Messages in this thread | | | Date | Mon, 9 Jan 2006 22:42:04 +0000 | From | Russell King <> | Subject | Re: [patch 3/5] Add MMC password protection (lock/unlock) support V3 |
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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 - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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