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Commit 8235777b authored by Juergen Gross's avatar Juergen Gross
Browse files

xen: make use of xenbus_read_unsigned() in xen-blkback 



Use xenbus_read_unsigned() instead of xenbus_scanf() when possible.
This requires to change the type of one read from int to unsigned,
but this case has been wrong before: negative values are not allowed
for the modified case.

Cc: konrad.wilk@oracle.com
Cc: roger.pau@citrix.com

Signed-off-by: default avatarJuergen Gross <jgross@suse.com>
Acked-by: default avatarDavid Vrabel <david.vrabel@citrix.com>
parent 9c53a179

drivers/block/xen-blkback/xenbus.c

+14 −22
Original line number Original line Diff line number Diff line
@@ -533,13 +533,11 @@ static void xen_blkbk_discard(struct xenbus_transaction xbt, struct backend_info 
	struct xenbus_device *dev = be->dev;

	struct xenbus_device *dev = be->dev;

	struct xen_blkif *blkif = be->blkif;

	struct xen_blkif *blkif = be->blkif;

	int err;

	int err;

	int state = 0, discard_enable;

	int state = 0;

	struct block_device *bdev = be->blkif->vbd.bdev;

	struct block_device *bdev = be->blkif->vbd.bdev;

	struct request_queue *q = bdev_get_queue(bdev);

	struct request_queue *q = bdev_get_queue(bdev);





	err = xenbus_scanf(XBT_NIL, dev->nodename, "discard-enable", "%d",

	if (!xenbus_read_unsigned(dev->nodename, "discard-enable", 1))

			   &discard_enable);

	if (err == 1 && !discard_enable)

		return;

		return;





	if (blk_queue_discard(q)) {

	if (blk_queue_discard(q)) {
@@ -1039,22 +1037,17 @@ static int connect_ring(struct backend_info *be) 
		xenbus_dev_fatal(dev, err, "unknown fe protocol %s", protocol);

		xenbus_dev_fatal(dev, err, "unknown fe protocol %s", protocol);

		return -ENOSYS;

		return -ENOSYS;

	}

	}

	err = xenbus_scanf(XBT_NIL, dev->otherend,

	pers_grants = xenbus_read_unsigned(dev->otherend, "feature-persistent",

			   "feature-persistent", "%u", &pers_grants);

					   0);

	if (err <= 0)

		pers_grants = 0;



	be->blkif->vbd.feature_gnt_persistent = pers_grants;

	be->blkif->vbd.feature_gnt_persistent = pers_grants;

	be->blkif->vbd.overflow_max_grants = 0;

	be->blkif->vbd.overflow_max_grants = 0;





	/*

	/*

	 * Read the number of hardware queues from frontend.

	 * Read the number of hardware queues from frontend.

	 */

	 */

	err = xenbus_scanf(XBT_NIL, dev->otherend, "multi-queue-num-queues",

	requested_num_queues = xenbus_read_unsigned(dev->otherend,

			   "%u", &requested_num_queues);

						    "multi-queue-num-queues",

	if (err < 0) {

						    1);

		requested_num_queues = 1;

	} else {

	if (requested_num_queues > xenblk_max_queues

	if (requested_num_queues > xenblk_max_queues

	    || requested_num_queues == 0) {

	    || requested_num_queues == 0) {

		/* Buggy or malicious guest. */

		/* Buggy or malicious guest. */
@@ -1063,7 +1056,6 @@ static int connect_ring(struct backend_info *be) 
				requested_num_queues, xenblk_max_queues);

				requested_num_queues, xenblk_max_queues);

		return -ENOSYS;

		return -ENOSYS;

	}

	}

	}

	be->blkif->nr_rings = requested_num_queues;

	be->blkif->nr_rings = requested_num_queues;

	if (xen_blkif_alloc_rings(be->blkif))

	if (xen_blkif_alloc_rings(be->blkif))

		return -ENOMEM;

		return -ENOMEM;