sched/signal/sig_dispatch.c: Simplify the nxsig_dispatch

The nxsig_dispatch should just deliver the signal to either a
thread by pid (tid) or to the process (group) by pid.

Simplify the code so that the intent is more obvious.

Signed-off-by: Jukka Laitinen <jukka.laitinen@tii.ae>

Author: jlaitine

sched/signal/sig_dispatch.c

@@ -725,70 +725,29 @@ int nxsig_tcbdispatch(FAR struct tcb_s *stcb, siginfo_t *info,
 int nxsig_dispatch(pid_t pid, FAR siginfo_t *info, bool thread)
 {
 #ifdef HAVE_GROUP_MEMBERS
-  FAR struct tcb_s *stcb;
-  FAR struct task_group_s *group;
-
-  /* Get the TCB associated with the pid */
-
-  stcb = nxsched_get_tcb(pid);
-  if (stcb != NULL)
+  if (!thread)
     {
-      /* The task/thread associated with this PID is still active. Get its
-       * task group.
+      /* Find the group by process PID and call group signal() to send the
+       * signal to the correct group member.
        */
 
-      group = stcb->group;
+      FAR struct task_group_s *group = task_getgroup(pid);
+      if (group != NULL)
+        {
+          return group_signal(group, info);
+        }
     }
   else
+#endif
     {
-      /* The task/thread associated with this PID has exited. In the normal
-       * usage model, the PID should correspond to the PID of the task that
-       * created the task group. Try looking it up.
-       */
-
-      group = task_getgroup(pid);
-    }
-
-  /* Did we locate the group? */
-
-  if (group != NULL)
-    {
-      if (thread)
-        {
-          /* Before the notification, we should validate the tid. If the
-           * signal is to be delivered to a thread which has exited, it is
-           * just dropped.
-           */
+      /* Get the TCB associated with the thread TID */
 
-          if (stcb != NULL)
-            {
-              return nxsig_tcbdispatch(stcb, info, false);
-            }
-        }
-      else
+      FAR struct tcb_s *stcb = nxsched_get_tcb(pid);
+      if (stcb != NULL)
         {
-          /* Yes.. call group_signal() to send the signal to the correct
-           * group member.
-           */
-
-          return group_signal(group, info);
+          return nxsig_tcbdispatch(stcb, info, false);
         }
     }
 
   return -ESRCH;
-
-#else
-  FAR struct tcb_s *stcb;
-
-  /* Get the TCB associated with the pid */
-
-  stcb = nxsched_get_tcb(pid);
-  if (stcb == NULL)
-    {
-      return -ESRCH;
-    }
-
-  return nxsig_tcbdispatch(stcb, info, false);
-
-#endif
 }