Re: 2.6.31-rc3: replugging USB serial converter uses new device node

From: Ferenc Wagner
Date: Thu Jul 23 2009 - 06:25:47 EST


Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> writes:

> On Sat, 18 Jul 2009 22:04:57 +0200 Ferenc Wagner <wferi@xxxxxxx> wrote:
>
>> Hi,
>>
>> Since upgrading to 2.6.31-rc3 from 2.6.30, my ttyUSB device number
>> keeps increasing on each replug. Output of udevadm monitor:
>>
>> ==poff==
>> UEVENT[1247946169.580772] remove /devices/virtual/net/ppp0 (net)
>> UDEV [1247946169.589775] remove /devices/virtual/net/ppp0 (net)
>> ==unplug==
>> UEVENT[1247946186.700698] remove /devices/pci0000:00/0000:00:1d.1/usb3/3-1/3-1:1.0/ttyUSB2/tty/ttyUSB2 (tty)
>> UEVENT[1247946186.700737] remove /devices/pci0000:00/0000:00:1d.1/usb3/3-1/3-1:1.0/ttyUSB2 (usb-serial)
>> UEVENT[1247946186.700749] remove /devices/pci0000:00/0000:00:1d.1/usb3/3-1/3-1:1.0 (usb)
>> UEVENT[1247946186.700760] remove /devices/pci0000:00/0000:00:1d.1/usb3/3-1/usb_device/usbdev3.6 (usb_device)
>> UEVENT[1247946186.700771] remove /devices/pci0000:00/0000:00:1d.1/usb3/3-1 (usb)
>> UDEV [1247946186.701535] remove /devices/pci0000:00/0000:00:1d.1/usb3/3-1/3-1:1.0/ttyUSB2/tty/ttyUSB2 (tty)
>> UDEV [1247946186.705822] remove /devices/pci0000:00/0000:00:1d.1/usb3/3-1/3-1:1.0/ttyUSB2 (usb-serial)
>> UDEV [1247946186.711662] remove /devices/pci0000:00/0000:00:1d.1/usb3/3-1/3-1:1.0 (usb)
>> UDEV [1247946186.715237] remove /devices/pci0000:00/0000:00:1d.1/usb3/3-1/usb_device/usbdev3.6 (usb_device)
>> UDEV [1247946186.718872] remove /devices/pci0000:00/0000:00:1d.1/usb3/3-1 (usb)
>> ==replug==
>> UEVENT[1247946199.654628] add /devices/pci0000:00/0000:00:1d.1/usb3/3-1 (usb)
>> UDEV [1247946199.660946] add /devices/pci0000:00/0000:00:1d.1/usb3/3-1 (usb)
>> UEVENT[1247946199.661096] add /devices/pci0000:00/0000:00:1d.1/usb3/3-1/3-1:1.0 (usb)
>> UEVENT[1247946199.688206] add /devices/pci0000:00/0000:00:1d.1/usb3/3-1/3-1:1.0/ttyUSB3 (usb-serial)
>> UEVENT[1247946199.688254] add /devices/pci0000:00/0000:00:1d.1/usb3/3-1/3-1:1.0/ttyUSB3/tty/ttyUSB3 (tty)
>> UEVENT[1247946199.688266] add /devices/pci0000:00/0000:00:1d.1/usb3/3-1/usb_device/usbdev3.7 (usb_device)
>> UDEV [1247946199.710642] add /devices/pci0000:00/0000:00:1d.1/usb3/3-1/3-1:1.0 (usb)
>> UDEV [1247946199.713898] add /devices/pci0000:00/0000:00:1d.1/usb3/3-1/3-1:1.0/ttyUSB3 (usb-serial)
>> UDEV [1247946199.729618] add /devices/pci0000:00/0000:00:1d.1/usb3/3-1/usb_device/usbdev3.7 (usb_device)
>> UDEV [1247946199.739566] add /devices/pci0000:00/0000:00:1d.1/usb3/3-1/3-1:1.0/ttyUSB3/tty/ttyUSB3 (tty)
>> ==pon==
>> UEVENT[1247946268.571857] add /devices/virtual/net/ppp0 (net)
>> UDEV [1247946268.593127] add /devices/virtual/net/ppp0 (net)
>>
>> Dmesg is available at http://pastebin.com/d516e3e00.
>
> Can anyone say whether this is expected behaviour?
> Does it actually cause any observeable problems?

The main problem is that I have to change my ppp config before each
pon. I guess it could be solved by some udev trickery, but didn't
want to go that route before getting sure it's expected behaviour,
which I find improbable as it depends on a pppd run in the middle.
That's also why I didn't report it as an USB problem originally.
--
Thanks,
Feri.
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