Re: [dpdk-dev] [PATCH] net/e1000: do not error out if rx_drop_en is set

["Zhang, Qi Z" <qi.z.zhang@intel.com>]

> -----Original Message-----
> From: Zhao1, Wei
> Sent: Wednesday, October 10, 2018 12:25 AM
> To: Luca Boccassi <bluca@debian.org>; dev@dpdk.org
> Cc: Lu, Wenzhuo <wenzhuo.lu@intel.com>; stable@dpdk.org; Zhang, Qi Z
> <qi.z.zhang@intel.com>; 3chas3@gmail.com
> Subject: RE: [dpdk-dev] [PATCH] net/e1000: do not error out if rx_drop_en is
> set
> 
> Acked-by: Wei Zhao <wei.zhao1@intel.com>

Applied to dpdk-next-net-intel with minor change on the title to avoid check-git-log warning.

Thanks
Qi

> 
> 
> > -----Original Message-----
> > From: Luca Boccassi [mailto:bluca@debian.org]
> > Sent: Monday, October 8, 2018 10:14 PM
> > To: Zhao1, Wei <wei.zhao1@intel.com>; dev@dpdk.org
> > Cc: Lu, Wenzhuo <wenzhuo.lu@intel.com>; stable@dpdk.org; Zhang, Qi Z
> > <qi.z.zhang@intel.com>; 3chas3@gmail.com
> > Subject: Re: [dpdk-dev] [PATCH] net/e1000: do not error out if
> > rx_drop_en is set
> >
> > On Mon, 2018-10-08 at 08:43 +0000, Zhao1, Wei wrote:
> > > Hi,  Luca Boccassi
> > >
> > > > -----Original Message-----
> > > > From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Luca Boccassi
> > > > Sent: Saturday, July 28, 2018 1:26 AM
> > > > To: dev@dpdk.org
> > > > Cc: Lu, Wenzhuo <wenzhuo.lu@intel.com>; Luca Boccassi
> > > > <bluca@debian.org>; stable@dpdk.org
> > > > Subject: [dpdk-dev] [PATCH] net/e1000: do not error out if
> > > > rx_drop_en is set
> > > >
> > > > rx_drop_en is an optimization that does nothing on single-queue
> > > > devices like e1000. Do not force applications that do not care to
> > > > select per- devices
> > >
> > > And aslo, eth_em_rx_queue_setup support set up of multiple queues
> > > for EM device.
> > >
> > > > optimizations flags by returning an error, just log it and carry on.
> > >
> > > rx_drop_en is a flag to enable receive packets drop when
> > > insufficient receive descriptors exist to write the packet into system
> memory.
> > > if we delete this parameter check protection, it may be misleading
> > > some applications for this point, why does not give some requirement
> > > for proper usage of this? I do not suggest for this change.
> > > You can also refer to function eth_igb_rx_queue_setup(), igb device
> > > support rx_drop_en set, so we do not have a such parameter check.
> >
> > Hi,
> >
> > As mentioned, because given it does nothing it's not worth aborting
> > the program with an error. Logging a notice level message and carrying
> > on is sufficient.
> > We should try not make it harder than necessary for application
> developers.
> >
> > > >
> > > > Fixes: 805803445a02 ("e1000: support EM devices (also known as
> > > > e1000/e1000e)")
> > > > Cc: stable@dpdk.org
> > > >
> > > > Signed-off-by: Luca Boccassi <bluca@debian.org>
> > > > ---
> > > >  drivers/net/e1000/em_rxtx.c | 7 ++++---
> > > >  1 file changed, 4 insertions(+), 3 deletions(-)
> > > >
> > > > diff --git a/drivers/net/e1000/em_rxtx.c
> > > > b/drivers/net/e1000/em_rxtx.c index a6b3e92a6..81dc41efb 100644
> > > > --- a/drivers/net/e1000/em_rxtx.c
> > > > +++ b/drivers/net/e1000/em_rxtx.c
> > > > @@ -1416,12 +1416,13 @@ eth_em_rx_queue_setup(struct
> > rte_eth_dev
> > > > *dev,
> > > >  	}
> > > >
> > > >  	/*
> > > > -	 * EM devices don't support drop_en functionality
> > > > +	 * EM devices don't support drop_en functionality.
> > > > +	 * It's an optimization that does nothing on single-queue
> > > > devices,
> > > > +	 * so just log the issue and carry on.
> > > >  	 */
> > > >  	if (rx_conf->rx_drop_en) {
> > > > -		PMD_INIT_LOG(ERR, "drop_en functionality not
> > > > supported
> > > > by "
> > > > +		PMD_INIT_LOG(NOTICE, "drop_en functionality not
> > > > supported by "
> > > >  			     "device");
> > > > -		return -EINVAL;
> > > >  	}
> > > >
> > > >  	/* Free memory prior to re-allocation if needed. */
> > > > --
> > > > 2.18.0
> > >
> > >
> >
> > --
> > Kind regards,
> > Luca Boccassi