[PATCHv3] PowerPC: Fix a race condition when eliding a lock

[Carlos O'Donell]

On 08/24/2015 02:11 PM, Tulio Magno Quites Machado Filho wrote:
> Changes since v2:
>  - Moved part of the source code comments to the commit message.
>  - Added O'Donnel's suggestion to the source code comments.
> 
> Changes since v1:
>  - Improved commit message.
>  - Added new comments in the source code alerting to the concurrency details
>    intrinsic to this code.
>  - Removed compiler barriers from this patch, which will be treated in another
>    patch and will be synchronized with the GCC implementation.

> +	  if (__builtin_tbegin (0))					\
> +	    {								\
> +	      if (is_lock_free)						\
> +		{							\
> +		  ret = 1;						\
> +		  break;						\
> +		}							\
> +	      __builtin_tabort (_ABORT_LOCK_BUSY);			\
> +	    }								\
> +	  else								\
> +	    if (!__get_new_count(&adapt_count))				\
> +	      break;							\

Toravld still suggests an atomic_load_relaxed here:
https://www.sourceware.org/ml/libc-alpha/2015-08/msg00893.html

Is there any technical objection to that request?

It does highlight, as he notes, the transactional and non-transactional
accesses for that evaluated value.

Cheers,
Carlos.