[PATCH 2/2] mtd: nand: Remove BUG() abuse in nand_scan_tail

Ezequiel Garcia
2016-04-01T21:30:05Z

There's no reason to BUG() when parameters are being
validated. Drivers can get things wrong, and it's much nicer
to just throw a noisy warn and fail gracefully, than calling
BUG() and throwing the whole system down the drain.

Signed-off-by: Ezequiel Garcia <ezequiel@vanguardiasur.com.ar>
---
drivers/mtd/nand/nand_base.c | 52 ++++++++++++++++++++++++++++----------------
1 file changed, 33 insertions(+), 19 deletions(-)

diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c
index befa04ef4a04..0fe644ebe264 100644
--- a/drivers/mtd/nand/nand_base.c
+++ b/drivers/mtd/nand/nand_base.c
@@ -4119,10 +4119,12 @@ int nand_scan_tail(struct mtd_info *mtd)
struct nand_chip *chip = mtd_to_nand(mtd);
struct nand_ecc_ctrl *ecc = &chip->ecc;
struct nand_buffers *nbuf;
+ int ret;

/* New bad blocks should be marked in OOB, flash-based BBT, or both */
- BUG_ON((chip->bbt_options & NAND_BBT_NO_OOB_BBM) &&
- !(chip->bbt_options & NAND_BBT_USE_FLASH));
+ if (WARN_ON((chip->bbt_options & NAND_BBT_NO_OOB_BBM) &&
+ !(chip->bbt_options & NAND_BBT_USE_FLASH)))
+ return -EINVAL;

if (!(chip->options & NAND_OWN_BUFFERS)) {
nbuf = kzalloc(sizeof(*nbuf) + mtd->writesize
@@ -4160,9 +4162,10 @@ int nand_scan_tail(struct mtd_info *mtd)
ecc->layout = &nand_oob_128;
break;
default:
- pr_warn("No oob scheme defined for oobsize %d\n",
- mtd->oobsize);
- BUG();
+ WARN(1, "No oob scheme defined for oobsize %d\n",
+ mtd->oobsize);
+ ret = -EINVAL;
+ goto err_free;
}
}

@@ -4178,8 +4181,9 @@ int nand_scan_tail(struct mtd_info *mtd)
case NAND_ECC_HW_OOB_FIRST:
/* Similar to NAND_ECC_HW, but a separate read_page handle */
if (!ecc->calculate || !ecc->correct || !ecc->hwctl) {
- pr_warn("No ECC functions supplied; hardware ECC not possible\n");
- BUG();
+ WARN(1, "No ECC functions supplied; hardware ECC not possible\n");
+ ret = -EINVAL;
+ goto err_free;
}
if (!ecc->read_page)
ecc->read_page = nand_read_page_hwecc_oob_first;
@@ -4209,8 +4213,9 @@ int nand_scan_tail(struct mtd_info *mtd)
ecc->read_page == nand_read_page_hwecc ||
!ecc->write_page ||
ecc->write_page == nand_write_page_hwecc)) {
- pr_warn("No ECC functions supplied; hardware ECC not possible\n");
- BUG();
+ WARN(1, "No ECC functions supplied; hardware ECC not possible\n");
+ ret = -EINVAL;
+ goto err_free;
}
/* Use standard syndrome read/write page function? */
if (!ecc->read_page)
@@ -4228,8 +4233,9 @@ int nand_scan_tail(struct mtd_info *mtd)

if (mtd->writesize >= ecc->size) {
if (!ecc->strength) {
- pr_warn("Driver must set ecc.strength when using hardware ECC\n");
- BUG();
+ WARN(1, "Driver must set ecc.strength when using hardware ECC\n");
+ ret = -EINVAL;
+ goto err_free;
}
break;
}
@@ -4255,8 +4261,9 @@ int nand_scan_tail(struct mtd_info *mtd)

case NAND_ECC_SOFT_BCH:
if (!mtd_nand_has_bch()) {
- pr_warn("CONFIG_MTD_NAND_ECC_BCH not enabled\n");
- BUG();
+ WARN(1, "CONFIG_MTD_NAND_ECC_BCH not enabled\n");
+ ret = -EINVAL;
+ goto err_free;
}
ecc->calculate = nand_bch_calculate_ecc;
ecc->correct = nand_bch_correct_data;
@@ -4281,8 +4288,9 @@ int nand_scan_tail(struct mtd_info *mtd)
ecc->bytes = 0;
ecc->priv = nand_bch_init(mtd);
if (!ecc->priv) {
- pr_warn("BCH ECC initialization failed!\n");
- BUG();
+ WARN(1, "BCH ECC initialization failed!\n");
+ ret = -EINVAL;
+ goto err_free;
}
break;

@@ -4300,8 +4308,9 @@ int nand_scan_tail(struct mtd_info *mtd)
break;

default:
- pr_warn("Invalid NAND_ECC_MODE %d\n", ecc->mode);
- BUG();
+ WARN(1, "Invalid NAND_ECC_MODE %d\n", ecc->mode);
+ ret = -EINVAL;
+ goto err_free;
}

/* For many systems, the standard OOB write also works for raw */
@@ -4331,8 +4340,9 @@ int nand_scan_tail(struct mtd_info *mtd)
*/
ecc->steps = mtd->writesize / ecc->size;
if (ecc->steps * ecc->size != mtd->writesize) {
- pr_warn("Invalid ECC parameters\n");
- BUG();
+ WARN(1, "Invalid ECC parameters\n");
+ ret = -EINVAL;
+ goto err_free;
}
ecc->total = ecc->steps * ecc->bytes;

@@ -4410,6 +4420,10 @@ int nand_scan_tail(struct mtd_info *mtd)

/* Build bad block table */
return chip->scan_bbt(mtd);
+err_free:
+ if (!(chip->options & NAND_OWN_BUFFERS))
+ kfree(chip->buffers);
+ return ret;
}
EXPORT_SYMBOL(nand_scan_tail);

--
2.7.0