mtd: add ECC error accounting for each read request

Extend struct mtd_req_stats with two new fields holding the number of
corrected bitflips and uncorrectable errors detected during a read
operation.  This is a prerequisite for ultimately passing those counters
to user space, where they can be useful to applications for making
better-informed choices about moving data around.

Unlike 'max_bitflips' (which is set - in a common code path - to the
return value of a function called while the MTD device's mutex is held),
these counters have to be maintained in each MTD driver which defines
the '_read_oob' callback because the statistics need to be calculated
while the MTD device's mutex is held.

Suggested-by: Boris Brezillon <boris.brezillon@collabora.com>
Signed-off-by: Michał Kępień <kernel@kempniu.pl>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20220629125737.14418-4-kernel@kempniu.pl

diff --git a/drivers/mtd/devices/docg3.c b/drivers/mtd/devices/docg3.c
index 80f8d44872f8b6f08dcdb3df12f3191306e9b8b1..a7714e3de887f317f1c618d1a1f4900c9b13ff50 100644 (file)
--- a/drivers/mtd/devices/docg3.c
+++ b/drivers/mtd/devices/docg3.c
@@ -871,6 +871,7 @@ static int doc_read_oob(struct mtd_info *mtd, loff_t from,
        u8 *buf = ops->datbuf;
        size_t len, ooblen, nbdata, nboob;
        u8 hwecc[DOC_ECC_BCH_SIZE], eccconf1;
+       struct mtd_ecc_stats old_stats;
        int max_bitflips = 0;
 
        if (buf)
@@ -895,6 +896,7 @@ static int doc_read_oob(struct mtd_info *mtd, loff_t from,
        ret = 0;
        skip = from % DOC_LAYOUT_PAGE_SIZE;
        mutex_lock(&docg3->cascade->lock);
+       old_stats = mtd->ecc_stats;
        while (ret >= 0 && (len > 0 || ooblen > 0)) {
                calc_block_sector(from - skip, &block0, &block1, &page, &ofs,
                        docg3->reliable);
@@ -966,6 +968,12 @@ static int doc_read_oob(struct mtd_info *mtd, loff_t from,
        }
 
 out:
+       if (ops->stats) {
+               ops->stats->uncorrectable_errors +=
+                       mtd->ecc_stats.failed - old_stats.failed;
+               ops->stats->corrected_bitflips +=
+                       mtd->ecc_stats.corrected - old_stats.corrected;
+       }
        mutex_unlock(&docg3->cascade->lock);
        return ret;
 err_in_read:

diff --git a/drivers/mtd/nand/onenand/onenand_base.c b/drivers/mtd/nand/onenand/onenand_base.c
index 5810104420a2b5786669de030cd53df0e2644014..f66385faf631cde6dd3fea7c707d40369e1ade3e 100644 (file)
--- a/drivers/mtd/nand/onenand/onenand_base.c
+++ b/drivers/mtd/nand/onenand/onenand_base.c
@@ -1440,6 +1440,7 @@ static int onenand_read_oob(struct mtd_info *mtd, loff_t from,
                            struct mtd_oob_ops *ops)
 {
        struct onenand_chip *this = mtd->priv;
+       struct mtd_ecc_stats old_stats;
        int ret;
 
        switch (ops->mode) {
@@ -1453,12 +1454,23 @@ static int onenand_read_oob(struct mtd_info *mtd, loff_t from,
        }
 
        onenand_get_device(mtd, FL_READING);
+
+       old_stats = mtd->ecc_stats;
+
        if (ops->datbuf)
                ret = ONENAND_IS_4KB_PAGE(this) ?
                        onenand_mlc_read_ops_nolock(mtd, from, ops) :
                        onenand_read_ops_nolock(mtd, from, ops);
        else
                ret = onenand_read_oob_nolock(mtd, from, ops);
+
+       if (ops->stats) {
+               ops->stats->uncorrectable_errors +=
+                       mtd->ecc_stats.failed - old_stats.failed;
+               ops->stats->corrected_bitflips +=
+                       mtd->ecc_stats.corrected - old_stats.corrected;
+       }
+
        onenand_release_device(mtd);
 
        return ret;

diff --git a/drivers/mtd/nand/raw/nand_base.c b/drivers/mtd/nand/raw/nand_base.c
index 6b67b7dfe7ce69601534d80e50fc86434d8e2c43..3e20de1e145c306ff589381a38384c1b4f6bca5c 100644 (file)
--- a/drivers/mtd/nand/raw/nand_base.c
+++ b/drivers/mtd/nand/raw/nand_base.c
@@ -3818,6 +3818,7 @@ static int nand_read_oob(struct mtd_info *mtd, loff_t from,
                         struct mtd_oob_ops *ops)
 {
        struct nand_chip *chip = mtd_to_nand(mtd);
+       struct mtd_ecc_stats old_stats;
        int ret;
 
        ops->retlen = 0;
@@ -3829,11 +3830,20 @@ static int nand_read_oob(struct mtd_info *mtd, loff_t from,
 
        nand_get_device(chip);
 
+       old_stats = mtd->ecc_stats;
+
        if (!ops->datbuf)
                ret = nand_do_read_oob(chip, from, ops);
        else
                ret = nand_do_read_ops(chip, from, ops);
 
+       if (ops->stats) {
+               ops->stats->uncorrectable_errors +=
+                       mtd->ecc_stats.failed - old_stats.failed;
+               ops->stats->corrected_bitflips +=
+                       mtd->ecc_stats.corrected - old_stats.corrected;
+       }
+
        nand_release_device(chip);
        return ret;
 }

diff --git a/drivers/mtd/nand/spi/core.c b/drivers/mtd/nand/spi/core.c
index 9d73910a7ae82744c57876e2db24d24a3462e79f..dacd9c0e8b202cf4cdf926f2fb70c2c17453e3b8 100644 (file)
--- a/drivers/mtd/nand/spi/core.c
+++ b/drivers/mtd/nand/spi/core.c
@@ -635,6 +635,7 @@ static int spinand_mtd_read(struct mtd_info *mtd, loff_t from,
 {
        struct spinand_device *spinand = mtd_to_spinand(mtd);
        struct nand_device *nand = mtd_to_nanddev(mtd);
+       struct mtd_ecc_stats old_stats;
        unsigned int max_bitflips = 0;
        struct nand_io_iter iter;
        bool disable_ecc = false;
@@ -646,6 +647,8 @@ static int spinand_mtd_read(struct mtd_info *mtd, loff_t from,
 
        mutex_lock(&spinand->lock);
 
+       old_stats = mtd->ecc_stats;
+
        nanddev_io_for_each_page(nand, NAND_PAGE_READ, from, ops, &iter) {
                if (disable_ecc)
                        iter.req.mode = MTD_OPS_RAW;
@@ -668,6 +671,13 @@ static int spinand_mtd_read(struct mtd_info *mtd, loff_t from,
                ops->oobretlen += iter.req.ooblen;
        }
 
+       if (ops->stats) {
+               ops->stats->uncorrectable_errors +=
+                       mtd->ecc_stats.failed - old_stats.failed;
+               ops->stats->corrected_bitflips +=
+                       mtd->ecc_stats.corrected - old_stats.corrected;
+       }
+
        mutex_unlock(&spinand->lock);
 
        if (ecc_failed && !ret)

diff --git a/include/linux/mtd/mtd.h b/include/linux/mtd/mtd.h
index fccad17664580f262b9ff77b7879ee9859e19d19..c12a5930f32c16228d5a636f98f677f2841d4125 100644 (file)
--- a/include/linux/mtd/mtd.h
+++ b/include/linux/mtd/mtd.h
@@ -41,6 +41,8 @@ struct mtd_erase_region_info {
 };
 
 struct mtd_req_stats {
+       unsigned int uncorrectable_errors;
+       unsigned int corrected_bitflips;
        unsigned int max_bitflips;
 };