[PATCH 2/2] mtd: nand_bbt: Skip bad blocks when searching for the BBT in NAND

[Stefan Riedmüller]

Hi Sascha,

On Wed, 2021-03-17 at 10:41 +0100, Sascha Hauer wrote:
> Hi Stefan,
> 
> On Tue, Mar 16, 2021 at 01:36:26PM +0100, Stefan Riedmueller wrote:
> > The blocks containing the bad block table can become bad as well. So
> > make sure to skip any blocks that are marked bad when searching for the
> > bad block table.
> 
> The file is a more or less direct copy from the kernel. Does the problem
> exist in the kernel as well?

From my point of view I would say yes. I have just made a small test Issue is
shown in the kernel as well. It is a very raw case where two BBT blocks need
to be worn out but on the other hand this fix should not have that much of an
impact.

I will send a similar patch to the kernel.

Stefan

> 
> Sascha
> 
> > Signed-off-by: Stefan Riedmueller <s.riedmueller at phytec.de>
> > ---
> >  drivers/mtd/nand/nand_bbt.c | 4 ++++
> >  1 file changed, 4 insertions(+)
> > 
> > diff --git a/drivers/mtd/nand/nand_bbt.c b/drivers/mtd/nand/nand_bbt.c
> > index a86b5b2da38e..0b48373e6a0b 100644
> > --- a/drivers/mtd/nand/nand_bbt.c
> > +++ b/drivers/mtd/nand/nand_bbt.c
> > @@ -528,6 +528,7 @@ static int search_bbt(struct nand_chip *this, uint8_t
> > *buf,
> >  {
> >  	u64 targetsize = nanddev_target_size(&this->base);
> >  	struct mtd_info *mtd = nand_to_mtd(this);
> > +	struct nand_bbt_descr *bd = this->badblock_pattern;
> >  	int i, chips;
> >  	int startblock, block, dir;
> >  	int scanlen = mtd->writesize + mtd->oobsize;
> > @@ -563,6 +564,9 @@ static int search_bbt(struct nand_chip *this, uint8_t
> > *buf,
> >  			int actblock = startblock + dir * block;
> >  			loff_t offs = (loff_t)actblock << this-
> > >bbt_erase_shift;
> >  
> > +			/* Check if block is marked bad */
> > +			if (scan_block_fast(this, bd, offs, buf))
> > +				continue;
> >  			/* Read first page */
> >  			scan_read(this, buf, offs, mtd->writesize, td);
> >  			if (!check_pattern(buf, scanlen, mtd->writesize, td))
> > {
> > -- 
> > 2.25.1
> > 
> > 
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> >