From: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
To: Al Viro <viro@ZenIV.linux.org.uk>
Cc: kosaki.motohiro@jp.fujitsu.com,
Am??rico Wang <xiyou.wangcong@gmail.com>,
"Eric W. Biederman" <ebiederm@xmission.com>,
Tavis Ormandy <taviso@google.com>, Jeff Dike <jdike@addtoit.com>,
Julien Tinnes <jln@google.com>, Matt Mackall <mpm@selenic.com>,
LKML <linux-kernel@vger.kernel.org>,
Oleg Nesterov <oleg@redhat.com>,
Alan Cox <alan@lxorguk.ukuu.org.uk>
Subject: Re: [2.6.33-rc5] starting emacs makes lockdep warning
Date: Tue, 26 Jan 2010 16:45:41 +0900 (JST) [thread overview]
Message-ID: <20100126164018.1D59.A69D9226@jp.fujitsu.com> (raw)
In-Reply-To: <20100126060705.GF19799@ZenIV.linux.org.uk>
Hi
> On Tue, Jan 26, 2010 at 02:01:12PM +0800, Am??rico Wang wrote:
>
> > I agree, it seems that patch is useless, since we already
> > do lock_kernel() before calling __f_setown()...
>
> What's to prevent pid from being freed under us? BKL won't...
I don't understand this issue at all. so, this is stupid dumb question.
Why can't we write following code?
enum pid_type type;
struct pid *pid;
if (!waitqueue_active(&tty->read_wait))
tty->minimum_to_wake = 1;
spin_lock_irqsave(&tty->ctrl_lock, flags);
if (tty->pgrp) {
pid = tty->pgrp;
type = PIDTYPE_PGID;
} else {
pid = task_pid(current);
type = PIDTYPE_PID;
}
get_pid(pid) // insert here
spin_unlock_irqrestore(&tty->ctrl_lock, flags);
retval = __f_setown(filp, pid, type, 0);
put_pid(pid) // insert here
next prev parent reply other threads:[~2010-01-26 7:45 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-01-26 3:20 KOSAKI Motohiro
2010-01-26 5:25 ` Américo Wang
2010-01-26 5:37 ` KOSAKI Motohiro
2010-01-26 5:49 ` KOSAKI Motohiro
2010-01-26 6:01 ` Américo Wang
2010-01-26 6:07 ` Al Viro
2010-01-26 6:24 ` Américo Wang
2010-01-26 6:54 ` Al Viro
2010-01-26 7:45 ` KOSAKI Motohiro [this message]
2010-01-26 8:45 ` Américo Wang
2010-01-26 9:14 ` Eric W. Biederman
2010-01-26 9:32 ` Américo Wang
2010-01-26 12:33 ` Eric W. Biederman
2010-01-26 15:58 ` [Patch] fix the lockdep warning in tty_fasync() Américo Wang
2010-01-27 1:09 ` KOSAKI Motohiro
2010-01-27 1:47 ` Greg KH
2010-01-26 6:17 ` [2.6.33-rc5] starting emacs makes lockdep warning Eric W. Biederman
2010-01-26 18:16 ` check_usage_backwards() && forwards? (Was: [2.6.33-rc5] starting emacs makes lockdep warning) Oleg Nesterov
2010-01-26 18:47 ` Peter Zijlstra
2010-01-27 2:58 ` Américo Wang
2010-01-27 13:15 ` [tip:core/urgent] lockdep: Fix check_usage_backwards() error message tip-bot for Oleg Nesterov
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