Re: [PATCH] mtd: partitions: Handle add_mtd_device() failures gracefully

From: Geert Uytterhoeven
Date: Tue Apr 10 2018 - 09:26:28 EST


Hi Marek,

On Mon, Apr 9, 2018 at 11:59 PM, Marek Vasut <marek.vasut@xxxxxxxxx> 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@xxxxxxxxx>
>> ---
>> 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?".
Note that if we go that route, it should be a "soft" failure, as we
probably don't
want to drop all other partitions on the device.

>> mtd_add_partition_attrs(slave);
>> if (parts[i].types)
>> mtd_parse_part(slave, parts[i].types);
>>

Gr{oetje,eeting}s,

Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds