Re: udev hangs USB-storage (HP r707 camera)

[Grant Grundler <grundler-6jwH94ZQLHl74goWV3ctuw@public.gmane.org>]

On Sat, Jan 19, 2008 at 08:56:31PM -0600, James Bottomley wrote:
....
> > it's children a few days ago (probably with 2.6.22-14-generic (Ubuntu
> > kernel). I've appended everything for PID 17972 (which is only 12k, full
> > output is 559KB). Key bit is this:
> > 17972 _llseek(3, 31129600, [31129600], SEEK_SET) = 0
> > 17972 read(3,  <unfinished ...>
> > 17972 <... read resumed> 0x804dc80, 512) = -1 EIO (Input/output error)
> > 
> > given the device reports "60801 512-byte hardware sectors (31 MB)"
> > and "31129600/512 == 60800"...it's obvious vol_id is trying to read
> > the last sector on the disk (I assume it's to verify the size).
> > ISTR "reading the last sector" caused problems else where.
> > I'll try to hunt that down.
> 
> If this is the problem, it ought to be reproducible without vol_id by
> doing
> 
> dd bs=512b if=/dev/<dev> of=/dev/null seek=60800 count=1

root@mb500:~ # dd bs=512b if=/dev/sda of=/dev/null seek=60800 count=1
1+0 records in
1+0 records out
262144 bytes (262 kB) copied, 0.433933 seconds, 604 kB/s

but since 512B is the default (I thought), I tried:
root@mb500:~ # dd if=/dev/sda of=/dev/null seek=60800 count=1
1+0 records in
1+0 records out
512 bytes (512 B) copied, 0.0239289 seconds, 21.4 kB/s

and got different output....wth?

Oh...and you mean "skip", not "seek"...no wonder that worked.

root@mb500:~ # strace -o strace-dd-HPr707.out dd if=/dev/sda of=/dev/null skip=60800 count=1
dd: reading `/dev/sda': Input/output error
0+0 records in
0+0 records out
0 bytes (0 B) copied, 55.7303 seconds, 0.0 kB/s


dmesg output:
Jan 19 19:08:12 localhost kernel: usb 1-1.1.4: reset full speed USB device using uhci_hcd and address 8
Jan 19 19:08:37 localhost last message repeated 3 times
Jan 19 19:08:37 localhost kernel: sd 3:0:0:0: scsi: Device offlined - not ready after error recovery
Jan 19 19:08:37 localhost kernel: sd 3:0:0:0: [sda] Result: hostbyte=DID_ABORT driverbyte=DRIVER_OK,SUGGEST_OK
Jan 19 19:08:37 localhost kernel: end_request: I/O error, dev sda, sector 60800


> There is a READ_CAPACITY bug where incompetent usb vendors misread the
> SCSI standard and actually report one sector more than the actual
> capacity (and crash when this is accessed), but let's verify first.

This seems to be exactly the case.
What's the work around?

thanks,
grant