debian/patches/extra/0002-monitor-delay-monitor-iothread-creation.patch

   1 From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
   2 From: Wolfgang Bumiller <w.bumiller@proxmox.com>
   3 Date: Tue, 25 Sep 2018 10:15:07 +0200
   4 Subject: [PATCH] monitor: delay monitor iothread creation
   5
   6 Commit d32749deb615 moved the call to monitor_init_globals()
   7 to before os_daemonize(), making it an unsuitable place to
   8 spawn the monitor iothread as it won't be inherited over the
   9 fork() in os_daemonize().
  10
  11 We now spawn the thread the first time we instantiate a
  12 monitor which actually has use_io_thread == true.
  13 Instantiation of monitors happens only after os_daemonize().
  14 We still need to create the qmp_dispatcher_bh when not using
  15 iothreads, so this now still happens in
  16 monitor_init_globals().
  17
  18 Signed-off-by: Wolfgang Bumiller <w.bumiller@proxmox.com>
  19 Fixes: d32749deb615 ("monitor: move init global earlier")
  20 Message-Id: <20180925081507.11873-3-w.bumiller@proxmox.com>
  21 Reviewed-by: Eric Blake <eblake@redhat.com>
  22 Reviewed-by: Peter Xu <peterx@redhat.com>
  23 Tested-by: Peter Xu <peterx@redhat.com>
  24 [This fixes a crash on shutdown with --daemonize]
  25 Signed-off-by: Markus Armbruster <armbru@redhat.com>
  26 ---
  27  monitor.c | 36 ++++++++++++++++++++++--------------
  28  1 file changed, 22 insertions(+), 14 deletions(-)
  29
  30 diff --git a/monitor.c b/monitor.c
  31 index 836c0bbdaa..c7eae64fd9 100644
  32 --- a/monitor.c
  33 +++ b/monitor.c
  34 @@ -807,9 +807,14 @@ static void monitor_qapi_event_init(void)
  35
  36  static void handle_hmp_command(Monitor *mon, const char *cmdline);
  37
  38 +static void monitor_iothread_init(void);
  39 +
  40  static void monitor_data_init(Monitor *mon, bool skip_flush,
  41                                bool use_io_thread)
  42  {
  43 +    if (use_io_thread && !mon_iothread) {
  44 +        monitor_iothread_init();
  45 +    }
  46      memset(mon, 0, sizeof(Monitor));
  47      qemu_mutex_init(&mon->mon_lock);
  48      qemu_mutex_init(&mon->qmp.qmp_queue_lock);
  49 @@ -4544,6 +4549,15 @@ static AioContext *monitor_get_aio_context(void)
  50  static void monitor_iothread_init(void)
  51  {
  52      mon_iothread = iothread_create("mon_iothread", &error_abort);
  53 +}
  54 +
  55 +void monitor_init_globals(void)
  56 +{
  57 +    monitor_init_qmp_commands();
  58 +    monitor_qapi_event_init();
  59 +    sortcmdlist();
  60 +    qemu_mutex_init(&monitor_lock);
  61 +    qemu_mutex_init(&mon_fdsets_lock);
  62
  63      /*
  64       * The dispatcher BH must run in the main loop thread, since we
  65 @@ -4559,21 +4573,11 @@ static void monitor_iothread_init(void)
  66       * monitors that are using the I/O thread have their output
  67       * written by the I/O thread.
  68       */
  69 -    qmp_respond_bh = aio_bh_new(monitor_get_aio_context(),
  70 +    qmp_respond_bh = aio_bh_new(iohandler_get_aio_context(),
  71                                  monitor_qmp_bh_responder,
  72                                  NULL);
  73  }
  74
  75 -void monitor_init_globals(void)
  76 -{
  77 -    monitor_init_qmp_commands();
  78 -    monitor_qapi_event_init();
  79 -    sortcmdlist();
  80 -    qemu_mutex_init(&monitor_lock);
  81 -    qemu_mutex_init(&mon_fdsets_lock);
  82 -    monitor_iothread_init();
  83 -}
  84 -
  85  /* These functions just adapt the readline interface in a typesafe way.  We
  86   * could cast function pointers but that discards compiler checks.
  87   */
  88 @@ -4711,7 +4715,9 @@ void monitor_cleanup(void)
  89       * we need to unregister from chardev below in
  90       * monitor_data_destroy(), and chardev is not thread-safe yet
  91       */
  92 -    iothread_stop(mon_iothread);
  93 +    if (mon_iothread) {
  94 +        iothread_stop(mon_iothread);
  95 +    }
  96
  97      /*
  98       * Flush all response queues.  Note that even after this flush,
  99 @@ -4735,8 +4741,10 @@ void monitor_cleanup(void)
 100      qemu_bh_delete(qmp_respond_bh);
 101      qmp_respond_bh = NULL;
 102
 103 -    iothread_destroy(mon_iothread);
 104 -    mon_iothread = NULL;
 105 +    if (mon_iothread) {
 106 +        iothread_destroy(mon_iothread);
 107 +        mon_iothread = NULL;
 108 +    }
 109  }
 110
 111  QemuOptsList qemu_mon_opts = {
 112 --
 113 2.11.0
 114