Re: [PATCH net-next 2/2] net/mlx5e: Log error messages when extack is not present

[Ido Schimmel <idosch@idosch.org>]

On Wed, Jun 04, 2025 at 12:01:05AM +0300, Yael Chemla wrote:
> Ethtool APIs: While Netlink support was introduced around versions
> 5.6–5.8, many LTS distributions (e.g., Ubuntu 20.04, CentOS 7) still
> ship with older userspace ethtool utilities that rely on ioctl for
> certain operations. In these ioctl-based paths, the extack pointer
> passed down to the driver may legitimately be NULL.

[...]

> If a narrower scope is preferred, I can revise the patch to include only
> the ethtool-related changes, which were the primary motivation behind
> this work.

FWIW, there is a netlink extack tracepoint that is always triggered from
NL_SET_ERR_MSG(). Example:

ethtool$ ./configure --disable-netlink &> /dev/null
ethtool$ make -j14 &> /dev/null
# echo "10 1" > /sys/bus/netdevsim/new_device
# echo 1 > /sys/kernel/tracing/events/netlink/netlink_extack/enable
# cat /sys/kernel/tracing/trace_pipe &
[1] 390
# ./ethtool --set-ring eni10np1 rx 1
         ethtool-413     [008] .....    80.588053: netlink_extack: msg=netdevsim: testing123

Used this dummy patch:

diff --git a/drivers/net/netdevsim/ethtool.c b/drivers/net/netdevsim/ethtool.c
index 4d191a3293c7..38022e8e1f37 100644
--- a/drivers/net/netdevsim/ethtool.c
+++ b/drivers/net/netdevsim/ethtool.c
@@ -85,6 +85,7 @@ static int nsim_set_ringparam(struct net_device *dev,
 {
 	struct netdevsim *ns = netdev_priv(dev);
 
+	NL_SET_ERR_MSG_MOD(extack, "testing123");
 	ns->ethtool.ring.rx_pending = ring->rx_pending;
 	ns->ethtool.ring.rx_jumbo_pending = ring->rx_jumbo_pending;
 	ns->ethtool.ring.rx_mini_pending = ring->rx_mini_pending;