[PATCH 1/2] add atomc_sub and atomic_compare_exchange into smpatomic08

[Sebastian Huber]

On 2013-08-31 03:49, WeiY wrote:
> +  while (!stop(ctx)) {
> +    while (_Atomic_Compare_exchange_uint(&ctx->global_swap, &ctx->global_swap_t,
> +      worker_index, ATOMIC_ORDER_ACQUIRE, ATOMIC_ORDER_RELEASE)) {
> +      /* Wait */
> +    }
> +    ++counter;
> +    ++ctx->flag_counter;
> +    ctx->global_swap_t = worker_index;
> +  }

This doesn't work since ctx->global_swap_t is a normal variable. Also 
the failure memory order is wrong.  You try to implement a mutex here.  
In case the compare exchange failed, then we try it again thus we don't 
care about a particular memory order here (ATOMIC_ORDER_RELAXED).  The 
success order is all right, since this is the mutex acquire path.

The init and fini handler for the test case don't fit to the body.

-- 
Sebastian Huber, embedded brains GmbH

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