On Tue, 20 Jun 2017 00:55:41 +0200, Daniel Borkmann wrote:
> On 06/17/2017 01:57 AM, Jakub Kicinski wrote:
> > Add an installation-time flag for requesting that the program
> > be installed only if it can be offloaded to HW.
> >
> > Internally new command for ndo_xdp is added, this way we avoid
> > putting checks into drivers since they all return -EINVAL on
> > an unknown command.
> >
> > Signed-off-by: Jakub Kicinski <jakub.kicin...@netronome.com>
> [...]
> > diff --git a/net/core/dev.c b/net/core/dev.c
> > index a04db264aa1c..05cec8e2cd82 100644
> > --- a/net/core/dev.c
> > +++ b/net/core/dev.c
> > @@ -6959,7 +6959,10 @@ static int dev_xdp_install(struct net_device *dev,
> > xdp_op_t xdp_op,
> > struct netdev_xdp xdp;
> >
> > memset(&xdp, 0, sizeof(xdp));
> > - xdp.command = XDP_SETUP_PROG;
> > + if (flags & XDP_FLAGS_HW_MODE)
> > + xdp.command = XDP_SETUP_PROG_HW;
> > + else
> > + xdp.command = XDP_SETUP_PROG;
> > xdp.extack = extack;
> > xdp.flags = flags;
> > xdp.prog = prog;
>
> One thing I'm not sure I follow is that while you pass flags to the ndo
> in patch 1, add a new XDP_SETUP_PROG_HW command here in patch 2 based on
> the flags, and later on in patch 6, you don't really make use of it, but
> look at the flags anyway? Then, why adding separate XDP_SETUP_PROG_HW
> in the first place?
>
> [patch 6:]
> @@ -3338,6 +3341,7 @@ static int nfp_net_xdp(struct net_device *netdev,
> struct netdev_xdp *xdp)
>
> switch (xdp->command) {
> case XDP_SETUP_PROG:
> + case XDP_SETUP_PROG_HW:
> return nfp_net_xdp_setup(nn, xdp->prog, xdp->flags,
> xdp->extack);
We still need the flags to be able to differentiate between default/no
flags case where we load to the driver and the HW ("both"), and when
the DRV_MODE flag is set, in which case we disable the HW offload and
only load to the driver. We have three cases:
drv offload
no flag yes attempted
DRV_MODE yes no
HW_MODE no yes
The XDP_SETUP_PROG_HW command is purely for convenience of drivers
without an offload. I felt it's not appropriate to burden all drivers
with:
if (xdp->flags & XDP_FLAGS_HW_MODE)
return -EOPNOTSUPP;
But, I do have a patch which does it, so I'm happy to drop the new
command if it's preferred.
