Re: [PATCH net] net: dsa: Do not leave DSA master with NULL netdev_ops
From: Vladimir Oltean <olteanv@gmail.com>
Date: 2020-05-04 20:34:17
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Hi Florian, On Mon, 4 May 2020 at 23:19, Florian Fainelli [off-list ref] wrote:
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>
---The fix makes complete sense. But on another note, if we don't overlay an ndo_get_phys_port_name if the master already has one, doesn't that render the entire mechanism of having a reliable way for user space to determine the CPU port number pointless?
quoted hunk ↗ jump to hunk
net/dsa/master.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)diff --git a/net/dsa/master.c b/net/dsa/master.c index b5c535af63a3..a621367c6e8c 100644 --- a/net/dsa/master.c +++ b/net/dsa/master.c@@ -289,7 +289,8 @@ static void dsa_master_ndo_teardown(struct net_device *dev) { struct dsa_port *cpu_dp = dev->dsa_ptr; - dev->netdev_ops = cpu_dp->orig_ndo_ops; + if (cpu_dp->orig_ndo_ops) + dev->netdev_ops = cpu_dp->orig_ndo_ops; cpu_dp->orig_ndo_ops = NULL; } --2.20.1
Regards, -Vladimir