tree bbd899b61dfd05a872a0f6e3e6023cee9ead40f3
parent 4e10fd5b4a7f4100007147558c304da3e73b25cf
author Alexander Drozdov <al.drozdov@gmail.com> 1424755108 +0300
committer David S. Miller <davem@davemloft.net> 1424812122 -0500

af_packet: don't pass empty blocks for PACKET_V3

Before da413eec729d ("packet: Fixed TPACKET V3 to signal poll when block is
closed rather than every packet") poll listening for an af_packet socket was
not signaled if there was no packets to process. After the patch poll is
signaled evety time when block retire timer expires. That happens because
af_packet closes the current block on timeout even if the block is empty.

Passing empty blocks to the user not only wastes CPU but also wastes ring
buffer space increasing probability of packets dropping on small timeouts.

Signed-off-by: Alexander Drozdov <al.drozdov@gmail.com>
Cc: Dan Collins <dan@dcollins.co.nz>
Cc: Willem de Bruijn <willemb@google.com>
Cc: Guy Harris <guy@alum.mit.edu>
Signed-off-by: David S. Miller <davem@davemloft.net>