[PATCH v7 0/1] util/async-teardown: appear in query-command-line-options

[PATCH v7 0/1] util/async-teardown: appear in query-command-line-options

[Claudio Imbrenda]

Add new -run-with option with an async-teardown=on|off parameter. It
is visible in the output of query-command-line-options QMP command, so
it can be discovered and used by libvirt.

The option -async-teardown is now redundant, deprecate it.

v6->v7
* move variable declaration inside #ifdef to avoid compile time errors
  on *BSD due to unused variables. [thomas]

v5->v6
* deprecate the old -async-teardown option instead of removing it,
  since it has now appeared in 2 QEMU releases
* use -run-with as a grab bag commandline option for the async-teardown
  boolean parameter [paolo,markus,thomas]

v4->v5
* reword commit message [Markus]
* document the removal of the -async-teardown commandline option in
  docs/about/removed-features.rst [Markus]

v3->v4
* completely remove the useless -async-teardown option, since it was
  not wired up properly and it had no users [thomas]
* QEMU should be always uppercase in text and documentation [thomas]
* if the new -teardown option fails to parse, exit immediately instead
  of returning an error [thomas]

v2->v3
* add a new teardown option with an async parameter [Markus]
* reworded documentation of existing -async-teardown option so that it
  points to the new teardown option

v1->v2
* remove the unneeded .implied_opt_name initializer [Thomas]

Claudio Imbrenda (1):
  util/async-teardown: wire up query-command-line-options

 docs/about/deprecated.rst |  5 +++++
 os-posix.c                | 13 +++++++++++++
 qemu-options.hx           | 34 +++++++++++++++++++++++-----------
 util/async-teardown.c     | 21 +++++++++++++++++++++
 4 files changed, 62 insertions(+), 11 deletions(-)

-- 
2.40.1

[PATCH v7 1/1] util/async-teardown: wire up query-command-line-options

[Claudio Imbrenda]

Add new -run-with option with an async-teardown=on|off parameter. It is
visible in the output of query-command-line-options QMP command, so it
can be discovered and used by libvirt.

The option -async-teardown is now redundant, deprecate it.

Reported-by: Boris Fiuczynski <fiuczy@linux.ibm.com>
Fixes: c891c24b1a ("os-posix: asynchronous teardown for shutdown on Linux")
Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
---
 docs/about/deprecated.rst |  5 +++++
 os-posix.c                | 13 +++++++++++++
 qemu-options.hx           | 34 +++++++++++++++++++++++-----------
 util/async-teardown.c     | 21 +++++++++++++++++++++
 4 files changed, 62 insertions(+), 11 deletions(-)

diff --git a/docs/about/deprecated.rst b/docs/about/deprecated.rst
index 1ca9dc33d6..0986db9a86 100644
--- a/docs/about/deprecated.rst
+++ b/docs/about/deprecated.rst
@@ -111,6 +111,11 @@ Use ``-machine acpi=off`` instead.
 The HAXM project has been retired (see https://github.com/intel/haxm#status).
 Use "whpx" (on Windows) or "hvf" (on macOS) instead.
 
+``-async-teardown`` (since 8.1)
+,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,
+
+Use ``-run-with async-teardown=on`` instead.
+
 
 QEMU Machine Protocol (QMP) commands
 ------------------------------------
diff --git a/os-posix.c b/os-posix.c
index 5adc69f560..ef910aaf94 100644
--- a/os-posix.c
+++ b/os-posix.c
@@ -36,6 +36,8 @@
 #include "qemu/log.h"
 #include "sysemu/runstate.h"
 #include "qemu/cutils.h"
+#include "qemu/config-file.h"
+#include "qemu/option.h"
 
 #ifdef CONFIG_LINUX
 #include <sys/prctl.h>
@@ -152,9 +154,20 @@ int os_parse_cmd_args(int index, const char *optarg)
         daemonize = 1;
         break;
 #if defined(CONFIG_LINUX)
+    /* deprecated */
     case QEMU_OPTION_asyncteardown:
         init_async_teardown();
         break;
+    case QEMU_OPTION_run_with:
+        QemuOpts *opts = qemu_opts_parse_noisily(qemu_find_opts("run-with"),
+                                                 optarg, false);
+        if (!opts) {
+            exit(1);
+        }
+        if (qemu_opt_get_bool(opts, "async-teardown", false)) {
+            init_async_teardown();
+        }
+        break;
 #endif
     default:
         return -1;
diff --git a/qemu-options.hx b/qemu-options.hx
index b5efa648ba..24a1d63bbe 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -4799,20 +4799,32 @@ DEF("qtest-log", HAS_ARG, QEMU_OPTION_qtest_log, "", QEMU_ARCH_ALL)
 DEF("async-teardown", 0, QEMU_OPTION_asyncteardown,
     "-async-teardown enable asynchronous teardown\n",
     QEMU_ARCH_ALL)
-#endif
 SRST
 ``-async-teardown``
-    Enable asynchronous teardown. A new process called "cleanup/<QEMU_PID>"
-    will be created at startup sharing the address space with the main qemu
-    process, using clone. It will wait for the main qemu process to
-    terminate completely, and then exit.
-    This allows qemu to terminate very quickly even if the guest was
-    huge, leaving the teardown of the address space to the cleanup
-    process. Since the cleanup process shares the same cgroups as the
-    main qemu process, accounting is performed correctly. This only
-    works if the cleanup process is not forcefully killed with SIGKILL
-    before the main qemu process has terminated completely.
+    This option is deprecated and should no longer be used. The new option
+    ``-run-with async-teardown=on`` is a replacement.
 ERST
+DEF("run-with", HAS_ARG, QEMU_OPTION_run_with,
+    "-run-with async-teardown[=on|off]\n"
+    "                misc QEMU process lifecycle options\n"
+    "                async-teardown=on enables asynchronous teardown\n",
+    QEMU_ARCH_ALL)
+SRST
+``-run-with``
+    Set QEMU process lifecycle options.
+
+    ``async-teardown=on`` enables asynchronous teardown. A new process called
+    "cleanup/<QEMU_PID>" will be created at startup sharing the address
+    space with the main QEMU process, using clone. It will wait for the
+    main QEMU process to terminate completely, and then exit. This allows
+    QEMU to terminate very quickly even if the guest was huge, leaving the
+    teardown of the address space to the cleanup process. Since the cleanup
+    process shares the same cgroups as the main QEMU process, accounting is
+    performed correctly. This only works if the cleanup process is not
+    forcefully killed with SIGKILL before the main QEMU process has
+    terminated completely.
+ERST
+#endif
 
 DEF("msg", HAS_ARG, QEMU_OPTION_msg,
     "-msg [timestamp[=on|off]][,guest-name=[on|off]]\n"
diff --git a/util/async-teardown.c b/util/async-teardown.c
index 62cdeb0f20..3ab19c8740 100644
--- a/util/async-teardown.c
+++ b/util/async-teardown.c
@@ -12,6 +12,9 @@
  */
 
 #include "qemu/osdep.h"
+#include "qemu/config-file.h"
+#include "qemu/option.h"
+#include "qemu/module.h"
 #include <dirent.h>
 #include <sys/prctl.h>
 #include <sched.h>
@@ -144,3 +147,21 @@ void init_async_teardown(void)
     clone(async_teardown_fn, new_stack_for_clone(), CLONE_VM, NULL);
     sigprocmask(SIG_SETMASK, &old_signals, NULL);
 }
+
+static QemuOptsList qemu_run_with_opts = {
+    .name = "run-with",
+    .head = QTAILQ_HEAD_INITIALIZER(qemu_run_with_opts.head),
+    .desc = {
+        {
+            .name = "async-teardown",
+            .type = QEMU_OPT_BOOL,
+        },
+        { /* end of list */ }
+    },
+};
+
+static void register_teardown(void)
+{
+    qemu_add_opts(&qemu_run_with_opts);
+}
+opts_init(register_teardown);
-- 
2.40.1

Re: [PATCH v7 1/1] util/async-teardown: wire up query-command-line-options

[Thomas Huth]

On 05/05/2023 14.00, Claudio Imbrenda wrote:
> Add new -run-with option with an async-teardown=on|off parameter. It is
> visible in the output of query-command-line-options QMP command, so it
> can be discovered and used by libvirt.
> 
> The option -async-teardown is now redundant, deprecate it.
> 
> Reported-by: Boris Fiuczynski <fiuczy@linux.ibm.com>
> Fixes: c891c24b1a ("os-posix: asynchronous teardown for shutdown on Linux")
> Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
> ---
>   docs/about/deprecated.rst |  5 +++++
>   os-posix.c                | 13 +++++++++++++
>   qemu-options.hx           | 34 +++++++++++++++++++++++-----------
>   util/async-teardown.c     | 21 +++++++++++++++++++++
>   4 files changed, 62 insertions(+), 11 deletions(-)

Reviewed-by: Thomas Huth <thuth@redhat.com>

Re: [PATCH v7 1/1] util/async-teardown: wire up query-command-line-options

[Thomas Huth]

On 05/05/2023 14.00, Claudio Imbrenda wrote:
> Add new -run-with option with an async-teardown=on|off parameter. It is
> visible in the output of query-command-line-options QMP command, so it
> can be discovered and used by libvirt.
> 
> The option -async-teardown is now redundant, deprecate it.
...
> diff --git a/os-posix.c b/os-posix.c
> index 5adc69f560..ef910aaf94 100644
> --- a/os-posix.c
> +++ b/os-posix.c
> @@ -36,6 +36,8 @@
>   #include "qemu/log.h"
>   #include "sysemu/runstate.h"
>   #include "qemu/cutils.h"
> +#include "qemu/config-file.h"
> +#include "qemu/option.h"
>   
>   #ifdef CONFIG_LINUX
>   #include <sys/prctl.h>
> @@ -152,9 +154,20 @@ int os_parse_cmd_args(int index, const char *optarg)
>           daemonize = 1;
>           break;
>   #if defined(CONFIG_LINUX)
> +    /* deprecated */
>       case QEMU_OPTION_asyncteardown:
>           init_async_teardown();
>           break;
> +    case QEMU_OPTION_run_with:
> +        QemuOpts *opts = qemu_opts_parse_noisily(qemu_find_opts("run-with"),
> +                                                 optarg, false);
> +        if (!opts) {
> +            exit(1);
> +        }
> +        if (qemu_opt_get_bool(opts, "async-teardown", false)) {
> +            init_async_teardown();
> +        }
> +        break;
>   #endif

This is causing now a compiler error with GCC 8.5 here:

../../devel/qemu/os-posix.c: In function ‘os_parse_cmd_args’:
../../devel/qemu/os-posix.c:162:9: error: a label can only be part
  of a statement and a declaration is not a statement
          QemuOpts *opts = qemu_opts_parse_noisily(qemu_find_opts("run-with"),
          ^~~~~~~~

I'll fix it up by adding some curly braces on top, no need to resend:

diff --git a/os-posix.c b/os-posix.c
--- a/os-posix.c
+++ b/os-posix.c
@@ -158,7 +158,7 @@ int os_parse_cmd_args(int index, const char *optarg)
      case QEMU_OPTION_asyncteardown:
          init_async_teardown();
          break;
-    case QEMU_OPTION_run_with:
+    case QEMU_OPTION_run_with: {
          QemuOpts *opts = qemu_opts_parse_noisily(qemu_find_opts("run-with"),
                                                   optarg, false);
          if (!opts) {
@@ -168,6 +168,7 @@ int os_parse_cmd_args(int index, const char *optarg)
              init_async_teardown();
          }
          break;
+    }
  #endif
      default:
          return -1;

Thomas