Link queues to NAPI instances via netdev-genl API so that users can
query this information with netlink. Handle a few cases in the driver:
  1. Link/unlink the NAPIs when XDP is enabled/disabled
  2. Handle IGC_FLAG_QUEUE_PAIRS enabled and disabled
Example output when IGC_FLAG_QUEUE_PAIRS is enabled:

$ ./tools/net/ynl/cli.py --spec Documentation/netlink/specs/netdev.yaml \
                         --dump queue-get --json='{"ifindex": 2}'

[{'id': 0, 'ifindex': 2, 'napi-id': 8193, 'type': 'rx'},
 {'id': 1, 'ifindex': 2, 'napi-id': 8194, 'type': 'rx'},
 {'id': 2, 'ifindex': 2, 'napi-id': 8195, 'type': 'rx'},
 {'id': 3, 'ifindex': 2, 'napi-id': 8196, 'type': 'rx'},
 {'id': 0, 'ifindex': 2, 'napi-id': 8193, 'type': 'tx'},
 {'id': 1, 'ifindex': 2, 'napi-id': 8194, 'type': 'tx'},
 {'id': 2, 'ifindex': 2, 'napi-id': 8195, 'type': 'tx'},
 {'id': 3, 'ifindex': 2, 'napi-id': 8196, 'type': 'tx'}]

Since IGC_FLAG_QUEUE_PAIRS is enabled, you'll note that the same NAPI ID
is present for both rx and tx queues at the same index, for example
index 0:

{'id': 0, 'ifindex': 2, 'napi-id': 8193, 'type': 'rx'},
{'id': 0, 'ifindex': 2, 'napi-id': 8193, 'type': 'tx'},

To test IGC_FLAG_QUEUE_PAIRS disabled, a test system was booted using
the grub command line option "maxcpus=2" to force
igc_set_interrupt_capability to disable IGC_FLAG_QUEUE_PAIRS.

Example output when IGC_FLAG_QUEUE_PAIRS is disabled:

$ lscpu | grep "On-line CPU"
On-line CPU(s) list:      0,2

$ ethtool -l enp86s0  | tail -5
Current hardware settings:
RX:             n/a
TX:             n/a
Other:          1
Combined:       2

$ cat /proc/interrupts  | grep enp
 144: [...] enp86s0
 145: [...] enp86s0-rx-0
 146: [...] enp86s0-rx-1
 147: [...] enp86s0-tx-0
 148: [...] enp86s0-tx-1

1 "other" IRQ, and 2 IRQs for each of RX and Tx, so we expect netlink to
report 4 IRQs with unique NAPI IDs:

$ ./tools/net/ynl/cli.py --spec Documentation/netlink/specs/netdev.yaml \
                         --dump napi-get --json='{"ifindex": 2}'
[{'id': 8196, 'ifindex': 2, 'irq': 148},
 {'id': 8195, 'ifindex': 2, 'irq': 147},
 {'id': 8194, 'ifindex': 2, 'irq': 146},
 {'id': 8193, 'ifindex': 2, 'irq': 145}]

Now we examine which queues these NAPIs are associated with, expecting
that since IGC_FLAG_QUEUE_PAIRS is disabled each RX and TX queue will
have its own NAPI instance:

$ ./tools/net/ynl/cli.py --spec Documentation/netlink/specs/netdev.yaml \
                         --dump queue-get --json='{"ifindex": 2}'
[{'id': 0, 'ifindex': 2, 'napi-id': 8193, 'type': 'rx'},
 {'id': 1, 'ifindex': 2, 'napi-id': 8194, 'type': 'rx'},
 {'id': 0, 'ifindex': 2, 'napi-id': 8195, 'type': 'tx'},
 {'id': 1, 'ifindex': 2, 'napi-id': 8196, 'type': 'tx'}]

Signed-off-by: Joe Damato <jdam...@fastly.com>
---
 v3:
   - Replace igc_unset_queue_napi with igc_set_queue_napi(adapater, i,
     NULL), as suggested by Vinicius Costa Gomes
   - Simplify implemention of igc_set_queue_napi as suggested by Kurt
     Kanzenbach, with a tweak to use ring->queue_index

 v2:
   - Update commit message to include tests for IGC_FLAG_QUEUE_PAIRS
     disabled
   - Refactored code to move napi queue mapping and unmapping to helper
     functions igc_set_queue_napi and igc_unset_queue_napi
   - Adjust the code to handle IGC_FLAG_QUEUE_PAIRS disabled
   - Call helpers to map/unmap queues to NAPIs in igc_up, __igc_open,
     igc_xdp_enable_pool, and igc_xdp_disable_pool

 drivers/net/ethernet/intel/igc/igc.h      |  2 ++
 drivers/net/ethernet/intel/igc/igc_main.c | 33 ++++++++++++++++++++---
 drivers/net/ethernet/intel/igc/igc_xdp.c  |  2 ++
 3 files changed, 33 insertions(+), 4 deletions(-)

diff --git a/drivers/net/ethernet/intel/igc/igc.h 
b/drivers/net/ethernet/intel/igc/igc.h
index eac0f966e0e4..b8111ad9a9a8 100644
--- a/drivers/net/ethernet/intel/igc/igc.h
+++ b/drivers/net/ethernet/intel/igc/igc.h
@@ -337,6 +337,8 @@ struct igc_adapter {
        struct igc_led_classdev *leds;
 };
 
+void igc_set_queue_napi(struct igc_adapter *adapter, int q_idx,
+                       struct napi_struct *napi);
 void igc_up(struct igc_adapter *adapter);
 void igc_down(struct igc_adapter *adapter);
 int igc_open(struct net_device *netdev);
diff --git a/drivers/net/ethernet/intel/igc/igc_main.c 
b/drivers/net/ethernet/intel/igc/igc_main.c
index 7964bbedb16c..783fc8e12ba1 100644
--- a/drivers/net/ethernet/intel/igc/igc_main.c
+++ b/drivers/net/ethernet/intel/igc/igc_main.c
@@ -4948,6 +4948,22 @@ static int igc_sw_init(struct igc_adapter *adapter)
        return 0;
 }
 
+void igc_set_queue_napi(struct igc_adapter *adapter, int vector,
+                       struct napi_struct *napi)
+{
+       struct igc_q_vector *q_vector = adapter->q_vector[vector];
+
+       if (q_vector->rx.ring)
+               netif_queue_set_napi(adapter->netdev,
+                                    q_vector->rx.ring->queue_index,
+                                    NETDEV_QUEUE_TYPE_RX, napi);
+
+       if (q_vector->tx.ring)
+               netif_queue_set_napi(adapter->netdev,
+                                    q_vector->tx.ring->queue_index,
+                                    NETDEV_QUEUE_TYPE_TX, napi);
+}
+
 /**
  * igc_up - Open the interface and prepare it to handle traffic
  * @adapter: board private structure
@@ -4955,6 +4971,7 @@ static int igc_sw_init(struct igc_adapter *adapter)
 void igc_up(struct igc_adapter *adapter)
 {
        struct igc_hw *hw = &adapter->hw;
+       struct napi_struct *napi;
        int i = 0;
 
        /* hardware has been reset, we need to reload some things */
@@ -4962,8 +4979,11 @@ void igc_up(struct igc_adapter *adapter)
 
        clear_bit(__IGC_DOWN, &adapter->state);
 
-       for (i = 0; i < adapter->num_q_vectors; i++)
-               napi_enable(&adapter->q_vector[i]->napi);
+       for (i = 0; i < adapter->num_q_vectors; i++) {
+               napi = &adapter->q_vector[i]->napi;
+               napi_enable(napi);
+               igc_set_queue_napi(adapter, i, napi);
+       }
 
        if (adapter->msix_entries)
                igc_configure_msix(adapter);
@@ -5192,6 +5212,7 @@ void igc_down(struct igc_adapter *adapter)
        for (i = 0; i < adapter->num_q_vectors; i++) {
                if (adapter->q_vector[i]) {
                        napi_synchronize(&adapter->q_vector[i]->napi);
+                       igc_set_queue_napi(adapter, i, NULL);
                        napi_disable(&adapter->q_vector[i]->napi);
                }
        }
@@ -6021,6 +6042,7 @@ static int __igc_open(struct net_device *netdev, bool 
resuming)
        struct igc_adapter *adapter = netdev_priv(netdev);
        struct pci_dev *pdev = adapter->pdev;
        struct igc_hw *hw = &adapter->hw;
+       struct napi_struct *napi;
        int err = 0;
        int i = 0;
 
@@ -6056,8 +6078,11 @@ static int __igc_open(struct net_device *netdev, bool 
resuming)
 
        clear_bit(__IGC_DOWN, &adapter->state);
 
-       for (i = 0; i < adapter->num_q_vectors; i++)
-               napi_enable(&adapter->q_vector[i]->napi);
+       for (i = 0; i < adapter->num_q_vectors; i++) {
+               napi = &adapter->q_vector[i]->napi;
+               napi_enable(napi);
+               igc_set_queue_napi(adapter, i, napi);
+       }
 
        /* Clear any pending interrupts. */
        rd32(IGC_ICR);
diff --git a/drivers/net/ethernet/intel/igc/igc_xdp.c 
b/drivers/net/ethernet/intel/igc/igc_xdp.c
index e27af72aada8..4da633430b80 100644
--- a/drivers/net/ethernet/intel/igc/igc_xdp.c
+++ b/drivers/net/ethernet/intel/igc/igc_xdp.c
@@ -84,6 +84,7 @@ static int igc_xdp_enable_pool(struct igc_adapter *adapter,
                napi_disable(napi);
        }
 
+       igc_set_queue_napi(adapter, queue_id, NULL);
        set_bit(IGC_RING_FLAG_AF_XDP_ZC, &rx_ring->flags);
        set_bit(IGC_RING_FLAG_AF_XDP_ZC, &tx_ring->flags);
 
@@ -133,6 +134,7 @@ static int igc_xdp_disable_pool(struct igc_adapter 
*adapter, u16 queue_id)
        xsk_pool_dma_unmap(pool, IGC_RX_DMA_ATTR);
        clear_bit(IGC_RING_FLAG_AF_XDP_ZC, &rx_ring->flags);
        clear_bit(IGC_RING_FLAG_AF_XDP_ZC, &tx_ring->flags);
+       igc_set_queue_napi(adapter, queue_id, napi);
 
        if (needs_reset) {
                napi_enable(napi);
-- 
2.25.1

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