[dm-devel] [PATCH v2 1/4] multipathd: move delayed_reconfig out of struct config

[Benjamin Marzinski]

delayed_reconfig was inside the config struct, but it wasn't updated
during an RCU write section, so there's no synchronization on it.
Instead, pull it out of the config structure, and use the config_lock
to synchronize it.

Signed-off-by: Benjamin Marzinski <bmarzins at redhat.com>
---
 libmultipath/config.h |  1 -
 multipathd/main.c     | 45 ++++++++++++++++++++++++++++---------------
 2 files changed, 29 insertions(+), 17 deletions(-)

diff --git a/libmultipath/config.h b/libmultipath/config.h
index 933fe0d1..c73389b5 100644
--- a/libmultipath/config.h
+++ b/libmultipath/config.h
@@ -178,7 +178,6 @@ struct config {
 	int strict_timing;
 	int retrigger_tries;
 	int retrigger_delay;
-	int delayed_reconfig;
 	int uev_wait_timeout;
 	int skip_kpartx;
 	int remove_retries;
diff --git a/multipathd/main.c b/multipathd/main.c
index 2b416af9..1ead0904 100644
--- a/multipathd/main.c
+++ b/multipathd/main.c
@@ -127,6 +127,8 @@ static int poll_dmevents = 1;
 #endif
 /* Don't access this variable without holding config_lock */
 static volatile enum daemon_status running_state = DAEMON_INIT;
+/* Don't access this variable without holding config_lock */
+static bool __delayed_reconfig;
 pid_t daemon_pid;
 static pthread_mutex_t config_lock = PTHREAD_MUTEX_INITIALIZER;
 static pthread_cond_t config_cond;
@@ -150,6 +152,23 @@ 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;
+}
+
+static void set_delayed_reconfig(bool val)
+{
+	pthread_mutex_lock(&config_lock);
+	__delayed_reconfig = val;
+	pthread_mutex_unlock(&config_lock);
+}
+
 /*
  * global copy of vecs for use in sig handlers
  */
@@ -297,8 +316,10 @@ static void __post_config_state(enum daemon_status state)
 			old_state = DAEMON_IDLE;
 			state = DAEMON_CONFIGURE;
 		}
-		if (reconfigure_pending && state == DAEMON_CONFIGURE)
+		if (state == DAEMON_CONFIGURE) {
 			reconfigure_pending = false;
+			__delayed_reconfig = false;
+		}
 		running_state = state;
 		pthread_cond_broadcast(&config_cond);
 		do_sd_notify(old_state, state);
@@ -765,7 +786,7 @@ int
 ev_add_map (char * dev, const char * alias, struct vectors * vecs)
 {
 	struct multipath * mpp;
-	int delayed_reconfig, reassign_maps;
+	int reassign_maps;
 	struct config *conf;
 
 	if (dm_is_mpath(alias) != 1) {
@@ -784,12 +805,11 @@ ev_add_map (char * dev, const char * alias, struct vectors * vecs)
 				return 1;
 		}
 		conf = get_multipath_config();
-		delayed_reconfig = conf->delayed_reconfig;
 		reassign_maps = conf->reassign_maps;
 		put_multipath_config(conf);
 		if (mpp->wait_for_udev) {
 			mpp->wait_for_udev = 0;
-			if (delayed_reconfig &&
+			if (get_delayed_reconfig() &&
 			    !need_to_delay_reconfig(vecs)) {
 				condlog(2, "reconfigure (delayed)");
 				schedule_reconfigure();
@@ -1791,8 +1811,7 @@ missing_uev_wait_tick(struct vectors *vecs)
 {
 	struct multipath * mpp;
 	unsigned int i;
-	int timed_out = 0, delayed_reconfig;
-	struct config *conf;
+	int timed_out = 0;
 
 	vector_foreach_slot (vecs->mpvec, mpp, i) {
 		if (mpp->wait_for_udev && --mpp->uev_wait_tick <= 0) {
@@ -1808,10 +1827,7 @@ missing_uev_wait_tick(struct vectors *vecs)
 		}
 	}
 
-	conf = get_multipath_config();
-	delayed_reconfig = conf->delayed_reconfig;
-	put_multipath_config(conf);
-	if (timed_out && delayed_reconfig &&
+	if (timed_out && get_delayed_reconfig() &&
 	    !need_to_delay_reconfig(vecs)) {
 		condlog(2, "reconfigure (delayed)");
 		schedule_reconfigure();
@@ -3257,13 +3273,10 @@ child (__attribute__((unused)) void *param)
 			pthread_cleanup_push(cleanup_lock, &vecs->lock);
 			lock(&vecs->lock);
 			pthread_testcancel();
-			if (!need_to_delay_reconfig(vecs)) {
+			if (!need_to_delay_reconfig(vecs))
 				reconfigure(vecs);
-			} else {
-				conf = get_multipath_config();
-				conf->delayed_reconfig = 1;
-				put_multipath_config(conf);
-			}
+			else
+				set_delayed_reconfig(true);
 			lock_cleanup_pop(vecs->lock);
 			post_config_state(DAEMON_IDLE);
 		}
-- 
2.17.2