Merge branch 'busypoll-preemption-and-other-optimizations'

Eric Dumazet says:

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net: busy-poll: allow preemption and other optimizations

It is time to have preemption points in sk_busy_loop() and improve
its scalability.

Also napi_complete() and friends can tell drivers when it is safe to
not re-enable device interrupts, saving some overhead under
high busy polling.

mlx4 and bnx2x are changed accordingly, to show how this busy polling
status can be exploited by drivers.

Next steps will implement Zach Brown suggestion, where NAPI polling
would be enabled all the time for some chosen queues.
This is needed for efficient epoll() support anyway.
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Signed-off-by: David S. Miller <davem@davemloft.net>