Re: [PATCH net] net: dsa: Do not leave DSA master with NULL netdev_ops

From: Florian Fainelli <f.fainelli@gmail.com>
Date: Mon,  4 May 2020 13:18:06 -0700

When ndo_get_phys_port_name() for the CPU port was added we introduced
an early check for when the DSA master network device in
dsa_master_ndo_setup() already implements ndo_get_phys_port_name(). When
we perform the teardown operation in dsa_master_ndo_teardown() we would
not be checking that cpu_dp->orig_ndo_ops was successfully allocated and
non-NULL initialized.

With network device drivers such as virtio_net, this leads to a NPD as
soon as the DSA switch hanging off of it gets torn down because we are
now assigning the virtio_net device's netdev_ops a NULL pointer.

Fixes: da7b9e9b00d4 ("net: dsa: Add ndo_get_phys_port_name() for CPU port")
Reported-by: Allen Pais <redacted>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>

Applied and queued up for -stable, thanks Florian.