Re: [PATCH iwl-next v2 2/4] igb: Link queues to NAPI instances

Kurt Kanzenbach
2025-02-19T07:41:04Z

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On Tue Feb 18 2025, Joe Damato wrote:
> On Mon, Feb 17, 2025 at 12:31:22PM +0100, Kurt Kanzenbach wrote:
>> Link queues to NAPI instances via netdev-genl API. This is required to use
>> XDP/ZC busy polling. See commit 5ef44b3cb43b ("xsk: Bring back busy polling
>> support") for details.
>>
>> This also allows users to query the info with netlink:
>>
>> |$ ./tools/net/ynl/pyynl/cli.py --spec Documentation/netlink/specs/netdev.yaml \
>> | --dump queue-get --json='{"ifindex": 2}'
>> |[{'id': 0, 'ifindex': 2, 'napi-id': 8201, 'type': 'rx'},
>> | {'id': 1, 'ifindex': 2, 'napi-id': 8202, 'type': 'rx'},
>> | {'id': 2, 'ifindex': 2, 'napi-id': 8203, 'type': 'rx'},
>> | {'id': 3, 'ifindex': 2, 'napi-id': 8204, 'type': 'rx'},
>> | {'id': 0, 'ifindex': 2, 'napi-id': 8201, 'type': 'tx'},
>> | {'id': 1, 'ifindex': 2, 'napi-id': 8202, 'type': 'tx'},
>> | {'id': 2, 'ifindex': 2, 'napi-id': 8203, 'type': 'tx'},
>> | {'id': 3, 'ifindex': 2, 'napi-id': 8204, 'type': 'tx'}]
>>
>> Add rtnl locking to PCI error handlers, because netif_queue_set_napi()
>> requires the lock held.
>>
>> While at __igb_open() use RCT coding style.
>>
>> Signed-off-by: Kurt Kanzenbach <kurt@linutronix.de>
>> ---
>> drivers/net/ethernet/intel/igb/igb.h | 2 ++
>> drivers/net/ethernet/intel/igb/igb_main.c | 43 +++++++++++++++++++++++++++----
>> drivers/net/ethernet/intel/igb/igb_xsk.c | 2 ++
>> 3 files changed, 42 insertions(+), 5 deletions(-)
>
> [...]
>
>> @@ -9737,16 +9765,21 @@ static void igb_io_resume(struct pci_dev *pdev)
>> struct net_device *netdev = pci_get_drvdata(pdev);
>> struct igb_adapter *adapter = netdev_priv(netdev);
>>
>> + rtnl_lock();
>> if (netif_running(netdev)) {
>> if (!test_bit(__IGB_DOWN, &adapter->state)) {
>> dev_dbg(&pdev->dev, "Resuming from non-fatal error, do nothing.\n");
>> + rtnl_unlock();
>> return;
>> }
>> +
>> if (igb_up(adapter)) {
>> dev_err(&pdev->dev, "igb_up failed after reset\n");
>> + rtnl_unlock();
>> return;
>> }
>> }
>> + rtnl_unlock();
>
> Does RTNL need to be held when calling netif_running()? If not, you
> could probably reduce the size of the section under the lock a bit?

All the other instances in the driver guard the netif_running(), too.

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