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Date:   Thu, 3 Dec 2020 19:24:10 +0100
From:   Greg KH <gregkh@linuxfoundation.org>
To:     Tudor.Ambarus@microchip.com
Cc:     michael@walle.cc, linux-mtd@lists.infradead.org,
        linux-kernel@vger.kernel.org, miquel.raynal@bootlin.com,
        richard@nod.at, vigneshr@ti.com, boris.brezillon@collabora.com,
        stable@vger.kernel.org
Subject: Re: [PATCH v7 1/7] mtd: spi-nor: sst: fix BPn bits for the
 SST25VF064C
Message-ID: <X8ktStibpw1phn4G@kroah.com>
References: <20201202230040.14009-1-michael@walle.cc>
 <20201202230040.14009-2-michael@walle.cc>
 <44be8e3c-86ca-501e-e575-55f17747bda6@microchip.com>
 <bf31d41ca489b5d1b7976bfb8ede88e9@walle.cc>
 <2c66659b-ecff-c6bb-38c1-c1172780c710@microchip.com>
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On Thu, Dec 03, 2020 at 03:08:49PM +0000, Tudor.Ambarus@microchip.com wrote:
> On 12/3/20 4:39 PM, Michael Walle wrote:
> > EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe
> > 
> > Am 2020-12-03 15:34, schrieb Tudor.Ambarus@microchip.com:
> >> On 12/3/20 1:00 AM, Michael Walle wrote:
> >>> EXTERNAL EMAIL: Do not click links or open attachments unless you know
> >>> the content is safe
> >>>
> >>> This flash part actually has 4 block protection bits.
> >>>
> >>> Reported-by: Tudor Ambarus <tudor.ambarus@microchip.com>
> >>> Cc: stable@vger.kernel.org # v5.7+
> >>
> >> While the patch is correct according to the datasheet, it was
> >> not tested, so it's not a candidate for stable. I would update
> >> the commit message to indicate that the the patch was made
> >> solely on datasheet info and not tested, I would add the fixes
> >> tag, and strip cc-ing to stable.
> > 
> > What is the difference? Any commit with a Fixes tag will also land
> > in the stable trees. Just that it will cause compile errors for
> > kernel older than 5.7.
> > 
> > So if you don't want to have it in stable then you must not add
> > a Fixes: tag either.
> > 
> 
> Documentation/process/stable-kernel-rules.rst doesn't say that the
> Fixes tag is a guarantee that a patch will hit the stable kernels.
> 
> Since this patch was not tested, it's not a candidate for stable as
> per the first rule. It's a theoretical fix, because it should indeed
> fix the locking as per the datasheet. Even for theoretical fixes, I
> would like to know what commit broke the functionality, and that's why
> I asked for the Fixes tag.
> 
> We don't want the patch in stable, so that's why I said that I would
> indicate in the commit message that it was not tested, and that I
> would strip the cc to stable.
> 
> Maybe it's just my understanding. Others may help.

Your understanding is correct.  But note that we might accidentally pick
it up with the Fixes: tag at a later date, so be aware that you might
want to make the text in the changelog really obvious that it should not
go into a stable kernel, and why not (hint, if you have a Fixes: tag,
that's usually a good reason _to_ include it...)

thanks,

greg k-h