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authorMike Snitzer <snitzer@redhat.com>2014-10-04 10:55:32 -0600
committerJens Axboe <axboe@fb.com>2014-10-04 10:55:32 -0600
commitb277da0a8a594308e17881f4926879bd5fca2a2d (patch)
tree1af7df6ade218a4b246dd43a0771701a672c6cb8 /drivers/s390
parent7b7b7f7e024460cb7d77f8f96b6eb1a8803f94d9 (diff)
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 <snitzer@redhat.com> Signed-off-by: Jens Axboe <axboe@fb.com>
Diffstat (limited to 'drivers/s390')
-rw-r--r--drivers/s390/block/scm_blk.c1
-rw-r--r--drivers/s390/block/xpram.c1
2 files changed, 2 insertions, 0 deletions
diff --git a/drivers/s390/block/scm_blk.c b/drivers/s390/block/scm_blk.c
index 76bed1743db1..56046ab39629 100644
--- a/drivers/s390/block/scm_blk.c
+++ b/drivers/s390/block/scm_blk.c
@@ -386,6 +386,7 @@ int scm_blk_dev_setup(struct scm_blk_dev *bdev, struct scm_device *scmdev)
blk_queue_max_hw_sectors(rq, nr_max_blk << 3); /* 8 * 512 = blk_size */
blk_queue_max_segments(rq, nr_max_blk);
queue_flag_set_unlocked(QUEUE_FLAG_NONROT, rq);
+ queue_flag_clear_unlocked(QUEUE_FLAG_ADD_RANDOM, rq);
scm_blk_dev_cluster_setup(bdev);
bdev->gendisk = alloc_disk(SCM_NR_PARTS);
diff --git a/drivers/s390/block/xpram.c b/drivers/s390/block/xpram.c
index 6969d39f1e2e..9e0de9c9a6fc 100644
--- a/drivers/s390/block/xpram.c
+++ b/drivers/s390/block/xpram.c
@@ -346,6 +346,7 @@ static int __init xpram_setup_blkdev(void)
goto out;
}
queue_flag_set_unlocked(QUEUE_FLAG_NONROT, xpram_queues[i]);
+ queue_flag_clear_unlocked(QUEUE_FLAG_ADD_RANDOM, xpram_queues[i]);
blk_queue_make_request(xpram_queues[i], xpram_make_request);
blk_queue_logical_block_size(xpram_queues[i], 4096);
}