[PL #3471] af_packet spin lock warning
Mark Huang via RT
devel at planet-lab.org
Tue Feb 8 10:42:34 EST 2005
Email Recipients (see http://www.planet-lab.org/Support)
Requestor: mef at cs.princeton.edu
vnet needs to disable softirqs before calling dev_queue_xmit_nit(), the
function that copies outbound packets to network taps. Network taps like
af_packet.c:packet_rcv() are not designed to be re-entrant.
The race is probably between a deferred call to packet_rcv() by
vnet_packet.c:packet_hook() via netif_rx(), and a direct call to
packet_rcv() by vnet_packet.c:packet_hook() via dev_queue_xmit_nit().
Fix is to disable softirqs via local_bh_disable() before calling
How To Reproduce:
1. /usr/sbin/tcpdump -i vnet >/dev/null
2. Generate a lot of traffic.
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