On Fri, 4 Sep 2009, Alan Cox wrote:
> On Fri, 4 Sep 2009 10:17:30 -0400 (EDT)
> Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> wrote:
>
> > On Fri, 4 Sep 2009, Miklos Szeredi wrote:
> >
> > > On Thu, 3 Sep 2009, Greg KH wrote:
> > > > On Thu, Sep 03, 2009 at 04:13:34PM +0200, Miklos Szeredi wrote:
> > > > > I get the following warnings in 2.6.31-rc. A lot of them:
> > > > >
> > > > > WARNING: at drivers/usb/serial/usb-serial.c:414
> > > > > serial_write_room+0x59/0x6e [usbserial]() WARNING: at
> > > > > drivers/usb/serial/usb-serial.c:401 serial_write+0x77/0x9d
> > > > > [usbserial]()
> > > > >
> > > > > This is a huawei-3565 modem.
> > > > >
> > > > > The messages don't seem to hurt, but there's lot of trouble
> > > > > with this gadget. Sometimes it just doesn't work after a while
> > > > > and a reboot is needed. Sometimes it hangs the kernel after
> > > > > suspend, etc. Not sure if this is related to the warnings...
> > > >
> > > > {sigh}
> > > >
> > > > The tty layer changes are being a pain here :(
> > > >
> > > > Alan Stern posted a set of patches to the linux-usb list to
> > > > hopefully address stuff like this, is there any way you could
> > > > test them out to see if they help or not?
> > >
> > > Nope, it doesn't seem to help. Still got the same warnings with the
> > > patched kernel (latest git + ghk tree + usbserial patches).
> >
> > What were you doing when these warnings appeared?
>
> The usual way to get it was
>
> close
> users = 0
> ldisc processing
> echo
> write room
> hey we are closed
> Spew
>
> I suspect the actual check in write_room is now simply bogus with it
> all being refcounted (the ldisc will hold a tty kref at that point)
That makes sense. It would mean that all those
WARN_ON(!port->port.count);
lines in usb-serial.c should simply be removed. Miklos, do you want to
try removing them?
Alan Stern
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