Subject: Re: [PATCH iwl-net 2/2] i40e: take into account XDP Tx queues when stopping rings

From: Maciej Fijalkowski <[email-masked]>
Date: Tue, 6 Feb 2024 13:08:25 +0100

On Thu, Feb 01, 2024 at 12:40:22PM -0600, Seth Forshee wrote:
> On Thu, Feb 01, 2024 at 04:42:19PM +0100, Maciej Fijalkowski wrote:
> > Seth reported that on his side XDP traffic can not survive a round of
> > down/up against i40e interface. Dmesg output was telling us that we were
> > not able to disable the very first XDP ring. That was due to the fact
> > that in i40e_vsi_stop_rings() in a pre-work that is done before calling
> > i40e_vsi_wait_queues_disabled(), XDP Tx queues were not taken into the
> > account.
> > 
> > To fix this, let us distinguish between Rx and Tx queue boundaries and
> > take into the account XDP queues for Tx side.
> > 
> > Reported-by: Seth Forshee <[email-masked]>
> > Closes: https://lore.kernel.org/netdev/ZbkE7Ep1N1Ou17sA@do-x1extreme/
> > Fixes: 65662a8dcdd0 ("i40e: Fix logic of disabling queues")
> > Signed-off-by: Maciej Fijalkowski <[email-masked]>
> 
> This fixes the issue we're seeing. Thanks!
> 
> Tested-by: Seth Forshee <[email-masked]>
> 
> > ---
> >  drivers/net/ethernet/intel/i40e/i40e_main.c | 13 +++++++------
> >  1 file changed, 7 insertions(+), 6 deletions(-)
> > 
> > diff --git a/drivers/net/ethernet/intel/i40e/i40e_main.c b/drivers/net/ethernet/intel/i40e/i40e_main.c
> > index 2c46a5e7d222..907be56965f5 100644
> > --- a/drivers/net/ethernet/intel/i40e/i40e_main.c
> > +++ b/drivers/net/ethernet/intel/i40e/i40e_main.c
> > @@ -4926,21 +4926,22 @@ int i40e_vsi_start_rings(struct i40e_vsi *vsi)
> >  void i40e_vsi_stop_rings(struct i40e_vsi *vsi)
> >  {
> >  	struct i40e_pf *pf = vsi->back;
> > -	int pf_q, q_end;
> > +	u32 pf_q, tx_q_end, rx_q_end;
> >  
> >  	/* When port TX is suspended, don't wait */
> >  	if (test_bit(__I40E_PORT_SUSPENDED, vsi->back->state))
> >  		return i40e_vsi_stop_rings_no_wait(vsi);
> >  
> > -	q_end = vsi->base_queue + vsi->num_queue_pairs;
> > -	for (pf_q = vsi->base_queue; pf_q < q_end; pf_q++)
> > -		i40e_pre_tx_queue_cfg(&pf->hw, (u32)pf_q, false);
> > +	tx_q_end = vsi->alloc_queue_pairs * (i40e_enabled_xdp_vsi(vsi) ? 2 : 1);

While this fixes one thing, it breaks another ;) vsi->base_queue needs to
be involved into tx_q_end, otherwise anything besides PF0 would not go
through Tx loops. I noticed that FDIR VSI started to get Tx disable
timeouts with this patch.

Will send a v2.

> > +	for (pf_q = vsi->base_queue; pf_q < tx_q_end; pf_q++)
> > +		i40e_pre_tx_queue_cfg(&pf->hw, pf_q, false);
> >  
> > -	for (pf_q = vsi->base_queue; pf_q < q_end; pf_q++)
> > +	rx_q_end = vsi->base_queue + vsi->num_queue_pairs;
> > +	for (pf_q = vsi->base_queue; pf_q < rx_q_end; pf_q++)
> >  		i40e_control_rx_q(pf, pf_q, false);
> >  
> >  	msleep(I40E_DISABLE_TX_GAP_MSEC);
> > -	for (pf_q = vsi->base_queue; pf_q < q_end; pf_q++)
> > +	for (pf_q = vsi->base_queue; pf_q < tx_q_end; pf_q++)
> >  		wr32(&pf->hw, I40E_QTX_ENA(pf_q), 0);
> >  
> >  	i40e_vsi_wait_queues_disabled(vsi);
> > -- 
> > 2.34.1
> > 
>