Networking: The network device list was protected by a re-entrant semaphore. ...

Networking:  The network device list was protected by a re-entrant semaphore.  With the recent change to support network device callback, the network stack needs to access the network device list too. Some drivers, however, run the network stack from the interrupt level -- this is bad but a fact in the current state.  Of course,those drivers are unable to take the semaphore and will assert.

The solution here is to eliminate the device devices semaphore altogether.  This eliminates netdev_semtake() and netdev_semgive() and replaces them with net_lock() and net_unlock() which have larger scope as needed for this purpose.