Re: 2.6.24-rc5-mm1

On Dec 17, 2007 9:14 AM, Dave Young <hidave.darkstar@xxxxxxxxx> wrote:
On Dec 14, 2007 11:44 PM, Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> wrote:
On Fri, 14 Dec 2007, Dave Young wrote:

Hi,
The behaviour of my mp3 player (also act as usb-storage device) seems
changed from rc5 to rc5-mm1.

This can't be considered a bug, right?

I'm not sure.


It's just that the player
changed from one slightly non-standard behavior to a different slightly
non-standard behavior.


<dmesg output under rc5>:
=========
usb 1-7: new high speed USB device using ehci_hcd and address 7
usb 1-7: configuration #1 chosen from 1 choice
scsi4 : SCSI emulation for USB Mass Storage devices
usb-storage: device found at 7
usb-storage: waiting for device to settle before scanning
scsi 4:0:0:0: Direct-Access Newman mp3 PQ: 0 ANSI: 0 CCS
sd 4:0:0:0: [sdb] 245248 512-byte hardware sectors (126 MB)
sd 4:0:0:0: [sdb] Write Protect is on
sd 4:0:0:0: [sdb] Mode Sense: 03 00 80 00
sd 4:0:0:0: [sdb] Assuming drive cache: write through
sd 4:0:0:0: [sdb] 245248 512-byte hardware sectors (126 MB)
sd 4:0:0:0: [sdb] Write Protect is on
sd 4:0:0:0: [sdb] Mode Sense: 03 00 80 00
sd 4:0:0:0: [sdb] Assuming drive cache: write through
sdb: sdb1
sd 4:0:0:0: [sdb] Attached SCSI removable disk
sd 4:0:0:0: Attached scsi generic sg1 type 0
usb-storage: device scan complete

==========
try mount it (or just blockdev --rereadpt), then write protect become off:
==========

sd 4:0:0:0: [sdb] 245248 512-byte hardware sectors (126 MB)
sd 4:0:0:0: [sdb] Write Protect is off
sd 4:0:0:0: [sdb] Mode Sense: 03 00 00 00
sd 4:0:0:0: [sdb] Assuming drive cache: write through
sd 4:0:0:0: [sdb] 245248 512-byte hardware sectors (126 MB)
sd 4:0:0:0: [sdb] Write Protect is off
sd 4:0:0:0: [sdb] Mode Sense: 03 00 00 00
sd 4:0:0:0: [sdb] Assuming drive cache: write through
sdb: sdb1

This output won't appear if you simply mount the device. So how do you
know that mounting turns off write protect?

This can be observed by eye:
dmesg -> mount -> dmesg


But under rc5-mm1, after mount command being executed, it is just
mouted as read only partition without set the write-protect to off

I tried "blockdev --rereadpt", it do set the write-protect to off as rc5 kernel.

Below is the output of dmesg under rc5-mm1
==========
usb 1-8: new high speed USB device using ehci_hcd and address 6
usb 1-8: configuration #1 chosen from 1 choice
scsi3 : SCSI emulation for USB Mass Storage devices
usb-storage: device found at 6
usb-storage: waiting for device to settle before scanning
scsi 3:0:0:0: Direct-Access Newman mp3 PQ: 0 ANSI: 0 CCS
sd 3:0:0:0: [sdb] 245248 512-byte hardware sectors (126 MB)
sd 3:0:0:0: [sdb] Write Protect is on
sd 3:0:0:0: [sdb] Mode Sense: 03 00 80 00
sd 3:0:0:0: [sdb] Assuming drive cache: write through
sd 3:0:0:0: [sdb] 245248 512-byte hardware sectors (126 MB)
sd 3:0:0:0: [sdb] Write Protect is on
sd 3:0:0:0: [sdb] Mode Sense: 03 00 80 00
sd 3:0:0:0: [sdb] Assuming drive cache: write through
sdb: sdb1

This looks exactly the same as the output above (except for various
port, device, and bus numbers).

Yes, but lacks the part of "'Write Protect if off' and other lines".


If you turn on CONFIG_USB_STORAGE_DEBUG for both kernels and compare
the dmesg output for the mount command, that might highlight the
difference.

Ok, I will test with do once have time, thanks.


There's not useful infomation with DEBUG on.

I tested on another machine with kernel 2.6.24-rc2. And the result is
diffrent again.
Here is the result:

1. on 2.6.24-rc2, when I plugin the player the kernel reports below messages:

usb-storage: waiting for device to settle before scanning
/*[lets mark the below part as part 1]*/
scsi 0:0:0:0: Direct-Access Newman mp3 PQ: 0 ANSI: 0 CCS
sd 0:0:0:0: [sda] 245248 512-byte hardware sectors (126 MB)
sd 0:0:0:0: [sda] Write Protect is on
sd 0:0:0:0: [sda] Mode Sense: 03 00 80 00
sd 0:0:0:0: [sda] Assuming drive cache: write through
sd 0:0:0:0: [sda] 245248 512-byte hardware sectors (126 MB)
sd 0:0:0:0: [sda] Write Protect is on
sd 0:0:0:0: [sda] Mode Sense: 03 00 80 00
sd 0:0:0:0: [sda] Assuming drive cache: write through
sda: sda1
/*[lets mark the below part as part 2]*/
sd 0:0:0:0: [sda] Attached SCSI removable disk
usb-storage: device scan complete
sd 0:0:0:0: [sda] 245248 512-byte hardware sectors (126 MB)
sd 0:0:0:0: [sda] Write Protect is off
sd 0:0:0:0: [sda] Mode Sense: 03 00 00 00
sd 0:0:0:0: [sda] Assuming drive cache: write through
sd 0:0:0:0: [sda] 245248 512-byte hardware sectors (126 MB)
sd 0:0:0:0: [sda] Write Protect is off
sd 0:0:0:0: [sda] Mode Sense: 03 00 00 00
sd 0:0:0:0: [sda] Assuming drive cache: write through
sda: sda1

2. on 2.6.24-rc5 kernel reports only the part 1, after try mount the
disk it reports the part 2 and mount the partition as rw

3. on 2.6.24-rc5 kernel reports only the part 1, after try mount the
disk it just mount the partition as ro with nothing more messages.

Regards
dave
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