[PATCH v2 4/9] bus/vmbus: use common sysfs routines

[Stephen Hemminger <stephen@networkplumber.org>]

Replace the open coded read in vmbus_uio_sysfs_read() with the EAL
routine. The range check and the -ERANGE return are unchanged.

Two things do change. On an open failure the helper now returns -EIO
rather than -errno; both callers only pass it to strerror(-err) in a
log message, so this is message text only. And subchannel_id and
monitor_id were read with fscanf("%u") and are now converted with
base 0, so a value with a leading zero would parse as octal. Neither
attribute is printed with leading zeros by the kernel.

Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
---
 drivers/bus/vmbus/linux/vmbus_uio.c | 24 +++++-------------------
 1 file changed, 5 insertions(+), 19 deletions(-)

diff --git a/drivers/bus/vmbus/linux/vmbus_uio.c b/drivers/bus/vmbus/linux/vmbus_uio.c
index fbafc5027d..50e58f9b65 100644
--- a/drivers/bus/vmbus/linux/vmbus_uio.c
+++ b/drivers/bus/vmbus/linux/vmbus_uio.c
@@ -18,6 +18,7 @@
 #include <rte_malloc.h>
 #include <rte_bus_vmbus.h>
 #include <rte_string_fns.h>
+#include <rte_sysfs.h>
 
 #include "private.h"
 
@@ -334,27 +335,12 @@ int vmbus_uio_map_rings(struct vmbus_channel *chan)
 static int vmbus_uio_sysfs_read(const char *dir, const char *name,
 				unsigned long *val, unsigned long max_range)
 {
-	char path[PATH_MAX];
-	FILE *f;
-	int ret;
-
-	snprintf(path, sizeof(path), "%s/%s", dir, name);
-	f = fopen(path, "r");
-	if (!f) {
-		VMBUS_LOG(ERR, "can't open %s:%s",
-			  path, strerror(errno));
-		return -errno;
+	if (rte_sysfs_parse_uint(val, "%s/%s", dir, name) < 0) {
+		VMBUS_LOG(ERR, "can't read %s/%s", dir, name);
+		return -EIO;
 	}
 
-	if (fscanf(f, "%lu", val) != 1)
-		ret = -EIO;
-	else if (*val > max_range)
-		ret = -ERANGE;
-	else
-		ret = 0;
-	fclose(f);
-
-	return ret;
+	return *val > max_range ? -ERANGE : 0;
 }
 
 static bool vmbus_uio_ring_present(const struct rte_vmbus_device *dev,
-- 
2.53.0