On Fri, 23 Feb 2007 22:16:59 +0300
Sergei Shtylyov <[EMAIL PROTECTED]> wrote:
> Hello.
>
> Stephen Hemminger wrote:
>
> >>>>>This thread came up on kgdb-bugreport mailing list. Could you please
> >>>>>suggest
> >>>>>us what's the correct way of fixing this problem?
>
> >>>>>1. When running a kgdb on RTL8139 ethernet interface: 8139too driver
> >>>>>prints
> >>>>>too many "Out-of-sync dirty pointer" messages on console and gdb can't
> >>>>>connect to kgdb stub. These messages can be suppressed, though it still
> >>>>>results in connection failures frequently.
>
> >>>>We think this comes from calling the driver while the queue is stopped.
> >>>>Drivers should not do horrible things when hard start is called with the
> >>>>queue stopped, but unfortunately, at this time, at least some drivers
> >>>>do explode or complain under that condition.
>
> >>>The kernel is built on a set of assumptions about calling context. Your
> >>>out of tree code is violating one of them. Why not check for stopped queue
> >>>and do some action to try and clear it, that is what netconsole does.
>
> >> The queue can't be stopped when the netpoll traffic trapping is enabled
> >>(cause this effectively bypasses queue control), So, the stopped queue
> >>indoication doesn't work also -- *that* is the problem. It's not at all
> >>specific to KGBoE -- only to traffic trapping.
>
> > You can't ask a device to send a packet when it has no resources.
>
> When traffic trapping is enabled, and driver stops the queue, the
> __LINK_STATE_XOFF flag does *not* get set, so netif_queue_stopped() resturns
> *zero*. What may be done in this situation?
Read netpoll_send_skb()
int status = NETDEV_TX_BUSY;
...
if (netif_tx_trylock(dev)) {
/* try until next clock tick */
for (tries = jiffies_to_usecs(1)/USEC_PER_POLL;
tries > 0; --tries) {
if (!netif_queue_stopped(dev))
status = dev->hard_start_xmit(skb, dev);
if (status == NETDEV_TX_OK)
break;
/* tickle device maybe there is some cleanup */
netpoll_poll(np);
udelay(USEC_PER_POLL);
}
netif_tx_unlock(dev);
netpoll_poll() allows device to try and cleanup transmit resources.
--
Stephen Hemminger <[EMAIL PROTECTED]>
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