From: Roland McGrath <roland@redhat.com>

All extant uses of `notify_parent' are for ptrace stops, unless it is used
by external modules that I have not seen.  This patch tightens up some of
the signal code by making notify_parent only work for the stopped case. 
That means that do_notify_parent is exclusively used for the dead case and
doesn't need to check for the stopped case.  The only outward effect of
this is to make ptrace stops (i.e.  notify_parent calls) obey the
SA_NOCLDSTOP behavior instead of incorrectly checking SA_NOCLDWAIT.  I'm
sure no ptrace user actually sets SA_NOCLDSTOP, so it won't be noticed in
reality at all.  

Also, no modules now need notify_parent(), so remove its export.

Signed-off-by: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
---

 25-akpm/kernel/signal.c |   60 ++++++++++++++++++++----------------------------
 1 files changed, 25 insertions(+), 35 deletions(-)

diff -puN kernel/signal.c~notify_parent-cleanup kernel/signal.c
--- 25/kernel/signal.c~notify_parent-cleanup	2004-08-17 23:44:04.591635744 -0700
+++ 25-akpm/kernel/signal.c	2004-08-17 23:44:46.439273936 -0700
@@ -1441,19 +1441,22 @@ static void __wake_up_parent(struct task
 }
 
 /*
- * Let a parent know about a status change of a child.
+ * Let a parent know about the death of a child.
+ * For a stopped/continued status change, use do_notify_parent_cldstop instead.
  */
 
 void do_notify_parent(struct task_struct *tsk, int sig)
 {
 	struct siginfo info;
 	unsigned long flags;
-	int why, status;
 	struct sighand_struct *psig;
 
 	if (sig == -1)
 		BUG();
 
+	/* do_notify_parent_cldstop should have been called instead.  */
+	BUG_ON(tsk->state == TASK_STOPPED);
+
 	BUG_ON(tsk->group_leader != tsk && tsk->group_leader->state != TASK_ZOMBIE && !tsk->ptrace);
 	BUG_ON(tsk->group_leader == tsk && !thread_group_empty(tsk) && !tsk->ptrace);
 
@@ -1467,34 +1470,19 @@ void do_notify_parent(struct task_struct
 	info.si_stime = tsk->stime;
 	k_getrusage(tsk, RUSAGE_BOTH, &info.si_rusage);
 
-	status = tsk->exit_code & 0x7f;
-	why = SI_KERNEL;	/* shouldn't happen */
-	switch (tsk->state) {
-	case TASK_STOPPED:
-		/* FIXME -- can we deduce CLD_TRAPPED or CLD_CONTINUED? */
-		if (tsk->ptrace & PT_PTRACED)
-			why = CLD_TRAPPED;
-		else
-			why = CLD_STOPPED;
-		break;
-
-	default:
-		if (tsk->exit_code & 0x80)
-			why = CLD_DUMPED;
-		else if (tsk->exit_code & 0x7f)
-			why = CLD_KILLED;
-		else {
-			why = CLD_EXITED;
-			status = tsk->exit_code >> 8;
-		}
-		break;
+	info.si_status = tsk->exit_code & 0x7f;
+	if (tsk->exit_code & 0x80)
+		info.si_code = CLD_DUMPED;
+	else if (tsk->exit_code & 0x7f)
+		info.si_code = CLD_KILLED;
+	else {
+		info.si_code = CLD_EXITED;
+		info.si_status = tsk->exit_code >> 8;
 	}
-	info.si_code = why;
-	info.si_status = status;
 
 	psig = tsk->parent->sighand;
 	spin_lock_irqsave(&psig->siglock, flags);
-	if (sig == SIGCHLD && tsk->state != TASK_STOPPED &&
+	if (sig == SIGCHLD &&
 	    (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN ||
 	     (psig->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT))) {
 		/*
@@ -1525,19 +1513,20 @@ void do_notify_parent(struct task_struct
 
 /*
  * We need the tasklist lock because it's the only
- * thing that protects out "parent" pointer.
+ * thing that protects our "parent" pointer.
  *
- * exit.c calls "do_notify_parent()" directly, because
- * it already has the tasklist lock.
+ * This entrypoint was once used in other ways, but now it is
+ * only ever called as "notify_parent(current, SIGCHLD)" after
+ * entering TASK_STOPPED state.
  */
 void
 notify_parent(struct task_struct *tsk, int sig)
 {
-	if (sig != -1) {
-		read_lock(&tasklist_lock);
-		do_notify_parent(tsk, sig);
-		read_unlock(&tasklist_lock);
-	}
+	BUG_ON(sig != SIGCHLD);
+	BUG_ON(tsk->state != TASK_STOPPED);
+	read_lock(&tasklist_lock);
+	do_notify_parent_cldstop(tsk, tsk->parent);
+	read_unlock(&tasklist_lock);
 }
 
 static void
@@ -1562,6 +1551,8 @@ do_notify_parent_cldstop(struct task_str
 	if (info.si_status == 0) {
 		info.si_status = SIGCONT;
 		info.si_code = CLD_CONTINUED;
+	} else if (tsk->ptrace & PT_PTRACED) {
+		info.si_code = CLD_TRAPPED;
 	} else {
 		info.si_code = CLD_STOPPED;
 	}
@@ -1929,7 +1920,6 @@ EXPORT_SYMBOL(kill_proc);
 EXPORT_SYMBOL(kill_proc_info);
 EXPORT_SYMBOL(kill_sl);
 EXPORT_SYMBOL(kill_sl_info);
-EXPORT_SYMBOL(notify_parent);
 EXPORT_SYMBOL(send_sig);
 EXPORT_SYMBOL(send_sig_info);
 EXPORT_SYMBOL(send_group_sig_info);
_