Re: mutex_lock_slowpath warning using mxser tty driver(input/output error)

[Alan Cox]

On Thu, 02 Apr 2009 22:23:57 +0200
Jiri Slaby <jirislaby@xxxxxxxxx> wrote:

> On 04/02/2009 08:44 PM, Alan Cox wrote:
> >> It appears to want to lock a mutex in interrupt context, something
> >> that's a definite no-no.
> >>
> >> CCed the folks who might know a thing or two about the driver.
> > 
> > Moxa is not a USB driver so the USB trace at the end makes no sense at
> > all.
> 
> Yes, unreliable stack entries, but echo_set_canon_col is called from irq
> context and locks mutex.

Which means that either the driver is calling the ldisc receive handlers
from an IRQ directly (not allowed) or calling the tty_flip_buffer_push
paths and set tty->low_latency

2.6.29 is the first kernel that catches this bug with warnings.

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