linux-kernel - Re: [PATCH 4/4] Add MMC Password Protection (lock/unlock) support V8: mmc

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Date:	Mon, 18 Dec 2006 08:41:19 -0400
From:	Anderson Briglia <anderson.briglia@...t.org.br>
To:	Anderson Briglia <anderson.briglia@...t.org.br>,
	"Lizardo Anderson (EXT-INdT/Manaus)" <anderson.lizardo@...t.org.br>,
	Pierre Ossman <drzeus-list@...eus.cx>,
	linux-kernel@...r.kernel.org,
	"Aguiar Carlos (EXT-INdT/Manaus)" <carlos.aguiar@...t.org.br>,
	Tony Lindgren <tony@...mide.com>,
	ext David Brownell <david-b@...bell.net>
Subject: Re: [PATCH 4/4] Add MMC Password Protection (lock/unlock) support
 V8: mmc_sysfs.diff

ext Russell King wrote:
> On Mon, Dec 04, 2006 at 04:13:39PM -0400, Anderson Briglia wrote:
>> Implement MMC password force erase, remove password, change password,
>> unlock card and assign password operations. It uses the sysfs mechanism
>> to send commands to the MMC subsystem. 
> 
> Sorry, this is still unsuitable for mainline.

Ok. I will fix the code and send another version of this patch on the V9 series e-mail thread.

> 
>> Signed-off-by: Carlos Eduardo Aguiar <carlos.aguiar <at> indt.org.br>
>> Signed-off-by: Anderson Lizardo <anderson.lizardo <at> indt.org.br>
>> Signed-off-by: Anderson Briglia <anderson.briglia <at> indt.org.br>
> 
> Please use the standard format, do not obfuscate these.  The kernel
> community utterly abhors this.

Ok.
> 
>> +/*
>> + * implement MMC password functions: force erase, remove password, change
>> + * password, unlock card and assign password.
>> + */
>> +static ssize_t
>> +mmc_lockable_store(struct device *dev, struct device_attribute *att,
>> +	const char *data, size_t len)
>> +{
>> +	struct mmc_card *card = dev_to_mmc_card(dev);
>> +	int err = 0;
> 
> Where is the check that the host can do byte-wise data transfers?

It's checked on the macro "mmc_card_lockable".

> 
>> +
>> +	err = mmc_card_claim_host(card);
>> +	if (err != MMC_ERR_NONE)
>> +		return -EINVAL;
>> +
>> +	if (!mmc_card_lockable(card))
>> +		return -EINVAL;
> 
> So writing to this file with a card which is not lockable results in
> deadlocking the host.  Suggest you do as other subsystems do and have
> one exit path, and use gotos, setting the appropriate return code in a
> variable.  If everything goes via that it forces you to think about
> where you want to jump to in each case.
> 

Thanks, as said before, I'll update the code and send it again.

Best Regards,

Anderson Briglia

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