Re: [PATCH net-next v4 3/5] net: Revalidate queue config for ringparam changes

On Fri, Sep 25, 2026 at 12:44:10PM +0200, Björn Töpel wrote:

Memory-provider queue configuration is validated when the provider is
bound. A later ethtool ring change may invalidate it because drivers
can size queue memory from both ring depth and RX page size. The fbnic
consumer is added in the following patch.

Keep configured RX ring depths in netdev_config and stage proposed
values in cfg_pending. Validate every RX queue before calling the
driver. Each check validates the device defaults, then any queue
memory-provider override. Commit the values only after the driver
accepts them.

Drivers which consume stored ring depths through queue configuration
must initialize every RX depth before registering the netdev. Stored
values override callback defaults, including when zero.

The callback receives a rendered configuration rather than a queue ID.
Validation should depend on the configuration, not queue identity.
Checking defaults also covers the case where every queue has a
memory-provider override.

Drivers may normalize ring depths when applying them. Require the
validation callback to use the same normalization. Drivers must report
the applied depths through the ethtool_ringparam argument so the core
records the result.

Use the same transaction for ioctl and netlink. Drivers without
ndo_validate_qcfg skip the new validation.

Link: https://lore.kernel.org/all/20250421222827.283737-14-kuba@kernel.org/ (local)

Signed-off-by: Björn Töpel <bjorn@kernel.org>
---
 include/linux/ethtool.h     |  4 ++-
 include/net/netdev_queues.h | 56 ++++++++++++++++++++++++++++++++-----
 net/core/dev.h              |  2 ++
 net/core/netdev_config.c    | 38 +++++++++++++++++++++++--
 net/ethtool/common.c        |  8 ++++++
 net/ethtool/common.h        |  2 ++
 net/ethtool/ioctl.c         | 24 ++++++++++++++--
 net/ethtool/rings.c         | 13 ++++++++-
 8 files changed, 133 insertions(+), 14 deletions(-)

Reviewed-by: Joe Damato <redacted>