From: gang.chen@asianux•com (Chen Gang)
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 19:36:11 +0800 [thread overview]
Message-ID: <52456DAB.8060900@asianux.com> (raw)
In-Reply-To: <20130927110618.GB9520@mudshark.cambridge.arm.com>
On 09/27/2013 07:06 PM, Will Deacon wrote:
> 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.
>
Hmm... if you like, I will send a follow-up patch for it, the reason is:
It is belong to internal implementation, not belong to API, so if it is
harmless, better to follow related maintainers' 'hobby' or 'tastes', it
will let the related code more clearer. :-)
I will wait 1-2 days to let another reviewers check, if no reply, I will
send 2 patches for it. (if you already applied the "u64 -> long long"
patch, please let me know, and I will send one patch enough).
> Will
>
>
Thanks.
--
Chen Gang
next prev parent reply other threads:[~2013-09-27 11:36 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
2013-09-27 11:36 ` Chen Gang [this message]
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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