From dc48263a6a213885e1a2bb432cceaa65a968a5e7 Mon Sep 17 00:00:00 2001
From: Gregory Nutt <gnutt@nuttx.org>
Date: Fri, 14 Sep 2018 09:02:03 -0600
Subject: [PATCH] libs/libc/wqueue/work_usrthread.c:  Revise commit
 49e725625ae9a08f7b2953aeb7e6714f8cc9b4b2.  Use sigprocmask() so tht we do not
 lose a signal, not sched_lock() which will not do the job in SMP mode.

---
 libs/libc/wqueue/work_usrthread.c | 36 ++++++++++++++++++++-----------
 sched/signal/sig_nanosleep.c      |  4 ++--
 2 files changed, 25 insertions(+), 15 deletions(-)

diff --git a/libs/libc/wqueue/work_usrthread.c b/libs/libc/wqueue/work_usrthread.c
index e28a4a20ca..b0f06c3a98 100644
--- a/libs/libc/wqueue/work_usrthread.c
+++ b/libs/libc/wqueue/work_usrthread.c
@@ -123,6 +123,8 @@ pthread_mutex_t g_usrmutex;
 void work_process(FAR struct usr_wqueue_s *wqueue)
 {
   volatile FAR struct work_s *work;
+  sigset_t sigset;
+  sigset_t oldset;
   worker_t  worker;
   FAR void *arg;
   clock_t elapsed;
@@ -145,6 +147,11 @@ void work_process(FAR struct usr_wqueue_s *wqueue)
       return;
     }
 
+  /* Set up the signal mask */
+
+  sigemptyset(&sigset);
+  sigaddset(&sigset, SIGWORK);
+
   /* Get the time that we started this polling cycle in clock ticks. */
 
   stick = clock();
@@ -215,7 +222,7 @@ void work_process(FAR struct usr_wqueue_s *wqueue)
             }
           else
             {
-              /* Cancelled.. Just move to the next work in the list with
+              /* Canceled.. Just move to the next work in the list with
                * the work queue still locked.
                */
 
@@ -255,36 +262,39 @@ void work_process(FAR struct usr_wqueue_s *wqueue)
         }
     }
 
-  /* Unlock the work queue before waiting.  In order to assure that these
-   * operations are atomic with respect to other user tasks, we disable
-   * pre-emption here.  Pre-emption will be re-enabled while we sleep.
+  /* Unlock the work queue before waiting.  In order to assure that we do
+   * not lose the SIGWORK signal before waiting, we block the SIGWORK
+   * signals before unlocking the work queue.  That will cause in SIGWORK
+   * signals directed to the worker thread to pend.
    */
 
-  sched_lock();
+  (void)nxsig_procmask(SIG_BLOCK, &sigset, &oldset);
   work_unlock();
 
   if (next == WORK_DELAY_MAX)
     {
-      sigset_t set;
-
       /* Wait indefinitely until signaled with SIGWORK */
 
-      sigemptyset(&set);
-      sigaddset(&set, SIGWORK);
-
-      sigwaitinfo(&set, NULL);
+      sigwaitinfo(&sigset, NULL);
     }
   else
     {
+      struct timespec rqtp;
+      time_t sec;
+
       /* Wait awhile to check the work list.  We will wait here until
        * either the time elapses or until we are awakened by a signal.
        * Interrupts will be re-enabled while we wait.
        */
 
-      usleep(next * USEC_PER_TICK);
+      sec          = next / 1000000;
+      rqtp.tv_sec  = sec;
+      rqtp.tv_nsec = (next - (sec * 1000000)) * 1000;
+
+      sigtimewait(&sigset, NULL, &rqtp);
     }
 
-  sched_unlock();
+  (void)nxsig_procmask(SIG_SETMASK, &oldset, NULL);
 }
 
 /****************************************************************************
diff --git a/sched/signal/sig_nanosleep.c b/sched/signal/sig_nanosleep.c
index 81f4014c5f..319af24214 100644
--- a/sched/signal/sig_nanosleep.c
+++ b/sched/signal/sig_nanosleep.c
@@ -113,7 +113,7 @@ int nxsig_nanosleep(FAR const struct timespec *rqtp,
 
   /* Sanity check */
 
-  if (!rqtp || rqtp->tv_nsec < 0 || rqtp->tv_nsec >= 1000000000)
+  if (rqtp != NULL || rqtp->tv_nsec < 0 || rqtp->tv_nsec >= 1000000000)
     {
       return -EINVAL;
     }
@@ -178,7 +178,7 @@ int nxsig_nanosleep(FAR const struct timespec *rqtp,
       elapsed = clock_systimer() - starttick;
 
       /* The difference between the number of ticks that we were requested
-       * to wait and the number of ticks that we actualy waited is that
+       * to wait and the number of ticks that we actually waited is that
        * amount of time that we failed to wait.
        */