Re: [dpdk-dev] [PATCH 1/2] librte_ethdev: Introduce a function to release HW rings

["Burakov, Anatoly" <anatoly.burakov@intel.com>]

On 03-May-20 5:26 PM, Renata Saiakhova wrote:
> Free previously allocated memzone for HW rings
> 
> Signed-off-by: Renata Saiakhova <Renata.Saiakhova@ekinops.com>
> ---
>   lib/librte_ethdev/rte_ethdev.c           | 23 +++++++++++++++++++++++
>   lib/librte_ethdev/rte_ethdev_driver.h    | 14 ++++++++++++++
>   lib/librte_ethdev/rte_ethdev_version.map |  1 +
>   3 files changed, 38 insertions(+)
> 
> diff --git a/lib/librte_ethdev/rte_ethdev.c b/lib/librte_ethdev/rte_ethdev.c
> index 72aed59a5..c6d27e1aa 100644
> --- a/lib/librte_ethdev/rte_ethdev.c
> +++ b/lib/librte_ethdev/rte_ethdev.c
> @@ -4206,6 +4206,29 @@ rte_eth_dma_zone_reserve(const struct rte_eth_dev *dev, const char *ring_name,
>   			RTE_MEMZONE_IOVA_CONTIG, align);
>   }
>   
> +int
> +rte_eth_dma_zone_free(const struct rte_eth_dev *dev, const char *ring_name,
> +		uint16_t queue_id)
> +{
> +	char z_name[RTE_MEMZONE_NAMESIZE];
> +	const struct rte_memzone *mz;
> +	int rc = 0;
> +
> +	snprintf(z_name, sizeof(z_name), "eth_p%d_q%d_%s",
> +			dev->data->port_id, queue_id, ring_name);
> +	if (rc >= RTE_MEMZONE_NAMESIZE) {
> +		RTE_ETHDEV_LOG(ERR, "ring name too long\n");
> +		rte_errno = ENAMETOOLONG;
> +		return NULL;
> +	}
> +
> +	mz = rte_memzone_lookup(z_name);
> +	if (mz)
> +		rc = rte_memzone_free(mz);

This is racy. Please just use rte_memzone_free() unconditionally. It'll 
return 0 if memzone existed, or will set rte_errno to EINVAL if it 
didn't. (this is suboptimal, it should be ENOENT, but changing this 
would be an API break... I'll submit a patch for future release to fix this)


-- 
Thanks,
Anatoly