Re: [dpdk-dev] [PATCH v5 3/3] eal/stack: enable lock-free stack for aarch64

["Eads, Gage" <gage.eads@intel.com>]

> diff --git a/lib/librte_stack/rte_stack_lf_stubs.h
> b/lib/librte_stack/rte_stack_lf_stubs.h
> new file mode 100644
> index 0000000..d924bc6
> --- /dev/null
> +++ b/lib/librte_stack/rte_stack_lf_stubs.h
> @@ -0,0 +1,59 @@
> +/* SPDX-License-Identifier: BSD-3-Clause
> + * Copyright(c) 2019 Arm Limited
> + */
> +
> +#ifndef _RTE_STACK_LF_STUBS_H_
> +#define _RTE_STACK_LF_STUBS_H_
> +
> +#include <rte_common.h>
> +#include <rte_atomic.h>
> +
> +static __rte_always_inline unsigned int __rte_stack_lf_count(struct
> +rte_stack *s) {
> +	/* stack_lf_push() and stack_lf_pop() do not update the list's
> contents
> +	 * and stack_lf->len atomically, which can cause the list to appear
> +	 * shorter than it actually is if this function is called while other
> +	 * threads are modifying the list.
> +	 *
> +	 * However, given the inherently approximate nature of the
> get_count
> +	 * callback -- even if the list and its size were updated atomically,
> +	 * the size could change between when get_count executes and
> when the
> +	 * value is returned to the caller -- this is acceptable.
> +	 *
> +	 * The stack_lf->len updates are placed such that the list may appear
> to
> +	 * have fewer elements than it does, but will never appear to have
> more
> +	 * elements. If the mempool is near-empty to the point that this is a
> +	 * concern, the user should consider increasing the mempool size.
> +	 */
> +	return (unsigned int)rte_atomic64_read((rte_atomic64_t *)
> +			&s->stack_lf.used.len);
> +}

Since the stub functions are not functional, these comments should be removed and the function simply return 0. The rte_atomic.h include can be removed as well.