[PATCH 3/3 v2] xen/xenbus: Improve failure processing code for __xenbus_switch_state()

[Chen Gang <gang.chen.5i5j@gmail.com>]

When failure occurs, need return failure code instead of 0, or some of
indirect upper callers may misunderstand.

e.g. in "block/xen-blkback/xenbus.c":

    connect() -> xenbus_switch_state() -> __xenbus_switch_state().

Signed-off-by: Chen Gang <gang.chen.5i5j@gmail.com>
---
 drivers/xen/xenbus/xenbus_client.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/xen/xenbus/xenbus_client.c b/drivers/xen/xenbus/xenbus_client.c
index ca74410..642a476 100644
--- a/drivers/xen/xenbus/xenbus_client.c
+++ b/drivers/xen/xenbus/xenbus_client.c
@@ -36,6 +36,7 @@
 #include <linux/spinlock.h>
 #include <linux/vmalloc.h>
 #include <linux/export.h>
+#include <linux/delay.h>
 #include <asm/xen/hypervisor.h>
 #include <asm/xen/page.h>
 #include <xen/interface/xen.h>
@@ -196,7 +197,7 @@ again:
 	err = xenbus_transaction_start(&xbt);
 	if (err) {
 		xenbus_switch_fatal(dev, depth, err, "starting transaction");
-		return 0;
+		return err;
 	}
 
 	err = xenbus_scanf(xbt, dev->nodename, "state", "%d", &current_state);
@@ -219,7 +220,7 @@ abort:
 	} else
 		dev->state = state;
 
-	return 0;
+	return err;
 }
 
 /**
-- 
1.9.3