mtd: nand: report ECC errors properly when reading BBT

Instead of just printing a warning when encountering ECC errors, we
should return a proper error status and print a more informative
warning. Later, we will handle these error messages in the upper layers
of the BBT scan.

Note that this patch makes our check for ECC error codes a little bit
more restrictive, leaving all unrecognized errors to the generic "else"
clause. This shouldn't cause problems and could even be a benefit.

This code is based on some findings reported by Matthieu Castet.

Reported-by: Matthieu CASTET <matthieu.castet@parrot.com>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@intel.com>

diff --git a/drivers/mtd/nand/nand_bbt.c b/drivers/mtd/nand/nand_bbt.c
index 584bdcb3c61af981e6a081a97adfc4a8b106a357..0ed8591dbd269b612e442bd68f87c8e2852712b3 100644 (file)
--- a/drivers/mtd/nand/nand_bbt.c
+++ b/drivers/mtd/nand/nand_bbt.c
@@ -178,7 +178,7 @@ static u32 add_marker_len(struct nand_bbt_descr *td)
 static int read_bbt(struct mtd_info *mtd, uint8_t *buf, int page, int num,
                struct nand_bbt_descr *td, int offs)
 {
-       int res, i, j, act = 0;
+       int res, ret = 0, i, j, act = 0;
        struct nand_chip *this = mtd->priv;
        size_t retlen, len, totlen;
        loff_t from;
@@ -204,11 +204,18 @@ static int read_bbt(struct mtd_info *mtd, uint8_t *buf, int page, int num,
                }
                res = mtd->read(mtd, from, len, &retlen, buf);
                if (res < 0) {
-                       if (retlen != len) {
-                               pr_info("nand_bbt: error reading bad block table\n");
+                       if (mtd_is_eccerr(res)) {
+                               pr_info("nand_bbt: ECC error in BBT at "
+                                       "0x%012llx\n", from & ~mtd->writesize);
+                               return res;
+                       } else if (mtd_is_bitflip(res)) {
+                               pr_info("nand_bbt: corrected error in BBT at "
+                                       "0x%012llx\n", from & ~mtd->writesize);
+                               ret = res;
+                       } else {
+                               pr_info("nand_bbt: error reading BBT\n");
                                return res;
                        }
-                       pr_warn("nand_bbt: ECC error while reading bad block table\n");
                }
 
                /* Analyse data */
@@ -242,7 +249,7 @@ static int read_bbt(struct mtd_info *mtd, uint8_t *buf, int page, int num,
                totlen -= len;
                from += len;
        }
-       return 0;
+       return ret;
 }
 
 /**