On Mon, 29 Jul 2013, Martin K. Petersen wrote:

> >>>>> "Alan" == Alan Stern <st...@rowland.harvard.edu> writes:
> 
> Alan,
> 
> Alan> It was introduced by commit 98dcc2946adb (SCSI: sd: Update WRITE
> Alan> SAME heuristics).  This commit adds a call to scsi_get_vpd_page()
> Alan> in sd_read_write_same() without first checking
> Alan> sd_try_extended_inquiry().  As noted in the latter routine, VPD
> Alan> inquiries will crash some devices.
> 
> Is REPORT SUPPORTED OPERATION CODES generally safe on USB devices?

Broadly speaking, practically nothing is safe on USB devices.  :-)  The 
general rule is: If Windows XP doesn't use the command then it will 
crash something.

In the case of these bug reports, the scsi_report_opcode() call returns 
-EINVAL.

> The reason I didn't wrap the WRITE SAME heuristics in
> sd_try_extended_inquiry() like I have done with most of the other VPDs
> is that there are a ton of older SPI/SAS/FC devices that support WRITE
> SAME just fine.
> 
> 
> Alan> As far as the stable kernels are concerned, the best thing for now
> Alan> may simply be to revert it.
> 
> No go. The above commit fixes issues for somebody else.
> 
> I could add an explicit check to the sd_read_write_same() function. But
> how about we do the following instead?

Stuart and Ed, does Martin's patch fix your problem?

Alan Stern

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