From 5e39c59eec7618b06fa2c26a77dfafd90a349e44 Mon Sep 17 00:00:00 2001
From: Thierry Bordaz <tbordaz@redhat.com>
Date: Jul 24 2018 09:45:35 +0000
Subject: Ticket 49848 - Nunc-stans event thread can be hanging shortly when a job is (re)armed


Bug Description:
	When a nunc-stans job is rearmed, event_q_notify enqueue the job and notify the event thread.

	The first thing event thread does is to lock the job.
	But until internal_ns_job_rearm release the lock, event thread is hanging.

	This is also the case of a worker thread (work_q_notify) but has less negative impact
Fix Description:
	Release the lock of the job before calling event_q_notify/work_q_notify

https://pagure.io/389-ds-base/issue/49848

Reviewed by: ?

Platforms tested: F27

Flag Day: no

Doc impact: no

---

diff --git a/src/nunc-stans/ns/ns_thrpool.c b/src/nunc-stans/ns/ns_thrpool.c
index 774607c..ae2072a 100644
--- a/src/nunc-stans/ns/ns_thrpool.c
+++ b/src/nunc-stans/ns/ns_thrpool.c
@@ -260,6 +260,15 @@ internal_ns_job_rearm(ns_job_t *job)
 
     /* I think we need to check about is_shutdown here? */
 
+    /*
+     * weither it will wakeup a NS worker thread (work_q) or the NS event thread (event_q)
+     * This thread will acquire the job->monitor.
+     * To prevent the thread to wait just release the lock before waking it
+     *
+     * This is specifically important for the event thread
+     */
+    pthread_mutex_unlock(&(job->monitor));
+
     if (NS_JOB_IS_IO(job->job_type) || NS_JOB_IS_TIMER(job->job_type) || NS_JOB_IS_SIGNAL(job->job_type)) {
         event_q_notify(job);
     } else {
@@ -267,7 +276,6 @@ internal_ns_job_rearm(ns_job_t *job)
         /* Prevents an un-necessary queue / dequeue to the event_q */
         work_q_notify(job);
     }
-    pthread_mutex_unlock(&(job->monitor));
 }
 
 static void
@@ -1027,6 +1035,7 @@ ns_add_job(ns_thrpool_t *tp, ns_job_type_t job_type, ns_job_func_t func, void *d
     if (!_job) {
         return NS_ALLOCATION_FAILURE;
     }
+    pthread_mutex_lock(&(_job->monitor));
     /* fill in a pointer to the job for the caller if requested */
     if (job) {
         *job = _job;
@@ -1036,6 +1045,7 @@ ns_add_job(ns_thrpool_t *tp, ns_job_type_t job_type, ns_job_func_t func, void *d
     ns_log(LOG_DEBUG, "ns_add_job %x state %d moving to NS_JOB_ARMED\n", _job, (_job)->state);
 #endif
     _job->state = NS_JOB_NEEDS_ARM;
+    pthread_mutex_unlock(&(_job->monitor));
     internal_ns_job_rearm(_job);
 
     return NS_SUCCESS;
@@ -1218,8 +1228,8 @@ ns_job_rearm(ns_job_t *job)
         ns_log(LOG_DEBUG, "ns_rearm_job %x state %d moving to NS_JOB_NEEDS_ARM\n", job, job->state);
 #endif
         job->state = NS_JOB_NEEDS_ARM;
-        internal_ns_job_rearm(job);
         pthread_mutex_unlock(&(job->monitor));
+        internal_ns_job_rearm(job);
         return NS_SUCCESS;
     } else if (!NS_JOB_IS_PERSIST(job->job_type) && job->state == NS_JOB_RUNNING) {
 /* For this to be called, and NS_JOB_RUNNING, we *must* be the callback thread! */