From mboxrd@z Thu Jan 1 00:00:00 1970 From: Russell King Subject: Re: [patch 3/5] Add MMC password protection (lock/unlock) support V3 Date: Mon, 9 Jan 2006 22:42:04 +0000 Message-ID: <20060109224204.GH19131@flint.arm.linux.org.uk> References: <43C2E0A2.3090701@indt.org.br> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <43C2E0A2.3090701@indt.org.br> Sender: linux-kernel-owner@vger.kernel.org To: Anderson Briglia Cc: linux-kernel@vger.kernel.org, "Linux-omap-open-source@linux.omap.com" , linux@arm.linux.org.uk, ext David Brownell , Tony Lindgren , drzeus-list@drzeus.cx, "Aguiar Carlos (EXT-INdT/Manaus)" , "Lizardo Anderson (EXT-INdT/Manaus)" List-Id: linux-omap@vger.kernel.org On Mon, Jan 09, 2006 at 06:16:02PM -0400, Anderson Briglia wrote: > + dev = bus_find_device(&mmc_bus_type, NULL, NULL, mmc_match_lockable); > + if (!dev) > + goto error; > + card = dev_to_mmc_card(dev); > + > + if (operation == KEY_OP_INSTANTIATE) { /* KEY_OP_INSTANTIATE */ > + if (mmc_card_locked(card)) { > + ret = mmc_lock_unlock(card, key, MMC_LOCK_MODE_UNLOCK); > + mmc_remove_card(card); > + mmc_register_card(card); > + } > + else > + ret = mmc_lock_unlock(card, key, MMC_LOCK_MODE_SET_PWD); I really don't like this - if the MMC card is not locked, we set a password on it. If it's locked, we unlock it. That's a potential race condition if you're trying to unlock a card and the card is changed beneath you while you slept waiting for memory - you end up setting that password on the new card. It's far better to have separate "unlock this card" and "set a password on this card" commands rather than trying to combine the two operations. Also, removing and re-registering a card is an offence. These things are ref-counted, and mmc_remove_card() will drop the last reference - so the memory associated with it will be freed. Then you re-register it. Whoops. If you merely want to try to attach a driver, use device_attach() instead. Also, what if you have multiple MMC cards? I have a board here with two MMC slots. I'd rather not have it try to set the same password on both devices. -- Russell King Linux kernel 2.6 ARM Linux - http://www.arm.linux.org.uk/ maintainer of: 2.6 Serial core