Re: [GIT] Sparc

[Julia Lawall]

On Sat, 7 Nov 2015, Julian Calaby wrote:

> Hi Julia,
> 
> On Fri, Nov 6, 2015 at 5:44 PM, Julia Lawall <julia.lawall@xxxxxxx> wrote:
> > On Fri, 6 Nov 2015, Julian Calaby wrote:
> >
> >> Hi Linus,
> >>
> >> On Fri, Nov 6, 2015 at 11:56 AM, Linus Torvalds
> >> <torvalds@xxxxxxxxxxxxxxxxxxxx> wrote:
> >> > On Thu, Nov 5, 2015 at 4:43 PM, Linus Torvalds
> >> > <torvalds@xxxxxxxxxxxxxxxxxxxx> wrote:
> >> >>
> >> >> Not that this *matters*, but it's a bit odd to have to cast constants
> >> >> to perfectly regular C types.
> >> >
> >> > Looking around with "git grep", there's a few more of these.
> >> >
> >> >  - btrfs seems to like "(unsigned long)-1"
> >> >
> >> >    There's a few other users of that too, including more sparc uses.
> >> >
> >> >  - scsi/qla seems to like "(unsigned long)<hexnumber>"
> >> >
> >> >  - fmdrv_common.h seems to like "((unsigned long)1<<x)" for bitmaps
> >> >
> >> > along with a smattering of random noise all over of "(unsigned long)
> >> > n" where 'n' is some integer.
> >> >
> >> > Apparently people aren't as aware of the normal "ul" postfix syntax as
> >> > I would have expected. That said, it's a hundred-odd cases in all of
> >> > the kernel, so it's still fairly rare.
> >>
> >> Maybe this is something the kernel-janitors team should look at? (CC'd)
> >
> > Do you have some concrete examples of the code that is undesirable?
> 
> Joe Perches produced a patch for checkpatch to check for this [1]
> 
> Linus was complaining [2] about people producing constants with casts
> to basic C types in them. For instance:
> 
> #define IOMMU_ERROR_CODE (~(unsigned long) 0)
> 
> This could be replaced with
> 
> #define IOMMU_ERROR_CODE (~0ul)
> 
> or potentially
> 
> #define IOMMU_ERROR_CODE (-1ul)
> 
> It's not overly common, but it looks wrong.

Thanks.  The checkpatch solution indeed looks fine in this case.

julia

> Thanks,
> 
> Julian Calaby
> 
> [1] https://lkml.org/lkml/2015/11/6/48
> [2] https://lkml.org/lkml/2015/11/5/785
> 
> -- 
> Julian Calaby
> 
> Email: julian.calaby@xxxxxxxxx
> Profile: http://www.google.com/profiles/julian.calaby/
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