diff mbox series

tests: Exit boot-serial-test loop if child dies

Message ID 20181217035816.21777-1-richard.henderson@linaro.org
State New
Headers show
Series tests: Exit boot-serial-test loop if child dies | expand

Commit Message

Richard Henderson Dec. 17, 2018, 3:58 a.m. UTC
There's no point in waiting 5 full minutes when there will be
no more output.  Compute timeout based on elapsed wall clock
time instead of N * delays, as the delay is a minimum sleep time.

Cc: Thomas Huth <thuth@redhat.com>
Cc: Laurent Vivier <lvivier@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

---
 tests/libqtest.h         |  8 +++++
 tests/boot-serial-test.c | 16 +++++++--
 tests/libqtest.c         | 70 +++++++++++++++++++++++++---------------
 3 files changed, 65 insertions(+), 29 deletions(-)

-- 
2.17.2

Comments

Thomas Huth Dec. 17, 2018, 10:39 a.m. UTC | #1
On 2018-12-17 04:58, Richard Henderson wrote:
> There's no point in waiting 5 full minutes when there will be

> no more output.


Sounds like a very good idea, indeed.

As a follow up patch, we should likely use this in the other tests that
use TCG, too (i.e. in boot_sector_test() in tests/boot-sector.c).

>  Compute timeout based on elapsed wall clock

> time instead of N * delays, as the delay is a minimum sleep time.

> 

> Cc: Thomas Huth <thuth@redhat.com>

> Cc: Laurent Vivier <lvivier@redhat.com>

> Cc: Paolo Bonzini <pbonzini@redhat.com>

> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

> ---

>  tests/libqtest.h         |  8 +++++

>  tests/boot-serial-test.c | 16 +++++++--

>  tests/libqtest.c         | 70 +++++++++++++++++++++++++---------------

>  3 files changed, 65 insertions(+), 29 deletions(-)

> 

> diff --git a/tests/libqtest.h b/tests/libqtest.h

> index 96a6c01352..9758c51be6 100644

> --- a/tests/libqtest.h

> +++ b/tests/libqtest.h

> @@ -1011,4 +1011,12 @@ bool qmp_rsp_is_err(QDict *rsp);

>   */

>  void qmp_assert_error_class(QDict *rsp, const char *class);

>  

> +/**

> + * qtest_probe_child:

> + * @s: QTestState instance to operate on.

> + *

> + * Returns: true if the child is still alive.

> + */

> +bool qtest_probe_child(QTestState *s);

> +

>  #endif

> diff --git a/tests/boot-serial-test.c b/tests/boot-serial-test.c

> index 8ec6aed35d..54b9347325 100644

> --- a/tests/boot-serial-test.c

> +++ b/tests/boot-serial-test.c

> @@ -130,11 +130,12 @@ static testdef_t tests[] = {

>  

>  static bool check_guest_output(const testdef_t *test, int fd)

>  {

> -    int i, nbr = 0, pos = 0, ccnt;

> +    int nbr = 0, pos = 0, ccnt;

> +    time_t now, start = time(NULL);

>      char ch;

>  

> -    /* Poll serial output... Wait at most 360 seconds */

> -    for (i = 0; i < 36000; ++i) {

> +    /* Poll serial output... */

> +    while (1) {

>          ccnt = 0;

>          while (ccnt++ < 512 && (nbr = read(fd, &ch, 1)) == 1) {

>              if (ch == test->expect[pos]) {

> @@ -148,6 +149,15 @@ static bool check_guest_output(const testdef_t *test, int fd)

>              }

>          }

>          g_assert(nbr >= 0);

> +        /* Wait only if the child is still alive.  */

> +        if (!qtest_probe_child(global_qtest)) {

> +            break;

> +        }

> +        /* Wait at most 360 seconds.  */

> +        now = time(NULL);

> +        if (now - start >= 360) {

> +            break;

> +        }

>          g_usleep(10000);

>      }

>  

> diff --git a/tests/libqtest.c b/tests/libqtest.c

> index 43be078518..1d75d3c936 100644

> --- a/tests/libqtest.c

> +++ b/tests/libqtest.c

> @@ -39,10 +39,11 @@ struct QTestState

>  {

>      int fd;

>      int qmp_fd;

> +    pid_t qemu_pid;  /* our child QEMU process */

> +    int wstatus;

> +    bool big_endian;

>      bool irq_level[MAX_IRQ];

>      GString *rx;

> -    pid_t qemu_pid;  /* our child QEMU process */

> -    bool big_endian;

>  };

>  

>  static GHookList abrt_hooks;

> @@ -96,36 +97,52 @@ static int socket_accept(int sock)

>      return ret;

>  }

>  

> +bool qtest_probe_child(QTestState *s)

> +{

> +    pid_t pid = s->qemu_pid;

> +

> +    if (pid != -1) {

> +        pid = waitpid(pid, &s->wstatus, WNOHANG);

> +        if (pid == 0) {

> +            return true;

> +        }

> +        s->qemu_pid = -1;

> +    }

> +    return false;

> +}

> +

>  static void kill_qemu(QTestState *s)

>  {

> -    if (s->qemu_pid != -1) {

> -        int wstatus = 0;

> -        pid_t pid;

> -

> -        kill(s->qemu_pid, SIGTERM);

> -        TFR(pid = waitpid(s->qemu_pid, &wstatus, 0));

> +    pid_t pid = s->qemu_pid;

> +    int wstatus;

>  

> +    /* Skip wait if qtest_probe_child already reaped.  */

> +    if (pid != -1) {

> +        kill(pid, SIGTERM);

> +        TFR(pid = waitpid(s->qemu_pid, &s->wstatus, 0));

>          assert(pid == s->qemu_pid);

> -        /*

> -         * We expect qemu to exit with status 0; anything else is

> -         * fishy and should be logged with as much detail as possible.

> -         */

> -        if (wstatus) {

> -            if (WIFEXITED(wstatus)) {

> -                fprintf(stderr, "%s:%d: kill_qemu() tried to terminate QEMU "

> -                        "process but encountered exit status %d\n",

> -                        __FILE__, __LINE__, WEXITSTATUS(wstatus));

> -            } else if (WIFSIGNALED(wstatus)) {

> -                int sig = WTERMSIG(wstatus);

> -                const char *signame = strsignal(sig) ?: "unknown ???";

> -                const char *dump = WCOREDUMP(wstatus) ? " (core dumped)" : "";

> +    }

>  

> -                fprintf(stderr, "%s:%d: kill_qemu() detected QEMU death "

> -                        "from signal %d (%s)%s\n",

> -                        __FILE__, __LINE__, sig, signame, dump);

> -            }

> -            abort();

> +    /*

> +     * We expect qemu to exit with status 0; anything else is

> +     * fishy and should be logged with as much detail as possible.

> +     */

> +    wstatus = s->wstatus;

> +    if (wstatus) {

> +        if (WIFEXITED(wstatus)) {

> +            fprintf(stderr, "%s:%d: kill_qemu() tried to terminate QEMU "

> +                    "process but encountered exit status %d\n",


The string is not 100% accurate now anymore - we might not have tried to
kill QEMU here since it exited earlier already. It's not that important,
but in case you respin, you could maybe adjust this text a little bit.

> +                    __FILE__, __LINE__, WEXITSTATUS(wstatus));

> +        } else if (WIFSIGNALED(wstatus)) {

> +            int sig = WTERMSIG(wstatus);

> +            const char *signame = strsignal(sig) ?: "unknown ???";

> +            const char *dump = WCOREDUMP(wstatus) ? " (core dumped)" : "";

> +

> +            fprintf(stderr, "%s:%d: kill_qemu() detected QEMU death "

> +                    "from signal %d (%s)%s\n",

> +                    __FILE__, __LINE__, sig, signame, dump);

>          }

> +        abort();

>      }

>  }

>  

> @@ -228,6 +245,7 @@ QTestState *qtest_init_without_qmp_handshake(const char *extra_args)

>  

>      g_test_message("starting QEMU: %s", command);

>  

> +    s->wstatus = 0;

>      s->qemu_pid = fork();

>      if (s->qemu_pid == 0) {

>          setenv("QEMU_AUDIO_DRV", "none", true);

> 


Patch looks fine to me, I'm going to queue this for the next qtests pull
request (unless you want to respin because of the error string or other
reasons).

Reviewed-by: Thomas Huth <thuth@redhat.com>
Philippe Mathieu-Daudé Dec. 17, 2018, 10:52 a.m. UTC | #2
On 12/17/18 4:58 AM, Richard Henderson wrote:
> There's no point in waiting 5 full minutes when there will be

> no more output.  Compute timeout based on elapsed wall clock

> time instead of N * delays, as the delay is a minimum sleep time.

> 

> Cc: Thomas Huth <thuth@redhat.com>

> Cc: Laurent Vivier <lvivier@redhat.com>

> Cc: Paolo Bonzini <pbonzini@redhat.com>

> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>


Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>


> ---

>  tests/libqtest.h         |  8 +++++

>  tests/boot-serial-test.c | 16 +++++++--

>  tests/libqtest.c         | 70 +++++++++++++++++++++++++---------------

>  3 files changed, 65 insertions(+), 29 deletions(-)

> 

> diff --git a/tests/libqtest.h b/tests/libqtest.h

> index 96a6c01352..9758c51be6 100644

> --- a/tests/libqtest.h

> +++ b/tests/libqtest.h

> @@ -1011,4 +1011,12 @@ bool qmp_rsp_is_err(QDict *rsp);

>   */

>  void qmp_assert_error_class(QDict *rsp, const char *class);

>  

> +/**

> + * qtest_probe_child:

> + * @s: QTestState instance to operate on.

> + *

> + * Returns: true if the child is still alive.

> + */

> +bool qtest_probe_child(QTestState *s);

> +

>  #endif

> diff --git a/tests/boot-serial-test.c b/tests/boot-serial-test.c

> index 8ec6aed35d..54b9347325 100644

> --- a/tests/boot-serial-test.c

> +++ b/tests/boot-serial-test.c

> @@ -130,11 +130,12 @@ static testdef_t tests[] = {

>  

>  static bool check_guest_output(const testdef_t *test, int fd)

>  {

> -    int i, nbr = 0, pos = 0, ccnt;

> +    int nbr = 0, pos = 0, ccnt;

> +    time_t now, start = time(NULL);

>      char ch;

>  

> -    /* Poll serial output... Wait at most 360 seconds */

> -    for (i = 0; i < 36000; ++i) {

> +    /* Poll serial output... */

> +    while (1) {

>          ccnt = 0;

>          while (ccnt++ < 512 && (nbr = read(fd, &ch, 1)) == 1) {

>              if (ch == test->expect[pos]) {

> @@ -148,6 +149,15 @@ static bool check_guest_output(const testdef_t *test, int fd)

>              }

>          }

>          g_assert(nbr >= 0);

> +        /* Wait only if the child is still alive.  */

> +        if (!qtest_probe_child(global_qtest)) {

> +            break;

> +        }

> +        /* Wait at most 360 seconds.  */

> +        now = time(NULL);

> +        if (now - start >= 360) {

> +            break;

> +        }

>          g_usleep(10000);

>      }

>  

> diff --git a/tests/libqtest.c b/tests/libqtest.c

> index 43be078518..1d75d3c936 100644

> --- a/tests/libqtest.c

> +++ b/tests/libqtest.c

> @@ -39,10 +39,11 @@ struct QTestState

>  {

>      int fd;

>      int qmp_fd;

> +    pid_t qemu_pid;  /* our child QEMU process */

> +    int wstatus;

> +    bool big_endian;

>      bool irq_level[MAX_IRQ];

>      GString *rx;

> -    pid_t qemu_pid;  /* our child QEMU process */

> -    bool big_endian;

>  };

>  

>  static GHookList abrt_hooks;

> @@ -96,36 +97,52 @@ static int socket_accept(int sock)

>      return ret;

>  }

>  

> +bool qtest_probe_child(QTestState *s)

> +{

> +    pid_t pid = s->qemu_pid;

> +

> +    if (pid != -1) {

> +        pid = waitpid(pid, &s->wstatus, WNOHANG);

> +        if (pid == 0) {

> +            return true;

> +        }

> +        s->qemu_pid = -1;

> +    }

> +    return false;

> +}

> +

>  static void kill_qemu(QTestState *s)

>  {

> -    if (s->qemu_pid != -1) {

> -        int wstatus = 0;

> -        pid_t pid;

> -

> -        kill(s->qemu_pid, SIGTERM);

> -        TFR(pid = waitpid(s->qemu_pid, &wstatus, 0));

> +    pid_t pid = s->qemu_pid;

> +    int wstatus;

>  

> +    /* Skip wait if qtest_probe_child already reaped.  */

> +    if (pid != -1) {

> +        kill(pid, SIGTERM);

> +        TFR(pid = waitpid(s->qemu_pid, &s->wstatus, 0));

>          assert(pid == s->qemu_pid);

> -        /*

> -         * We expect qemu to exit with status 0; anything else is

> -         * fishy and should be logged with as much detail as possible.

> -         */

> -        if (wstatus) {

> -            if (WIFEXITED(wstatus)) {

> -                fprintf(stderr, "%s:%d: kill_qemu() tried to terminate QEMU "

> -                        "process but encountered exit status %d\n",

> -                        __FILE__, __LINE__, WEXITSTATUS(wstatus));

> -            } else if (WIFSIGNALED(wstatus)) {

> -                int sig = WTERMSIG(wstatus);

> -                const char *signame = strsignal(sig) ?: "unknown ???";

> -                const char *dump = WCOREDUMP(wstatus) ? " (core dumped)" : "";

> +    }

>  

> -                fprintf(stderr, "%s:%d: kill_qemu() detected QEMU death "

> -                        "from signal %d (%s)%s\n",

> -                        __FILE__, __LINE__, sig, signame, dump);

> -            }

> -            abort();

> +    /*

> +     * We expect qemu to exit with status 0; anything else is

> +     * fishy and should be logged with as much detail as possible.

> +     */

> +    wstatus = s->wstatus;

> +    if (wstatus) {

> +        if (WIFEXITED(wstatus)) {

> +            fprintf(stderr, "%s:%d: kill_qemu() tried to terminate QEMU "

> +                    "process but encountered exit status %d\n",

> +                    __FILE__, __LINE__, WEXITSTATUS(wstatus));

> +        } else if (WIFSIGNALED(wstatus)) {

> +            int sig = WTERMSIG(wstatus);

> +            const char *signame = strsignal(sig) ?: "unknown ???";

> +            const char *dump = WCOREDUMP(wstatus) ? " (core dumped)" : "";

> +

> +            fprintf(stderr, "%s:%d: kill_qemu() detected QEMU death "

> +                    "from signal %d (%s)%s\n",

> +                    __FILE__, __LINE__, sig, signame, dump);

>          }

> +        abort();

>      }

>  }

>  

> @@ -228,6 +245,7 @@ QTestState *qtest_init_without_qmp_handshake(const char *extra_args)

>  

>      g_test_message("starting QEMU: %s", command);

>  

> +    s->wstatus = 0;

>      s->qemu_pid = fork();

>      if (s->qemu_pid == 0) {

>          setenv("QEMU_AUDIO_DRV", "none", true);

>
Wainer dos Santos Moschetta Dec. 17, 2018, 2:12 p.m. UTC | #3
On 12/17/2018 01:58 AM, Richard Henderson wrote:
> There's no point in waiting 5 full minutes when there will be

> no more output.  Compute timeout based on elapsed wall clock

> time instead of N * delays, as the delay is a minimum sleep time.

>

> Cc: Thomas Huth <thuth@redhat.com>

> Cc: Laurent Vivier <lvivier@redhat.com>

> Cc: Paolo Bonzini <pbonzini@redhat.com>

> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

> ---

>   tests/libqtest.h         |  8 +++++

>   tests/boot-serial-test.c | 16 +++++++--

>   tests/libqtest.c         | 70 +++++++++++++++++++++++++---------------

>   3 files changed, 65 insertions(+), 29 deletions(-)


Reviewed-by: Wainer dos Santos Moschetta <wainersm@redhat.com>


>

> diff --git a/tests/libqtest.h b/tests/libqtest.h

> index 96a6c01352..9758c51be6 100644

> --- a/tests/libqtest.h

> +++ b/tests/libqtest.h

> @@ -1011,4 +1011,12 @@ bool qmp_rsp_is_err(QDict *rsp);

>    */

>   void qmp_assert_error_class(QDict *rsp, const char *class);

>   

> +/**

> + * qtest_probe_child:

> + * @s: QTestState instance to operate on.

> + *

> + * Returns: true if the child is still alive.

> + */

> +bool qtest_probe_child(QTestState *s);

> +

>   #endif

> diff --git a/tests/boot-serial-test.c b/tests/boot-serial-test.c

> index 8ec6aed35d..54b9347325 100644

> --- a/tests/boot-serial-test.c

> +++ b/tests/boot-serial-test.c

> @@ -130,11 +130,12 @@ static testdef_t tests[] = {

>   

>   static bool check_guest_output(const testdef_t *test, int fd)

>   {

> -    int i, nbr = 0, pos = 0, ccnt;

> +    int nbr = 0, pos = 0, ccnt;

> +    time_t now, start = time(NULL);

>       char ch;

>   

> -    /* Poll serial output... Wait at most 360 seconds */

> -    for (i = 0; i < 36000; ++i) {

> +    /* Poll serial output... */

> +    while (1) {

>           ccnt = 0;

>           while (ccnt++ < 512 && (nbr = read(fd, &ch, 1)) == 1) {

>               if (ch == test->expect[pos]) {

> @@ -148,6 +149,15 @@ static bool check_guest_output(const testdef_t *test, int fd)

>               }

>           }

>           g_assert(nbr >= 0);

> +        /* Wait only if the child is still alive.  */

> +        if (!qtest_probe_child(global_qtest)) {

> +            break;

> +        }

> +        /* Wait at most 360 seconds.  */

> +        now = time(NULL);

> +        if (now - start >= 360) {

> +            break;

> +        }

>           g_usleep(10000);

>       }

>   

> diff --git a/tests/libqtest.c b/tests/libqtest.c

> index 43be078518..1d75d3c936 100644

> --- a/tests/libqtest.c

> +++ b/tests/libqtest.c

> @@ -39,10 +39,11 @@ struct QTestState

>   {

>       int fd;

>       int qmp_fd;

> +    pid_t qemu_pid;  /* our child QEMU process */

> +    int wstatus;

> +    bool big_endian;

>       bool irq_level[MAX_IRQ];

>       GString *rx;

> -    pid_t qemu_pid;  /* our child QEMU process */

> -    bool big_endian;

>   };

>   

>   static GHookList abrt_hooks;

> @@ -96,36 +97,52 @@ static int socket_accept(int sock)

>       return ret;

>   }

>   

> +bool qtest_probe_child(QTestState *s)

> +{

> +    pid_t pid = s->qemu_pid;

> +

> +    if (pid != -1) {

> +        pid = waitpid(pid, &s->wstatus, WNOHANG);

> +        if (pid == 0) {

> +            return true;

> +        }

> +        s->qemu_pid = -1;

> +    }

> +    return false;

> +}

> +

>   static void kill_qemu(QTestState *s)

>   {

> -    if (s->qemu_pid != -1) {

> -        int wstatus = 0;

> -        pid_t pid;

> -

> -        kill(s->qemu_pid, SIGTERM);

> -        TFR(pid = waitpid(s->qemu_pid, &wstatus, 0));

> +    pid_t pid = s->qemu_pid;

> +    int wstatus;

>   

> +    /* Skip wait if qtest_probe_child already reaped.  */

> +    if (pid != -1) {

> +        kill(pid, SIGTERM);

> +        TFR(pid = waitpid(s->qemu_pid, &s->wstatus, 0));

>           assert(pid == s->qemu_pid);

> -        /*

> -         * We expect qemu to exit with status 0; anything else is

> -         * fishy and should be logged with as much detail as possible.

> -         */

> -        if (wstatus) {

> -            if (WIFEXITED(wstatus)) {

> -                fprintf(stderr, "%s:%d: kill_qemu() tried to terminate QEMU "

> -                        "process but encountered exit status %d\n",

> -                        __FILE__, __LINE__, WEXITSTATUS(wstatus));

> -            } else if (WIFSIGNALED(wstatus)) {

> -                int sig = WTERMSIG(wstatus);

> -                const char *signame = strsignal(sig) ?: "unknown ???";

> -                const char *dump = WCOREDUMP(wstatus) ? " (core dumped)" : "";

> +    }

>   

> -                fprintf(stderr, "%s:%d: kill_qemu() detected QEMU death "

> -                        "from signal %d (%s)%s\n",

> -                        __FILE__, __LINE__, sig, signame, dump);

> -            }

> -            abort();

> +    /*

> +     * We expect qemu to exit with status 0; anything else is

> +     * fishy and should be logged with as much detail as possible.

> +     */

> +    wstatus = s->wstatus;

> +    if (wstatus) {

> +        if (WIFEXITED(wstatus)) {

> +            fprintf(stderr, "%s:%d: kill_qemu() tried to terminate QEMU "

> +                    "process but encountered exit status %d\n",

> +                    __FILE__, __LINE__, WEXITSTATUS(wstatus));

> +        } else if (WIFSIGNALED(wstatus)) {

> +            int sig = WTERMSIG(wstatus);

> +            const char *signame = strsignal(sig) ?: "unknown ???";

> +            const char *dump = WCOREDUMP(wstatus) ? " (core dumped)" : "";

> +

> +            fprintf(stderr, "%s:%d: kill_qemu() detected QEMU death "

> +                    "from signal %d (%s)%s\n",

> +                    __FILE__, __LINE__, sig, signame, dump);

>           }

> +        abort();

>       }

>   }

>   

> @@ -228,6 +245,7 @@ QTestState *qtest_init_without_qmp_handshake(const char *extra_args)

>   

>       g_test_message("starting QEMU: %s", command);

>   

> +    s->wstatus = 0;

>       s->qemu_pid = fork();

>       if (s->qemu_pid == 0) {

>           setenv("QEMU_AUDIO_DRV", "none", true);
diff mbox series

Patch

diff --git a/tests/libqtest.h b/tests/libqtest.h
index 96a6c01352..9758c51be6 100644
--- a/tests/libqtest.h
+++ b/tests/libqtest.h
@@ -1011,4 +1011,12 @@  bool qmp_rsp_is_err(QDict *rsp);
  */
 void qmp_assert_error_class(QDict *rsp, const char *class);
 
+/**
+ * qtest_probe_child:
+ * @s: QTestState instance to operate on.
+ *
+ * Returns: true if the child is still alive.
+ */
+bool qtest_probe_child(QTestState *s);
+
 #endif
diff --git a/tests/boot-serial-test.c b/tests/boot-serial-test.c
index 8ec6aed35d..54b9347325 100644
--- a/tests/boot-serial-test.c
+++ b/tests/boot-serial-test.c
@@ -130,11 +130,12 @@  static testdef_t tests[] = {
 
 static bool check_guest_output(const testdef_t *test, int fd)
 {
-    int i, nbr = 0, pos = 0, ccnt;
+    int nbr = 0, pos = 0, ccnt;
+    time_t now, start = time(NULL);
     char ch;
 
-    /* Poll serial output... Wait at most 360 seconds */
-    for (i = 0; i < 36000; ++i) {
+    /* Poll serial output... */
+    while (1) {
         ccnt = 0;
         while (ccnt++ < 512 && (nbr = read(fd, &ch, 1)) == 1) {
             if (ch == test->expect[pos]) {
@@ -148,6 +149,15 @@  static bool check_guest_output(const testdef_t *test, int fd)
             }
         }
         g_assert(nbr >= 0);
+        /* Wait only if the child is still alive.  */
+        if (!qtest_probe_child(global_qtest)) {
+            break;
+        }
+        /* Wait at most 360 seconds.  */
+        now = time(NULL);
+        if (now - start >= 360) {
+            break;
+        }
         g_usleep(10000);
     }
 
diff --git a/tests/libqtest.c b/tests/libqtest.c
index 43be078518..1d75d3c936 100644
--- a/tests/libqtest.c
+++ b/tests/libqtest.c
@@ -39,10 +39,11 @@  struct QTestState
 {
     int fd;
     int qmp_fd;
+    pid_t qemu_pid;  /* our child QEMU process */
+    int wstatus;
+    bool big_endian;
     bool irq_level[MAX_IRQ];
     GString *rx;
-    pid_t qemu_pid;  /* our child QEMU process */
-    bool big_endian;
 };
 
 static GHookList abrt_hooks;
@@ -96,36 +97,52 @@  static int socket_accept(int sock)
     return ret;
 }
 
+bool qtest_probe_child(QTestState *s)
+{
+    pid_t pid = s->qemu_pid;
+
+    if (pid != -1) {
+        pid = waitpid(pid, &s->wstatus, WNOHANG);
+        if (pid == 0) {
+            return true;
+        }
+        s->qemu_pid = -1;
+    }
+    return false;
+}
+
 static void kill_qemu(QTestState *s)
 {
-    if (s->qemu_pid != -1) {
-        int wstatus = 0;
-        pid_t pid;
-
-        kill(s->qemu_pid, SIGTERM);
-        TFR(pid = waitpid(s->qemu_pid, &wstatus, 0));
+    pid_t pid = s->qemu_pid;
+    int wstatus;
 
+    /* Skip wait if qtest_probe_child already reaped.  */
+    if (pid != -1) {
+        kill(pid, SIGTERM);
+        TFR(pid = waitpid(s->qemu_pid, &s->wstatus, 0));
         assert(pid == s->qemu_pid);
-        /*
-         * We expect qemu to exit with status 0; anything else is
-         * fishy and should be logged with as much detail as possible.
-         */
-        if (wstatus) {
-            if (WIFEXITED(wstatus)) {
-                fprintf(stderr, "%s:%d: kill_qemu() tried to terminate QEMU "
-                        "process but encountered exit status %d\n",
-                        __FILE__, __LINE__, WEXITSTATUS(wstatus));
-            } else if (WIFSIGNALED(wstatus)) {
-                int sig = WTERMSIG(wstatus);
-                const char *signame = strsignal(sig) ?: "unknown ???";
-                const char *dump = WCOREDUMP(wstatus) ? " (core dumped)" : "";
+    }
 
-                fprintf(stderr, "%s:%d: kill_qemu() detected QEMU death "
-                        "from signal %d (%s)%s\n",
-                        __FILE__, __LINE__, sig, signame, dump);
-            }
-            abort();
+    /*
+     * We expect qemu to exit with status 0; anything else is
+     * fishy and should be logged with as much detail as possible.
+     */
+    wstatus = s->wstatus;
+    if (wstatus) {
+        if (WIFEXITED(wstatus)) {
+            fprintf(stderr, "%s:%d: kill_qemu() tried to terminate QEMU "
+                    "process but encountered exit status %d\n",
+                    __FILE__, __LINE__, WEXITSTATUS(wstatus));
+        } else if (WIFSIGNALED(wstatus)) {
+            int sig = WTERMSIG(wstatus);
+            const char *signame = strsignal(sig) ?: "unknown ???";
+            const char *dump = WCOREDUMP(wstatus) ? " (core dumped)" : "";
+
+            fprintf(stderr, "%s:%d: kill_qemu() detected QEMU death "
+                    "from signal %d (%s)%s\n",
+                    __FILE__, __LINE__, sig, signame, dump);
         }
+        abort();
     }
 }
 
@@ -228,6 +245,7 @@  QTestState *qtest_init_without_qmp_handshake(const char *extra_args)
 
     g_test_message("starting QEMU: %s", command);
 
+    s->wstatus = 0;
     s->qemu_pid = fork();
     if (s->qemu_pid == 0) {
         setenv("QEMU_AUDIO_DRV", "none", true);