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Date: Mon, 31 Oct 2016 17:48:21 +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 03/12] xen: make use of xenbus_read_unsigned() in xen-blkfront
Use xenbus_read_unsigned() instead of xenbus_scanf() when possible.
This requires to change the type of some reads from int to unsigned,
but these cases have been wrong before: negative values are not allowed
for the modified cases.
Cc: konrad.wilk@...cle.com
Cc: roger.pau@...rix.com
Signed-off-by: Juergen Gross <jgross@...e.com>
---
drivers/block/xen-blkfront.c | 81 ++++++++++++++------------------------------
1 file changed, 26 insertions(+), 55 deletions(-)
diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c
index 9908597..2ee9646 100644
--- a/drivers/block/xen-blkfront.c
+++ b/drivers/block/xen-blkfront.c
@@ -1758,17 +1758,13 @@ static int talk_to_blkback(struct xenbus_device *dev,
const char *message = NULL;
struct xenbus_transaction xbt;
int err;
- unsigned int i, max_page_order = 0;
- unsigned int ring_page_order = 0;
+ unsigned int i, max_page_order;
+ unsigned int ring_page_order;
- err = xenbus_scanf(XBT_NIL, info->xbdev->otherend,
- "max-ring-page-order", "%u", &max_page_order);
- if (err != 1)
- info->nr_ring_pages = 1;
- else {
- ring_page_order = min(xen_blkif_max_ring_order, max_page_order);
- info->nr_ring_pages = 1 << ring_page_order;
- }
+ max_page_order = xenbus_read_unsigned(info->xbdev->otherend,
+ "max-ring-page-order", 0);
+ ring_page_order = min(xen_blkif_max_ring_order, max_page_order);
+ info->nr_ring_pages = 1 << ring_page_order;
for (i = 0; i < info->nr_rings; i++) {
struct blkfront_ring_info *rinfo = &info->rinfo[i];
@@ -1877,18 +1873,14 @@ static int talk_to_blkback(struct xenbus_device *dev,
static int negotiate_mq(struct blkfront_info *info)
{
- unsigned int backend_max_queues = 0;
- int err;
+ unsigned int backend_max_queues;
unsigned int i;
BUG_ON(info->nr_rings);
/* Check if backend supports multiple queues. */
- err = xenbus_scanf(XBT_NIL, info->xbdev->otherend,
- "multi-queue-max-queues", "%u", &backend_max_queues);
- if (err < 0)
- backend_max_queues = 1;
-
+ backend_max_queues = xenbus_read_unsigned(info->xbdev->otherend,
+ "multi-queue-max-queues", 1);
info->nr_rings = min(backend_max_queues, xen_blkif_max_queues);
/* We need at least one ring. */
if (!info->nr_rings)
@@ -2195,7 +2187,6 @@ static void blkfront_setup_discard(struct blkfront_info *info)
int err;
unsigned int discard_granularity;
unsigned int discard_alignment;
- unsigned int discard_secure;
info->feature_discard = 1;
err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
@@ -2206,10 +2197,9 @@ static void blkfront_setup_discard(struct blkfront_info *info)
info->discard_granularity = discard_granularity;
info->discard_alignment = discard_alignment;
}
- err = xenbus_scanf(XBT_NIL, info->xbdev->otherend,
- "discard-secure", "%u", &discard_secure);
- if (err > 0)
- info->feature_secdiscard = !!discard_secure;
+ info->feature_secdiscard =
+ !!xenbus_read_unsigned(info->xbdev->otherend, "discard-secure",
+ 0);
}
static int blkfront_setup_indirect(struct blkfront_ring_info *rinfo)
@@ -2301,16 +2291,11 @@ static int blkfront_setup_indirect(struct blkfront_ring_info *rinfo)
*/
static void blkfront_gather_backend_features(struct blkfront_info *info)
{
- int err;
- int barrier, flush, discard, persistent;
unsigned int indirect_segments;
info->feature_flush = 0;
info->feature_fua = 0;
- err = xenbus_scanf(XBT_NIL, info->xbdev->otherend,
- "feature-barrier", "%d", &barrier);
-
/*
* If there's no "feature-barrier" defined, then it means
* we're dealing with a very old backend which writes
@@ -2318,7 +2303,7 @@ static void blkfront_gather_backend_features(struct blkfront_info *info)
*
* If there are barriers, then we use flush.
*/
- if (err > 0 && barrier) {
+ if (xenbus_read_unsigned(info->xbdev->otherend, "feature-barrier", 0)) {
info->feature_flush = 1;
info->feature_fua = 1;
}
@@ -2327,35 +2312,23 @@ static void blkfront_gather_backend_features(struct blkfront_info *info)
* And if there is "feature-flush-cache" use that above
* barriers.
*/
- err = xenbus_scanf(XBT_NIL, info->xbdev->otherend,
- "feature-flush-cache", "%d", &flush);
-
- if (err > 0 && flush) {
+ if (xenbus_read_unsigned(info->xbdev->otherend, "feature-flush-cache",
+ 0)) {
info->feature_flush = 1;
info->feature_fua = 0;
}
- err = xenbus_scanf(XBT_NIL, info->xbdev->otherend,
- "feature-discard", "%d", &discard);
-
- if (err > 0 && discard)
+ if (xenbus_read_unsigned(info->xbdev->otherend, "feature-discard", 0))
blkfront_setup_discard(info);
- err = xenbus_scanf(XBT_NIL, info->xbdev->otherend,
- "feature-persistent", "%d", &persistent);
- if (err <= 0)
- info->feature_persistent = 0;
- else
- info->feature_persistent = persistent;
+ info->feature_persistent =
+ xenbus_read_unsigned(info->xbdev->otherend,
+ "feature-persistent", 0);
- err = xenbus_scanf(XBT_NIL, info->xbdev->otherend,
- "feature-max-indirect-segments", "%u",
- &indirect_segments);
- if (err <= 0)
- info->max_indirect_segments = 0;
- else
- info->max_indirect_segments = min(indirect_segments,
- xen_blkif_max_segments);
+ indirect_segments = xenbus_read_unsigned(info->xbdev->otherend,
+ "feature-max-indirect-segments", 0);
+ info->max_indirect_segments = min(indirect_segments,
+ xen_blkif_max_segments);
}
/*
@@ -2420,11 +2393,9 @@ static void blkfront_connect(struct blkfront_info *info)
* provide this. Assume physical sector size to be the same as
* sector_size in that case.
*/
- err = xenbus_scanf(XBT_NIL, info->xbdev->otherend,
- "physical-sector-size", "%u", &physical_sector_size);
- if (err != 1)
- physical_sector_size = sector_size;
-
+ physical_sector_size = xenbus_read_unsigned(info->xbdev->otherend,
+ "physical-sector-size",
+ sector_size);
blkfront_gather_backend_features(info);
for (i = 0; i < info->nr_rings; i++) {
err = blkfront_setup_indirect(&info->rinfo[i]);
--
2.6.6
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