Re: [PATCH] mtd: fix calculating partition end address

From: Miquel Raynal <miquel.raynal@bootlin.com>
To: "Rafał Miłecki" <rafal@milecki.pl>
Cc: "Richard Weinberger" <richard@nod.at>,
	"Rafał Miłecki" <zajec5@gmail.com>,
	linux-mtd@lists.infradead.org,
	"Vignesh Raghavendra" <vigneshr@ti.com>,
	"Boris Brezillon" <bbrezillon@kernel.org>
Subject: Re: [PATCH] mtd: fix calculating partition end address
Date: Mon, 9 Mar 2020 15:22:21 +0100	[thread overview]
Message-ID: <20200309152221.28dc38ab@xps13> (raw)
In-Reply-To: <6125d86fee0c83653cc281b3069e1587@milecki.pl>

Hi Rafał,

Rafał Miłecki <rafal@milecki.pl> wrote on Mon, 09 Mar 2020 15:19:10
+0100:

> On 2020-03-09 15:04, Miquel Raynal wrote:
> > Rafał Miłecki <zajec5@gmail.com> wrote on Mon,  9 Mar 2020 08:44:45
> > +0100:
> >   
> >> From: Rafał Miłecki <rafal@milecki.pl>  
> >> >> This fixes check for partitions that don't start at beginning of their  
> >> parents. Missing partition's offset in formula could result in forcing
> >> read-only incorrectly.  
> >> >> Fixes: 6750f61a13a0 ("mtd: improve calculating partition boundaries >> when checking for alignment")  
> >> Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
> >> ---
> >>  drivers/mtd/mtdpart.c | 2 +-
> >>  1 file changed, 1 insertion(+), 1 deletion(-)  
> >> >> diff --git a/drivers/mtd/mtdpart.c b/drivers/mtd/mtdpart.c  
> >> index 7328c066c5ba..c683b432cc5e 100644
> >> --- a/drivers/mtd/mtdpart.c
> >> +++ b/drivers/mtd/mtdpart.c
> >> @@ -524,7 +524,7 @@ static struct mtd_part *allocate_partition(struct >> mtd_info *parent,
> >>  			part->name);
> >>  	}  
> >> >> -	tmp = part_absolute_offset(parent) + slave->mtd.size;  
> >> +	tmp = part_absolute_offset(parent) + slave->offset + >> slave->mtd.size;  
> > 
> > I think you are doing the change at the wrong place, if you want to
> > check where the partition *starts* you should do it a few lines above.
> > But I think the check should be here as well, probably.  
> 
> The check where the partition *starts* is OK and I don't mean to change
> it. The bug is about calculating absolute *end* address of partition.

Can you detail a little bit then? Because I don't see the issue anymore
even though I am convinced something is wrong here :)

> 
> 
> > Anyway, I just applied on my local tree a patch rewriting a bit the
> > partitioning scheme, could you please rebase on top of today's
> > mtd/next and resend this patch updated?
> > 
> > Here is the change that I've done at this place:
> > 	-       tmp = part_absolute_offset(parent) + slave->mtd.size;
> > 	+       tmp = mtd_get_master_ofs(child, 0) + child->size;  
> 
> I'll give it a try.

Thanks,
Miquèl

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