linux-kernel - Re: size_t/ssize_t warnings (was: Re: Build regressions/improvements in v3.5-rc5)

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Date:	Wed, 4 Jul 2012 21:25:13 -0400
From:	Mike Frysinger <vapier@...too.org>
To:	Geert Uytterhoeven <geert@...ux-m68k.org>
Cc:	Jan Kara <jack@...e.cz>, linux-kernel@...r.kernel.org,
	"Linux-Arch" <linux-arch@...r.kernel.org>,
	linux-cris-kernel@...s.com
Subject: Re: size_t/ssize_t warnings (was: Re: Build regressions/improvements in v3.5-rc5)

On Wednesday 04 July 2012 16:17:28 Geert Uytterhoeven wrote:
> On Wed, Jul 4, 2012 at 3:34 PM, Jan Kara <jack@...e.cz> wrote:
> >>   + fs/quota/quota_tree.c: warning: format '%zd' expects argument of
> >>   type 'signed size_t', but argument 4 has type 'ssize_t' [-Wformat]: 
> >>   => 372:4 + fs/quota/quota_v2.c: warning: format '%zd' expects
> >>   argument of type 'signed size_t', but argument 5 has type 'ssize_t'
> >>   [-Wformat]:  => 66:92
> >   
> >   These really look like false positives (there are quite a few of this
> > 
> > kind). Can we possibly silence them?
> 
> These 2 warnings happen on cris only, because size_t is unsigned int and
> ssize_t is (signed) long. They go away if I make ssize_t int.
> 
> I had a look at the various definitions of size_t and ssize_t:
> 
>                         __kernel_size_t                        
> __kernel_ssize_t ---------------                         ----------------
> 
> generic 32-bit:         unsigned int                            int
> generic 64-bit:         __kernel_ulong_t (unsigned long)
> __kernel_long_t (long)
> 
> Exceptions:
> 
> avr32:                  unsigned long                           long
> blackfin:               unsigned long                           long
> cris:                   __SIZE_TYPE__ (unsigned int)            long
> mn10300/__GNUC__ == 4:  unsigned int                            signed int
> mn10300/__GNUC__ != 4:  unsigned long                           signed long
> s390 (32-bit):          unsigned long                           int
> x32:                    __kernel_ulong_t (unsigned long long)
> __kernel_long_t (long long)
> 
> On cris, I get the warning if ssize_t != int.
> Whether size_t is unsigned int or unsigned long doesn't matter.
> So it's not just a mismatch between int and long.
> 
> I also tried blackfin, which has matching unsigned long/long, and it
> doesn't give the warning. Presumably the toolchain has size_t hardcoded to
> long for printf-style format checking?

well, every gcc arch has to declare a type for size_t.  on Blackfin, we picked:
gcc/config/bfin/bfin.h:/* what is the 'type' of size_t */
gcc/config/bfin/bfin.h-#define SIZE_TYPE "long unsigned int"

grep shows that many other arches do the same
-mike

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