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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org,
        Takahiro Kuwano <Takahiro.Kuwano@infineon.com>,
        Tudor Ambarus <tudor.ambarus@microchip.com>
Subject: [PATCH 5.10 590/663] mtd: spi-nor: core: Fix erase type discovery for overlaid region
Date:   Mon,  1 Mar 2021 17:13:58 +0100
Message-Id: <20210301161211.054452450@linuxfoundation.org>
In-Reply-To: <20210301161141.760350206@linuxfoundation.org>
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From: Takahiro Kuwano <Takahiro.Kuwano@infineon.com>

commit 969b276718de37dfe66fce3a5633f611e8cd58fd upstream.

In case of overlaid regions in which their biggest erase size command
overpasses in size the region's size, only the non-overlaid portion of
the sector gets erased. For example, if a Sector Erase command is applied
to a 256-kB range that is overlaid by 4-kB sectors, the overlaid 4-kB
sectors are not affected by the erase.
For overlaid regions, 'region->size' is assigned to 'cmd->size' later in
spi_nor_init_erase_cmd(), so 'erase->size' can be greater than 'len'.

Fixes: 5390a8df769e ("mtd: spi-nor: add support to non-uniform SFDP SPI NOR flash memories")
Cc: stable@vger.kernel.org
Signed-off-by: Takahiro Kuwano <Takahiro.Kuwano@infineon.com>
[ta: Update commit description, add Fixes tag and Cc to stable]
Signed-off-by: Tudor Ambarus <tudor.ambarus@microchip.com>
Link: https://lore.kernel.org/r/fa5d8b944a5cca488ac54ba37c95e775ac2deb34.1601612872.git.Takahiro.Kuwano@infineon.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/mtd/spi-nor/core.c |    9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

--- a/drivers/mtd/spi-nor/core.c
+++ b/drivers/mtd/spi-nor/core.c
@@ -1212,14 +1212,15 @@ spi_nor_find_best_erase_type(const struc
 
 		erase = &map->erase_type[i];
 
+		/* Alignment is not mandatory for overlaid regions */
+		if (region->offset & SNOR_OVERLAID_REGION &&
+		    region->size <= len)
+			return erase;
+
 		/* Don't erase more than what the user has asked for. */
 		if (erase->size > len)
 			continue;
 
-		/* Alignment is not mandatory for overlaid regions */
-		if (region->offset & SNOR_OVERLAID_REGION)
-			return erase;
-
 		spi_nor_div_by_erase_size(erase, addr, &rem);
 		if (rem)
 			continue;