[iwl-next v4 0/2] igc: Link IRQs and queues to NAPIs

[Joe Damato <jdamato@fastly.com>]

Greetings:

Welcome to v4.

See changelog below and in each patch for changes from v3 [1].

This revision was inspired by a bug report for e1000 [2] and analysis of
the call paths for igc on the mailing list [3] to ensure that RTNL is
held in all appropriate paths.

This series adds support for netdev-genl to igc so that userland apps
can query IRQ, queue, and NAPI instance relationships. This is useful
because developers who have igc NICs (for example, in their Intel NUCs)
who are working on epoll-based busy polling apps and using
SO_INCOMING_NAPI_ID, need access to this API to map NAPI IDs back to
queues.

See the commit messages of each patch for example output I got on my igc
hardware.

I've taken the feedback from both Kurt Kanzenbach and Vinicius Costa
Gomes to simplify the code from the rfc v2.

Thanks to reviewers and maintainers for their comments/feedback!

Thanks,
Joe

[1]: https://lore.kernel.org/netdev/20241018171343.314835-1-jdamato@fastly.com/
[2]: https://lore.kernel.org/netdev/8cf62307-1965-46a0-a411-ff0080090ff9@yandex.ru/
[3]: https://lore.kernel.org/netdev/ZxgK5jsCn5VmKKrH@LQ3V64L9R2/

v4:
  - Fixed a typo in Patch 1's commit message for the "other" IRQ number
  - Based on a bug report for e1000, closer scrutiny of the code
    revealed two paths where rtnl_lock / rtnl_unlock should be added in
    Patch 2: igc_resume and igc_io_error_detected. The code added to
    igc_io_error_detected is inspired by ixgbe's
    ixgbe_io_error_detected

v3: https://lore.kernel.org/netdev/20241018171343.314835-1-jdamato@fastly.com/
  - No longer an RFC
  - Patch 1: no changes
  - Patch 2:
      - Replace igc_unset_queue_napi with igc_set_queue_napi(..., NULL),
        as suggested by Vinicius Costa Gomes
      - Simplify implementation of igc_set_queue_napi as suggested by Kurt
        Kanzenbach, with a minor change to use the ring->queue_index

rfcv2: https://lore.kernel.org/netdev/20241014213012.187976-1-jdamato@fastly.com/
  - Patch 1: update line wrapping to 80 chars
  - Patch 2:
    - Update commit message to include output for IGC_FLAG_QUEUE_PAIRS
      enabled and disabled
    - Significant refactor to move queue mapping code to helpers to be
      called from multiple locations
    - Adjusted code to handle IGC_FLAG_QUEUE_PAIRS disabled as suggested
      by Kurt Kanzenbach
    - Map / unmap queues in igc_xdp_disable_pool and
      igc_xdp_enable_pool, respectively, as suggested by Vinicius Costa
      Gomes to handle the XDP case

rfcv1: https://lore.kernel.org/lkml/20241003233850.199495-1-jdamato@fastly.com/

Joe Damato (2):
  igc: Link IRQs to NAPI instances
  igc: Link queues to NAPI instances

 drivers/net/ethernet/intel/igc/igc.h      |  2 ++
 drivers/net/ethernet/intel/igc/igc_main.c | 44 ++++++++++++++++++++---
 drivers/net/ethernet/intel/igc/igc_xdp.c  |  2 ++
 3 files changed, 43 insertions(+), 5 deletions(-)


base-commit: d811ac148f0afd2f3f7e1cd7f54de8da973ec5e3
-- 
2.25.1