Re: 2.6.11-rc5 and 2.6.12: cannot transmit anything - more info

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Denis Vlasenko wrote:

As reported earlier, sometimes my home box don't want
to send anything.

# ip r dev tun0  proto kernel  scope link  src dev if  proto kernel  scope link  src
default via dev tun0
# ping -i 0.01
2005-08-02_19:12:18.19551 qdisc_restart: start, q->dequeue=c03e8662
2005-08-02_19:12:19.19536 qdisc_restart: start, q->dequeue=c03e8662
c03e8662 t noop_dequeue

I guess this explains why I do not see calls to pfifo_fast_dequeue! :)
But how come my interface is using noop queue, is a mystery to me.
Because link is down.  Or at least the kernel thinks so.

# ip l
1: if: <BROADCAST,MULTICAST,UP> mtu 1500 qdisc pfifo_fast qlen 1000
    link/ether 00:0a:e6:7c:dd:79 brd ff:ff:ff:ff:ff:ff
2: lo: <LOOPBACK,UP> mtu 16436 qdisc noqueue
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
17: tun0: <POINTOPOINT,MULTICAST,NOARP,UP> mtu 1464 qdisc pfifo_fast qlen 100

As you can see, ip l reports that iface 'if' uses pfifo_fast, not noop...
Yeah, a bit confusing.  pfifo_fast is the *configured* qdisc, but in this
case it is not the *active* qdisc.  The qdisc is set to noop when carrier
is lost.

Any ideas?
Try tracking the calls to netif_carrier_on/off.

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