From: Oleg Nesterov <oleg@redhat.com>
To: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: "Serge E. Hallyn" <serge@hallyn.com>,
Andrew Morton <akpm@linux-foundation.org>,
David Howells <dhowells@redhat.com>,
"Serge E. Hallyn" <serge.hallyn@canonical.com>,
lkml <linux-kernel@vger.kernel.org>,
richard@nod.at, "Eric W. Biederman" <ebiederm@xmission.com>,
Tejun Heo <tj@kernel.org>
Subject: Re: [PATCH 1/2] creds: kill __task_cred()->task_is_dead() check
Date: Tue, 20 Sep 2011 17:40:15 +0200 [thread overview]
Message-ID: <20110920154015.GB17731@redhat.com> (raw)
In-Reply-To: <20110920152816.GD2380@linux.vnet.ibm.com>
On 09/20, Paul E. McKenney wrote:
>
> On Tue, Sep 20, 2011 at 04:39:42PM +0200, Oleg Nesterov wrote:
> >
> > --- 3.1/include/linux/cred.h~1_kill_task_is_dead 2011-09-20 16:28:22.000000000 +0200
> > +++ 3.1/include/linux/cred.h 2011-09-20 16:28:47.000000000 +0200
> > @@ -284,8 +284,7 @@ static inline void put_cred(const struct
> > #define __task_cred(task) \
> > ({ \
> > const struct task_struct *__t = (task); \
> > - rcu_dereference_check(__t->real_cred, \
> > - task_is_dead(__t)); \
> > + rcu_dereference_check(__t->real_cred, 0); \
>
> The "0" above will make lockdep-RCU complain unconditionally. My guess
> is that you want rcu_dereference_raw().
Hmm. I hope you are wrong this time ;)
rcu_dereference_check() checks rcu_read_lock_held(). IOW, with this
change __task_cred() always requires rcu_read_lock(), and this is
what the patch wants.
The next one adds " || (task == current" to the rcu_read_lock_held()
check above.
Oleg.
next prev parent reply other threads:[~2011-09-20 15:44 UTC|newest]
Thread overview: 63+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-09-19 21:45 [PATCH] user namespace: make signal.c respect user namespaces Serge E. Hallyn
2011-09-19 21:47 ` [PATCH] user namespace: usb: make usb urbs user namespace aware Serge E. Hallyn
2011-09-20 13:17 ` Oleg Nesterov
2011-09-20 13:33 ` Serge E. Hallyn
2011-09-21 5:01 ` [PATCH] user namespace: usb: make usb urbs user namespace aware (v2) Serge E. Hallyn
2011-09-21 18:31 ` Oleg Nesterov
2011-09-21 19:12 ` Serge E. Hallyn
2011-09-21 19:18 ` Greg KH
2011-09-23 1:27 ` [PATCH resend] " Serge E. Hallyn
2011-09-23 15:48 ` Alan Stern
2011-09-23 16:06 ` Serge E. Hallyn
2011-09-23 16:21 ` Alan Stern
2011-09-23 17:22 ` Serge E. Hallyn
2011-09-23 18:35 ` Alan Stern
2011-09-20 12:22 ` [PATCH] user namespace: make signal.c respect user namespaces Oleg Nesterov
2011-09-20 12:44 ` Serge E. Hallyn
2011-09-20 13:41 ` Oleg Nesterov
2011-09-20 14:39 ` [PATCH 0/2] (Was: user namespace: make signal.c respect user namespaces) Oleg Nesterov
2011-09-20 14:39 ` [PATCH 1/2] creds: kill __task_cred()->task_is_dead() check Oleg Nesterov
2011-09-20 15:14 ` drivers/staging/usbip/ abuses task_is_dead/exit_state Oleg Nesterov
2011-09-20 18:38 ` Greg KH
2012-03-06 17:39 ` ping: " Oleg Nesterov
2012-03-06 19:30 ` Tobias Klauser
2012-03-08 18:57 ` Oleg Nesterov
2012-03-13 11:45 ` Tobias Klauser
2012-03-13 18:07 ` [PATCH] staging: usbip: fix the usage of kthread_stop() Oleg Nesterov
2012-04-01 23:17 ` Oleg Nesterov
2012-04-02 8:11 ` Tobias Klauser
2011-09-20 15:28 ` [PATCH 1/2] creds: kill __task_cred()->task_is_dead() check Paul E. McKenney
2011-09-20 15:40 ` Oleg Nesterov [this message]
2011-09-20 15:48 ` Paul E. McKenney
2011-09-20 16:27 ` David Howells
2011-09-20 14:39 ` [PATCH 2/2] creds: __task_cred(current) doesn't need rcu_read_lock_held() Oleg Nesterov
2011-09-20 15:07 ` Serge Hallyn
2011-09-20 15:35 ` Oleg Nesterov
2011-09-20 16:19 ` David Howells
2011-09-20 16:38 ` Oleg Nesterov
2011-09-20 16:50 ` David Howells
2011-09-20 17:13 ` Oleg Nesterov
2011-09-20 15:39 ` [PATCH] user namespace: make signal.c respect user namespaces Serge Hallyn
2011-09-20 16:24 ` Oleg Nesterov
2011-09-20 16:45 ` Serge E. Hallyn
2011-09-20 18:17 ` Oleg Nesterov
2011-09-21 5:00 ` [PATCH] user namespace: make signal.c respect user namespaces (v2) Serge E. Hallyn
2011-09-20 17:48 ` [PATCH] user namespace: make signal.c respect user namespaces Oleg Nesterov
2011-09-20 18:53 ` Serge E. Hallyn
2011-09-21 17:53 ` Oleg Nesterov
2011-09-22 15:23 ` Serge Hallyn
2011-09-23 16:31 ` Serge E. Hallyn
2011-09-23 17:36 ` Oleg Nesterov
2011-09-23 21:20 ` Serge E. Hallyn
2011-09-24 16:37 ` Oleg Nesterov
2011-09-25 20:17 ` Serge E. Hallyn
2011-09-26 16:06 ` Oleg Nesterov
2011-09-27 14:28 ` Serge Hallyn
2011-09-27 14:38 ` Oleg Nesterov
2011-09-27 15:27 ` Serge Hallyn
2011-09-27 17:12 ` Oleg Nesterov
2011-10-04 17:42 ` Serge E. Hallyn
2011-10-09 19:00 ` Oleg Nesterov
2011-10-11 13:08 ` Serge E. Hallyn
2011-10-08 20:02 ` Serge E. Hallyn
2011-10-09 19:03 ` Oleg Nesterov
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