Patch "mtd: spinand: Fix double counting of ECC stats" has been added to the 5.13-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    mtd: spinand: Fix double counting of ECC stats

to the 5.13-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     mtd-spinand-fix-double-counting-of-ecc-stats.patch
and it can be found in the queue-5.13 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit c563ecfe7f2b65207a2cf46d139706baae70e507
Author: Miquel Raynal <miquel.raynal@xxxxxxxxxxx>
Date:   Thu May 27 10:43:45 2021 +0200

    mtd: spinand: Fix double counting of ECC stats
    
    [ Upstream commit c93081b265735db2417f0964718516044d06b1a2 ]
    
    In the raw NAND world, ECC engines increment ecc_stats and the final
    caller is responsible for returning -EBADMSG if the verification
    failed.
    
    In the SPI-NAND world it was a bit different until now because there was
    only one possible ECC engine: the on-die one. Indeed, the
    spinand_mtd_read() call was incrementing the ecc_stats counters
    depending on the outcome of spinand_check_ecc_status() directly.
    
    So now let's split the logic like this:
    - spinand_check_ecc_status() is specific to the SPI-NAND on-die engine
      and is kept very simple: it just returns the ECC status (bonus point:
      the content of this helper can be overloaded).
    - spinand_ondie_ecc_finish_io_req() is the caller of
      spinand_check_ecc_status() and will increment the counters and
      eventually return -EBADMSG.
    - spinand_mtd_read() is not tied to the on-die ECC implementation and
      should be able to handle results coming from other ECC engines: it has
      the responsibility of returning the maximum number of bitflips which
      happened during the entire operation as this is the only helper that
      is aware that several pages may be read in a row.
    
    Fixes: 945845b54c9c ("mtd: spinand: Instantiate a SPI-NAND on-die ECC engine")
    Reported-by: YouChing Lin <ycllin@xxxxxxxxxxx>
    Signed-off-by: Miquel Raynal <miquel.raynal@xxxxxxxxxxx>
    Tested-by: YouChing Lin <ycllin@xxxxxxxxxxx>
    Link: https://lore.kernel.org/linux-mtd/20210527084345.208215-1-miquel.raynal@xxxxxxxxxxx
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/mtd/nand/spi/core.c b/drivers/mtd/nand/spi/core.c
index 17f63f95f4a2..54ae540bc66b 100644
--- a/drivers/mtd/nand/spi/core.c
+++ b/drivers/mtd/nand/spi/core.c
@@ -290,6 +290,8 @@ static int spinand_ondie_ecc_finish_io_req(struct nand_device *nand,
 {
 	struct spinand_ondie_ecc_conf *engine_conf = nand->ecc.ctx.priv;
 	struct spinand_device *spinand = nand_to_spinand(nand);
+	struct mtd_info *mtd = spinand_to_mtd(spinand);
+	int ret;
 
 	if (req->mode == MTD_OPS_RAW)
 		return 0;
@@ -299,7 +301,13 @@ static int spinand_ondie_ecc_finish_io_req(struct nand_device *nand,
 		return 0;
 
 	/* Finish a page write: check the status, report errors/bitflips */
-	return spinand_check_ecc_status(spinand, engine_conf->status);
+	ret = spinand_check_ecc_status(spinand, engine_conf->status);
+	if (ret == -EBADMSG)
+		mtd->ecc_stats.failed++;
+	else if (ret > 0)
+		mtd->ecc_stats.corrected += ret;
+
+	return ret;
 }
 
 static struct nand_ecc_engine_ops spinand_ondie_ecc_engine_ops = {
@@ -620,13 +628,10 @@ static int spinand_mtd_read(struct mtd_info *mtd, loff_t from,
 		if (ret < 0 && ret != -EBADMSG)
 			break;
 
-		if (ret == -EBADMSG) {
+		if (ret == -EBADMSG)
 			ecc_failed = true;
-			mtd->ecc_stats.failed++;
-		} else {
-			mtd->ecc_stats.corrected += ret;
+		else
 			max_bitflips = max_t(unsigned int, max_bitflips, ret);
-		}
 
 		ret = 0;
 		ops->retlen += iter.req.datalen;