macvlan: Move broadcasts into a work queue
Currently broadcasts are handled in network RX context, where the packets are sent through netif_rx. This means that the number of macvlans will be constrained by the capacity of netif_rx. For example, setting up 4096 macvlans practically causes all broadcast packets to be dropped as the default netif_rx queue size simply can't handle 4096 skbs being stuffed into it all at once. Fundamentally, we need to ensure that the amount of work handled in each netif_rx backlog run is constrained. As broadcasts are anything but constrained, it either needs to be limited per run or moved to process context. This patch picks the second option and moves all broadcast handling bar the trivial case of packets going to a single interface into a work queue. Obviously there also needs to be a limit on how many broadcast packets we postpone in this way. I've arbitrarily chosen tx_queue_len of the master device as the limit (act_mirred also happens to use this parameter in a similar way). In order to ensure we don't exceed the backlog queue we will use netif_rx_ni instead of netif_rx for broadcast packets. Signed-off-by:Herbert Xu <herbert@gondor.apana.org.au> Thanks, Signed-off-by:
David S. Miller <davem@davemloft.net>
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a0265d28
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