Hello.
Mithlesh Thukral wrote:
>>>>Even with this patch, the packets probably get stuck somewhere in the
>>>>driver, as cross-gdb sees tail of the $g packet reply only in reply to
>>>>next packet...
This wasn;t happeing on x86 probably because the register packet should be
much shorted there than on PPC...
>>> Argh! That's all because of the CONFIG_NETPOLL_TRAP that
>>>CONFIG_KGDBOE* options select -- since the initial breakpoint enables
>>>trapping via KGDBoE's pre_exception() handler, netif_{stop/wake}_queue()
>>>stop to work and that causes KGDBoE to literally flood 8139too with
>>>packets (although it can't queue up more than 4). Looks like a general
>>>design issue to me... :-/
>> Well, maybe not. But many drivers are surely unprepared to their
>>hard_start_xmit() method being called with queue alraedy stopped and those
>>with small TX queue (like natsemi with which we're also having trouble)
>>would get flooded as well. I'm going to submit a patch to netdev adding
>>extra check for TX ring being full -- after/if it gets accepted, this patch
>>won't be needed anymore.
> Here is what comes to my mind right away. It might need some more polishing
> or
> cleaning up:
> A potential solution will be to check the if hard_start_xmit() returns
> NETDEV_TX_BUSY. In case transmit queue is busy (due to lot of threads or
> queue getting full), we should wait in netpoll_send_skb(), call a cleanup
> through poll() and then retry sending packet.
This is already being done by netpoll iself. The thing is that
hard_start_xmit() doesdn't return NETDEV_TX_BUSY in those drivers. :-/
> Regards,
> Mithlesh Thukral
WBR, Sergei
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