Hi Yoshio,
Yoshio Furuyama <ytc-mb-yfuruya...@kioxia.com> wrote on Tue, 6 Apr
2021 10:47:26 +0900:
Could you add "mtd: nand: bbt:" as prefix for the title (same for the
other patch, even though you're not the original author).
> In the unlikely event of bad block,
> it should update its block status to BBT,
> In this case, there are 2 kind of issue for handling
> a) Mark bad block status to BBT: It was fixed by Patric's patch
> b) Clear status to BBT: I posted patch for this issue
>
> Patch:
> Issue of handing BBT (Bad Block Table) for
> some particular blocks (Ex:10, 11)
> Updating status is, first clear status, second set bad block status.
> Patrick's patch is only fixed the issue for setting status process,
> so this patch fix the clearing status process.
This commit message is not clearly describing the situation, could you
please reword it?
>
> Signed-off-by: Yoshio Furuyama <ytc-mb-yfuruya...@kioxia.com>
> ---
> drivers/mtd/nand/bbt.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/mtd/nand/bbt.c b/drivers/mtd/nand/bbt.c
> index 64af6898131d..0780896eaafe 100644
> --- a/drivers/mtd/nand/bbt.c
> +++ b/drivers/mtd/nand/bbt.c
> @@ -112,11 +112,13 @@ int nanddev_bbt_set_block_status(struct nand_device
> *nand, unsigned int entry,
> ((entry * bits_per_block) / BITS_PER_LONG);
> unsigned int offs = (entry * bits_per_block) % BITS_PER_LONG;
> unsigned long val = status & GENMASK(bits_per_block - 1, 0);
> + unsigned long shift = ((bits_per_block + offs <= BITS_PER_LONG) ?
> + (offs + bits_per_block - 1) :
> (BITS_PER_LONG - 1));
Given the fact that we do arithmetic operations (&, |) on an unsigned
long value I don't think the operation tampers with the next entry in
the pos array.
I'm fine fixing it but I don't think this implementation works. It is
fine if offs is 29 or 30 but not if it is 31 (assuming 32-bits
arithmetic, it's the same for the 64-bit case).
>
> if (entry >= nanddev_neraseblocks(nand))
> return -ERANGE;
>
> - pos[0] &= ~GENMASK(offs + bits_per_block - 1, offs);
Would something like the following work?
pos[0] &= ~GENMASK(MIN(offs + bits_per_block - 1, BITS_PER_LONG - 1),
offs)
Again, I am not convinced it is worth darkening the logic unless I am
not understanding it correctly.
> + pos[0] &= ~GENMASK(shift, offs);
> pos[0] |= val << offs;
>
> if (bits_per_block + offs > BITS_PER_LONG) {
Thanks,
Miquèl
