Re: Async suspend-resume patch w/ completions (was: Re: Asyncsuspend-resume patch w/ rwsems)

[Alan Stern]

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 
suspend/resume.

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

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/