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SubjectRe: Async suspend-resume patch w/ completions (was: Re: Async suspend-resume patch w/ rwsems)
On Tue, 15 Dec 2009, Linus Torvalds wrote:

> My whole point was that by doing the whole "wait for children" in generic
> code, you also made devices - such as PCI bridges - have to wait for
> children, even though they don't need to, and don't want to.
> So I suggested an admittedly ugly hack to take care of it - rather than
> some complex infrastructure.

It doesn't feel like an ugly hack to me. It seems like exactly the
Right Thing To Do: Make as many devices as possible use async

The only reason we don't make every device async is because we don't
know whether it's safe. In the case of PCI bridges we _do_ know --
because they don't have any work to do outside of
late_suspend/early_resume -- and so they _should_ be async.

The same goes for devices that don't have suspend or resume methods.

There remains a separate question: Should async devices also be forced
to wait for their children? I don't see why not. For PCI bridges it
won't make any significant difference. As long as the async code
doesn't have to do anything, who cares when it runs?

Alan Stern

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