Re: size_t/ssize_t warnings (was: Re: Build regressions/improvementsin v3.5-rc5)

From: Geert Uytterhoeven
Date: Fri Jul 06 2012 - 03:18:51 EST

Hi Hans-Peter,

On Fri, Jul 6, 2012 at 3:12 AM, Hans-Peter Nilsson
<hans-peter.nilsson@xxxxxxxx> wrote:
>> From: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>
>> Date: Wed, 4 Jul 2012 22:17:28 +0200
>> On Wed, Jul 4, 2012 at 3:34 PM, Jan Kara <jack@xxxxxxx> 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.
> Um, no, ssize_t isn't long. Do you mean __kernel_ssize_t?

In the kernel, (s)size_t == __kernel_(s)size_t

> (Or are you looking at cris-axis-elf?, that can't be it,
> as you see __SIZE_TYPE__ being unsigned int.)
>> They go away if I make ssize_t int.
> But ssize_t already is int...
> N.B. size_t is different between cris-axis-elf and
> cris-axis-linux-gnu. The former uses the default definition in
> gcc/defaults.h (long unsigned int) and the latter sets it
> specifically to "unsigned int", in gcc/config/cris/linux.h (or
> before 2010-12-09, from config/svr4.h). The ssize_t definition
> comes from glibc, where it is "int".

OK, so (s)size_t should be (unsigned) int for Linux.

>> __kernel_size_t __kernel_ssize_t
>> --------------- ----------------
>> cris: __SIZE_TYPE__ (unsigned int) long
> A bit odd; __kernel_ssize_t should probably change to int, to
> match ssize_t.

In the kernel, ssize_t == __kernel_ssize_t.

Probably the "long" dates from the time people used cris-axis-elf
instead of cris-axis-linux-gnu, and "__SIZE_TYPE" from the time
people started using cris-axis-linux-gnu?
Ah, yes, commit ac505a9fd19c99fdb622fe4896446f995151babc
("[PATCH] CRIS architecture update for 2.5.74") in full-history-linux
changed size_t from "unsigned long" to __SIZE_TYPE, but didn't
update ssize_t. Probably "signed __SIZE_TYPE" doesn't work?

So I guess they should be changed to (explicit) "unsigned int", resp.
"int". Or does it make sense to retain __SIZE_TYPE?

>> Cris-people: __SIZE_TYPE__ turned out to be hardcoded in my compiler (gcc
>> 4.6.3 from Tony's collection) to unsigned int. Is that correct?
> Correct, for cris-axis-linux-gnu.
>> And why do some 32-bit architectures use unsigned long/long?
> I'd guess from the gcc default.

OK, that makes sense.



Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
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