Re: [PATCH v7 3/4] driver core: shut down devices asynchronously

[stuart hayes]

On 7/2/2024 12:04 AM, Christoph Hellwig wrote:
> On Mon, Jul 01, 2024 at 12:57:40PM -0500, stuart hayes wrote:
> > > We discussed this before, but there is no summary of it and I of course
> > > forgot the conclusion:
> > >
> > >    - why don't we do this by default?
> >
> > It is done by default in this version, for devices whose drivers opt-in.
> >
> > In the previous discussion, you mentioned that you thought "safe" was the
> > only sensible option (where "safe" was driver opt-in to async shutdown)...
> > that is the default (and only) option with this version.  Greg K-H also
> > requested opt-in as well, and suggested that "on" (driver opt-out) could
> > be removed.
> >
> > >    - why is it safe to user enable it?
> >
> > I guess it isn't necessarily safe, if there are any drivers that can't
> > handle their devices shutting down asynchronously. I thought it would be
> > nice to be able to enable driver opt-in from user space for testing, before
> > changing the default setting for the driver.
>
> I was mostly getting into the contradiction that either we think the
> async shutdown is safe everywhere, in which case we don't need a driver
> opt-in, or it is not, in which case allowing user to just enabled it
> also seems like a bad idea.

I understand. My thinking was that is was very likely to be safe (the initial
version of this patch didn't have an opt-in or opt-out).

I have no issue removing the sysfs attribute if you think that's best.

> > I can correct these lines. I thought that an 80 character line length limit
> > was no longer required, and saw another line a few lines above these that was
> > even longer... and the checkpatch script didn't flag it either.
>
> checkpatch is unfortunately completely broken, it flags totally harmless
> things and doesn't catch other things.  > 80 characters are allowed for
> individual lines where it improves readability.  The exact definition
> of that depends on the maintainers and reviewers, but outside of
> string constants I can't really find anything where it does.

Got it, thanks for the feedback.