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SubjectRe: [PATCH] mtd: partitions: Handle add_mtd_device() failures gracefully
On Thu, 26 Apr 2018 19:56:58 +0200
Geert Uytterhoeven <geert@linux-m68k.org> wrote:

> Hi Boris,
>
> On Thu, Apr 26, 2018 at 7:53 PM, Boris Brezillon
> <boris.brezillon@bootlin.com> wrote:
> > On Tue, 10 Apr 2018 15:26:20 +0200
> > Geert Uytterhoeven <geert@linux-m68k.org> wrote:
> >> On Mon, Apr 9, 2018 at 11:59 PM, Marek Vasut <marek.vasut@gmail.com> wrote:
> >> > On 04/09/2018 02:25 PM, Geert Uytterhoeven wrote:
> >> >> Currently add_mtd_device() failures are plainly ignored, which may lead
> >> >> to kernel crashes later.
> >>
> >> >> Fix this by ignoring and freeing partitions that failed to add in
> >> >> add_mtd_partitions(). The same issue is present in mtd_add_partition(),
> >> >> so fix that as well.
> >> >>
> >> >> Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
> >> >> ---
> >> >> I don't know if it is worthwhile factoring out the common handling.
> >> >>
> >> >> Should allocate_partition() fail instead? There's a comment saying
> >> >> "let's register it anyway to preserve ordering".
> >>
> >> >> --- a/drivers/mtd/mtdpart.c
> >> >> +++ b/drivers/mtd/mtdpart.c
> >>
> >> >> @@ -746,7 +753,15 @@ int add_mtd_partitions(struct mtd_info *master,
> >> >> list_add(&slave->list, &mtd_partitions);
> >> >> mutex_unlock(&mtd_partitions_mutex);
> >> >>
> >> >> - add_mtd_device(&slave->mtd);
> >> >> + ret = add_mtd_device(&slave->mtd);
> >> >> + if (ret) {
> >> >> + mutex_lock(&mtd_partitions_mutex);
> >> >> + list_del(&slave->list);
> >> >> + mutex_unlock(&mtd_partitions_mutex);
> >> >> + free_partition(slave);
> >> >> + continue;
> >> >> + }
> >> >
> >> > Why is the partition even in the list in the first place ? Can we avoid
> >> > adding it rather than adding and removing it ?
> >>
> >> Hence my question "Should allocate_partition() fail instead?".
> >
> > I'd prefer this option too. Can you prepare a new version doing that?
>
> OK, then I have another question ;-)
>
> Should this be a special failure, so all other valid partitions on the
> same FLASH
> are still added, or should it be fatal, so no partitions are added at all?

I guess we can go for the "drop the invalid partitions and print a
warning" approach. Anyway, I'm sure people will notice really quickly
when one of their partition is missing, so it's not a big deal IMO.

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