Alternative to 2) would be to use a generation id, incremented every
time a napi used in spin polling enabled driver is dismantled (and freed
after RCU grace period)

And store in sockets not only the pointer to napi_struct, but the
current generation id : If the generation id doesnt match, disable
the spinpoll until next packet rebuilds the cache again.

This would require rcu_read_lock, aka preempt off, during polling, right?

-Andi

-- 
ak@linux.intel.com -- Speaking for myself only.