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Commit aaa2a97e authored by Oleg Nesterov's avatar Oleg Nesterov Committed by Linus Torvalds
Browse files

[PATCH] sys_get_robust_list(): don't take tasklist_lock 



use rcu locks for find_task_by_pid().

Signed-off-by: default avatarOleg Nesterov <oleg@tv-sign.ru>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent d359b549

kernel/futex.c

+3 −3
Original line number Original line Diff line number Diff line
@@ -1624,7 +1624,7 @@ sys_get_robust_list(int pid, struct robust_list_head __user **head_ptr, 
		struct task_struct *p;

		struct task_struct *p;





		ret = -ESRCH;

		ret = -ESRCH;

		read_lock(&tasklist_lock);

		rcu_read_lock();

		p = find_task_by_pid(pid);

		p = find_task_by_pid(pid);

		if (!p)

		if (!p)

			goto err_unlock;

			goto err_unlock;
@@ -1633,7 +1633,7 @@ sys_get_robust_list(int pid, struct robust_list_head __user **head_ptr, 
				!capable(CAP_SYS_PTRACE))

				!capable(CAP_SYS_PTRACE))

			goto err_unlock;

			goto err_unlock;

		head = p->robust_list;

		head = p->robust_list;

		read_unlock(&tasklist_lock);

		rcu_read_unlock();

	}

	}





	if (put_user(sizeof(*head), len_ptr))

	if (put_user(sizeof(*head), len_ptr))
@@ -1641,7 +1641,7 @@ sys_get_robust_list(int pid, struct robust_list_head __user **head_ptr, 
	return put_user(head, head_ptr);

	return put_user(head, head_ptr);





err_unlock:

err_unlock:

	read_unlock(&tasklist_lock);

	rcu_read_unlock();





	return ret;

	return ret;

}

}