Re: [Xen-devel] [PATCH v2 09/13] xsplice: Implement support for applying/reverting/replacing patches. (v2)

[Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>]

> >>As far as I can tell, the mechanics of how this works haven't changed, the
> >>code has just been reorganized. Which means the points that Martin raised
> >>about this mechanism are still outstanding.
> >
> >A bit. I added the extra timeout on both of the 'spin-around' and also
> >moved some of the barriers around. Also removed your spin-lock and used
> >the atomic_t mechanism to synchronize.
> >
> >But the one thing that I didn't do was the spin on the 'workers?' that
> >are just spinnig idly. They will do that forever if say the 'master'
> >hasn't gone to the IRQ semaphore part.
> >
> >My thinking was that the 'workers' could also use the timeout feature
> >but just multiple it by two?
> >
> 
> After looking at this again, I remembered that the algorithm I used is the
> same as the one used by stop_machine_run(). That function runs without
> timeouts at all (seemingly without problems), so why shouldn't this one?

Because we may have a very busy system and we do not want to impair
the running guests.

> (The only reason stop_machine_run() itself isn't used for patching is
> because we need to enter the function without a stack, i.e. not from a
> tasklet.)
> 
> -- 
> Ross Lagerwall

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