linux-kernel - Re: [PATCH 4/4] UBI: Fastmap: Ensure that only one fastmap work is scheduled

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Message-ID: <542D5FB1.3090307@codeaurora.org>
Date:	Thu, 02 Oct 2014 17:22:41 +0300
From:	Tanya Brokhman <tlinder@...eaurora.org>
To:	Richard Weinberger <richard@....at>,
	"Bityutskiy, Artem" <artem.bityutskiy@...el.com>
CC:	"linux-mtd@...ts.infradead.org" <linux-mtd@...ts.infradead.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"dedekind1@...il.com" <dedekind1@...il.com>
Subject: Re: [PATCH 4/4] UBI: Fastmap: Ensure that only one fastmap work is
 scheduled

On 9/30/2014 10:44 AM, Richard Weinberger wrote:
> Am 30.09.2014 09:39, schrieb Bityutskiy, Artem:
>> On Tue, 2014-09-30 at 08:59 +0200, Richard Weinberger wrote:
>>> Am 30.09.2014 08:45, schrieb Bityutskiy, Artem:
>>>> On Tue, 2014-09-30 at 00:20 +0200, Richard Weinberger wrote:
>>>>> +       spin_lock(&ubi->wl_lock);
>>>>> +       ubi->fm_work_scheduled = 0;
>>>>> +       spin_unlock(&ubi->wl_lock);
>>>>
>>>> Andrew Morton once said me that if I am protecting an integer change
>>>> like this with a spinlock, I have a problem in my locking design. He was
>>>> right for my particular case.
>>>>
>>>> Integer is changes atomic. The only other thing spinlock adds are the
>>>> barriers.
>>>
>>> I've added the spinlock to have a barrier in any case.
>>
>> Examples of any?
>
> You mean a case where the compiler would reorder code and the barrier is needed?
> I don't have one, but I'm not that creative as a modern C compiler.
> If you say that no barrier is needed I'll trust you. :-)

we just implemented the same thing :) It's being tested....
Why not use atomic_t fm_work_scheduled and save the spin_lock?

>
> Thanks,
> //richard
>
>
> ______________________________________________________
> Linux MTD discussion mailing list
> http://lists.infradead.org/mailman/listinfo/linux-mtd/
>

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