Re: [dpdk-dev] [PATCH] ethdev: verify reserved HW ring

[Andrew Rybchenko <arybchenko@solarflare.com>]

On 6/23/20 7:41 PM, Ferruh Yigit wrote:
> Function 'rte_eth_dma_zone_reserve()' returns an existing memzone based
> on name match, but other requested attributes are discarded.
> This may cause driver using a memzone with wrong size or alignment.
> 
> Verify size, alignment and socket_id for matched memzone, and do not use
> memzone if any one of the attributes are not justified.
> 
> Reported-by: Renata Saiakhova <renata.saiakhova@ekinops.com>
> Signed-off-by: Ferruh Yigit <ferruh.yigit@intel.com>

Few minor notes below, other than that:
Reviewed-by: Andrew Rybchenko <arybchenko@solarflare.com>

> ---
> Cc: Anatoly Burakov <anatoly.burakov@intel.com>
> ---
>  lib/librte_ethdev/rte_ethdev.c | 12 +++++++++++-
>  1 file changed, 11 insertions(+), 1 deletion(-)
> 
> diff --git a/lib/librte_ethdev/rte_ethdev.c b/lib/librte_ethdev/rte_ethdev.c
> index 8e10a6fc3..0fe84aadc 100644
> --- a/lib/librte_ethdev/rte_ethdev.c
> +++ b/lib/librte_ethdev/rte_ethdev.c
> @@ -4202,8 +4202,18 @@ rte_eth_dma_zone_reserve(const struct rte_eth_dev *dev, const char *ring_name,
>  	}
>  
>  	mz = rte_memzone_lookup(z_name);
> -	if (mz)
> +	if (mz) {
> +		if ((socket_id != SOCKET_ID_ANY && socket_id != mz->socket_id) ||
> +				size > mz->len ||
> +				(uintptr_t)mz->addr & (align - 1)) {

IMHO, it would be a bit more readable if the result compared
with 0. Up to you.

> +			RTE_ETHDEV_LOG(ERR,
> +				"memzone %s does not justify the requested attributes\n",
> +				mz->name);
> +			return NULL;

Initially I thought it is a bad behaviour and memzone should
be freed and reallocated, but it is even worse (implicit free).
May be it is better to highlight it in the description.

> +		}
> +
>  		return mz;
> +	}
>  
>  	return rte_memzone_reserve_aligned(z_name, size, socket_id,
>  			RTE_MEMZONE_IOVA_CONTIG, align);
>