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mtd: spi-nor: swp: Improve locking user experience

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commit e1d456b26b upstream.

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: 3dd8012a8e ("mtd: spi-nor: add TB (Top/Bottom) protect support")
Cc: stable@kernel.org
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Reviewed-by: Michael Walle <mwalle@kernel.org>
Signed-off-by: Pratyush Yadav <pratyush@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Miquel Raynal
2026-07-24 16:03:37 +02:00
committed by Greg Kroah-Hartman
parent 0d3766fecd
commit dc341272cf
1 changed files with 9 additions and 2 deletions
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drivers/mtd/spi-nor/swp.c
+9 -2
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@@ -277,8 +277,15 @@ static int spi_nor_sr_unlock(struct spi_nor *nor, loff_t ofs, uint64_t len)
/* Prefer top, if both are valid */
use_top = can_be_top;
/* lock_len: length of region that should remain locked */
if (use_top)
/*
* lock_len: length of region that should remain locked.
*
* When can_be_top and can_be_bottom booleans are true, both adjacent
* regions are unlocked, thus the entire flash can be unlocked.
*/
if (can_be_top && can_be_bottom)
lock_len = 0;
else if (use_top)
lock_len = nor->params->size - (ofs + len);
else
lock_len = ofs;