From b277da0a8a594308e17881f4926879bd5fca2a2d Mon Sep 17 00:00:00 2001 From: Mike Snitzer Date: Sat, 4 Oct 2014 10:55:32 -0600 Subject: block: disable entropy contributions for nonrot devices Clear QUEUE_FLAG_ADD_RANDOM in all block drivers that set QUEUE_FLAG_NONROT. Historically, all block devices have automatically made entropy contributions. But as previously stated in commit e2e1a148 ("block: add sysfs knob for turning off disk entropy contributions"): - On SSD disks, the completion times aren't as random as they are for rotational drives. So it's questionable whether they should contribute to the random pool in the first place. - Calling add_disk_randomness() has a lot of overhead. There are more reliable sources for randomness than non-rotational block devices. From a security perspective it is better to err on the side of caution than to allow entropy contributions from unreliable "random" sources. Signed-off-by: Mike Snitzer Signed-off-by: Jens Axboe --- drivers/mmc/card/queue.c | 1 + 1 file changed, 1 insertion(+) (limited to 'drivers/mmc') diff --git a/drivers/mmc/card/queue.c b/drivers/mmc/card/queue.c index 3e049c13429c..c19bfc1e565a 100644 --- a/drivers/mmc/card/queue.c +++ b/drivers/mmc/card/queue.c @@ -210,6 +210,7 @@ int mmc_init_queue(struct mmc_queue *mq, struct mmc_card *card, blk_queue_prep_rq(mq->queue, mmc_prep_request); queue_flag_set_unlocked(QUEUE_FLAG_NONROT, mq->queue); + queue_flag_clear_unlocked(QUEUE_FLAG_ADD_RANDOM, mq->queue); if (mmc_can_erase(card)) mmc_queue_setup_discard(mq->queue, card); -- cgit v1.2.3