Re: [PATCH v2 3/4] mtd: cfi_cmdset_0002: Avoid point less unlocking/locking

[Boris Brezillon <boris.brezillon@bootlin.com>]

On Wed,  6 Jun 2018 12:13:29 +0200
Joakim Tjernlund <joakim.tjernlund@infinera.com> wrote:

> cfi_ppb_unlock() walks all flash chips when unlocking sectors.
> testing lock status on each chip which causes relocking of already
> locked sectors. Test against offset to aviod this aliasing.

					 ^ avoid

As I said before, I think the current code is doing worse than just
relocking already locked sectors. As soon as you cross a chip boundary,
addr is set back to 0, and the (addr < offs || adr >= (ofs + len)) might
be true while it shouldn't be (absolute offset still in the unlock
range), which means you'll lock sectors that the caller expect to be
unlocked.

> 
> Fixes: 1648eaaa1575 ("mtd: cfi_cmdset_0002: Support Persistent Protection Bits (PPB) locking")
> Cc: stable@vger.kernel.org
> Signed-off-by: Joakim Tjernlund <joakim.tjernlund@infinera.com>
> ---
> 
>  v2 - Spilt into several patches
> 
> 
>  drivers/mtd/chips/cfi_cmdset_0002.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/mtd/chips/cfi_cmdset_0002.c b/drivers/mtd/chips/cfi_cmdset_0002.c
> index cb85cccc48c1..b6273ce83de7 100644
> --- a/drivers/mtd/chips/cfi_cmdset_0002.c
> +++ b/drivers/mtd/chips/cfi_cmdset_0002.c
> @@ -2670,7 +2670,7 @@ static int __maybe_unused cfi_ppb_unlock(struct mtd_info *mtd, loff_t ofs,
>  		 * sectors shall be unlocked, so lets keep their locking
>  		 * status at "unlocked" (locked=0) for the final re-locking.
>  		 */
> -		if ((adr < ofs) || (adr >= (ofs + len))) {
> +		if ((offset < ofs) || (offset >= (ofs + len))) {
>  			sect[sectors].chip = &cfi->chips[chipnum];
>  			sect[sectors].adr = adr;
>  			sect[sectors].locked = do_ppb_xxlock(