From: will.deacon@arm.com (Will Deacon)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH v2] ARM: include: asm: use 'long long' instead of 'u64' within atomic.h
Date: Fri, 27 Sep 2013 12:06:19 +0100 [thread overview]
Message-ID: <20130927110618.GB9520@mudshark.cambridge.arm.com> (raw)
In-Reply-To: <5244148F.6080405@asianux.com>
On Thu, Sep 26, 2013 at 12:03:43PM +0100, Chen Gang wrote:
> On 09/26/2013 06:04 PM, Will Deacon wrote:
> > On Thu, Sep 26, 2013 at 03:00:30AM +0100, Chen Gang wrote:
> >> On 09/26/2013 12:07 AM, Will Deacon wrote:
> >>> On Wed, Sep 25, 2013 at 03:25:19AM +0100, Chen Gang wrote:
> >>>> atomic* value is signed value, and atomic* functions need also process
> >>>> signed value (parameter value, and return value), so 32-bit arm need
> >>>> use 'long long' instead of 'u64'.
> >>>>
> >>>> After replacement, it will also fix a bug for atomic64_add_negative():
> >>>> "u64 is never less than 0".
> >>>>
> >>>> The modifications are:
> >>>>
> >>>> in vim, use "1,% s/\<u64\>/long long/g" command.
> >>>> remove '__aligned(8)' which is useless for 64-bit.
> >>>> be sure of 80 column limitation after replacement.
> >>>>
> >>>>
> >>>> Signed-off-by: Chen Gang <gang.chen@asianux.com>
> >>>
> >>> Looks better to me, thanks. While you're here, we could also replace the use
> >>> of `unsigned long' with `int' for the 32-bit atomics, then the whole header
> >>> is consistent with the generic types.
> >>>
> >>> Will
> >>>
> >>>
> >>
> >> Hmm... at least, it seems we can let "use 'int' for 32-bit atomics" in
> >> another patch.
> >
> > Sure, it can be a follow-up to this one.
> >
>
> OK, if it is really a useful patch too, I will follow-up.
It's a cosmetic change to bring the signedness of our 32-bit atomics in-line
with your proposal for 64-bit atomics.
> 'unsigned long' can be used as a register related variable, it is always
> 32-bit under 32-bit machine, and always 64-bit under 64-bit machine.
Not necessarily (c.f. ILP32).
> So can use it for both arm and arm64, for arm, it can not cause issue,
> and for arm64, it is also OK (if changed to 'int' under arm64, may cause
> real issue).
arm and arm64 have different instructions sets. There's no way the inline
assembly used to implement the atomic operations can be made portable
between them.
Will
next prev parent reply other threads:[~2013-09-27 11:06 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-09-21 11:06 [PATCH] ARM: include: asm: atomic.h: use type cast 's64' for the return value of atomic64_add_return() Chen Gang
2013-09-24 9:30 ` Will Deacon
2013-09-24 10:27 ` Russell King - ARM Linux
2013-09-24 10:37 ` Chen Gang
2013-09-24 10:30 ` Chen Gang
2013-09-25 2:25 ` [PATCH v2] ARM: include: asm: use 'long long' instead of 'u64' within atomic.h Chen Gang
2013-09-25 16:07 ` Will Deacon
2013-09-26 2:00 ` Chen Gang
2013-09-26 10:04 ` Will Deacon
2013-09-26 11:03 ` Chen Gang
2013-09-27 11:06 ` Will Deacon [this message]
2013-09-27 11:36 ` Chen Gang
2013-09-29 3:43 ` [PATCH 0/2] ARM: include: asm: change functions' and variables' types in atomic.h Chen Gang
2013-09-29 3:43 ` [PATCH 1/2] ARM: include: asm: use 'long long' instead of 'u64' within atomic.h Chen Gang
2013-09-29 3:52 ` [PATCH 2/2] ARM: include: asm: use 'int' instead of 'unsigned long' for normal register variables " Chen Gang
2013-09-30 16:11 ` Will Deacon
2013-10-01 2:05 ` Chen Gang
2013-10-01 9:01 ` Will Deacon
2013-10-01 12:03 ` Chen Gang
2013-10-02 10:41 ` Will Deacon
2013-10-02 15:19 ` Chen Gang
2013-10-03 10:05 ` Chen Gang
2013-10-03 16:32 ` Will Deacon
2013-10-04 9:51 ` Chen Gang
2013-10-04 15:37 ` Will Deacon
2013-10-04 15:42 ` Will Deacon
2013-10-04 23:55 ` Chen Gang
2013-10-05 0:11 ` Chen Gang
2013-10-08 4:10 ` Chen Gang
2013-10-08 10:34 ` Will Deacon
2013-10-08 10:56 ` [PATCH v2 0/2] ARM: include: asm: change functions' and variables' types in atomic.h Chen Gang
2013-10-08 10:57 ` [PATCH v2 1/2] ARM: include: asm: use 'long long' instead of 'u64' within atomic.h Chen Gang
2013-10-08 10:59 ` [PATCH v2 2/2] ARM: include: asm: use 'int' instead of 'unsigned long' for 'oldval' in atomic_cmpxchg() Chen Gang
2013-10-09 10:48 ` Will Deacon
2013-10-10 0:56 ` Chen Gang
2013-10-09 10:46 ` [PATCH v2 1/2] ARM: include: asm: use 'long long' instead of 'u64' within atomic.h Will Deacon
2013-10-08 11:00 ` [PATCH 2/2] ARM: include: asm: use 'int' instead of 'unsigned long' for normal register variables " Chen Gang
2013-10-08 10:33 ` Will Deacon
2013-10-08 11:29 ` Chen Gang
2013-10-08 17:49 ` Will Deacon
2013-10-09 0:18 ` Chen Gang
2013-10-09 1:22 ` Chen Gang
2013-09-30 16:07 ` [PATCH 1/2] ARM: include: asm: use 'long long' instead of 'u64' " Will Deacon
2013-10-01 2:09 ` Chen Gang
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