Re: [Bisected] [Bug #13821] Replugging USB serial converter uses new device node

Carlos R. Mafra
2009-07-27T16:50:05Z

On Mon 27.Jul'09 at 12:18:36 -0400, Alan Stern wrote:
> On Mon, 27 Jul 2009, Ferenc Wagner wrote:
>
> > > Are you certain this really is a regression? Under 2.6.30 and 2.6.27
> > > the same thing happened if I unplugged a USB serial device while it was
> > > in use.
> >
> > My original report is about unplugging the USB servial device *after*
> > using it.
> >
> > > Can you check whether the device is still being used when you unplug
> > > it? For instance, is there still a pppd process trying to communicate
> > > with the device?
> >
> > I checked and rechecked that the pppd process is already dead by the
> > time I unplug the device. However, the minor number did not increase
> > if I unplugged the device without using it beforehand, as expected.
> >
> > > In short, it seems likely that this is not new behavior but rather the
> > > way usb-serial has worked all along.
> >
> > I didn't experience this problem with 2.6.30: my ppp script was
> > hardwired to use ttyUSB0 and it always worked. Now with 2.6.31-rc3 it
> > does not, as the device node keeps changing.
> >
> > I'll test this with opening ttyUSB directly from the shell, instead of
> > via pppd, and report back whether it makes a difference.
>
> Another thing to check is whether this patch (not yet merged) fixes it:
>
> http://marc.info/?l=linux-usb&m=124825571403844&w=2

No, unfortunately it does not fix it. I've just tested it.