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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 <jgross@suse.com>
Acked-by: David Vrabel <david.vrabel@citrix.com>
This commit is contained in:
Juergen Gross 2016-10-31 14:58:40 +01:00
parent 9c53a1792a
commit 8235777b20
1 changed files with 14 additions and 22 deletions
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36
drivers/block/xen-blkback/xenbus.c
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@ -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)) {
@ -1039,30 +1037,24 @@ 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; if (requested_num_queues > xenblk_max_queues
} else { || requested_num_queues == 0) {
if (requested_num_queues > xenblk_max_queues /* Buggy or malicious guest. */
|| requested_num_queues == 0) { xenbus_dev_fatal(dev, err,
/* Buggy or malicious guest. */ "guest requested %u queues, exceeding the maximum of %u.",
xenbus_dev_fatal(dev, err, requested_num_queues, xenblk_max_queues);
"guest requested %u queues, exceeding the maximum of %u.", return -ENOSYS;
requested_num_queues, xenblk_max_queues);
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))