Subject: RE: [net-next 1/2] ena: Link IRQs to NAPI instances

From: "Arinzon, David" <[email-masked]>
Date: Tue, 1 Oct 2024 08:57:47 +0000

> Link IRQs to NAPI instances with netif_napi_set_irq. This information can be
> queried with the netdev-genl API. Note that the ENA device appears to
> allocate an IRQ for management purposes which does not have a NAPI
> associated with it; this commit takes this into consideration to accurately
> construct a map between IRQs and NAPI instances.
> 
> Compare the output of /proc/interrupts for my ena device with the output
> of netdev-genl after applying this patch:
> 
> $ cat /proc/interrupts | grep enp55s0 | cut -f1 --delimiter=':'
>  94
>  95
>  96
>  97
>  98
>  99
> 100
> 101
> 
> $ ./tools/net/ynl/cli.py --spec Documentation/netlink/specs/netdev.yaml \
>                          --dump napi-get --json='{"ifindex": 2}'
> 
> [{'id': 8208, 'ifindex': 2, 'irq': 101},
>  {'id': 8207, 'ifindex': 2, 'irq': 100},
>  {'id': 8206, 'ifindex': 2, 'irq': 99},
>  {'id': 8205, 'ifindex': 2, 'irq': 98},
>  {'id': 8204, 'ifindex': 2, 'irq': 97},
>  {'id': 8203, 'ifindex': 2, 'irq': 96},
>  {'id': 8202, 'ifindex': 2, 'irq': 95},
>  {'id': 8201, 'ifindex': 2, 'irq': 94}]
> 
> Signed-off-by: Joe Damato <[email-masked]>
> ---
>  drivers/net/ethernet/amazon/ena/ena_netdev.c | 12 +++++++++++-
>  1 file changed, 11 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/net/ethernet/amazon/ena/ena_netdev.c
> b/drivers/net/ethernet/amazon/ena/ena_netdev.c
> index c5b50cfa935a..e88de5e426ef 100644
> --- a/drivers/net/ethernet/amazon/ena/ena_netdev.c
> +++ b/drivers/net/ethernet/amazon/ena/ena_netdev.c
> @@ -1679,7 +1679,7 @@ static int ena_request_io_irq(struct ena_adapter
> *adapter)
>         u32 io_queue_count = adapter->num_io_queues + adapter-
> >xdp_num_queues;
>         unsigned long flags = 0;
>         struct ena_irq *irq;
> -       int rc = 0, i, k;
> +       int rc = 0, i, k, irq_idx;

nit: This breaks RCT guidelines, can you please move it to be below io_queue_count?

> 
>         if (!test_bit(ENA_FLAG_MSIX_ENABLED, &adapter->flags)) {
>                 netif_err(adapter, ifup, adapter->netdev, @@ -1705,6 +1705,16 @@
> static int ena_request_io_irq(struct ena_adapter *adapter)
>                 irq_set_affinity_hint(irq->vector, &irq->affinity_hint_mask);
>         }
> 
> +       /* Now that IO IRQs have been successfully allocated map them to the
> +        * corresponding IO NAPI instance. Note that the mgmnt IRQ does not
> +        * have a NAPI, so care must be taken to correctly map IRQs to NAPIs.
> +        */
> +       for (i = 0; i < io_queue_count; i++) {
> +               irq_idx = ENA_IO_IRQ_IDX(i);
> +               irq = &adapter->irq_tbl[irq_idx];
> +               netif_napi_set_irq(&adapter->ena_napi[i].napi, irq->vector);
> +       }
> +
>         return rc;
> 
>  err:
> --
> 2.43.0

Thank you for uploading this patch.