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Date: Tue, 4 Nov 2008 09:11:28 -0800 From: Greg KH <greg@...ah.com> To: Alan Cox <alan@...rguk.ukuu.org.uk> Cc: linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org Subject: Re: [PATCH] tty: Fix close races in USB serial On Tue, Nov 04, 2008 at 03:29:24PM +0000, Alan Cox wrote: > From: Alan Cox <alan@...hat.com> > > USB serial has always had races where the tty port usage count can hit zero > during a receive event. The internal locking is a mutex so we can't use > that in the IRQ handlers. > > With krefs we can tackle this differently but we still need to be careful. > > Signed-off-by: Alan Cox <alan@...hat.com> > --- > > drivers/usb/serial/usb-serial.c | 15 ++++++++++----- > 1 files changed, 10 insertions(+), 5 deletions(-) > > > diff --git a/drivers/usb/serial/usb-serial.c b/drivers/usb/serial/usb-serial.c > index 794b5ff..aafa684 100644 > --- a/drivers/usb/serial/usb-serial.c > +++ b/drivers/usb/serial/usb-serial.c > @@ -269,15 +269,19 @@ static void serial_close(struct tty_struct *tty, struct file *filp) > return; > } > > - --port->port.count; > - if (port->port.count == 0) > + if (port->port.count == 1) > /* only call the device specific close if this > - * port is being closed by the last owner */ > + * port is being closed by the last owner. Ensure we do > + * this before we drop the port count. The call is protected > + * by the port mutex > + */ > port->serial->type->close(tty, port, filp); > > - if (port->port.count == (port->console? 1 : 0)) { > + if (port->port.count == (port->console ? 2 : 1)) { Why are you testing for 2 here? confused, greg k-h -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.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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