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SubjectRe: [PATCH 5/5] usb_debug: EXPERIMENTAL - poll hcd device to forcewrites
Greg KH wrote:
>> Doing enough printk's such as in register_console() will cause loss
>> because you run out of URBs unless you can force them to complete.
>>
>
> Why not just make the upper bound of urbs very large? We used to have
> an unlimited number of in-flight urbs for some drivers until it was
> pointed out that a simple:
> cat /dev/null > /dev/ttyUSB0
> would cause a DoS :)
>
> What happens if your upper bound is 400? 4000? Will that work
> properly?
>
Sure, if you have enough of a urb available, ultimately you get all the
printk's.

If I want to printk from the nmi_watchdog out to this device, am I going
to get anything if the write is not synchronous, because in theory the
hcd device is never going to get accessed again?

Ideally I want to make sure that somehow I get my debug output out to
the console, even if it means we do some polling after the oops state is
set.

Jason.


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