Re: [dpdk-dev] [PATCH v4 15/23] rte_ethdev.h: align sign and scope of temp var

[Bruce Richardson <bruce.richardson@intel.com>]

On Thu, May 17, 2018 at 10:17:04PM +0800, Andy Green wrote:
> 
> 
> On 05/17/2018 09:54 PM, Bruce Richardson wrote:
> > On Mon, May 14, 2018 at 01:10:43PM +0800, Andy Green wrote:
> > > Signed-off-by: Andy Green <andy@warmcat.com>
> > > ---
> > >   lib/librte_ethdev/rte_ethdev.h |   25 +++++++++++++++----------
> > >   1 file changed, 15 insertions(+), 10 deletions(-)
> > > 
> > 
> > While I dislike the changes below, since I believe it's always more
> > readable to declare variables at first use, if the changes are needed to
> > remove compiler errors in apps, then they need to be fixed.
> > 
> > Patch needs a suitable commit log explaining the changes or giving the
> > error message.
> 
> It has this in the last push (which overlapped with your comment)... I seem
> to have missed the error about declarations after code not being allowed in
> C90, but I guess that part being an issue is not controversial.
> 
> > 
> > > diff --git a/lib/librte_ethdev/rte_ethdev.h b/lib/librte_ethdev/rte_ethdev.h
> > > index 49c2ebbd5..2cb5fe3be 100644
> > > --- a/lib/librte_ethdev/rte_ethdev.h
> > > +++ b/lib/librte_ethdev/rte_ethdev.h
> > > @@ -3801,6 +3801,7 @@ rte_eth_rx_burst(uint16_t port_id, uint16_t queue_id,
> > >   		 struct rte_mbuf **rx_pkts, const uint16_t nb_pkts)
> > >   {
> > >   	struct rte_eth_dev *dev = &rte_eth_devices[port_id];
> > > +	uint16_t nb_rx;
> > >   #ifdef RTE_LIBRTE_ETHDEV_DEBUG
> > >   	RTE_ETH_VALID_PORTID_OR_ERR_RET(port_id, 0);
> > > @@ -3811,18 +3812,22 @@ rte_eth_rx_burst(uint16_t port_id, uint16_t queue_id,
> > >   		return 0;
> > >   	}
> > >   #endif
> > > -	int16_t nb_rx = (*dev->rx_pkt_burst)(dev->data->rx_queues[queue_id],
> > > -			rx_pkts, nb_pkts);
> > > +	nb_rx = (*dev->rx_pkt_burst)(dev->data->rx_queues[queue_id],
> > > +				     rx_pkts, nb_pkts);
> > >   #ifdef RTE_ETHDEV_RXTX_CALLBACKS
> > > -	struct rte_eth_rxtx_callback *cb = dev->post_rx_burst_cbs[queue_id];
> > > -
> > > -	if (unlikely(cb != NULL)) {
> > > -		do {
> > > -			nb_rx = cb->fn.rx(port_id, queue_id, rx_pkts, nb_rx,
> > > -						nb_pkts, cb->param);
> > > -			cb = cb->next;
> > > -		} while (cb != NULL);
> > > +	{
> > > +		struct rte_eth_rxtx_callback *cb =
> > > +				dev->post_rx_burst_cbs[queue_id];
> > > +
> > > +		if (unlikely(cb != NULL)) {
> > > +			do {
> > > +				nb_rx = cb->fn.rx(port_id, queue_id,
> > > +						  rx_pkts, nb_rx,
> > > +						  nb_pkts, cb->param);
> > > +				cb = cb->next;
> > > +			} while (cb != NULL);
> > > +		}
> > >   	}
> > >   #endif
> > 
> > Rather than increasing the level of indentation needed with the extra
> > braces, it's probably best to separate variable definition and assignment
> > as you did in the first change above.
> 
> IIRC my thinking was I had a choice to repeat the conditional compilation
> stuff around the declaration (because it's in an #ifdef), (void)cb; to dodge
> the unused var warning, or add a basic block for it to scope to.  The last
> one didn't seem so bad.
> 
Ok, that makes sense. For completeness, I'd add a "do" and "while(0)" to the
braces, but that's not important here, it's ok as-is.

BTW: for your v5, I don't think you kept the previous ack's that myself and
Olivier had given for a number of your patches. It's strongly recommended
that you put any previously-given acks in any new revisions after the
signoff line, so as to make it easier to track for maintainers, and to save
us having to re-ack the same patches multiple times.

Thanks,
/Bruce