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Message-Id: <1477932510-28594-3-git-send-email-jgross@suse.com>
Date: Mon, 31 Oct 2016 17:48:20 +0100
From: Juergen Gross <jgross@...e.com>
To: linux-kernel@...r.kernel.org, xen-devel@...ts.xen.org
Cc: david.vrabel@...rix.com, boris.ostrovsky@...cle.com,
Juergen Gross <jgross@...e.com>, konrad.wilk@...cle.com,
roger.pau@...rix.com
Subject: [PATCH 02/12] 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@...cle.com
Cc: roger.pau@...rix.com
Signed-off-by: Juergen Gross <jgross@...e.com>
---
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))
--
2.6.6
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