Delayed kernel "change" event for USB storage device

Hello,

I am trying to use a special USB stick (Stealth MXP) under Ubuntu. This USB stick has hardware encryption (fingerprint reader) and when plugging it in, it usually shows two different scsi devices. Only one of them is accessible in the beginning and when I unlock the stick, the second one shows a partition as well and can be used. This works fine under other Linux distros (tested on Gentoo for example).

Under Ubuntu the following happens when I plug in the stick:

[18212.850151] sd 13:0:0:0: [sdb] Attached SCSI removable disk
[18212.850846] sd 13:0:0:1: [sdc] 163840 512-byte logical blocks: (83.8 MB/80.0 MiB)
[18212.852284] sd 13:0:0:1: [sdc] Write Protect is off
[18212.852287] sd 13:0:0:1: [sdc] Mode Sense: 03 00 00 00
[18212.852289] sd 13:0:0:1: [sdc] Assuming drive cache: write through
[18212.860239] sd 13:0:0:1: [sdc] Assuming drive cache: write through
[18212.860245] sdc:
[18212.866567] sd 13:0:0:1: [sdc] Assuming drive cache: write through
[18212.866573] sd 13:0:0:1: [sdc] Attached SCSI removable disk

Here sdb is the locked part of the stick, and sdc is the "open" part (contains some software).

When I unlock the stick now, no additional udev event is generated (checked with udevadm monitor).

However, when I access /dev/sdb in any way (for example fdisk -l, or even less -f /dev/sdb), a udev change event is immediately generated:

KERNEL[1263936195.520104] change /devices/pci0000:00/0000:00:1a.7/usb1/1-1/1-1:1.0/host14/target14:0:0/14:0:0:0/block/sdb (block)

And then sdb is recognized properly:

[18816.805297] sd 14:0:0:0: [sdb] 3813376 512-byte logical blocks: (1.95 GB/1.81 GiB)
[18816.805911] sd 14:0:0:0: [sdb] Assuming drive cache: write through
[18816.808066] sd 14:0:0:0: [sdb] Assuming drive cache: write through
[18816.808075] sdb: sdb1

However, this doesnt happen at all, until I access /dev/sdb somehow. I only saw this behavior under ubuntu so far, it works perfectly everywhere else I tested.

Version Information: Ubuntu 9.10
Kernel: Linux 2.6.31-14-generic #48-Ubuntu SMP Fri Oct 16 14:04:26 UTC 2009 i686 GNU/Linux

Best regards,

Chris