On Thu, Mar 11, 2010 at 04:50:15PM +0100, Michał Mirosław wrote: > On Thu, Mar 11, 2010 at 05:50:09AM -0800, Greg KH wrote: > > On Thu, Mar 11, 2010 at 02:32:22PM +0100, Micha? Miros?aw wrote: > > > Looks like there's some race contition in switching ldiscs on USB serial > > > ports. The following warnings trigger sometimes after killing and restarting > > > process that changes ldisc and waits forever. In case you want to look at > > > the code, there it is: http://rere.qmqm.pl/~mirq/sermmc/ > > If you apply git commit 638b9648ab51c9c549ff5735d3de519ef6199df3 to the > > 2.6.33 kernel, does it solve the issue for you? > I'm running with the patch now. After couple cycles of starting and killing > the ldisc-setting process I get no warnings. I'll get back to you when/if > I encounter them again. Hah. Just seconds after I sent that mail I hit this again. The stack traces are exactly the same (except for different starting address of flush_to_ldisc()). The warnings are triggered by: struct usb_serial_port *port = tty->driver_data; ... /* count is managed under the mutex lock for the tty so cannot drop to zero until after the last close completes */ WARN_ON(!port->port.count); BTW, Couple of minutes earlier I got this message: [ 201.629616] cp210x ttyUSB0: usb_serial_generic_resubmit_read_urb - failed resubmitting read urb, error -1 But after that I disconnected and reconnected the device, so this is probably not relevant here. Best Regards, Michał Mirosław -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
