From: Tejun Heo <tj@kernel.org>
To: Vivek Goyal <vgoyal@redhat.com>
Cc: axboe@kernel.dk, ctalbott@google.com, rni@google.com,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 01/12] blkcg: obtaining blkg should be enclosed inside rcu_read_lock()
Date: Thu, 19 Jan 2012 07:58:44 -0800 [thread overview]
Message-ID: <20120119155844.GE5198@google.com> (raw)
In-Reply-To: <20120119155445.GB10908@redhat.com>
On Thu, Jan 19, 2012 at 10:54:45AM -0500, Vivek Goyal wrote:
> > No, no matter whatever synchronization scheme is in use, the code is
> > seriously screwed up if it's doing something like,
> >
> > lock();
> > a = lookup();
> > unlock();
> > return a;
> >
> > You should *NEVER* be doing that.
>
> I guess ioc_lookup_icq() is doing something similar. We call it under
> queue lock. Take rcu lock inside for sanity of radix tree and then
> release rcu lock and return icq.
Yeap, it is. We should be using rcu_dereference_check() there too.
Thanks.
--
tejun
next prev parent reply other threads:[~2012-01-19 15:58 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-01-19 1:11 [PATCHSET] blkcg: kill policy node and blkg->dev Tejun Heo
2012-01-19 1:11 ` [PATCH 01/12] blkcg: obtaining blkg should be enclosed inside rcu_read_lock() Tejun Heo
2012-01-19 10:07 ` Vivek Goyal
2012-01-19 15:39 ` Tejun Heo
2012-01-19 15:54 ` Vivek Goyal
2012-01-19 15:58 ` Tejun Heo [this message]
2012-01-19 1:11 ` [PATCH 02/12] cfq: don't register propio policy if !CONFIG_CFQ_GROUP_IOSCHED Tejun Heo
2012-01-19 10:11 ` Vivek Goyal
2012-01-19 1:11 ` [PATCH 03/12] elevator: clear auxiliary data earlier during elevator switch Tejun Heo
2012-01-19 1:11 ` [PATCH 04/12] elevator: make elevator_init_fn() return 0/-errno Tejun Heo
2012-01-19 11:11 ` Vivek Goyal
2012-01-19 15:44 ` Tejun Heo
2012-01-19 1:11 ` [PATCH 05/12] blkcg: update blkg get functions take blkio_cgroup as parameter Tejun Heo
2012-01-19 11:21 ` Vivek Goyal
2012-01-19 15:45 ` Tejun Heo
2012-01-19 1:11 ` [PATCH 06/12] blkcg: use q and plid instead of opaque void * for blkio_group association Tejun Heo
2012-01-19 14:04 ` Vivek Goyal
2012-01-19 15:55 ` Tejun Heo
2012-01-19 16:16 ` Vivek Goyal
2012-01-19 16:25 ` Tejun Heo
2012-01-19 16:42 ` Tejun Heo
2012-01-19 1:11 ` [PATCH 07/12] blkcg: add blkio_policy[] array and allow one policy per policy ID Tejun Heo
2012-01-19 1:11 ` [PATCH 08/12] blkcg: use the usual get blkg path for root blkio_group Tejun Heo
2012-01-19 14:41 ` Vivek Goyal
2012-01-19 16:17 ` Tejun Heo
2012-01-19 1:11 ` [PATCH 09/12] blkcg: factor out blkio_group creation Tejun Heo
2012-01-19 1:11 ` [PATCH 10/12] blkcg: don't allow or retain configuration of missing devices Tejun Heo
2012-01-19 1:11 ` [PATCH 11/12] blkcg: kill blkio_policy_node Tejun Heo
2012-01-19 20:32 ` Vivek Goyal
2012-01-19 22:03 ` Tejun Heo
2012-01-19 22:30 ` Vivek Goyal
2012-01-19 1:11 ` [PATCH 12/12] blkcg: kill the mind-bending blkg->dev Tejun Heo
2012-01-19 15:49 ` Vivek Goyal
2012-01-19 16:30 ` Tejun Heo
2012-01-19 16:46 ` Vivek Goyal
2012-01-19 1:18 ` [PATCHSET] blkcg: kill policy node and blkg->dev Tejun Heo
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