From: Martin Wilck <mwilck@xxxxxxxx>
With the previous patch, one race condition between child() and
the uevent handler (ev_add_map()) remains: 1. child() sets
__delayed_reconfig, 2. ev_add_map() calls schedule_reconfigure() and
thus DAEMON_CONFIGURE, 3. child() sets DAEMON_IDLE. This would cause
the pending reconfigure request to be missed.
To fix this, reset __delayed_reconfig immediately from ev_add_map()
(and likewise, missing_uev_wait_tick()). This way the wait loop in
child() terminates on the reconfigure_pending condition.
Also, these schedule_reconfigure() callers don't really request a
reconfigure() call; they just unblock processing previously requested
reconfigure() calls. Add a new helper, unblock_reconfigure(), that
does just that.
Suggested-by: Benjamin Marzinski <bmarzins@xxxxxxxxxx>
Signed-off-by: Martin Wilck <mwilck@xxxxxxxx>
---
multipathd/main.c | 45 +++++++++++++++++++++++++--------------------
1 file changed, 25 insertions(+), 20 deletions(-)
diff --git a/multipathd/main.c b/multipathd/main.c
index d033a9a..1454a18 100644
--- a/multipathd/main.c
+++ b/multipathd/main.c
@@ -155,16 +155,6 @@ int should_exit(void)
return get_running_state() == DAEMON_SHUTDOWN;
}
-static bool get_delayed_reconfig(void)
-{
- bool val;
-
- pthread_mutex_lock(&config_lock);
- val = __delayed_reconfig;
- pthread_mutex_unlock(&config_lock);
- return val;
-}
-
/*
* global copy of vecs for use in sig handlers
*/
@@ -308,6 +298,27 @@ void post_config_state(enum daemon_status state)
pthread_cleanup_pop(1);
}
+static bool unblock_reconfigure(void)
+{
+ bool was_delayed;
+
+ pthread_mutex_lock(&config_lock);
+ was_delayed = __delayed_reconfig;
+ if (was_delayed) {
+ __delayed_reconfig = false;
+ /*
+ * In IDLE state, make sure child() is woken up
+ * Otherwise it will wake up when state switches to IDLE
+ */
+ if (running_state == DAEMON_IDLE)
+ __post_config_state(DAEMON_CONFIGURE);
+ }
+ pthread_mutex_unlock(&config_lock);
+ if (was_delayed)
+ condlog(3, "unblocked delayed reconfigure");
+ return was_delayed;
+}
+
void schedule_reconfigure(enum force_reload_types requested_type)
{
pthread_mutex_lock(&config_lock);
@@ -790,12 +801,9 @@ ev_add_map (char * dev, const char * alias, struct vectors * vecs)
dm_get_info(mpp->alias, &mpp->dmi);
if (mpp->wait_for_udev) {
mpp->wait_for_udev = 0;
- if (get_delayed_reconfig() &&
- !need_to_delay_reconfig(vecs)) {
- condlog(2, "reconfigure (delayed)");
- schedule_reconfigure(FORCE_RELOAD_WEAK);
+ if (!need_to_delay_reconfig(vecs) &&
+ unblock_reconfigure())
return 0;
- }
}
/*
* Not really an error -- we generate our own uevent
@@ -1899,11 +1907,8 @@ missing_uev_wait_tick(struct vectors *vecs)
}
}
- if (timed_out && get_delayed_reconfig() &&
- !need_to_delay_reconfig(vecs)) {
- condlog(2, "reconfigure (delayed)");
- schedule_reconfigure(FORCE_RELOAD_WEAK);
- }
+ if (timed_out && !need_to_delay_reconfig(vecs))
+ unblock_reconfigure();
}
static void
--
2.35.1
--
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