait.h> #include <sys/un.h> +#ifdef __linux__ +#include <sys/prctl.h> +#endif /* __linux__ */ #include "libqtest.h" #include "libqmp.h" @@ -301,6 +304,20 @@ QTestState *qtest_init_without_qmp_handshake(const char *extra_args) s->expected_status = 0; s->qemu_pid = fork(); if (s->qemu_pid == 0) { +#ifdef __linux__ + /* + * Although we register a ABRT handler to kill off QEMU + * when g_assert() triggers, we want an extra safety + * net. The QEMU process might be non-functional and + * thus not have responded to SIGTERM. The test script + * might also have crashed with SEGV, in which case the + * cleanup handlers won't ever run. + * + * This PR_SET_PDEATHSIG setup will ensure any remaining + * QEMU will get terminated with SIGKILL in these cases. + */ + prctl(PR_SET_PDEATHSIG, SIGKILL, 0, 0, 0); +#endif /* __linux__ */ if (!g_setenv("QEMU_AUDIO_DRV", "none", true)) { exit(1); }
Although we register a ABRT handler to kill off QEMU when g_assert() triggers, we want an extra safety net. The QEMU process might be non-functional and thus not have responded to SIGTERM. The test script might also have crashed with SEGV, in which case the cleanup handlers won't ever run. Using the Linux specific prctl(PR_SET_PDEATHSIG) syscall, we can ensure that QEMU gets sent SIGKILL as soon as the controlling qtest exits, if nothing else has correctly told it to quit. Note, technically the death signal is sent when the *thread* that called fork() exits. IOW, if you are calling qtest_init() in one thread, letting that thread exit, and then expecting to run qtest_quit() in a different thread, things are not going to work out. Fortunately that is not a scenario that exists in qtests, as pairs of qtest_init and qtest_quit are always called from the same thread. Signed-off-by: Daniel P. Berrangé <berrange@redhat.com> --- tests/qtest/libqtest.c | 17 +++++++++++++++++ 1 file changed, 17 insertions(+)