From: gang.chen@asianux•com (Chen Gang)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH] ARM: include: asm: atomic.h: use type cast 's64' for the return value of atomic64_add_return().
Date: Tue, 24 Sep 2013 18:30:48 +0800 [thread overview]
Message-ID: <524169D8.1080904@asianux.com> (raw)
In-Reply-To: <20130924093041.GB15119@mudshark.cambridge.arm.com>
On 09/24/2013 05:30 PM, Will Deacon wrote:
> Hello,
>
> On Sat, Sep 21, 2013 at 12:06:47PM +0100, Chen Gang wrote:
>> The return value of atomic64_add_return() is u64 which never less than
>> zero, so need type cast 's64' for comparing in atomic64_add_negative().
>>
>> The related error: (allmodconfig for S5PV210, with "EXTRA_CFLAGS=-W"):
>>
>> kernel/events/core.c:5404:2: warning: comparison of unsigned expression < 0 is always false [-Wtype-limits]
>>
>>
>> Signed-off-by: Chen Gang <gang.chen@asianux•com>
>> ---
>> arch/arm/include/asm/atomic.h | 2 +-
>> 1 files changed, 1 insertions(+), 1 deletions(-)
>>
>> diff --git a/arch/arm/include/asm/atomic.h b/arch/arm/include/asm/atomic.h
>> index da1c77d..8cf005d 100644
>> --- a/arch/arm/include/asm/atomic.h
>> +++ b/arch/arm/include/asm/atomic.h
>> @@ -475,7 +475,7 @@ static inline int atomic64_add_unless(atomic64_t *v, u64 a, u64 u)
>> return ret;
>> }
>>
>> -#define atomic64_add_negative(a, v) (atomic64_add_return((a), (v)) < 0)
>> +#define atomic64_add_negative(a, v) ((s64)atomic64_add_return((a), (v)) < 0)
>> #define atomic64_inc(v) atomic64_add(1LL, (v))
>> #define atomic64_inc_return(v) atomic64_add_return(1LL, (v))
>> #define atomic64_inc_and_test(v) (atomic64_inc_return(v) == 0)
>
> Is this the right fix? It looks more like atomic[64]_t should be signed, but
> some 32-bit architectures (ARM, x86, tile) are actually implementing
> atomic64_t as u64. Furthermore, there are discrepencies in the operands to
> the various atomic64_* function (long long vs u64) which probably need
> sorting out.
>
> Since the 32-bit interface is well defined (Documentation/atomic_ops.txt),
> I think we should just follow the same signedness rules for the 64-bit
> versions.
>
That sounds reasonable, excluding arm and tile_32, all are defined as
signed (even for related 32-bits functions, arm and tile are also use
signed).
For atomic64_add_negative(), like arm, tile also has the same issue
(unsigned type is never less than zero).
Tomorrow, I will send patch v2 for arm, and another fix patch for tile.
:-)
Thanks.
The related search:
arm/include/asm/atomic.h:314:static inline u64 atomic64_add_return(u64 i, atomic64_t *v)
tile/include/asm/atomic_32.h:123:static inline u64 atomic64_add_return(u64 i, atomic64_t *v)
ia64/include/asm/atomic.h:137:#define atomic64_add_return(i,v) \
alpha/include/asm/atomic.h:115:static __inline__ long atomic64_add_return(long i, atomic64_t * v)
arm64/include/asm/atomic.h:194:static inline long atomic64_add_return(long i, atomic64_t *v)
frv/include/asm/atomic.h:152:extern long long atomic64_add_return(long long i, atomic64_t *v);
mips/include/asm/atomic.h:499:static __inline__ long atomic64_add_return(long i, atomic64_t * v)
parisc/include/asm/atomic.h:156:__atomic64_add_return(s64 i, atomic64_t *v)
parisc/include/asm/atomic.h:190:#define atomic64_add_return(i,v) (__atomic64_add_return( ((s64)(i)),(v)))
powerpc/include/asm/atomic.h:310:static __inline__ long atomic64_add_return(long a, atomic64_t *v)
s390/include/asm/atomic.h:199:static inline long long atomic64_add_return(long long i, atomic64_t *v)
s390/include/asm/atomic.h:284:static inline long long atomic64_add_return(long long i, atomic64_t *v)
sparc/include/asm/atomic_64.h:42:#define atomic64_add_return(i, v) atomic64_add_ret(i, v)
tile/include/asm/atomic_64.h:73:static inline long atomic64_add_return(long i, atomic64_t *v)
x86/include/asm/atomic64_32.h:134:static inline long long atomic64_add_return(long long i, atomic64_t *v)
x86/include/asm/atomic64_64.h:171:static inline long atomic64_add_return(long i, atomic64_t *v)
> Will
>
>
Thanks
--
Chen Gang
next prev parent reply other threads:[~2013-09-24 10:30 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 [this message]
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
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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