bge(4) one packet wedge

[Gleb Smirnoff]

  Colleagues,

  I've faced a problem in bge(4) when a single packet is in the RX
ring, but it isn't noticed by the driver. A reception of a packet
triggers interrupt and both packets are processed - an old one
and the new one.

  To reproduce the problem you need to run netperf (from ports
collection): netserver on another host (10.0.0.1) and netperf on
the host, where tested bge(4) is installed - 10.0.0.2. No traffic
except netperf's should flow through this NIC, or the problem won't
be reproduced!

  So, I run netperf client and simultaneously tcpdump on the
another host. After few seconds there is a wedge. The last packet
seen on 10.0.0.1 is the packet sent by 10.0.0.1 to 10.0.0.2. However
it isn't seen on 10.0.0.2.

Ok, let's look at the receive ring:

(kgdb) p $sc->bge_rx_saved_considx
$14 = 51
(kgdb) p $sc->bge_ldata.bge_status_block->bge_idx[0].bge_rx_prod_idx
$15 = 51

Looks like there is nothing to process.

However, if I run 'ping -c 1 10.0.0.2' I will get an interrupt and read
two packets: first the old packet, and then recently sent ping.

-- 
Totus tuus, Glebius.
GLEBIUS-RIPN GLEB-RIPE