---

yaml
---
r: 36210
b: refs/heads/master
c: c18258c
h: refs/heads/master
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 35fa2048ab13d1be846be612e395c15c200bd51c
+refs/heads/master: c18258c6f0848f97e85287f6271c511a092bb784

trunk/fs/exec.c

@@ -696,23 +696,20 @@ static int de_thread(struct task_struct *tsk)
 		 */
 
 		/* Become a process group leader with the old leader's pid.
-		 * Note: The old leader also uses thispid until release_task
+		 * The old leader becomes a thread of the this thread group.
+		 * Note: The old leader also uses this pid until release_task
 		 *       is called.  Odd but simple and correct.
 		 */
 		detach_pid(current, PIDTYPE_PID);
 		current->pid = leader->pid;
 		attach_pid(current, PIDTYPE_PID,  current->pid);
-		attach_pid(current, PIDTYPE_PGID, current->signal->pgrp);
-		attach_pid(current, PIDTYPE_SID,  current->signal->session);
+		transfer_pid(leader, current, PIDTYPE_PGID);
+		transfer_pid(leader, current, PIDTYPE_SID);
 		list_replace_rcu(&leader->tasks, &current->tasks);
 
 		current->group_leader = current;
 		leader->group_leader = current;
 
-		/* Reduce leader to a thread */
-		detach_pid(leader, PIDTYPE_PGID);
-		detach_pid(leader, PIDTYPE_SID);
-
 		current->exit_signal = SIGCHLD;
 
 		BUG_ON(leader->exit_state != EXIT_ZOMBIE);

trunk/include/linux/pid.h

@@ -76,6 +76,8 @@ extern int FASTCALL(attach_pid(struct task_struct *task,
 				enum pid_type type, int nr));
 
 extern void FASTCALL(detach_pid(struct task_struct *task, enum pid_type));
+extern void FASTCALL(transfer_pid(struct task_struct *old,
+				  struct task_struct *new, enum pid_type));
 
 /*
  * look up a PID in the hash table. Must be called with the tasklist_lock

trunk/kernel/pid.c

@@ -252,6 +252,15 @@ void fastcall detach_pid(struct task_struct *task, enum pid_type type)
 	free_pid(pid);
 }
 
+/* transfer_pid is an optimization of attach_pid(new), detach_pid(old) */
+void fastcall transfer_pid(struct task_struct *old, struct task_struct *new,
+			   enum pid_type type)
+{
+	new->pids[type].pid = old->pids[type].pid;
+	hlist_replace_rcu(&old->pids[type].node, &new->pids[type].node);
+	old->pids[type].pid = NULL;
+}
+
 struct task_struct * fastcall pid_task(struct pid *pid, enum pid_type type)
 {
 	struct task_struct *result = NULL;