[Bug 14118] USB storage: "No sense [current]" when connecting

[Bug 14118] USB storage: "No sense [current]" when connecting

[bugzilla-daemon]

http://bugzilla.kernel.org/show_bug.cgi?id=14118


Andrew Morton <akpm@linux-foundation.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
          Component|USB                         |SCSI
         AssignedTo|greg@kroah.com              |linux-scsi@vger.kernel.org
            Product|Drivers                     |IO/Storage




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[Bug 14118] USB storage: "No sense [current]" when connecting

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http://bugzilla.kernel.org/show_bug.cgi?id=14118





--- Comment #7 from Andrew Morton <akpm@linux-foundation.org>  2009-09-05 20:53:45 ---
On Sat, 5 Sep 2009 16:40:06 -0400 (EDT) Alan Stern <stern@rowland.harvard.edu>
wrote:

> > > The second problem has nothing to do with USB; it is a bug in the SCSI
> > > layer.  If the module parameter doesn't fix everything, I suggest this
> > > bug report be reassigned to James Bottomley rather than Greg
> > > Kroah-Hartman and the component be changed from USB to SCSI.
> > 
> > Should I edit the bug myself? (If yes, what address do I reassign it to?)
> 
> Maybe we can prevail upon Andrew Morton to reassign it for you.

OK, I reassigned it to scsi, but I expect it would help the scsi guys
if someone could add a new summary of what they think the actual bug is.

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[Bug 14118] USB storage: "No sense [current]" when connecting

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http://bugzilla.kernel.org/show_bug.cgi?id=14118





--- Comment #8 from Alan Stern <stern@rowland.harvard.edu>  2009-09-05 21:18:18 ---
On Sat, 5 Sep 2009, Andrew Morton wrote:

> OK, I reassigned it to scsi, but I expect it would help the scsi guys
> if someone could add a new summary of what they think the actual bug is.

Okay, here's a quick summary.  This USB mass storage device has a bug: 
It doesn't like to access the last 16 or so sectors of LUN 0.  When 
asked to read from those sectors it returns no data and Check Condition 
set.  Then in response to REQUEST SENSE it returns no information 
(SK=0, ASC=ASCQ=0).

This causes the SCSI midlayer to reissue the read request, with the 
same result.  We enter an unending loop because each READ is a new 
request with a new timeout.  That's the real problem -- the bug in the 
phone wouldn't matter much if SCSI would just give up and fail the READ 
after a couple of retries.

There are a few more details in comment #4.  Note that recently people
have been encountering more and more devices with this same kind of bug
(READ fails, REQUEST SENSE returns nothing).

My suggestion for a fix: Don't call scsi_requeue_command() if the 
current command made zero forward progress.  But this will have to be 
elaborated and made reliable.

Alan Stern

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[Bug 14118] USB storage: "No sense [current]" when connecting

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--- Comment #9 from Alan Stern <stern@rowland.harvard.edu>  2009-09-28 18:01:16 ---
Created an attachment (id=23196)
 --> (http://bugzilla.kernel.org/attachment.cgi?id=23196)
Patch to handle errors with no sense

Try this patch.  It should fix the problem of the unending retries.  There will
still be errors, but each one will be retried only a small number of times.

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[Bug 14118] USB storage: "No sense [current]" when connecting

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--- Comment #10 from Mantas Mikulėnas <grawity@gmail.com>  2009-10-03 20:19:36 ---
> Try this patch.  It should fix the problem of the unending retries.  There will
> still be errors, but each one will be retried only a small number of times.

The patch seems to fix the problems.

(Tried with 2.6.31.1 kernel, default Arch Linux configuration, if that
matters.)

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[Bug 14118] USB storage: "No sense [current]" when connecting

[bugzilla-daemon]

http://bugzilla.kernel.org/show_bug.cgi?id=14118





--- Comment #11 from Alan Stern <stern@rowland.harvard.edu>  2009-10-03 21:29:39 ---
Thanks for testing.  I will submit the patch for inclusion in 2.6.32 and
2.6.31.stable.

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[Bug 14118] USB storage: "No sense [current]" when connecting

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--- Comment #12 from Alan Stern <stern@rowland.harvard.edu>  2009-10-13 02:40:33 ---
The patch has been merged as commit f1a0743bc0e7a30c032b1eb78f6a2b0f805b4597. 
You can close out this bug report.

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[Bug 14118] USB storage: "No sense [current]" when connecting

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http://bugzilla.kernel.org/show_bug.cgi?id=14118


Mantas Mikulėnas <grawity@gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|                            |CODE_FIX




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