Re: [PATCH 0/3] Fix USB deadlock caused by SCSI error handling

From: Andreas Reis <andreas.reis@gmail.com>
To: Alan Stern <stern@rowland.harvard.edu>, Hannes Reinecke <hare@suse.de>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>,
	SCSI development list <linux-scsi@vger.kernel.org>,
	USB list <linux-usb@vger.kernel.org>
Subject: Re: [PATCH 0/3] Fix USB deadlock caused by SCSI error handling
Date: Thu, 10 Apr 2014 12:58:24 +0200	[thread overview]
Message-ID: <53467950.3010403@gmail.com> (raw)
In-Reply-To: <Pine.LNX.4.44L0.1404091358340.28384-100000@netrider.rowland.org>

That patch appears to work in preventing the crashes, judged on one 
repeated appearance of the bug.

dmesg had the usual
[  215.229903] usb 4-2: usb_disable_lpm called, do nothing
[  215.336941] usb 4-2: reset SuperSpeed USB device number 3 using xhci_hcd
[  215.350296] xhci_hcd 0000:00:14.0: xHCI xhci_drop_endpoint called 
with disabled ep ffff880427b829c0
[  215.350305] xhci_hcd 0000:00:14.0: xHCI xhci_drop_endpoint called 
with disabled ep ffff880427b82a08
[  215.350621] usb 4-2: usb_enable_lpm called, do nothing

repeated five times, followed by one
[  282.795801] sd 8:0:0:0: Device offlined - not ready after error recovery

and then as often as something tried to read from it:
[  295.585472] sd 8:0:0:0: rejecting I/O to offline device

The stick could then be properly un- and remounted (the latter if it had 
been physically replugged) without issue — for the bug to reoccur after 
one to three minutes. I tried this three times, no dmesg difference 
except the ep addresses varied on two of that.

Andreas Reis

On 09.04.2014 20:02, Alan Stern wrote:
> On Wed, 9 Apr 2014, Hannes Reinecke wrote:
>
>>> I finally got a chance to try it out.  It does seem to do what we want.
>>> I didn't track the flow of control in complete detail, but the command
>>> definitely got aborted both times it was issued.
>>>
>> Good, so it is as I thought. James, can we include this patch instead of
>> your prior solution?
>
> First, we should have the original bug reporter try it out.
>
> Andreas, the patch in question can be found here:
>
> 	http://marc.info/?l=linux-usb&m=139627666606597&w=2
>
> Can you try this in place of the 1/3 patch posted by James?  It should
> have the same effect, of preventing your system from crashing when the
> READ command fails.
>
> Alan Stern
>

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