From 27c7974cb112e77012a1c9f0723aeb0af50e67ea Mon Sep 17 00:00:00 2001
From: Xiang Xiao <xiaoxiang@xiaomi.com>
Date: Thu, 8 Nov 2018 07:39:37 -0600
Subject: [PATCH] sched/signal/sig_suspend.c:  sigsuspend() shouldn't eat the
 pending signal but dispatch all instead

---
 sched/signal/sig_suspend.c             | 38 ++++++++++----------------
 sched/signal/sig_unmaskpendingsignal.c | 11 ++++++--
 sched/signal/signal.h                  |  2 +-
 3 files changed, 25 insertions(+), 26 deletions(-)

diff --git a/sched/signal/sig_suspend.c b/sched/signal/sig_suspend.c
index 242596c419..a4f5ebdf68 100644
--- a/sched/signal/sig_suspend.c
+++ b/sched/signal/sig_suspend.c
@@ -93,11 +93,8 @@
 int sigsuspend(FAR const sigset_t *set)
 {
   FAR struct tcb_s *rtcb = this_task();
-  sigset_t intersection;
   sigset_t saved_sigprocmask;
-  FAR sigpendq_t *sigpend;
   irqstate_t flags;
-  int unblocksigno;
 
   /* sigsuspend() is a cancellation point */
 
@@ -112,36 +109,30 @@ int sigsuspend(FAR const sigset_t *set)
   sched_lock();  /* Not necessary */
   flags = enter_critical_section();
 
+  /* Save a copy of the old sigprocmask and install
+   * the new (temporary) sigprocmask
+   */
+
+  saved_sigprocmask = rtcb->sigprocmask;
+  rtcb->sigprocmask = *set;
+  rtcb->sigwaitmask = NULL_SIGNAL_SET;
+
   /* Check if there is a pending signal corresponding to one of the
    * signals that will be unblocked by the new sigprocmask.
    */
 
-  intersection = ~(*set) & nxsig_pendingset(rtcb);
-  if (intersection != NULL_SIGNAL_SET)
+  if (nxsig_unmask_pendingsignal())
     {
-      /* One or more of the signals in intersections is sufficient to cause
-       * us to not wait.  Pick the lowest numbered signal and mark it not
-       * pending.
+      /* Dispatching one or more of the signals is sufficient to cause
+       * us to not wait. Restore the original sigprocmask.
        */
 
-      unblocksigno = nxsig_lowest(&intersection);
-      sigpend = nxsig_remove_pendingsignal(rtcb, unblocksigno);
-      DEBUGASSERT(sigpend);
-
-      nxsig_release_pendingsignal(sigpend);
+      rtcb->sigprocmask = saved_sigprocmask;
       leave_critical_section(flags);
     }
   else
     {
-      /* Its time to wait. Save a copy of the old sigprocmask and install
-       * the new (temporary) sigprocmask
-       */
-
-      saved_sigprocmask = rtcb->sigprocmask;
-      rtcb->sigprocmask = *set;
-      rtcb->sigwaitmask = NULL_SIGNAL_SET;
-
-      /* And wait until one of the unblocked signals is posted */
+      /* Its time to wait until one of the unblocked signals is posted */
 
       up_block_task(rtcb, TSTATE_WAIT_SIG);
 
@@ -160,5 +151,6 @@ int sigsuspend(FAR const sigset_t *set)
 
   sched_unlock();
   leave_cancellation_point();
-  return ERROR; /* ??REVISIT:  Always returns ERROR?? */
+  set_errno(EINTR);
+  return ERROR;
 }
diff --git a/sched/signal/sig_unmaskpendingsignal.c b/sched/signal/sig_unmaskpendingsignal.c
index c47392ad6f..ef439f635e 100644
--- a/sched/signal/sig_unmaskpendingsignal.c
+++ b/sched/signal/sig_unmaskpendingsignal.c
@@ -58,7 +58,7 @@
  *
  ****************************************************************************/
 
-void nxsig_unmask_pendingsignal(void)
+bool nxsig_unmask_pendingsignal(void)
 {
   FAR struct tcb_s *rtcb = this_task();
   sigset_t unmaskedset;
@@ -79,10 +79,15 @@ void nxsig_unmask_pendingsignal(void)
    */
 
   unmaskedset = ~(rtcb->sigprocmask) & nxsig_pendingset(rtcb);
+  if (unmaskedset == NULL_SIGNAL_SET)
+    {
+      sched_unlock();
+      return false;
+    }
 
   /* Loop while there are unmasked pending signals to be processed. */
 
-  while (unmaskedset != NULL_SIGNAL_SET)
+  do
     {
       /* Pending signals will be processed from lowest numbered signal
        * to highest
@@ -117,7 +122,9 @@ void nxsig_unmask_pendingsignal(void)
             }
         }
     }
+  while (unmaskedset != NULL_SIGNAL_SET);
 
   sched_unlock();
+  return true;
 }
 
diff --git a/sched/signal/signal.h b/sched/signal/signal.h
index 3ecaf7906b..32d72a6c38 100644
--- a/sched/signal/signal.h
+++ b/sched/signal/signal.h
@@ -215,6 +215,6 @@ int                nxsig_mqnotempty(int tid, int signo, FAR void *sival_ptr);
 void               nxsig_release_pendingsigaction(FAR sigq_t *sigq);
 void               nxsig_release_pendingsignal(FAR sigpendq_t *sigpend);
 FAR sigpendq_t    *nxsig_remove_pendingsignal(FAR struct tcb_s *stcb, int signo);
-void               nxsig_unmask_pendingsignal(void);
+bool               nxsig_unmask_pendingsignal(void);
 
 #endif /* __SCHED_SIGNAL_SIGNAL_H */