introduce kill_orphaned_pgrp() helper

Factor out the common code in reparent_thread() and exit_notify().

No functional changes.
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

kernel/exit.c

@@ -255,6 +255,37 @@ static int has_stopped_jobs(struct pid *pgrp)
 	return retval;
 }
 
+/*
+ * Check to see if any process groups have become orphaned as
+ * a result of our exiting, and if they have any stopped jobs,
+ * send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2)
+ */
+static void
+kill_orphaned_pgrp(struct task_struct *tsk, struct task_struct *parent)
+{
+	struct pid *pgrp = task_pgrp(tsk);
+	struct task_struct *ignored_task = tsk;
+
+	if (!parent)
+		 /* exit: our father is in a different pgrp than
+		  * we are and we were the only connection outside.
+		  */
+		parent = tsk->real_parent;
+	else
+		/* reparent: our child is in a different pgrp than
+		 * we are, and it was the only connection outside.
+		 */
+		ignored_task = NULL;
+
+	if (task_pgrp(parent) != pgrp &&
+	    task_session(parent) == task_session(tsk) &&
+	    will_become_orphaned_pgrp(pgrp, ignored_task) &&
+	    has_stopped_jobs(pgrp)) {
+		__kill_pgrp_info(SIGHUP, SEND_SIG_PRIV, pgrp);
+		__kill_pgrp_info(SIGCONT, SEND_SIG_PRIV, pgrp);
+	}
+}
+
 /**
  * reparent_to_kthreadd - Reparent the calling kernel thread to kthreadd
  *
@@ -635,22 +666,7 @@ reparent_thread(struct task_struct *p, struct task_struct *father, int traced)
 	    p->exit_signal != -1 && thread_group_empty(p))
 		do_notify_parent(p, p->exit_signal);
 
-	/*
-	 * process group orphan check
-	 * Case ii: Our child is in a different pgrp
-	 * than we are, and it was the only connection
-	 * outside, so the child pgrp is now orphaned.
-	 */
-	if ((task_pgrp(p) != task_pgrp(father)) &&
-	    (task_session(p) == task_session(father))) {
-		struct pid *pgrp = task_pgrp(p);
-
-		if (will_become_orphaned_pgrp(pgrp, NULL) &&
-		    has_stopped_jobs(pgrp)) {
-			__kill_pgrp_info(SIGHUP, SEND_SIG_PRIV, pgrp);
-			__kill_pgrp_info(SIGCONT, SEND_SIG_PRIV, pgrp);
-		}
-	}
+	kill_orphaned_pgrp(p, father);
 }
 
 /*
@@ -738,8 +754,6 @@ static void forget_original_parent(struct task_struct *father)
 static void exit_notify(struct task_struct *tsk)
 {
 	int state;
-	struct task_struct *t;
-	struct pid *pgrp;
 
 	/*
 	 * This does two things:
@@ -753,25 +767,7 @@ static void exit_notify(struct task_struct *tsk)
 	exit_task_namespaces(tsk);
 
 	write_lock_irq(&tasklist_lock);
-	/*
-	 * Check to see if any process groups have become orphaned
-	 * as a result of our exiting, and if they have any stopped
-	 * jobs, send them a SIGHUP and then a SIGCONT.  (POSIX 3.2.2.2)
-	 *
-	 * Case i: Our father is in a different pgrp than we are
-	 * and we were the only connection outside, so our pgrp
-	 * is about to become orphaned.
-	 */
-	t = tsk->real_parent;
-
-	pgrp = task_pgrp(tsk);
-	if ((task_pgrp(t) != pgrp) &&
-	    (task_session(t) == task_session(tsk)) &&
-	    will_become_orphaned_pgrp(pgrp, tsk) &&
-	    has_stopped_jobs(pgrp)) {
-		__kill_pgrp_info(SIGHUP, SEND_SIG_PRIV, pgrp);
-		__kill_pgrp_info(SIGCONT, SEND_SIG_PRIV, pgrp);
-	}
+	kill_orphaned_pgrp(tsk, NULL);
 
 	/* Let father know we died
 	 *
@@ -788,8 +784,8 @@ static void exit_notify(struct task_struct *tsk)
 	 * the same after a fork.
 	 */
 	if (tsk->exit_signal != SIGCHLD && tsk->exit_signal != -1 &&
-	    ( tsk->parent_exec_id != t->self_exec_id  ||
-	      tsk->self_exec_id != tsk->parent_exec_id)
+	    (tsk->parent_exec_id != tsk->real_parent->self_exec_id ||
+	     tsk->self_exec_id != tsk->parent_exec_id)
 	    && !capable(CAP_KILL))
 		tsk->exit_signal = SIGCHLD;