[MTD] [NAND] fix race in nand_base.c

When we mark block bad we have to get chip because this involves
writing to the page's OOB. We hit this bug in UBI - we observed
random obscure crashes when it marks block bad from the background
thread and there is some parallel task which utilizes flash.

This patch also adds a TODO note about BBT table protection which
it seems does not exist.

Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
Signed-off-by: David Woodhouse <dwmw2@infradead.org>

diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c
index 7e68203..4b019c6 100644 (file)
--- a/drivers/mtd/nand/nand_base.c
+++ b/drivers/mtd/nand/nand_base.c
@@ -24,6 +24,7 @@
  *     if we have HW ecc support.
  *     The AG-AND chips have nice features for speed improvement,
  *     which are not supported yet. Read / program 4 pages in one go.
+ *     BBT table is not serialized, has to be fixed
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 2 as
@@ -360,6 +361,7 @@ static int nand_default_block_markbad(struct mtd_info *mtd, loff_t ofs)
                /* We write two bytes, so we dont have to mess with 16 bit
                 * access
                 */
+               nand_get_device(chip, mtd, FL_WRITING);
                ofs += mtd->oobsize;
                chip->ops.len = chip->ops.ooblen = 2;
                chip->ops.datbuf = NULL;
@@ -367,9 +369,11 @@ static int nand_default_block_markbad(struct mtd_info *mtd, loff_t ofs)
                chip->ops.ooboffs = chip->badblockpos & ~0x01;
 
                ret = nand_do_write_oob(mtd, ofs, &chip->ops);
+               nand_release_device(mtd);
        }
        if (!ret)
                mtd->ecc_stats.badblocks++;
+
        return ret;
 }