patchdir/0004-dmeventd-schedule-exit-on-break.patch

   1 From 9940c2f754e3292b6d96628682c254941ae6cc58 Mon Sep 17 00:00:00 2001
   2 From: Zdenek Kabelac <zkabelac@redhat.com>
   3 Date: Wed, 4 Oct 2017 13:58:21 +0200
   4 Subject: [PATCH] dmeventd: schedule exit on break
   5
   6 When dmeventd receives SIGTERM/INT/HUP/QUIT it validates if exit is possible.
   7 If there was any device still monitored, such exit request used to
   8 be ignored/refused. This 'usually' worked reasonably well, however if there
   9 is very short time period between last device is unmonitored and signal
  10 reception - there was possibility such EXIT was ignored, as dmeventd has
  11 not yet got into idle state even commands like 'vgchange -an' has already
  12 finished.
  13
  14 This patch changes logic towards scheduling EXIT to the nearest
  15 point when there is no monitored device.
  16
  17 EXIT is never forgotten.
  18
  19 NOTE: if there is only a single monitored device and someone sends
  20 SIGTERM and later someone uses i.e. 'lvchange --refresh' after
  21 unmonitoring dmeventd will exit and new instance needs to be
  22 started.
  23
  24 cherry picked from commit 9940c2f754e3292b6d96628682c254941ae6cc58
  25
  26 Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>
  27 ---
  28  daemons/dmeventd/dmeventd.c | 13 ++++++++-----
  29  1 files changed, 8 insertions(+), 5 deletions(-)
  30
  31 diff --git a/daemons/dmeventd/dmeventd.c b/daemons/dmeventd/dmeventd.c
  32 index 3a92ab6..cc520d3 100644
  33 --- a/daemons/dmeventd/dmeventd.c
  34 +++ b/daemons/dmeventd/dmeventd.c
  35 @@ -62,6 +62,8 @@
  36
  37  #include <syslog.h>
  38
  39 +#define DM_SIGNALED_EXIT  1
  40 +#define DM_SCHEDULED_EXIT 2
  41  static volatile sig_atomic_t _exit_now = 0;    /* set to '1' when signal is given to exit */
  42
  43  /* List (un)link macros. */
  44 @@ -1750,7 +1752,7 @@ static void _init_thread_signals(void)
  45   */
  46  static void _exit_handler(int sig __attribute__((unused)))
  47  {
  48 -       _exit_now = 1;
  49 +       _exit_now = DM_SIGNALED_EXIT;
  50  }
  51
  52  #ifdef __linux__
  53 @@ -2248,6 +2250,8 @@ int main(int argc, char *argv[])
  54         for (;;) {
  55                 if (_idle_since) {
  56                         if (_exit_now) {
  57 +                               if (_exit_now == DM_SCHEDULED_EXIT)
  58 +                                       break; /* Only prints shutdown message */
  59                                 log_info("dmeventd detected break while being idle "
  60                                          "for %ld second(s), exiting.",
  61                                          (long) (time(NULL) - _idle_since));
  62 @@ -2264,15 +2268,14 @@ int main(int argc, char *argv[])
  63                                         break;
  64                                 }
  65                         }
  66 -               } else if (_exit_now) {
  67 -                       _exit_now = 0;
  68 +               } else if (_exit_now == DM_SIGNALED_EXIT) {
  69 +                       _exit_now = DM_SCHEDULED_EXIT;
  70                         /*
  71                          * When '_exit_now' is set, signal has been received,
  72                          * but can not simply exit unless all
  73                          * threads are done processing.
  74                          */
  75 -                       log_warn("WARNING: There are still devices being monitored.");
  76 -                       log_warn("WARNING: Refusing to exit.");
  77 +                       log_info("dmeventd received break, scheduling exit.");
  78                 }
  79                 _process_request(&fifos);
  80                 _cleanup_unused_threads();
  81 --
  82 2.9.3