On Thu, Sep 24, 2009 at 09:02:17PM +0200, Oliver Neukum wrote:
> Am Donnerstag, 24. September 2009 17:19:11 schrieb Johan Hovold:
> > On Thu, Sep 24, 2009 at 03:21:25PM +0200, Oliver Neukum wrote:
> > Agree on open, but is such a flag for cancelling the tasklets always
> > necessary?
>
> Yes :-)
>
> > --- a/drivers/usb/serial/ftdi_sio.c
> > +++ b/drivers/usb/serial/ftdi_sio.c
> > @@ -1787,12 +1787,12 @@ static void ftdi_close(struct usb_serial_port
> > *port)
> >
> > dbg("%s", __func__);
> >
> > + /* shutdown our bulk read */
> > + usb_kill_urb(port->read_urb);
>
> And here's the window that screws things up. If you hit that window
> the read_urb isn't submitted, usb_kill_urb() is a nop,
> but after it has run,the tasklet can submit the urb again.
>
Indeed. :)
> > /* cancel any scheduled reading */
> > cancel_delayed_work_sync(&priv->rx_work);
>
> You can, if you wish to hide what's going on, poison the urb. The
> correct sequence is:
>
> 1. poison the urb
> 2. cancel_delayed_work_sync
>
> 3. unpoison the urb
<snip>
> Step 1 sets a flag.
And this is what we generally want to be doing I assume, rather than
adding an explicit state flag?
Thanks,
Johan
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