Re: [GIT] Sparc

[Julian Calaby]

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,

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/
--
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/