ethdev: fix check of rx configure

  From: Yunjian Wang <wangyunjian@huawei.com>

Coverity flags that 'rx_conf' variable is used before
it's checked for NULL. This patch fixes this issue.

Coverity issue: 363570
Fixes: 4ff702b5dfa9 ("ethdev: introduce Rx buffer split")

Signed-off-by: Yunjian Wang <wangyunjian@huawei.com>
---
 lib/librte_ethdev/rte_ethdev.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)
  

On 11/3/2020 1:31 PM, wangyunjian wrote:
> From: Yunjian Wang <wangyunjian@huawei.com>
> 
> Coverity flags that 'rx_conf' variable is used before
> it's checked for NULL. This patch fixes this issue.
> 
> Coverity issue: 363570
> Fixes: 4ff702b5dfa9 ("ethdev: introduce Rx buffer split")
> 
> Signed-off-by: Yunjian Wang <wangyunjian@huawei.com>
> ---
>   lib/librte_ethdev/rte_ethdev.c | 9 +++++----
>   1 file changed, 5 insertions(+), 4 deletions(-)
> 
> diff --git a/lib/librte_ethdev/rte_ethdev.c b/lib/librte_ethdev/rte_ethdev.c
> index b12bb3854d..c74502d45e 100644
> --- a/lib/librte_ethdev/rte_ethdev.c
> +++ b/lib/librte_ethdev/rte_ethdev.c
> @@ -1978,16 +1978,17 @@ rte_eth_rx_queue_setup(uint16_t port_id, uint16_t rx_queue_id,
>   			return -EINVAL;
>   		}
>   	} else {
> -		const struct rte_eth_rxseg_split *rx_seg =
> -			(const struct rte_eth_rxseg_split *)rx_conf->rx_seg;
> -		uint16_t n_seg = rx_conf->rx_nseg;
> -
>   		/* Extended multi-segment configuration check. */
>   		if (rx_conf == NULL || rx_conf->rx_seg == NULL || rx_conf->rx_nseg == 0) {
>   			RTE_ETHDEV_LOG(ERR,
>   				       "Memory pool is null and no extended configuration provided\n");
>   			return -EINVAL;
>   		}
> +
> +		const struct rte_eth_rxseg_split *rx_seg =
> +			(const struct rte_eth_rxseg_split *)rx_conf->rx_seg;
> +		uint16_t n_seg = rx_conf->rx_nseg;
> +

Can you please leave the declaration of the variables at the beginning of the 
block, but move the assignment?
  

> -----Original Message-----
> From: Ferruh Yigit [mailto:ferruh.yigit@intel.com]
> Sent: Tuesday, November 3, 2020 9:58 PM
> To: wangyunjian <wangyunjian@huawei.com>; dev@dpdk.org
> Cc: thomas@monjalon.net; andrew.rybchenko@oktetlabs.ru; Lilijun (Jerry)
> <jerry.lilijun@huawei.com>; xudingke <xudingke@huawei.com>
> Subject: Re: [dpdk-dev] [PATCH] ethdev: fix check of rx configure
> 
> On 11/3/2020 1:31 PM, wangyunjian wrote:
> > From: Yunjian Wang <wangyunjian@huawei.com>
> >
> > Coverity flags that 'rx_conf' variable is used before it's checked for
> > NULL. This patch fixes this issue.
> >
> > Coverity issue: 363570
> > Fixes: 4ff702b5dfa9 ("ethdev: introduce Rx buffer split")
> >
> > Signed-off-by: Yunjian Wang <wangyunjian@huawei.com>
> > ---
> >   lib/librte_ethdev/rte_ethdev.c | 9 +++++----
> >   1 file changed, 5 insertions(+), 4 deletions(-)
> >
> > diff --git a/lib/librte_ethdev/rte_ethdev.c
> > b/lib/librte_ethdev/rte_ethdev.c index b12bb3854d..c74502d45e 100644
> > --- a/lib/librte_ethdev/rte_ethdev.c
> > +++ b/lib/librte_ethdev/rte_ethdev.c
> > @@ -1978,16 +1978,17 @@ rte_eth_rx_queue_setup(uint16_t port_id,
> uint16_t rx_queue_id,
> >   			return -EINVAL;
> >   		}
> >   	} else {
> > -		const struct rte_eth_rxseg_split *rx_seg =
> > -			(const struct rte_eth_rxseg_split *)rx_conf->rx_seg;
> > -		uint16_t n_seg = rx_conf->rx_nseg;
> > -
> >   		/* Extended multi-segment configuration check. */
> >   		if (rx_conf == NULL || rx_conf->rx_seg == NULL ||
> rx_conf->rx_nseg == 0) {
> >   			RTE_ETHDEV_LOG(ERR,
> >   				       "Memory pool is null and no extended
> configuration provided\n");
> >   			return -EINVAL;
> >   		}
> > +
> > +		const struct rte_eth_rxseg_split *rx_seg =
> > +			(const struct rte_eth_rxseg_split *)rx_conf->rx_seg;
> > +		uint16_t n_seg = rx_conf->rx_nseg;
> > +
> 
> Can you please leave the declaration of the variables at the beginning of the
> block, but move the assignment?

OK, thanks for your suggestion, will include it in next version.

Yunjian