netdev - Re: [PATCH net-next v7 1/4] gve: Add support for raw addressing device option

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Date:   Thu, 19 Nov 2020 21:07:56 -0800
From:   David Awogbemila <awogbemila@...gle.com>
To:     Maciej Fijalkowski <maciej.fijalkowski@...el.com>
Cc:     Saeed Mahameed <saeed@...nel.org>, Netdev <netdev@...r.kernel.org>,
        Catherine Sullivan <csully@...gle.com>,
        Yangchun Fu <yangchun@...gle.com>
Subject: Re: [PATCH net-next v7 1/4] gve: Add support for raw addressing
 device option

On Thu, Nov 19, 2020 at 6:10 PM Maciej Fijalkowski
<maciej.fijalkowski@...el.com> wrote:
>
> On Thu, Nov 19, 2020 at 04:22:24PM -0800, David Awogbemila wrote:
> > On Thu, Nov 19, 2020 at 12:21 PM Saeed Mahameed <saeed@...nel.org> wrote:
> > >
> > > On Wed, 2020-11-18 at 15:20 -0800, David Awogbemila wrote:
> > > > From: Catherine Sullivan <csully@...gle.com>
> > > >
> > > > Add support to describe device for parsing device options. As
> > > > the first device option, add raw addressing.
> > > >
> > > > "Raw Addressing" mode (as opposed to the current "qpl" mode) is an
> > > > operational mode which allows the driver avoid bounce buffer copies
> > > > which it currently performs using pre-allocated qpls
> > > > (queue_page_lists)
> > > > when sending and receiving packets.
> > > > For egress packets, the provided skb data addresses will be
> > > > dma_map'ed and
> > > > passed to the device, allowing the NIC can perform DMA directly - the
> > > > driver will not have to copy the buffer content into pre-allocated
> > > > buffers/qpls (as in qpl mode).
> > > > For ingress packets, copies are also eliminated as buffers are handed
> > > > to
> > > > the networking stack and then recycled or re-allocated as
> > > > necessary, avoiding the use of skb_copy_to_linear_data().
> > > >
> > > > This patch only introduces the option to the driver.
> > > > Subsequent patches will add the ingress and egress functionality.
> > > >
> > > > Reviewed-by: Yangchun Fu <yangchun@...gle.com>
> > > > Signed-off-by: Catherine Sullivan <csully@...gle.com>
> > > > Signed-off-by: David Awogbemila <awogbemila@...gle.com>
> > > > ---
> > > >
> > > ...
> > > > diff --git a/drivers/net/ethernet/google/gve/gve_adminq.c
> > > > b/drivers/net/ethernet/google/gve/gve_adminq.c
> > > > index 24ae6a28a806..1e2d407cb9d2 100644
> > > > --- a/drivers/net/ethernet/google/gve/gve_adminq.c
> > > > +++ b/drivers/net/ethernet/google/gve/gve_adminq.c
> > > > @@ -14,6 +14,57 @@
> > > >  #define GVE_ADMINQ_SLEEP_LEN         20
> > > >  #define GVE_MAX_ADMINQ_EVENT_COUNTER_CHECK   100
> > > >
> > > > +#define GVE_DEVICE_OPTION_ERROR_FMT "%s option error:\n" \
> > > > +"Expected: length=%d, feature_mask=%x.\n" \
> > > > +"Actual: length=%d, feature_mask=%x.\n"
> > > > +
> > > > +static inline
> > > > +struct gve_device_option *gve_get_next_option(struct
> > > >
> > >
> > > Following Dave's policy, no static inline functions in C files.
> > > This is control path so you don't really need the inline here.
> >
> > Okay, I'll move it to a header file.
>
> That's not what Saeed meant I suppose. Policy says that we let the
> compiler to make the decision whether or not such static function should
> be inlined. And since it's not a performance critical path as Saeed says
> then drop the inline and keep the rest as-is.

Oh I see, thanks for the clarification, I was going to remove the
inline keyword and move it to a header file but I see now that I can
just remove the inline keyword. thanks.