Re: [PATCH 1/3] mmc: skip detection of nonremovable cards on rescan - card removal detection regression

[Jaehoon Chung <jh80.chung@samsung.com>]

Hi..

I agreed Chris's opinion..If use CONFIG_MMC_UNSAFE_RESUME, you can know to
occur some problem..so mentions to "DANGEROUS"
If card can be removed during suspend, i think we have too many cases.
So this configuration...i think good that use only non-removable card.
If you considered every case, you should not use UNSAFE_RESUME..

Regards,
Jaehoon Chung

Maxim Levitsky wrote:
> On Thu, 2011-03-03 at 21:28 -0500, Chris Ball wrote:
>> Hi,
>>
>> On Thu, Mar 03 2011, Maxim Levitsky wrote:
>>> This patch breaks the CONFIG_MMC_UNSAFE_RESUME, because it sets fake
>>> non-removeable flag, but the intended use of this option is to assume
>>> that card is not removed _during_ suspend,  and it can still be removed
>>> during normal use.
>>> With this commit, card removal isn't detected.
>> I guess we disagree about the semantics of CONFIG_MMC_UNSAFE_RESUME.
>> The Kconfig text says:
>>
>> config MMC_UNSAFE_RESUME
>>         bool "Assume MMC/SD cards are non-removable (DANGEROUS)"
>>
>> which I interpret as meaning that you should set MMC_UNSAFE_RESUME
>> *if you're using a card that cannot be removed*.  If your card *can* be
>> removed, then it would be extremely foolish to turn on MMC_UNSAFE_RESUME,
>> because then if someone removed your removable card during suspend and
>> modified it in another machine before resuming, you'd get massive
>> filesystem corruption.
> That is assuming that someone kindly inserted the card back, while
> system still was suspended, which is really unlikely, and besides, I
> know who uses my computer (me mostly) and I know what I am doing.
> 
> 
> The description also says:
> 
> "If you say Y here, the MMC layer will assume that all cards
> stayed in their respective slots during the suspend. The
> normal behaviour is to remove them at suspend and
> redetecting them at resume. Breaking this assumption will
> in most cases result in data corruption."
> 
> 
> I own my computer, and I don't need the OS to take the decisions for me.
> 
> I don't want to have FS corruption if I accidentally suspend the system
> with the card in the slot which could happen if that option is disabled.
> 
> 
> Best regards,
> 	Maxim Levitsky
> 
> 
> 
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