Messages in this thread | | | Date | Thu, 11 Mar 2010 17:06:53 +0100 | From | Michał Mirosław <> | Subject | Re: Race condition in TTY ldisc layer in 2.6.33 |
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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-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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