Re: [PATCH 1/3] igb: Link IRQs to NAPI instances

[Joe Damato <jdamato@fastly.com>]

On Mon, Feb 10, 2025 at 10:19:35AM +0100, Kurt Kanzenbach wrote:
> Link IRQs to NAPI instances via netdev-genl API. This allows users to query
> that information via netlink:
> 
> |$ ./tools/net/ynl/pyynl/cli.py --spec Documentation/netlink/specs/netdev.yaml \
> |                               --dump napi-get --json='{"ifindex": 2}'
> |[{'defer-hard-irqs': 0,
> |  'gro-flush-timeout': 0,
> |  'id': 8204,
> |  'ifindex': 2,
> |  'irq': 127,
> |  'irq-suspend-timeout': 0},
> | {'defer-hard-irqs': 0,
> |  'gro-flush-timeout': 0,
> |  'id': 8203,
> |  'ifindex': 2,
> |  'irq': 126,
> |  'irq-suspend-timeout': 0},
> | {'defer-hard-irqs': 0,
> |  'gro-flush-timeout': 0,
> |  'id': 8202,
> |  'ifindex': 2,
> |  'irq': 125,
> |  'irq-suspend-timeout': 0},
> | {'defer-hard-irqs': 0,
> |  'gro-flush-timeout': 0,
> |  'id': 8201,
> |  'ifindex': 2,
> |  'irq': 124,
> |  'irq-suspend-timeout': 0}]
> |$ cat /proc/interrupts | grep enp2s0
> |123:          0          1 IR-PCI-MSIX-0000:02:00.0   0-edge      enp2s0
> |124:          0          7 IR-PCI-MSIX-0000:02:00.0   1-edge      enp2s0-TxRx-0
> |125:          0          0 IR-PCI-MSIX-0000:02:00.0   2-edge      enp2s0-TxRx-1
> |126:          0          5 IR-PCI-MSIX-0000:02:00.0   3-edge      enp2s0-TxRx-2
> |127:          0          0 IR-PCI-MSIX-0000:02:00.0   4-edge      enp2s0-TxRx-3
> 
> Signed-off-by: Kurt Kanzenbach <kurt@linutronix.de>
> ---
>  drivers/net/ethernet/intel/igb/igb_main.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/net/ethernet/intel/igb/igb_main.c b/drivers/net/ethernet/intel/igb/igb_main.c
> index d368b753a4675d01b5dfa50dee4cd218e6a5e14b..d4128d19cc08f62f95682069bb5ed9b8bbbf10cb 100644
> --- a/drivers/net/ethernet/intel/igb/igb_main.c
> +++ b/drivers/net/ethernet/intel/igb/igb_main.c
> @@ -947,6 +947,9 @@ static int igb_request_msix(struct igb_adapter *adapter)
>  				  q_vector);
>  		if (err)
>  			goto err_free;
> +
> +		netif_napi_set_irq(&q_vector->napi,
> +				   adapter->msix_entries[vector].vector);
>  	}

As far as I can tell, all paths that lead here hold RTNL:
  - power management (__igb_resume)
  - ethtool set_channels (igb_reinit_queues)
  - and regular ndo_open

So:

Reviewed-by: Joe Damato <jdamato@fastly.com>