Re: [Xen-devel] [PATCH 1/3] xen/cpu: Distinguish "cpu already in that state" in cpu_{up, down}()

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 02.04.19 at 21:57, <andrew.cooper3@xxxxxxxxxx> wrote:
> All methods of querying the online state of a CPU are racy without the hotplug
> lock held, which can lead to a TOCTOU race trying to online or offline CPUs.
> 
> Distinguish this case with -EEXIST rather than -EINVAL, so the caller can take
> other actions if necessary.
> 
> While adjusting this, rework the code slightly to fold the exit paths, which
> results in a minor reduction in compiled code size.
> 
> Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>

Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>



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