Re: [Xen-devel] [PATCH 3/5] xen: RCU/x86/ARM: discount CPUs that were idle when grace period started.

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 09.08.17 at 11:20, <dario.faggioli@xxxxxxxxxx> wrote:
> On Wed, 2017-08-09 at 02:57 -0600, Jan Beulich wrote:
>> > > > On 09.08.17 at 10:48, <dario.faggioli@xxxxxxxxxx> wrote:
>> > 
>> > _I_think_ what the original author meant was something along the
>> > line
>> > of <<Accessing nohz_cpu_mask before incrementing rcp->cur is
>> > unsafe.
>> > Therefore, let's access it afterwords, and put a barrier in
>> > between.>>
>> > 
>> > But yeah, as said, I don't like it myself. In fact, it's the same
>> > exact
>> > wording used in the changelog of the patch (Linux commit
>> > c3f5902325d3053986e7359f706581d8f032e72f), but while it is fine
>> > there,
>> > here is completely misleading, as it does not comment/describe the
>> > final look of the code.
>> > 
>> > I'm going to change it.
>> 
>> Perhaps worth submitting a Linux patch too then?
>> 
> That code is long gone.
> 
> The file itself doesn't exist any longer, and the mask has been killed,
> in favour of other mechanisms (depending of the variant of RCU, of the
> degree of tickles-idleness, etc). :-)

Oh, I see - in that case we're fine with the comment being
whatever makes most sense for us.

Jan


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