Re: [PATCH net-next 3/3] net: ethernet: ti: cpsw: add XDP support

[Ivan Khoronzhuk]

On Fri, May 24, 2019 at 02:05:11PM +0300, Ilias Apalodimas wrote:
> On Thu, May 23, 2019 at 09:20:35PM +0300, Ivan Khoronzhuk wrote:
> > Add XDP support based on rx page_pool allocator, one frame per page.
> > Page pool allocator is used with assumption that only one rx_handler
> > is running simultaneously. DMA map/unmap is reused from page pool
> > despite there is no need to map whole page.
> >
> > Due to specific of cpsw, the same TX/RX handler can be used by 2
> > network devices, so special fields in buffer are added to identify
> > an interface the frame is destined to. Thus XDP works for both
> > interfaces, that allows to test xdp redirect between two interfaces
> > easily.
> >
> > XDP prog is common for all channels till appropriate changes are added
> > in XDP infrastructure.
> >
> > Signed-off-by: Ivan Khoronzhuk <ivan.khoronzhuk@xxxxxxxxxx>
> > ---
> >  drivers/net/ethernet/ti/Kconfig        |   1 +
> >  drivers/net/ethernet/ti/cpsw.c         | 555 ++++++++++++++++++++++---
> >  drivers/net/ethernet/ti/cpsw_ethtool.c |  53 +++
> >  drivers/net/ethernet/ti/cpsw_priv.h    |   7 +
> >  4 files changed, 554 insertions(+), 62 deletions(-)
> >
> > diff --git a/drivers/net/ethernet/ti/Kconfig b/drivers/net/ethernet/ti/Kconfig
> > index bd05a977ee7e..3cb8c5214835 100644
> > --- a/drivers/net/ethernet/ti/Kconfig
> > +++ b/drivers/net/ethernet/ti/Kconfig
> > @@ -50,6 +50,7 @@ config TI_CPSW
> >  	depends on ARCH_DAVINCI || ARCH_OMAP2PLUS || COMPILE_TEST
> >  	select TI_DAVINCI_MDIO
> >  	select MFD_SYSCON
> > +	select PAGE_POOL
> >  	select REGMAP
> >  	---help---
> >  	  This driver supports TI's CPSW Ethernet Switch.
> > diff --git a/drivers/net/ethernet/ti/cpsw.c b/drivers/net/ethernet/ti/cpsw.c
> > index 87a600aeee4a..274e6b64ea9e 100644
> > --- a/drivers/net/ethernet/ti/cpsw.c
> > +++ b/drivers/net/ethernet/ti/cpsw.c
> > @@ -31,6 +31,10 @@
> >  #include <linux/if_vlan.h>
> >  #include <linux/kmemleak.h>
> >  #include <linux/sys_soc.h>
> > +#include <net/page_pool.h>
> > +#include <linux/bpf.h>
> > +#include <linux/bpf_trace.h>
> > +#include <linux/filter.h>
> >
> >  #include <linux/pinctrl/consumer.h>

[...]

> > +			start_free = 1;
> > +			continue;
> > +		}
> > +
> > +		/* if refcnt > 1, page has been holding by netstack, it's pity,
> > +		 * so put it to the ring to be consumed later when fast cash is
> s/cash/cache
>
> > +		 * empty. If ring is full then free page by recycling as above.
> > +		 */
> > +		ret = ptr_ring_produce(&pool->ring, page);
> > +		if (ret) {
> > +			page_pool_recycle_direct(pool, page);
> > +			continue;
> > +		}
> Although this should be fine since this part won't be called during the driver
> init, i think i'd prefer unmapping the buffer and let the network stack free it,
> instead of pushing it for recycling. The occurence should be pretty low, so
> allocating a buffer every once in a while shouldn't have a noticeable
> performance impact

Ok, I will leave previous version from RFC.

--
Regards,
Ivan Khoronzhuk