Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 5debfa6d authored by Oleg Nesterov's avatar Oleg Nesterov Committed by Linus Torvalds
Browse files

[PATCH] coredump: shutdown current process first 



This patch optimizes zap_threads() for the case when there are no ->mm
users except the current's thread group.  In that case we can avoid
'for_each_process()' loop.

It also adds a useful invariant: SIGNAL_GROUP_EXIT (if checked under
->siglock) always implies that all threads (except may be current) have
pending SIGKILL.

Signed-off-by: default avatarOleg Nesterov <oleg@tv-sign.ru>
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent dcf560c5

fs/exec.c

+17 −12
Original line number Diff line number Diff line
@@ -1371,13 +1371,7 @@ static void format_corename(char *corename, const char *pattern, long signr) 
static void zap_process(struct task_struct *start)

{

	struct task_struct *t;

	unsigned long flags;



	/*

	 * start->sighand can't disappear, but may be

	 * changed by de_thread()

	 */

	lock_task_sighand(start, &flags);

	start->signal->flags = SIGNAL_GROUP_EXIT;

	start->signal->group_stop_count = 0;
@@ -1389,40 +1383,51 @@ static void zap_process(struct task_struct *start) 
			signal_wake_up(t, 1);

		}

	} while ((t = next_thread(t)) != start);



	unlock_task_sighand(start, &flags);

}



static inline int zap_threads(struct task_struct *tsk, struct mm_struct *mm,

				int exit_code)

{

	struct task_struct *g, *p;

	unsigned long flags;

	int err = -EAGAIN;



	spin_lock_irq(&tsk->sighand->siglock);

	if (!(tsk->signal->flags & SIGNAL_GROUP_EXIT)) {

		tsk->signal->flags = SIGNAL_GROUP_EXIT;

		tsk->signal->group_exit_code = exit_code;

		tsk->signal->group_stop_count = 0;

		zap_process(tsk);

		err = 0;

	}

	spin_unlock_irq(&tsk->sighand->siglock);

	if (err)

		return err;



	if (atomic_read(&mm->mm_users) == mm->core_waiters + 1)

		goto done;



	rcu_read_lock();

	for_each_process(g) {

		if (g == tsk->group_leader)

			continue;



		p = g;

		do {

			if (p->mm) {

				if (p->mm == mm)

				if (p->mm == mm) {

					/*

					 * p->sighand can't disappear, but

					 * may be changed by de_thread()

					 */

					lock_task_sighand(p, &flags);

					zap_process(p);

					unlock_task_sighand(p, &flags);

				}

				break;

			}

		} while ((p = next_thread(p)) != g);

	}

	rcu_read_unlock();



done:

	return mm->core_waiters;

}