linux-kernel - Re: [PATCH v2] libnvdimm, nd_blk: mask off reserved status bits

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Date:	Mon, 8 Aug 2016 12:36:30 -0700
From:	Dan Williams <dan.j.williams@...el.com>
To:	Ross Zwisler <ross.zwisler@...ux.intel.com>
Cc:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	Len Brown <lenb@...nel.org>,
	Linux ACPI <linux-acpi@...r.kernel.org>,
	"linux-nvdimm@...ts.01.org" <linux-nvdimm@...ts.01.org>,
	"Lee, Chun-Yi" <jlee@...e.com>,
	"stable@...r.kernel.org" <stable@...r.kernel.org>
Subject: Re: [PATCH v2] libnvdimm, nd_blk: mask off reserved status bits

On Mon, Aug 8, 2016 at 12:10 PM, Ross Zwisler
<ross.zwisler@...ux.intel.com> wrote:
> On Tue, Aug 02, 2016 at 12:26:53PM -0600, Ross Zwisler wrote:
>> The "NVDIMM Block Window Driver Writer's Guide":
>>
>> http://pmem.io/documents/
>> http://pmem.io/documents/NVDIMM_DriverWritersGuide-July-2016.pdf
>>
>> defines the layout of the block window status register.  For the July 2016
>> version of the spec linked to above, this happens in Figure 4 on page 26.
>>
>> The only bits defined in this spec are bits 31, 5, 4, 2, 1 and 0.  The rest
>> of the bits in the status register are reserved, and there is a warning
>> following the diagram that says:
>>
>>   Note: The driver cannot assume the value of the RESERVED bits in the
>>   status register are zero. These reserved bits need to be masked off, and
>>   the driver must avoid checking the state of those bits.
>>
>> This change ensures that for hardware implementations that set these
>> reserved bits in the status register, the driver won't incorrectly fail the
>> block I/Os.
>>
>> Signed-off-by: Ross Zwisler <ross.zwisler@...ux.intel.com>
>> Reviewed-by: Lee, Chun-Yi <jlee@...e.com>
>> Cc: Dan Williams <dan.j.williams@...el.com>
>> Cc: stable@...r.kernel.org # v4.2+
>
> Ping on this patch - through which tree should we merge this for v4.8-rc2?
> Dan's nvdimm tree?

It's getting 0-day coverage on my libnvdimm-pending branch and will go
to Linus at the end of the week.