[Devel] Re: [PATCH] cgroup: fix reverse unlock sequence in cgroup_get_sb

[Paul Menage]

On Tue, Jul 21, 2009 at 5:01 AM, Balbir Singh<balbir at linux.vnet.ibm.com> wrote:
>
> lock(A)
> lock(B)
> unlock(A)
> unlock(B)
>
> Tomorrow if a unsuspecting programmer does this
>
> lock(A)
> lock(B)
> unlock(A)
>
> code block
>
> unlock(B)
>
>
> What protects code block? lock B? Is that the intention?
>

An "unsuspecting programmer" shouldn't be adding code to
multi-threaded routines without thoroughly understanding the locking.

I guess there's no harm in this patch, but as Li says, it doesn't
really change anything.

Paul
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