(on Knoppix 5.0DVD) plugging second usb-storage device removes the first one!

(on Knoppix 5.0DVD) plugging second usb-storage device removes the first one!

[Russell Senior]

I am having a problem with hotplugging two usb storage devices.  This
is using the new Knoppix 5.0DVD recently released.  I'd like to fix
or, barring that, workaround it.  Here's the outline of what happens:

  a) i plug a usb-storage device;

  b) a desktop icon for the device appears, i get a dialog box asking
     me what I want to do with the device (open or "do nothing"), I
     say do nothing;
 
  c) from a shell, i manually mount the device: 
      # mount /dev/sda1 /media/sda1

  d) /proc/mounts shows /dev/sda1 mounted

  e) i plug a second usb-storage device;

  f) the desktop icon for the first device disappears for a few
     moments, then it reappears with a second desktop icon for the second
     usb-storage device.  I get two more dialog boxes asking me what I
     want to do with the devices.  I look in /proc/mounts and my
     /dev/sda1 mount is gone.  Ouch.

I've attached an strace to udevd during this procedure, you can find
it at:

  <http://www.personaltelco.net/~russell/strace-udevd.log>

On line 6887, I see a recv(4, "remove@/class/scsi-device/[...]
which I presume is udevd receiving a request to remove the /dev/sda1.
How do I figure out where that remove request is coming from?
  
Any other clues about debugging this?

Thanks!


-- 
Russell Senior         ``I have nine fingers; you have ten.''
seniorr@aracnet.com


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Re: (on Knoppix 5.0DVD) plugging second usb-storage device removes the first one!

[Russell Senior]

>>>>> "Russell" = Russell Senior <seniorr@aracnet.com> writes:

Russell> I am having a problem with hotplugging two usb storage
Russell> devices.  This is using the new Knoppix 5.0DVD recently
Russell> released.  I'd like to fix or, barring that, workaround it.
Russell> Here's the outline of what happens:

Russell>   a) i plug a usb-storage device;

Russell>   b) a desktop icon for the device appears, i get a dialog
Russell> box asking me what I want to do with the device (open or "do
Russell> nothing"), I say do nothing;
 
Russell>   c) from a shell, i manually mount the device: # mount
Russell> /dev/sda1 /media/sda1

Russell>   d) /proc/mounts shows /dev/sda1 mounted

Russell>   e) i plug a second usb-storage device;

Russell>   f) the desktop icon for the first device disappears for a
Russell> few moments, then it reappears with a second desktop icon for
Russell> the second usb-storage device.  I get two more dialog boxes
Russell> asking me what I want to do with the devices.  I look in
Russell> /proc/mounts and my /dev/sda1 mount is gone.  Ouch.

Russell> I've attached an strace to udevd during this procedure, you
Russell> can find it at:

Russell>   <http://www.personaltelco.net/~russell/strace-udevd.log>

[...]

I've learned a little more about this.  I have discovered that more or
less the same thing occurs on Debian/unstable (with a vanilla kernel).
I've just retested on a 2.6.16.1 kernel.  I also found udevmonitor.
Here's what I see from that when I plug the two devices on the
Debian/unstable box with 2.6.16.1:

  # udevmonitor 
  udevmonitor prints the received event from the kernel [UEVENT]
  and the event which udev sends out after rule processing [UDEV]

  UEVENT[1144060933.782273] add@/devices/pci0000:00/0000:00:0b.0/0000:02:08.2/usb4/4-3/4-3.1/4-3.1.1
  UEVENT[1144060933.782382] add@/devices/pci0000:00/0000:00:0b.0/0000:02:08.2/usb4/4-3/4-3.1/4-3.1.1/4-3.1.1:1.0
  UEVENT[1144060933.782405] add@/class/scsi_host/host7
  UEVENT[1144060933.782424] add@/class/usb_device/usbdev4.14
  UDEV  [1144060933.784163] add@/devices/pci0000:00/0000:00:0b.0/0000:02:08.2/usb4/4-3/4-3.1/4-3.1.1
  UDEV  [1144060933.822599] add@/devices/pci0000:00/0000:00:0b.0/0000:02:08.2/usb4/4-3/4-3.1/4-3.1.1/4-3.1.1:1.0
  UDEV  [1144060933.878505] add@/class/scsi_host/host7
  UDEV  [1144060933.892363] add@/class/usb_device/usbdev4.14
  UEVENT[1144060938.800149] add@/devices/pci0000:00/0000:00:0b.0/0000:02:08.2/usb4/4-3/4-3.1/4-3.1.1/4-3.1.1:1.0/host7/target7:0:0/7:0:0:0
  UEVENT[1144060938.802896] add@/block/sda
  UEVENT[1144060938.807103] add@/block/sda/sda1
  UEVENT[1144060938.807154] add@/class/scsi_device/7:0:0:0
  UDEV  [1144060938.823077] add@/devices/pci0000:00/0000:00:0b.0/0000:02:08.2/usb4/4-3/4-3.1/4-3.1.1/4-3.1.1:1.0/host7/target7:0:0/7:0:0:0
  UDEV  [1144060938.838759] add@/class/scsi_device/7:0:0:0
  UDEV  [1144060938.881802] add@/block/sda
  UDEV  [1144060938.939771] add@/block/sda/sda1
  UEVENT[1144060953.195921] remove@/class/scsi_device/7:0:0:0
  UEVENT[1144060953.196013] remove@/block/sda/sda1
  UEVENT[1144060953.196035] remove@/block/sda
  UEVENT[1144060953.196057] remove@/devices/pci0000:00/0000:00:0b.0/0000:02:08.2/usb4/4-3/4-3.1/4-3.1.1/4-3.1.1:1.0/host7/target7:0:0/7:0:0:0
  UEVENT[1144060953.196080] remove@/class/scsi_host/host7
  UEVENT[1144060953.196101] remove@/devices/pci0000:00/0000:00:0b.0/0000:02:08.2/usb4/4-3/4-3.1/4-3.1.1/4-3.1.1:1.0
  UEVENT[1144060953.196123] remove@/class/usb_device/usbdev4.14
  UEVENT[1144060953.196148] remove@/devices/pci0000:00/0000:00:0b.0/0000:02:08.2/usb4/4-3/4-3.1/4-3.1.1
  UDEV  [1144060953.198097] remove@/class/scsi_device/7:0:0:0
  UDEV  [1144060953.199573] remove@/devices/pci0000:00/0000:00:0b.0/0000:02:08.2/usb4/4-3/4-3.1/4-3.1.1/4-3.1.1:1.0/host7/target7:0:0/7:0:0:0
  UDEV  [1144060953.204013] remove@/class/scsi_host/host7
  UDEV  [1144060953.209152] remove@/block/sda/sda1
  UDEV  [1144060953.212780] remove@/class/usb_device/usbdev4.14
  UDEV  [1144060953.221786] remove@/devices/pci0000:00/0000:00:0b.0/0000:02:08.2/usb4/4-3/4-3.1/4-3.1.1/4-3.1.1:1.0
  UDEV  [1144060953.229281] remove@/block/sda
  UDEV  [1144060953.242272] remove@/devices/pci0000:00/0000:00:0b.0/0000:02:08.2/usb4/4-3/4-3.1/4-3.1.1
  UEVENT[1144060953.522434] add@/devices/pci0000:00/0000:00:0b.0/0000:02:08.2/usb4/4-3/4-3.1/4-3.1.1
  UEVENT[1144060953.523274] add@/devices/pci0000:00/0000:00:0b.0/0000:02:08.2/usb4/4-3/4-3.1/4-3.1.1/4-3.1.1:1.0
  UEVENT[1144060953.523335] add@/class/scsi_host/host8
  UEVENT[1144060953.523358] add@/class/usb_device/usbdev4.15
  UDEV  [1144060953.525767] add@/devices/pci0000:00/0000:00:0b.0/0000:02:08.2/usb4/4-3/4-3.1/4-3.1.1
  UDEV  [1144060953.565114] add@/devices/pci0000:00/0000:00:0b.0/0000:02:08.2/usb4/4-3/4-3.1/4-3.1.1/4-3.1.1:1.0
  UDEV  [1144060953.621186] add@/class/scsi_host/host8
  UDEV  [1144060953.634874] add@/class/usb_device/usbdev4.15
  UEVENT[1144060953.818125] add@/devices/pci0000:00/0000:00:0b.0/0000:02:08.2/usb4/4-3/4-3.1/4-3.1.3
  UEVENT[1144060953.820214] add@/devices/pci0000:00/0000:00:0b.0/0000:02:08.2/usb4/4-3/4-3.1/4-3.1.3/4-3.1.3:1.0
  UEVENT[1144060953.820290] add@/class/scsi_host/host9
  UEVENT[1144060953.820312] add@/class/usb_device/usbdev4.16
  UDEV  [1144060953.820724] add@/devices/pci0000:00/0000:00:0b.0/0000:02:08.2/usb4/4-3/4-3.1/4-3.1.3
  UDEV  [1144060953.858802] add@/devices/pci0000:00/0000:00:0b.0/0000:02:08.2/usb4/4-3/4-3.1/4-3.1.3/4-3.1.3:1.0
  UDEV  [1144060953.914400] add@/class/scsi_host/host9
  UDEV  [1144060953.928954] add@/class/usb_device/usbdev4.16
  UEVENT[1144060958.537592] add@/devices/pci0000:00/0000:00:0b.0/0000:02:08.2/usb4/4-3/4-3.1/4-3.1.1/4-3.1.1:1.0/host8/target8:0:0/8:0:0:0
  UEVENT[1144060958.540764] add@/block/sda
  UEVENT[1144060958.545060] add@/block/sda/sda1
  UEVENT[1144060958.545120] add@/class/scsi_device/8:0:0:0
  UDEV  [1144060958.561068] add@/devices/pci0000:00/0000:00:0b.0/0000:02:08.2/usb4/4-3/4-3.1/4-3.1.1/4-3.1.1:1.0/host8/target8:0:0/8:0:0:0
  UDEV  [1144060958.577157] add@/class/scsi_device/8:0:0:0
  UDEV  [1144060958.619965] add@/block/sda
  UDEV  [1144060958.676679] add@/block/sda/sda1
  UEVENT[1144060959.340269] add@/devices/pci0000:00/0000:00:0b.0/0000:02:08.2/usb4/4-3/4-3.1/4-3.1.3/4-3.1.3:1.0/host9/target9:0:0/9:0:0:0
  UEVENT[1144060959.342911] add@/block/sdb
  UEVENT[1144060959.347502] add@/block/sdb/sdb1
  UEVENT[1144060959.347557] add@/class/scsi_device/9:0:0:0
  UDEV  [1144060959.365249] add@/devices/pci0000:00/0000:00:0b.0/0000:02:08.2/usb4/4-3/4-3.1/4-3.1.3/4-3.1.3:1.0/host9/target9:0:0/9:0:0:0
  UDEV  [1144060959.377210] add@/class/scsi_device/9:0:0:0
  UDEV  [1144060959.423595] add@/block/sdb
  UDEV  [1144060959.465071] add@/block/sdb/sdb1

I don't understand why does /block/sda1 get removed on a plug of a
different usb-storage?  What is the solution for this to behave sanely?

Thanks!


-- 
Russell Senior         ``I have nine fingers; you have ten.''
seniorr@aracnet.com


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Re: (on Knoppix 5.0DVD) plugging second usb-storage device removes the first one!

[Duncan Sands]

Hi Russel,

> I don't understand why does /block/sda1 get removed on a plug of a
> different usb-storage?  What is the solution for this to behave sanely?

did this ever work correctly?  Some old VIA cards have the interesting
property that they disconnect any plugged in usb device if you plug in
a second one.

Ciao,

Duncan.


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