linux-kernel - Re: [PATCH v2 03/27] mtd: spi-nor: swp: Improve locking user experience

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Message-Id: <DGAD7N254PVR.1PEPJM24A6679@kernel.org>
Date: Mon, 09 Feb 2026 11:39:17 +0100
From: "Michael Walle" <mwalle@...nel.org>
To: "Miquel Raynal" <miquel.raynal@...tlin.com>, "Tudor Ambarus"
 <tudor.ambarus@...aro.org>, "Pratyush Yadav" <pratyush@...nel.org>,
 "Richard Weinberger" <richard@....at>, "Vignesh Raghavendra"
 <vigneshr@...com>, "Jonathan Corbet" <corbet@....net>
Cc: "Sean Anderson" <sean.anderson@...ux.dev>, "Thomas Petazzoni"
 <thomas.petazzoni@...tlin.com>, "Steam Lin" <STLin2@...bond.com>,
 <linux-mtd@...ts.infradead.org>, <linux-kernel@...r.kernel.org>,
 <linux-doc@...r.kernel.org>, <stable@...nel.org>
Subject: Re: [PATCH v2 03/27] mtd: spi-nor: swp: Improve locking user
 experience

On Thu Jan 8, 2026 at 5:57 PM CET, Miquel Raynal wrote:
> In the case of the first block being locked (or the few first blocks),
> if the user want to fully unlock the device it has two possibilities:
> - either it asks to unlock the entire device, and this works;
> - or it asks to unlock just the block(s) that are currently locked,
>   which fails.
>
> It fails because the conditions "can_be_top" and "can_be_bottom" are
> true. Indeed, in this case, we unlock everything, so the TB bit does not
> matter. However in the current implementation, use_top would be true (as
> this is the favourite option) and lock_len, which in practice should be
> reduced down to 0, is set to "nor->params->size - (ofs + len)" which is
> a positive number. This is wrong.
>
> An easy way is to simply add an extra condition. In the unlock() path,
> if we can achieve the same result from both sides, it means we unlock
> everything and lock_len must simply be 0. A comment is added to clarify
> that logic.
>
> Fixes: 3dd8012a8eeb ("mtd: spi-nor: add TB (Top/Bottom) protect support")
> Cc: stable@...nel.org
> Signed-off-by: Miquel Raynal <miquel.raynal@...tlin.com>

Reviewed-by: Michael Walle <mwalle@...nel.org>

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