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Groups > linux.kernel > #1288771
| From | "Geyslan G. Bem" <geyslan@gmail.com> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: [PATCH 4/9v2] usb: host: ehci.h: fix single statement macros |
| Date | 2015-12-10 19:10 +0100 |
| Message-ID | <qEdPd-1ez-31@gated-at.bofh.it> (permalink) |
| References | (5 earlier) <qEaHD-7v5-5@gated-at.bofh.it> <qEaRk-7yx-17@gated-at.bofh.it> <qEdcw-Km-53@gated-at.bofh.it> <qEdvQ-Ss-9@gated-at.bofh.it> <qEdvQ-Ss-7@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
2015-12-10 14:47 GMT-03:00 Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>:
> On 12/10/2015 08:40 PM, Geyslan G. Bem wrote:
>
>>>>>>>>> Don't use the 'do {} while (0)' wrapper in a single statement
>>>>>>>>> macro.
>>>>>>>>>
>>>>>>>>> Caught by checkpatch: "WARNING: Single statement macros should not
>>>>>>>>> use a do {} while (0) loop"
>>>>>>>>>
>>>>>>>>> Signed-off-by: Geyslan G. Bem <geyslan@gmail.com>
>>>>>>>>> ---
>>>>>>>>> drivers/usb/host/ehci.h | 4 ++--
>>>>>>>>> 1 file changed, 2 insertions(+), 2 deletions(-)
>>>>>>>>>
>>>>>>>>> diff --git a/drivers/usb/host/ehci.h b/drivers/usb/host/ehci.h
>>>>>>>>> index cfeebd8..945000a 100644
>>>>>>>>> --- a/drivers/usb/host/ehci.h
>>>>>>>>> +++ b/drivers/usb/host/ehci.h
>>>>>>>>> @@ -244,9 +244,9 @@ struct ehci_hcd { /* one per
>>>>>>>>> controller */
>>>>>>>>> /* irq statistics */
>>>>>>>>> #ifdef EHCI_STATS
>>>>>>>>> struct ehci_stats stats;
>>>>>>>>> -# define COUNT(x) do { (x)++; } while (0)
>>>>>>>>> +# define COUNT(x) ((x)++)
>>>>>>>>> #else
>>>>>>>>> -# define COUNT(x) do {} while (0)
>>>>>>>>> +# define COUNT(x) ((void) 0)
>>>>>>>>
>>>>>>>>
>>>>>>>> Why not just empty #define?
>>>>>>>
>>>>>>>
>>>>>>> Indeed. I'll change it.
>>>>>>> Tks Sergei.
>>>>>>
>>>>>>
>>>>>> Since COUNT is not used to return the empty #define is ok. Another way
>>>>>> is to use #define COUNT(x) (0) to get a 0 when necessary to read
>>>>>> returns.
>>>
>>>
>>>>> Just 0, no parens please.
>>>
>>>
>>>> Ok, no parens, since there's no evaluation.
>>>
>>>
>>> It's because the literals don't need parens at all.
>>>
>>>> Then my change is:
>>>>
>>>> -# define COUNT(x) do { (x)++; } while (0)
>>>> +# define COUNT(x) (++(x))
>>>> #else
>>>> -# define COUNT(x) do {} while (0)
>>>> +# define COUNT(x) 0
>>>>
>>>> Pre-increment allowing to return the updated x.
>>>
>>>
>>>
>>> Why if there was a post-increment before?
>
>
>> There's nothing wrong with post-increment. The pre one would be
>> necessary if using return.
>
>
> Maybe it was intended to return the old value? :-)
>
>>>
>>> Anyway, this talk is quite pointless since the macro didn't return
>>> any
>>> value anyway.
>>
>> You're sure, there's no use anywhere of the return of that macro indeed.
>
>
> *do* {} *while* (0) just couldn't return any value, it's not just a
> compound statement which gcc indeed allows to be evaluated.
Indeed. :-)
v2 in the oven.
>
>
>> Sending v2 soon.
>
>
> MBR, Sergei
>
--
Regards,
Geyslan G. Bem
hackingbits.com
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[PATCH 1/9v2] usb: host: ehci.h: remove space before comma "Geyslan G. Bem" <geyslan@gmail.com> - 2015-12-09 23:40 +0100
[PATCH 3/9v2] usb: host: ehci.h: remove space before open square bracket "Geyslan G. Bem" <geyslan@gmail.com> - 2015-12-09 23:40 +0100
Re: [PATCH 3/9v2] usb: host: ehci.h: remove space before open square bracket Peter Senna Tschudin <peter.senna@gmail.com> - 2015-12-10 10:30 +0100
[PATCH 4/9v2] usb: host: ehci.h: fix single statement macros "Geyslan G. Bem" <geyslan@gmail.com> - 2015-12-09 23:40 +0100
Re: [PATCH 4/9v2] usb: host: ehci.h: fix single statement macros Peter Senna Tschudin <peter.senna@gmail.com> - 2015-12-10 11:00 +0100
Re: [PATCH 4/9v2] usb: host: ehci.h: fix single statement macros Sergei Shtylyov <sergei.shtylyov@cogentembedded.com> - 2015-12-10 13:00 +0100
Re: [PATCH 4/9v2] usb: host: ehci.h: fix single statement macros "Geyslan G. Bem" <geyslan@gmail.com> - 2015-12-10 13:30 +0100
Re: [PATCH 4/9v2] usb: host: ehci.h: fix single statement macros "Geyslan G. Bem" <geyslan@gmail.com> - 2015-12-10 14:10 +0100
Re: [PATCH 4/9v2] usb: host: ehci.h: fix single statement macros Sergei Shtylyov <sergei.shtylyov@cogentembedded.com> - 2015-12-10 15:50 +0100
Re: [PATCH 4/9v2] usb: host: ehci.h: fix single statement macros "Geyslan G. Bem" <geyslan@gmail.com> - 2015-12-10 16:00 +0100
Re: [PATCH 4/9v2] usb: host: ehci.h: fix single statement macros Sergei Shtylyov <sergei.shtylyov@cogentembedded.com> - 2015-12-10 18:30 +0100
Re: [PATCH 4/9v2] usb: host: ehci.h: fix single statement macros Sergei Shtylyov <sergei.shtylyov@cogentembedded.com> - 2015-12-10 18:50 +0100
Re: [PATCH 4/9v2] usb: host: ehci.h: fix single statement macros "Geyslan G. Bem" <geyslan@gmail.com> - 2015-12-10 19:10 +0100
Re: [PATCH 4/9v2] usb: host: ehci.h: fix single statement macros "Geyslan G. Bem" <geyslan@gmail.com> - 2015-12-10 18:50 +0100
[PATCH 5/9v2] usb: host: ehci.h: remove direct use of __attribute__ keyword "Geyslan G. Bem" <geyslan@gmail.com> - 2015-12-09 23:40 +0100
Re: [PATCH 5/9v2] usb: host: ehci.h: remove direct use of __attribute__ keyword Peter Senna Tschudin <peter.senna@gmail.com> - 2015-12-10 11:10 +0100
Re: [PATCH 5/9v2] usb: host: ehci.h: remove direct use of __attribute__ keyword "Geyslan G. Bem" <geyslan@gmail.com> - 2015-12-10 11:30 +0100
[PATCH 7/9v2] usb: host: ehci.h: remove macros trailing semicolon "Geyslan G. Bem" <geyslan@gmail.com> - 2015-12-09 23:40 +0100
Re: [PATCH 7/9v2] usb: host: ehci.h: remove macros trailing semicolon Peter Senna Tschudin <peter.senna@gmail.com> - 2015-12-10 11:30 +0100
[PATCH 6/9v2] usb: host: ehci.h: use space after comma "Geyslan G. Bem" <geyslan@gmail.com> - 2015-12-09 23:40 +0100
Re: [PATCH 6/9v2] usb: host: ehci.h: use space after comma Peter Senna Tschudin <peter.senna@gmail.com> - 2015-12-10 11:20 +0100
Re: [PATCH 6/9v2] usb: host: ehci.h: use space after comma Alan Stern <stern@rowland.harvard.edu> - 2015-12-10 17:00 +0100
Re: [PATCH 6/9v2] usb: host: ehci.h: use space after comma "Geyslan G. Bem" <geyslan@gmail.com> - 2015-12-10 17:10 +0100
Re: [PATCH 1/9v2] usb: host: ehci.h: remove space before comma Peter Senna Tschudin <peter.senna@gmail.com> - 2015-12-10 10:20 +0100
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