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

From: Denis Vlasenko (vda_at_ilport.com.ua)
Date: 08/07/05

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    To: Tommy Christensen <tommy.christensen@tpack.net>
Date:	Sun, 7 Aug 2005 16:51:43 +0300

    On Thursday 04 August 2005 23:45, Tommy Christensen wrote:
    > Denis Vlasenko wrote:
    > > Hi,
    > >
    > > As reported earlier, sometimes my home box don't want
    > > to send anything.
    > >
    > > # ip r
    > > 1.1.5.5 dev tun0 proto kernel scope link src 1.1.5.6
    > > 1.1.4.0/24 dev if proto kernel scope link src 1.1.4.6
    > > default via 1.1.5.5 dev tun0
    > > # ping 1.1.4.1 -i 0.01
    >
    > > 2005-08-02_19:12:18.19551 kern.info: qdisc_restart: start, q->dequeue=c03e8662
    > > 2005-08-02_19:12:19.19536 kern.info: qdisc_restart: start, q->dequeue=c03e8662
    > >
    > > System.map:
    > > 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
    > > link/[65534]
    > >
    > > 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.

    Your analysis is correct. I just caught it again. diff between logs:

    /* Basic mode status register. */
    #define BMSR_ERCAP 0x0001 /* Ext-reg capability */
    #define BMSR_JCD 0x0002 /* Jabber detected */
    #define BMSR_LSTATUS 0x0004 /* Link status */
    #define BMSR_ANEGCAPABLE 0x0008 /* Able to do auto-negotiation */
    #define BMSR_RFAULT 0x0010 /* Remote fault detected */
    #define BMSR_ANEGCOMPLETE 0x0020 /* Auto-negotiation complete */
    #define BMSR_RESV 0x07c0 /* Unused... */
    #define BMSR_10HALF 0x0800 /* Can do 10mbps, half-duplex */
    #define BMSR_10FULL 0x1000 /* Can do 10mbps, full-duplex */
    #define BMSR_100HALF 0x2000 /* Can do 100mbps, half-duplex */
    #define BMSR_100FULL 0x4000 /* Can do 100mbps, full-duplex */
    #define BMSR_100BASE4 0x8000 /* Can do 100mbps, 4k packets */

    9 = 1001 - link down
    D = 1101 - link up

    --- klog Sun Aug 7 14:21:20 2005
    +++ klog2 Sun Aug 7 14:21:29 2005
    @@ -125,7 +125,7 @@
     kern.warn: PCI: setting IRQ 11 as level-triggered
     kern.info: ACPI: PCI Interrupt 0000:00:12.0[A] -> Link [LNKA] -> GSI 11 (level, low) -> IRQ 11
     kern.info: eth0: VIA Rhine II at 0x1e800, 00:0a:e6:7c:dd:79, IRQ 11.
    -kern.info: eth0: MII PHY found at address 1, status 0x7849 advertising 05e1 Link 0000.
    +kern.info: eth0: MII PHY found at address 1, status 0x784d advertising 05e1 Link 0000.
                                                         ^^^^^^
            Here. It thinks that link is down.
            I will run ethtool next time...

     kern.warn: cs89x0:cs89x0_probe(0x0)
     kern.warn: PP_addr=0xffff
     kern.err: eth1: incorrect signature 0xffff
    @@ -287,13 +287,27 @@
     kern.info: ACPI: PCI Interrupt 0000:00:11.5[C] -> Link [LNKC] -> GSI 10 (level, low) -> IRQ 10
     kern.debug: PCI: Setting latency timer of device 0000:00:11.5 to 64
     kern.warn: netdev tun0: qdisc = pfifo_fast_qdisc
    -kern.warn: qdisc_restart: start, q->dequeue=c03e8662
    -kern.warn: qdisc_restart: start, q->dequeue=c03e8662
    -kern.warn: qdisc_restart: start, q->dequeue=c03e8662 <== noop
    +kern.warn: pfifo_fast_enqueue returns 0
    +kern.warn: qdisc_restart: start, q->dequeue=c03e8752 <== pfifo_fast
    +kern.warn: pfifo_fast_dequeue returns a skb
    +kern.warn: qdisc_restart: skb!=NULL
    +kern.warn: qdisc_restart: start, q->dequeue=c03e8752
    +kern.warn: pfifo_fast_dequeue returns NULL
    +kern.warn: pfifo_fast_enqueue returns 0
    +kern.warn: qdisc_restart: start, q->dequeue=c03e8752
    +kern.warn: pfifo_fast_dequeue returns a skb
    +kern.warn: qdisc_restart: skb!=NULL
    +kern.warn: qdisc_restart: start, q->dequeue=c03e8752
    +kern.warn: pfifo_fast_dequeue returns NULL
     kern.warn: pfifo_fast_enqueue returns 0
     kern.warn: pfifo_fast_dequeue returns a skb
     kern.warn: pfifo_fast_dequeue returns NULL
    -kern.warn: qdisc_restart: start, q->dequeue=c03e8662
    +kern.warn: pfifo_fast_enqueue returns 0
    +kern.warn: qdisc_restart: start, q->dequeue=c03e8752
    +kern.warn: pfifo_fast_dequeue returns a skb
    +kern.warn: qdisc_restart: skb!=NULL
    +kern.warn: qdisc_restart: start, q->dequeue=c03e8752
    +kern.warn: pfifo_fast_dequeue returns NULL
     kern.info: usbcore: registered new driver usbfs
    ... 

    --
vda
-
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