From 8235777b2068e3280b6fa1413f1940ade31f0adf Mon Sep 17 00:00:00 2001 From: Juergen Gross Date: Mon, 31 Oct 2016 14:58:40 +0100 Subject: [PATCH] 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: Juergen Gross Acked-by: David Vrabel --- drivers/block/xen-blkback/xenbus.c | 36 ++++++++++++++---------------------- 1 file changed, 14 insertions(+), 22 deletions(-) diff --git a/drivers/block/xen-blkback/xenbus.c b/drivers/block/xen-blkback/xenbus.c index 3cc6d1d..415e79b 100644 --- a/drivers/block/xen-blkback/xenbus.c +++ b/drivers/block/xen-blkback/xenbus.c @@ -533,13 +533,11 @@ static void xen_blkbk_discard(struct xenbus_transaction xbt, struct backend_info struct xenbus_device *dev = be->dev; struct xen_blkif *blkif = be->blkif; int err; - int state = 0, discard_enable; + int state = 0; struct block_device *bdev = be->blkif->vbd.bdev; struct request_queue *q = bdev_get_queue(bdev); - err = xenbus_scanf(XBT_NIL, dev->nodename, "discard-enable", "%d", - &discard_enable); - if (err == 1 && !discard_enable) + if (!xenbus_read_unsigned(dev->nodename, "discard-enable", 1)) return; if (blk_queue_discard(q)) { @@ -1039,30 +1037,24 @@ static int connect_ring(struct backend_info *be) xenbus_dev_fatal(dev, err, "unknown fe protocol %s", protocol); return -ENOSYS; } - err = xenbus_scanf(XBT_NIL, dev->otherend, - "feature-persistent", "%u", &pers_grants); - if (err <= 0) - pers_grants = 0; - + pers_grants = xenbus_read_unsigned(dev->otherend, "feature-persistent", + 0); be->blkif->vbd.feature_gnt_persistent = pers_grants; be->blkif->vbd.overflow_max_grants = 0; /* * Read the number of hardware queues from frontend. */ - err = xenbus_scanf(XBT_NIL, dev->otherend, "multi-queue-num-queues", - "%u", &requested_num_queues); - if (err < 0) { - requested_num_queues = 1; - } else { - if (requested_num_queues > xenblk_max_queues - || requested_num_queues == 0) { - /* Buggy or malicious guest. */ - xenbus_dev_fatal(dev, err, - "guest requested %u queues, exceeding the maximum of %u.", - requested_num_queues, xenblk_max_queues); - return -ENOSYS; - } + requested_num_queues = xenbus_read_unsigned(dev->otherend, + "multi-queue-num-queues", + 1); + if (requested_num_queues > xenblk_max_queues + || requested_num_queues == 0) { + /* Buggy or malicious guest. */ + xenbus_dev_fatal(dev, err, + "guest requested %u queues, exceeding the maximum of %u.", + requested_num_queues, xenblk_max_queues); + return -ENOSYS; } be->blkif->nr_rings = requested_num_queues; if (xen_blkif_alloc_rings(be->blkif)) -- 2.7.4