From 3c2a00bc4bd4bb93b6217183d8366ebdcd4d9b26 Mon Sep 17 00:00:00 2001
From: Heesub Shin <heesub@gmail.com>
Date: Sun, 6 Nov 2016 07:56:38 -0600
Subject: [PATCH] LP worker:  When queuing new work, don't signal any threads
 if they are all busy

---
 sched/wqueue/kwork_queue.c  |  4 ++--
 sched/wqueue/kwork_signal.c | 17 ++++++++++-------
 2 files changed, 12 insertions(+), 9 deletions(-)

diff --git a/sched/wqueue/kwork_queue.c b/sched/wqueue/kwork_queue.c
index 3c4acb2d00..0ac27a87b7 100644
--- a/sched/wqueue/kwork_queue.c
+++ b/sched/wqueue/kwork_queue.c
@@ -152,7 +152,7 @@ int work_queue(int qid, FAR struct work_s *work, worker_t worker,
 #ifdef CONFIG_SCHED_HPWORK
   if (qid == HPWORK)
     {
-      /* Cancel high priority work */
+      /* Queue high priority work */
 
       work_qqueue((FAR struct kwork_wqueue_s *)&g_hpwork, work, worker, arg, delay);
       return work_signal(HPWORK);
@@ -162,7 +162,7 @@ int work_queue(int qid, FAR struct work_s *work, worker_t worker,
 #ifdef CONFIG_SCHED_LPWORK
   if (qid == LPWORK)
     {
-      /* Cancel low priority work */
+      /* Queue low priority work */
 
       work_qqueue((FAR struct kwork_wqueue_s *)&g_lpwork, work, worker, arg, delay);
       return work_signal(LPWORK);
diff --git a/sched/wqueue/kwork_signal.c b/sched/wqueue/kwork_signal.c
index 9359fb2e2a..9c5b9a8e97 100644
--- a/sched/wqueue/kwork_signal.c
+++ b/sched/wqueue/kwork_signal.c
@@ -85,12 +85,11 @@ int work_signal(int qid)
 #ifdef CONFIG_SCHED_LPWORK
   if (qid == LPWORK)
     {
-      int wndx;
       int i;
 
       /* Find an IDLE worker thread */
 
-      for (wndx = 0, i = 0; i < CONFIG_SCHED_LPNTHREADS; i++)
+      for (i = 0; i < CONFIG_SCHED_LPNTHREADS; i++)
         {
           /* Is this worker thread busy? */
 
@@ -98,16 +97,20 @@ int work_signal(int qid)
             {
               /* No.. select this thread */
 
-              wndx = i;
               break;
             }
         }
 
-      /* Use the process ID of the IDLE worker thread (or the ID of worker
-       * thread 0 if all of the worker threads are busy).
-       */
+      /* If all of the IDLE threads are busy, then just return successfully */
 
-      pid = g_lpwork.worker[wndx].pid;
+      if (i >= CONFIG_SCHED_LPNTHREADS)
+        {
+          return OK;
+        }
+
+      /* Otherwise, signal the first IDLE thread found */
+
+      pid = g_lpwork.worker[i].pid;
     }
   else
 #endif