[Intel-wired-lan] [PATCH] i40e: Add error message when MTU on device is out of the range

[Maciej Fijalkowski <maciej.fijalkowski@intel.com>]

On Wed, Jan 06, 2021 at 10:36:23AM +0100, Paul Menzel wrote:
> Dear Eryk,

Eryk, you still haven't specified the tree that this patch is supposed to
land (nit - it will be net-next :))

> 
> 
> Am 18.12.20 um 17:52 schrieb Eryk Rybak:
> 
> Maybe a shorter summary:
> 
> > i40e: Log error for oversized MTU on device
> 
> > When attempting to link XDP prog with MTU larger than supported,
> > user is not informed why XDP linking fails. Adding proper
> 
> Nit: Imperative mood could be used instead: Add proper ?

+1, thanks Paul!

> 
> > error message.
> 
> Personally, when adding new log message, I find it nice to see them in the
> commit message too.
> 
> > Signed-off-by: Arkadiusz Kubalewski <arkadiusz.kubalewski@intel.com>
> > Signed-off-by: Eryk Rybak <eryk.roch.rybak@intel.com>
> > ---
> >   drivers/net/ethernet/intel/i40e/i40e_main.c | 11 +++++++----
> >   1 file changed, 7 insertions(+), 4 deletions(-)
> > 
> > diff --git a/drivers/net/ethernet/intel/i40e/i40e_main.c b/drivers/net/ethernet/intel/i40e/i40e_main.c
> > index 630258e..4fdef00 100644
> > --- a/drivers/net/ethernet/intel/i40e/i40e_main.c
> > +++ b/drivers/net/ethernet/intel/i40e/i40e_main.c
> > @@ -12933,9 +12933,10 @@ static netdev_features_t i40e_features_check(struct sk_buff *skb,
> >    * i40e_xdp_setup - add/remove an XDP program
> >    * @vsi: VSI to changed
> >    * @prog: XDP program
> > + * @extack: netlink extended ack
> >    **/
> > -static int i40e_xdp_setup(struct i40e_vsi *vsi,
> > -			  struct bpf_prog *prog)
> > +static int i40e_xdp_setup(struct i40e_vsi *vsi, struct bpf_prog *prog,
> > +			  struct netlink_ext_ack *extack)
> >   {
> >   	int frame_size = vsi->netdev->mtu + ETH_HLEN + ETH_FCS_LEN + VLAN_HLEN;
> >   	struct i40e_pf *pf = vsi->back;
> > @@ -12944,8 +12945,10 @@ static int i40e_xdp_setup(struct i40e_vsi *vsi,
> >   	int i;
> >   	/* Don't allow frames that span over multiple buffers */
> > -	if (frame_size > vsi->rx_buf_len)
> > +	if (frame_size > vsi->rx_buf_len) {
> > +		NL_SET_ERR_MSG_MOD(extack, "MTU too large to enable XDP");
> 
> Could you please also print out both values? Maybe (unsure about the units):
> 
>    MTU of %u bytes(?) too large to enable XDP (maximum: %u bytes)

No, extack does not support printf-like format specifiers, unfortunately
:<

Maybe we can double the message and have a separate dev_info() in here?

> 
> 
> Kind regards,
> 
> Paul
> 
> 
> >   		return -EINVAL;
> > +	}
> >   	/* When turning XDP on->off/off->on we reset and rebuild the rings. */
> >   	need_reset = (i40e_enabled_xdp_vsi(vsi) != !!prog);
> > @@ -13254,7 +13257,7 @@ static int i40e_xdp(struct net_device *dev,
> >   	switch (xdp->command) {
> >   	case XDP_SETUP_PROG:
> > -		return i40e_xdp_setup(vsi, xdp->prog);
> > +		return i40e_xdp_setup(vsi, xdp->prog, xdp->extack);
> >   	case XDP_SETUP_XSK_POOL:
> >   		return i40e_xsk_pool_setup(vsi, xdp->xsk.pool,
> >   					   xdp->xsk.queue_id);
> > 
> > base-commit: d2c2bbad93b818020657a82121a147e9ace1230d
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