performance/io-threads: Exit all threads on PARENT_DOWN

Problem:
When glfs_fini() is called on a volume where client.io-threads is enabled,
fini() will free up iothread xl's private structure but there would be some
threads that are sleeping which would wakeup after the timedwait completes
leading to accessing already free'd memory.

Fix:
As part of parent-down, exit all sleeping threads.

Please note that the upstream patch differs from this a little bit,
because least-prio-throttling feature is removed from master, 3.9

 >BUG: 1381830
 >Change-Id: I0bb8d90241112c355fb22ee3fbfd7307f475b339
 >Signed-off-by: Pranith Kumar K <pkarampu@redhat.com>
 >Reviewed-on: http://review.gluster.org/15620
 >Smoke: Gluster Build System <jenkins@build.gluster.org>
 >CentOS-regression: Gluster Build System <jenkins@build.gluster.org>
 >NetBSD-regression: NetBSD Build System <jenkins@build.gluster.org>
 >Reviewed-by: Raghavendra G <rgowdapp@redhat.com>
 >(cherry picked from commit d7a5ca16911caca03cec1112d4be56a9cda2ee30)

BUG: 1412941
Change-Id: I6341156251279b24ab2323cedf1b9722e42da671
Signed-off-by: Pranith Kumar K <pkarampu@redhat.com>
Reviewed-on: http://review.gluster.org/16396
Smoke: Gluster Build System <jenkins@build.gluster.org>
NetBSD-regression: NetBSD Build System <jenkins@build.gluster.org>
CentOS-regression: Gluster Build System <jenkins@build.gluster.org>

2 files changed, 49 insertions, 23 deletions

diff --git a/xlators/performance/io-threads/src/io-threads.c b/xlators/performance/io-threads/src/io-threads.c
index c81a97d8a39..394be8acb75 100644
--- a/xlators/performance/io-threads/src/io-threads.c
+++ b/xlators/performance/io-threads/src/io-threads.c
@@ -153,9 +153,8 @@ iot_worker (void *data)
         struct timespec   sleep_till = {0, };
         int               ret = 0;
         int               pri = -1;
-        char              timeout = 0;
-        char              bye = 0;
 	struct timespec	  sleep = {0,};
+        gf_boolean_t      bye = _gf_false;
 
         conf = data;
         this = conf->this;
@@ -171,6 +170,11 @@ iot_worker (void *data)
                                 pri = -1;
                         }
                         while (conf->queue_size == 0) {
+                                if (conf->down) {
+                                        bye = _gf_true;/*Avoid sleep*/
+                                        break;
+                                }
+
                                 conf->sleep_count++;
 
                                 ret = pthread_cond_timedwait (&conf->cond,
@@ -178,48 +182,48 @@ iot_worker (void *data)
                                                               &sleep_till);
                                 conf->sleep_count--;
 
-                                if (ret == ETIMEDOUT) {
-                                        timeout = 1;
+                                if (conf->down || ret == ETIMEDOUT) {
+                                        bye = _gf_true;
                                         break;
                                 }
                         }
 
-                        if (timeout) {
-                                if (conf->curr_count > IOT_MIN_THREADS) {
+                        if (bye) {
+                                if (conf->down ||
+                                    conf->curr_count > IOT_MIN_THREADS) {
                                         conf->curr_count--;
-                                        bye = 1;
+                                        if (conf->curr_count == 0)
+                                           pthread_cond_broadcast (&conf->cond);
                                         gf_msg_debug (conf->this->name, 0,
-                                                      "timeout, terminated. conf->curr_count=%d",
+                                                      "terminated. "
+                                                      "conf->curr_count=%d",
                                                       conf->curr_count);
                                 } else {
-                                        timeout = 0;
+                                        bye = _gf_false;
                                 }
                         }
 
-                        stub = __iot_dequeue (conf, &pri, &sleep);
-			if (!stub && (sleep.tv_sec || sleep.tv_nsec)) {
-				pthread_cond_timedwait(&conf->cond,
-						       &conf->mutex, &sleep);
-				pthread_mutex_unlock(&conf->mutex);
-				continue;
-			}
+                        if (!bye) {
+                                stub = __iot_dequeue (conf, &pri, &sleep);
+                                if (!stub && (sleep.tv_sec || sleep.tv_nsec)) {
+                                        pthread_cond_timedwait(&conf->cond,
+                                                               &conf->mutex,
+                                                               &sleep);
+                                        pthread_mutex_unlock(&conf->mutex);
+                                        continue;
+                                }
+                        }
                 }
                 pthread_mutex_unlock (&conf->mutex);
 
                 if (stub) /* guard against spurious wakeups */
                         call_resume (stub);
+                stub = NULL;
 
                 if (bye)
                         break;
         }
 
-        if (pri != -1) {
-                pthread_mutex_lock (&conf->mutex);
-                {
-                        conf->ac_iot_count[pri]--;
-                }
-                pthread_mutex_unlock (&conf->mutex);
-        }
         return NULL;
 }
 
@@ -1021,6 +1025,27 @@ out:
 	return ret;
 }
 
+int
+notify (xlator_t *this, int32_t event, void *data, ...)
+{
+        iot_conf_t *conf = this->private;
+
+        if (GF_EVENT_PARENT_DOWN == event) {
+                pthread_mutex_lock (&conf->mutex);
+                {
+                        conf->down = _gf_true;
+                        /*Let all the threads know that xl is going down*/
+                        pthread_cond_broadcast (&conf->cond);
+                        while (conf->curr_count)/*Wait for threads to exit*/
+                                pthread_cond_wait (&conf->cond, &conf->mutex);
+                }
+                pthread_mutex_unlock (&conf->mutex);
+        }
+
+        default_notify (this, event, data);
+
+        return 0;
+}
 
 void
 fini (xlator_t *this)
diff --git a/xlators/performance/io-threads/src/io-threads.h b/xlators/performance/io-threads/src/io-threads.h
index d8eea2cf77a..cb984f0d967 100644
--- a/xlators/performance/io-threads/src/io-threads.h
+++ b/xlators/performance/io-threads/src/io-threads.h
@@ -79,6 +79,7 @@ struct iot_conf {
         xlator_t            *this;
         size_t              stack_size;
 
+        gf_boolean_t         down; /*PARENT_DOWN event is notified*/
 	struct iot_least_throttle throttle;
 };