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SubjectRe: [PATCH 01/12] blkcg: obtaining blkg should be enclosed inside rcu_read_lock()
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


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