Re: [PATCH net,stable] net: cdc_mbim: __vlan_find_dev_deep need rcu_read_lock

Eric Dumazet [off-list ref] writes:

While this 'removes' the warning, this doesn't solve the fundamental
problem.

If you write :

rcu_read_lock();
netdev = __vlan_find_dev_deep(...)
rcu_read_unlock();

Then you cannot dereference netdev safely after the unlock.

In order to do so, you need to take a reference on netdev (aka
dev_hold()) before doing rcu_read_unlock();

And of course, release it later (aka dev_put()) when you are done with
netdev.

Doh! Now that you tell me, this is pretty obvious.  Thanks.  Will fix
and resubmit.


Bjørn
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