Re: [intel-next 1/2] net/i40e: link NAPI instances to queues and IRQs

["Nambiar, Amritha" <amritha.nambiar@intel.com>]

On 4/9/2024 9:39 PM, Joe Damato wrote:
> Make i40e compatible with the newly added netlink queue GET APIs.
> 
> $ ./cli.py --spec ../../../Documentation/netlink/specs/netdev.yaml \
>    --do queue-get --json '{"ifindex": 3, "id": 1, "type": "rx"}'
> 
> {'id': 1, 'ifindex': 3, 'napi-id': 162, 'type': 'rx'}
> 
> $ ./cli.py --spec ../../../Documentation/netlink/specs/netdev.yaml \
>    --do napi-get --json '{"id": 162}'
> 
> {'id': 162, 'ifindex': 3, 'irq': 136}
> 
> The above output suggests that irq 136 was allocated for queue 1, which has
> a NAPI ID of 162.
> 
> To double check this is correct, the IRQ to queue mapping can be verified
> by checking /proc/interrupts:
> 
> $ cat /proc/interrupts  | grep 136\: | \
>    awk '{print "irq: " $1 " name " $76}'
> 
> irq: 136: name i40e-vlan300-TxRx-1
> 
> Suggests that queue 1 has IRQ 136, as expected.
> 
> Signed-off-by: Joe Damato <jdamato@fastly.com>
> ---
>   drivers/net/ethernet/intel/i40e/i40e.h      |  2 +
>   drivers/net/ethernet/intel/i40e/i40e_main.c | 58 +++++++++++++++++++++
>   drivers/net/ethernet/intel/i40e/i40e_txrx.c |  4 ++
>   3 files changed, 64 insertions(+)
> 
> diff --git a/drivers/net/ethernet/intel/i40e/i40e.h b/drivers/net/ethernet/intel/i40e/i40e.h
> index 2fbabcdb5bb5..5900ed5c7170 100644
> --- a/drivers/net/ethernet/intel/i40e/i40e.h
> +++ b/drivers/net/ethernet/intel/i40e/i40e.h
> @@ -1267,6 +1267,8 @@ int i40e_ioctl(struct net_device *netdev, struct ifreq *ifr, int cmd);
>   int i40e_open(struct net_device *netdev);
>   int i40e_close(struct net_device *netdev);
>   int i40e_vsi_open(struct i40e_vsi *vsi);
> +void i40e_queue_set_napi(struct i40e_vsi *vsi, unsigned int queue_index,
> +			 enum netdev_queue_type type, struct napi_struct *napi);
>   void i40e_vlan_stripping_disable(struct i40e_vsi *vsi);
>   int i40e_add_vlan_all_mac(struct i40e_vsi *vsi, s16 vid);
>   int i40e_vsi_add_vlan(struct i40e_vsi *vsi, u16 vid);
> diff --git a/drivers/net/ethernet/intel/i40e/i40e_main.c b/drivers/net/ethernet/intel/i40e/i40e_main.c
> index 0bdcdea0be3e..6384a0c73a05 100644
> --- a/drivers/net/ethernet/intel/i40e/i40e_main.c
> +++ b/drivers/net/ethernet/intel/i40e/i40e_main.c
> @@ -3448,6 +3448,58 @@ static struct xsk_buff_pool *i40e_xsk_pool(struct i40e_ring *ring)
>   	return xsk_get_pool_from_qid(ring->vsi->netdev, qid);
>   }
>   
> +/**
> + * __i40e_queue_set_napi - Set the napi instance for the queue
> + * @dev: device to which NAPI and queue belong
> + * @queue_index: Index of queue
> + * @type: queue type as RX or TX
> + * @napi: NAPI context
> + * @locked: is the rtnl_lock already held
> + *
> + * Set the napi instance for the queue. Caller indicates the lock status.
> + */
> +static void
> +__i40e_queue_set_napi(struct net_device *dev, unsigned int queue_index,
> +		      enum netdev_queue_type type, struct napi_struct *napi,
> +		      bool locked)
> +{
> +	if (!locked)
> +		rtnl_lock();
> +	netif_queue_set_napi(dev, queue_index, type, napi);
> +	if (!locked)
> +		rtnl_unlock();
> +}
> +
> +/**
> + * i40e_queue_set_napi - Set the napi instance for the queue
> + * @vsi: VSI being configured
> + * @queue_index: Index of queue
> + * @type: queue type as RX or TX
> + * @napi: NAPI context
> + *
> + * Set the napi instance for the queue. The rtnl lock state is derived from the
> + * execution path.
> + */
> +void
> +i40e_queue_set_napi(struct i40e_vsi *vsi, unsigned int queue_index,
> +		    enum netdev_queue_type type, struct napi_struct *napi)
> +{
> +	struct i40e_pf *pf = vsi->back;
> +
> +	if (!vsi->netdev)
> +		return;
> +
> +	if (current_work() == &pf->service_task ||
> +	    test_bit(__I40E_PF_RESET_REQUESTED, pf->state) ||

I think we might need something like ICE_PREPARED_FOR_RESET which 
detects all kinds of resets(PFR/CORE/GLOBR). __I40E_PF_RESET_REQUESTED 
handles PFR only. So, this might assert for RTNL lock on CORER/GLOBR.

> +	    test_bit(__I40E_DOWN, pf->state) ||
> +	    test_bit(__I40E_SUSPENDED, pf->state))
> +		__i40e_queue_set_napi(vsi->netdev, queue_index, type, napi,
> +				      false);
> +	else
> +		__i40e_queue_set_napi(vsi->netdev, queue_index, type, napi,
> +				      true);
> +}
> +
>   /**
>    * i40e_configure_tx_ring - Configure a transmit ring context and rest
>    * @ring: The Tx ring to configure
> @@ -3558,6 +3610,8 @@ static int i40e_configure_tx_ring(struct i40e_ring *ring)
>   	/* cache tail off for easier writes later */
>   	ring->tail = hw->hw_addr + I40E_QTX_TAIL(pf_q);
>   
> +	i40e_queue_set_napi(vsi, ring->queue_index, NETDEV_QUEUE_TYPE_TX,
> +			    &ring->q_vector->napi);

I am not sure very sure of this, have you tested this for the 
reset/rebuild path as well (example: ethtool -L and change queues). Just 
wondering if this path is taken for first time VSI init or additionally 
for any VSI rebuilds as well.

>   	return 0;
>   }
>   
> @@ -3716,6 +3770,8 @@ static int i40e_configure_rx_ring(struct i40e_ring *ring)
>   			 ring->queue_index, pf_q);
>   	}
>   
> +	i40e_queue_set_napi(vsi, ring->queue_index, NETDEV_QUEUE_TYPE_RX,
> +			    &ring->q_vector->napi);
>
Same as above.

   	return 0;
>   }
>   
> @@ -4178,6 +4234,8 @@ static int i40e_vsi_request_irq_msix(struct i40e_vsi *vsi, char *basename)
>   		q_vector->affinity_notify.notify = i40e_irq_affinity_notify;
>   		q_vector->affinity_notify.release = i40e_irq_affinity_release;
>   		irq_set_affinity_notifier(irq_num, &q_vector->affinity_notify);
> +		netif_napi_set_irq(&q_vector->napi, q_vector->irq_num);
> +
>   		/* Spread affinity hints out across online CPUs.
>   		 *
>   		 * get_cpu_mask returns a static constant mask with
> diff --git a/drivers/net/ethernet/intel/i40e/i40e_txrx.c b/drivers/net/ethernet/intel/i40e/i40e_txrx.c
> index 64d198ed166b..d380885ff26d 100644
> --- a/drivers/net/ethernet/intel/i40e/i40e_txrx.c
> +++ b/drivers/net/ethernet/intel/i40e/i40e_txrx.c
> @@ -821,6 +821,8 @@ void i40e_clean_tx_ring(struct i40e_ring *tx_ring)
>   void i40e_free_tx_resources(struct i40e_ring *tx_ring)
>   {
>   	i40e_clean_tx_ring(tx_ring);
> +	i40e_queue_set_napi(tx_ring->vsi, tx_ring->queue_index,
> +			    NETDEV_QUEUE_TYPE_TX, NULL);
>   	kfree(tx_ring->tx_bi);
>   	tx_ring->tx_bi = NULL;
>   
> @@ -1526,6 +1528,8 @@ void i40e_clean_rx_ring(struct i40e_ring *rx_ring)
>   void i40e_free_rx_resources(struct i40e_ring *rx_ring)
>   {
>   	i40e_clean_rx_ring(rx_ring);
> +	i40e_queue_set_napi(rx_ring->vsi, rx_ring->queue_index,
> +			    NETDEV_QUEUE_TYPE_RX, NULL);
>   	if (rx_ring->vsi->type == I40E_VSI_MAIN)
>   		xdp_rxq_info_unreg(&rx_ring->xdp_rxq);
>   	rx_ring->xdp_prog = NULL;