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

[Vegard Nossum <vegard.nossum@gmail.com>]

2009/10/14 Bart Van Assche <bart.vanassche@gmail.com>:
> On Fri, Oct 2, 2009 at 9:51 AM, Vegard Nossum <vegard.nossum@gmail.com> wrote:
>>
>> 2009/10/2 Bart Van Assche <bart.vanassche@gmail.com>:
>> > On Sat, Sep 26, 2009 at 2:28 PM, Bart Van Assche
>> > <bart.vanassche@gmail.com> 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@gmail.com>
>> >> Cc: Vegard Nossum <vegardno@ifi.uio.no>
>> >> Cc: Andrew Morton <akpm@linux-foundation.org>
>> >>
>> >> --- 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    2009-09-26 13:53:56.000000000 +0200
>> >> @@ -137,13 +137,13 @@ static inline void kmemcheck_mark_initia
>> >>        int name##_end[0];
>> >>
>> >>  #define kmemcheck_annotate_bitfield(ptr, name)                         \
>> >> -       do if (ptr) {                                                   \
>> >> +       do { if (ptr) {                                                 \
>> >>                int _n = (long) &((ptr)->name##_end)                    \
>> >>                        - (long) &((ptr)->name##_begin);                \
>> >>                BUILD_BUG_ON(_n < 0);                                   \
>> >>                                                                        \
>> >>                kmemcheck_mark_initialized(&((ptr)->name##_begin), _n); \
>> >> -       } while (0)
>> >> +       } } while (0)
>> >>
>> >>  #define kmemcheck_annotate_variable(var)                               \
>> >>        do {                                                            \
>> >
>> > (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