Re: [PATCH v3 03/15] iommu: Always register bus notifiers

[Robin Murphy]

On 2022-07-07 07:34, Tian, Kevin wrote:
> > From: Baolu Lu <baolu.lu@xxxxxxxxxxxxxxx>
> > Sent: Thursday, July 7, 2022 8:21 AM
> >
> > On 2022/7/6 21:43, Robin Murphy wrote:
> > > On 2022-07-06 02:53, Baolu Lu wrote:
> > > > On 2022/7/6 01:08, Robin Murphy wrote:
> > > > >    /*
> > > > >     * Use a function instead of an array here because the domain-type
> > > > > is a
> > > > >     * bit-field, so an array would waste memory.
> > > > > @@ -152,6 +172,10 @@ static int __init iommu_subsys_init(void)
> > > > >                (iommu_cmd_line & IOMMU_CMD_LINE_STRICT) ?
> > > > >                    "(set via kernel command line)" : "");
> > > > > +    /* If the system is so broken that this fails, it will WARN
> > > > > anyway */
> > > >
> > > > Can you please elaborate a bit on this? iommu_bus_init() still return
> > > > errors.
> > >
> > > Indeed, it's commenting on the fact that we don't try to clean up or
> > > propagate an error value further even if it did ever manage to return
> > > one. I feared that if I strip the error handling out of iommu_bus_init()
> > > itself on the same reasoning, we'll just get constant patches from the
> > > static checker brigade trying to add it back, so it seemed like the
> > > neatest compromise to keep that decision where it's obviously in an
> > > early initcall, rather than in the helper function which can be viewed
> > > out of context. However, I'm happy to either expand this comment or go
> > > the whole way and make iommu_bus_init() return void if you think it's
> > > worthwhile.
> >
> > Thanks for the explanation. It would be helpful if the comment could be
> > expanded. In this case, after a long time, people will not consider it
> > an oversight. :-)
>
> I'd prefer to making iommu_bus_init() return void plus expanding
> the comment otherwise the question arises that if the only caller
> is not interested in the return value then why bother returning it
> in the first place. 😊

OK, that's fair enough, will do.

Thanks,
Robin.