Re: PROBLEM: kernel oops with g_serial USB gadget on 2.6.30

From: Alan Cox
Date: Tue Jun 23 2009 - 05:20:50 EST

> that g_serial driver interacts with tty layer in that packet_done callback,
> so this is the source of the problems. I noticed that some other UDC
> drivers also does all its job from an interrupt, so they also might be
> affected. How this bug should be properly resolved?

Either by not setting ->low_latency or by running the data paths from a
non IRQ context.

Basically: don't set tty->low_latency if you are handling the processing
from the IRQ path. The only case low_latency is useful is handling data
from a non-IRQ path where you have latency concerns for tx/rx switching.

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