Re: [PATCH 2.6.31.1] include/linux/kmemcheck.h: fix a sparse warning

From: Vegard Nossum
Date: Wed Oct 14 2009 - 07:28:05 EST


2009/10/14 Bart Van Assche <bart.vanassche@xxxxxxxxx>:
> On Fri, Oct 2, 2009 at 9:51 AM, Vegard Nossum <vegard.nossum@xxxxxxxxx> wrote:
>>
>> 2009/10/2 Bart Van Assche <bart.vanassche@xxxxxxxxx>:
>> > On Sat, Sep 26, 2009 at 2:28 PM, Bart Van Assche
>> > <bart.vanassche@xxxxxxxxx> wrote:
>> >>
>> >> Checking a 2.6.31.1 kernel configured with allyesconfig/allmodconfig
>> >> with sparse (make C=2) triggers a sparse warning on code that uses the
>> >> kmemcheck_annotate_bitfield() macro. An example of such a warning:
>> >>
>> >> include/net/inet_sock.h:208:17: warning: do-while statement is not a compound statement
>> >>
>> >> Signed-off-by: Bart Van Assche <bart.vanassche@xxxxxxxxx>
>> >> Cc: Vegard Nossum <vegardno@xxxxxxxxxx>
>> >> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
>> >>
>> >> --- linux-2.6.31.1/include/linux/kmemcheck-orig.h    2009-09-26 13:53:44.000000000 +0200
>> >> +++ linux-2.6.31.1/include/linux/kmemcheck.h  Â2009-09-26 13:53:56.000000000 +0200
>> >> @@ -137,13 +137,13 @@ static inline void kmemcheck_mark_initia
>> >> Â Â Â Âint name##_end[0];
>> >>
>> >> Â#define kmemcheck_annotate_bitfield(ptr, name) Â Â Â Â Â Â Â Â Â Â Â Â \
>> >> - Â Â Â do if (ptr) { Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â \
>> >> + Â Â Â do { if (ptr) { Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â \
>> >> Â Â Â Â Â Â Â Âint _n = (long) &((ptr)->name##_end) Â Â Â Â Â Â Â Â Â Â\
>> >> Â Â Â Â Â Â Â Â Â Â Â Â- (long) &((ptr)->name##_begin); Â Â Â Â Â Â Â Â\
>> >> Â Â Â Â Â Â Â ÂBUILD_BUG_ON(_n < 0); Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â \
>> >> Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â\
>> >> Â Â Â Â Â Â Â Âkmemcheck_mark_initialized(&((ptr)->name##_begin), _n); \
>> >> - Â Â Â } while (0)
>> >> + Â Â Â } } while (0)
>> >>
>> >> Â#define kmemcheck_annotate_variable(var) Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â \
>> >> Â Â Â Âdo { Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â\
>> >
>> > (ping)
>> >
>> > Did anyone already have the time to review the patch above ?
>>
>> A patch for this problem has already been applied in latest mainline.
>
> Unfortunately this issue is still present in 2.6.31.4, which has been
> released on October 12 (yesterday). Is the patch that has been applied
> in the mainline kernel suitable for backporting ?

I assumed that this wouldn't be suitable for stable kernels, as the
change is purely syntactic. Is there a good reason for applying this
patch to the stable series? Perhaps Greg can answer this (Cced)?


Vegard
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