[SCSI] uas: disable use of blk-mq I/O path
The uas driver uses the block layer tag for USB3 stream IDs. With
blk-mq we can get larger tag numbers that the queue depth, which breaks
this assumption. A fix is under way for 3.18, but sits on top of
large changes so can't easily be backported. Set the disable_blk_mq
path so that a uas device can't easily crash the system when using
blk-mq for SCSI.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>
diff --git a/drivers/usb/storage/uas.c b/drivers/usb/storage/uas.c
index 3f42785..9bfa725 100644
--- a/drivers/usb/storage/uas.c
+++ b/drivers/usb/storage/uas.c
@@ -970,6 +970,13 @@
.cmd_per_lun = 1, /* until we override it */
.skip_settle_delay = 1,
.ordered_tag = 1,
+
+ /*
+ * The uas drivers expects tags not to be bigger than the maximum
+ * per-device queue depth, which is not true with the blk-mq tag
+ * allocator.
+ */
+ .disable_blk_mq = true,
};
#define UNUSUAL_DEV(id_vendor, id_product, bcdDeviceMin, bcdDeviceMax, \
