Merge branch 'arp-random-clean-up-and-rcu-conversion-for-ioctl-siocgarp'

Kuniyuki Iwashima says:

====================
arp: Random clean up and RCU conversion for ioctl(SIOCGARP).

arp_ioctl() holds rtnl_lock() regardless of cmd (SIOCDARP, SIOCSARP,
and SIOCGARP) to get net_device by __dev_get_by_name() and copy
dev->name safely.

In the SIOCGARP path, arp_req_get() calls neigh_lookup(), which looks
up a neighbour entry under RCU.

This series cleans up ioctl() code a bit and extends the RCU section
not to take rtnl_lock() and instead use dev_get_by_name_rcu() and
netdev_copy_name() for SIOCGARP.

v2: https://lore.kernel.org/netdev/20240425170002.68160-1-kuniyu@amazon.com/
v1: https://lore.kernel.org/netdev/20240422194755.4221-1-kuniyu@amazon.com/
====================

Link: https://lore.kernel.org/r/20240430015813.71143-1-kuniyu@amazon.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>