On 09/27/2013 07:06 PM, Will Deacon wrote:

On Thu, Sep 26, 2013 at 12:03:43PM +0100, Chen Gang wrote:

quoted

On 09/26/2013 06:04 PM, Will Deacon wrote:

quoted

On Thu, Sep 26, 2013 at 03:00:30AM +0100, Chen Gang wrote:

quoted

On 09/26/2013 12:07 AM, Will Deacon wrote:

quoted

On Wed, Sep 25, 2013 at 03:25:19AM +0100, Chen Gang wrote:

quoted

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 <redacted>

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.

quoted

'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).

quoted

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