linux-kernel - Re: [PATCH 3/6] UBI: Fastmap: Ensure that all fastmap work is done upon WL shutdown

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Date:	Thu, 27 Nov 2014 17:08:17 +0100
From:	Richard Weinberger <richard@....at>
To:	dedekind1@...il.com
CC:	linux-mtd@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/6] UBI: Fastmap: Ensure that all fastmap work is done
 upon WL shutdown

Am 27.11.2014 um 16:38 schrieb Artem Bityutskiy:
> On Mon, 2014-11-24 at 14:20 +0100, Richard Weinberger wrote:
>> ...otherwise the deferred work might run after datastructures
>> got freed and corrupt memory.
>>
>> Signed-off-by: Richard Weinberger <richard@....at>
>> ---
>>  drivers/mtd/ubi/wl.c | 3 +++
>>  1 file changed, 3 insertions(+)
>>
>> diff --git a/drivers/mtd/ubi/wl.c b/drivers/mtd/ubi/wl.c
>> index 7f135df..cb2e571 100644
>> --- a/drivers/mtd/ubi/wl.c
>> +++ b/drivers/mtd/ubi/wl.c
>> @@ -2041,6 +2041,9 @@ static void protection_queue_destroy(struct ubi_device *ubi)
>>  void ubi_wl_close(struct ubi_device *ubi)
>>  {
>>  	dbg_wl("close the WL sub-system");
>> +#ifdef CONFIG_MTD_UBI_FASTMAP
>> +	flush_work(&ubi->fm_work);
>> +#endif
> 
> If you are using the work infrastructure implemented in wl.c, then
> fastmap work should be no different to any other work. And we do flush
> all works in 'shutdown_work()'. The fastmap work should be flushed there
> too.
> 
> I think we discussed this already - there should be one single queue of
> works, managed by the same set of functions, all flushed in the same
> place, one-by-one...
> 
> Obviously, there is some misunderstanding. This looks like lack of
> separation and misuse of layering. I am missing explanations why I am
> wrong...

So you want me to use the UBI WL background thread for the scheduled fastmap work?
I didn't do it that way because you said more than once that fastmap is fastmap and
WL is WL. Therefore I've separated it.

Thanks,
//richard
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