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authorMikulas Patocka <mpatocka@redhat.com>2015-10-27 19:06:55 -0400
committerMike Snitzer <snitzer@redhat.com>2015-10-29 22:09:40 -0400
commitad5f498f610fa3fd8bd265139098bc1405cd2783 (patch)
tree9e3fa163b68180e4d0ddc3466d04c91d4e7e3a5f /drivers/md
parenta6dd1020d8ac55782f3e04856644cf68765f8c1b (diff)
downloadop-kernel-dev-ad5f498f610fa3fd8bd265139098bc1405cd2783.zip
op-kernel-dev-ad5f498f610fa3fd8bd265139098bc1405cd2783.tar.gz
dm: initialize non-blk-mq queue data before queue is used
Commit bfebd1cdb497a57757c83f5fbf1a29931591e2a4 ("dm: add full blk-mq support to request-based DM") moves the initialization of the fields backing_dev_info.congested_fn, backing_dev_info.congested_data and queuedata from the function dm_init_md_queue (that is called when the device is created) to dm_init_old_md_queue (that is called after the device type is determined). There is no locking when accessing these variables, thus it is possible for other parts of the kernel to briefly see this data in a transient state (e.g. queue->backing_dev_info.congested_fn initialized and md->queue->backing_dev_info.congested_data uninitialized, resulting in passing an incorrect parameter to the function dm_any_congested). This queue data is left initialized for blk-mq devices even though they that don't use it. Fixes: bfebd1cdb497 ("dm: add full blk-mq support to request-based DM") Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com> Cc: stable@vger.kernel.org # v4.1+
Diffstat (limited to 'drivers/md')
-rw-r--r--drivers/md/dm.c10
1 files changed, 7 insertions, 3 deletions
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 6264781..77ebb98 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -2197,6 +2197,13 @@ static void dm_init_md_queue(struct mapped_device *md)
* This queue is new, so no concurrency on the queue_flags.
*/
queue_flag_clear_unlocked(QUEUE_FLAG_STACKABLE, md->queue);
+
+ /*
+ * Initialize data that will only be used by a non-blk-mq DM queue
+ * - must do so here (in alloc_dev callchain) before queue is used
+ */
+ md->queue->queuedata = md;
+ md->queue->backing_dev_info.congested_data = md;
}
static void dm_init_old_md_queue(struct mapped_device *md)
@@ -2207,10 +2214,7 @@ static void dm_init_old_md_queue(struct mapped_device *md)
/*
* Initialize aspects of queue that aren't relevant for blk-mq
*/
- md->queue->queuedata = md;
md->queue->backing_dev_info.congested_fn = dm_any_congested;
- md->queue->backing_dev_info.congested_data = md;
-
blk_queue_bounce_limit(md->queue, BLK_BOUNCE_ANY);
}
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