From: Arnd Bergmann <arnd@arndb.de>
To: linux-arm-kernel@lists.infradead.org
Cc: Geert Uytterhoeven <geert@linux-m68k.org>,
Linux MIPS Mailing List <linux-mips@linux-mips.org>,
Russell King - ARM Linux <linux@arm.linux.org.uk>,
Ralf Baechle <ralf@linux-mips.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
DRI Development <dri-devel@lists.freedesktop.org>,
virtualization@lists.linux-foundation.org,
Gerd Hoffmann <kraxel@redhat.com>,
Dave Airlie <airlied@redhat.com>
Subject: Re: [PATCH] drm/virtio: use %llu format string form atomic64_t
Date: Mon, 19 Oct 2015 12:11 +0200 [thread overview]
Message-ID: <4345582.jiHe94XBb3@wuerfel> (raw)
In-Reply-To: <CAMuHMdWbzEFqVctMXTWtdBn2B+guFdphQX5nXUnHPo1szQbtPg@mail.gmail.com>
On Monday 19 October 2015 09:34:15 Geert Uytterhoeven wrote:
> On Wed, Oct 7, 2015 at 1:23 PM, Arnd Bergmann <arnd@arndb.de> wrote:
> > static __inline__ int atomic64_add_unless(atomic64_t *v, long a, long u)
> >
> > which truncates the result to 32 bit.
>
> Woops.
>
> See also my unanswered question in "atomic64 on 32-bit vs 64-bit (was:
> Re: Add virtio gpu driver.)", which is still valid:
> https://lkml.org/lkml/2015/6/28/18
>
Regarding your question of
> Instead of sprinkling casts, is there any good reason why atomic64_read()
> and atomic64_t aren't "long long" everywhere, cfr. u64?
I assume the answer is that some (all?) 64-bit architectures intentionally
return 'long' here, in order for atomic_long_read() to return 'long' on
all architectures, given the definitions from
include/asm-generic/atomic-long.h
We would have to either change those, or we have to pick between
atomic_long_* or atomic64_* to have a consistent return type.
Arnd
WARNING: multiple messages have this Message-ID (diff)
From: Arnd Bergmann <arnd@arndb.de>
To: linux-arm-kernel@lists.infradead.org
Cc: Linux MIPS Mailing List <linux-mips@linux-mips.org>,
Russell King - ARM Linux <linux@arm.linux.org.uk>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
DRI Development <dri-devel@lists.freedesktop.org>,
virtualization@lists.linux-foundation.org,
Geert Uytterhoeven <geert@linux-m68k.org>,
Ralf Baechle <ralf@linux-mips.org>,
Dave Airlie <airlied@redhat.com>
Subject: Re: [PATCH] drm/virtio: use %llu format string form atomic64_t
Date: Mon, 19 Oct 2015 12:11 +0200 [thread overview]
Message-ID: <4345582.jiHe94XBb3@wuerfel> (raw)
In-Reply-To: <CAMuHMdWbzEFqVctMXTWtdBn2B+guFdphQX5nXUnHPo1szQbtPg@mail.gmail.com>
On Monday 19 October 2015 09:34:15 Geert Uytterhoeven wrote:
> On Wed, Oct 7, 2015 at 1:23 PM, Arnd Bergmann <arnd@arndb.de> wrote:
> > static __inline__ int atomic64_add_unless(atomic64_t *v, long a, long u)
> >
> > which truncates the result to 32 bit.
>
> Woops.
>
> See also my unanswered question in "atomic64 on 32-bit vs 64-bit (was:
> Re: Add virtio gpu driver.)", which is still valid:
> https://lkml.org/lkml/2015/6/28/18
>
Regarding your question of
> Instead of sprinkling casts, is there any good reason why atomic64_read()
> and atomic64_t aren't "long long" everywhere, cfr. u64?
I assume the answer is that some (all?) 64-bit architectures intentionally
return 'long' here, in order for atomic_long_read() to return 'long' on
all architectures, given the definitions from
include/asm-generic/atomic-long.h
We would have to either change those, or we have to pick between
atomic_long_* or atomic64_* to have a consistent return type.
Arnd
WARNING: multiple messages have this Message-ID (diff)
From: arnd@arndb.de (Arnd Bergmann)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH] drm/virtio: use %llu format string form atomic64_t
Date: Mon, 19 Oct 2015 12:11 +0200 [thread overview]
Message-ID: <4345582.jiHe94XBb3@wuerfel> (raw)
In-Reply-To: <CAMuHMdWbzEFqVctMXTWtdBn2B+guFdphQX5nXUnHPo1szQbtPg@mail.gmail.com>
On Monday 19 October 2015 09:34:15 Geert Uytterhoeven wrote:
> On Wed, Oct 7, 2015 at 1:23 PM, Arnd Bergmann <arnd@arndb.de> wrote:
> > static __inline__ int atomic64_add_unless(atomic64_t *v, long a, long u)
> >
> > which truncates the result to 32 bit.
>
> Woops.
>
> See also my unanswered question in "atomic64 on 32-bit vs 64-bit (was:
> Re: Add virtio gpu driver.)", which is still valid:
> https://lkml.org/lkml/2015/6/28/18
>
Regarding your question of
> Instead of sprinkling casts, is there any good reason why atomic64_read()
> and atomic64_t aren't "long long" everywhere, cfr. u64?
I assume the answer is that some (all?) 64-bit architectures intentionally
return 'long' here, in order for atomic_long_read() to return 'long' on
all architectures, given the definitions from
include/asm-generic/atomic-long.h
We would have to either change those, or we have to pick between
atomic_long_* or atomic64_* to have a consistent return type.
Arnd
next prev parent reply other threads:[~2015-10-19 10:11 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-10-07 10:41 [PATCH] drm/virtio: use %llu format string form atomic64_t Arnd Bergmann
2015-10-07 10:41 ` Arnd Bergmann
2015-10-07 10:41 ` Arnd Bergmann
2015-10-07 10:45 ` Russell King - ARM Linux
2015-10-07 10:45 ` Russell King - ARM Linux
2015-10-07 10:45 ` Russell King - ARM Linux
2015-10-07 11:04 ` Arnd Bergmann
2015-10-07 11:04 ` Arnd Bergmann
2015-10-07 11:04 ` Arnd Bergmann
2015-10-07 11:23 ` Arnd Bergmann
2015-10-07 11:23 ` Arnd Bergmann
2015-10-07 11:23 ` Arnd Bergmann
2015-10-19 7:34 ` Geert Uytterhoeven
2015-10-19 7:34 ` Geert Uytterhoeven
2015-10-19 7:34 ` Geert Uytterhoeven
2015-10-19 7:34 ` Geert Uytterhoeven
2015-10-19 7:34 ` Geert Uytterhoeven
2015-10-19 10:11 ` Arnd Bergmann [this message]
2015-10-19 10:11 ` Arnd Bergmann
2015-10-19 10:11 ` Arnd Bergmann
2015-10-19 10:39 ` Geert Uytterhoeven
2015-10-19 10:39 ` Geert Uytterhoeven
2015-10-19 10:39 ` Geert Uytterhoeven
2015-10-19 10:39 ` Geert Uytterhoeven
2015-10-19 10:39 ` Geert Uytterhoeven
2015-10-19 9:37 ` Ralf Baechle
2015-10-19 9:37 ` Ralf Baechle
2015-10-19 9:37 ` Ralf Baechle
2015-10-19 10:06 ` Arnd Bergmann
2015-10-19 10:06 ` Arnd Bergmann
2015-10-19 10:06 ` Arnd Bergmann
2015-10-19 10:06 ` Arnd Bergmann
2015-10-07 11:04 ` Arnd Bergmann
2015-10-07 10:45 ` Russell King - ARM Linux
2015-10-07 10:41 Arnd Bergmann
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