[PATCH 4/4] drivers/xen/xenbus/xenbus_client.c: Improve the failure processing for __xenbus_switch_state()

Chen Gang
2014-09-14T10:52:40Z

When failure occurs, need return failure code instead of 0, or the upper
caller will misunderstand.

Also when retry for EAGAIN reason, better to schedule out for a while,
so can let others have chance to continue their tasks (especially,
their tasks are related EAGAIN under UP kernel).

Signed-off-by: Chen Gang <gang.chen.5i5j@gmail.com>
---
drivers/xen/xenbus/xenbus_client.c | 9 ++++++---
1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/drivers/xen/xenbus/xenbus_client.c b/drivers/xen/xenbus/xenbus_client.c
index 620ffd2..fc8699b 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);
@@ -213,13 +214,15 @@ again:
abort:
err = xenbus_transaction_end(xbt, abort);
if (err) {
- if (err == -EAGAIN && !abort)
+ if (err == -EAGAIN && !abort) {
+ msleep(20);
goto again;
+ }
xenbus_switch_fatal(dev, depth, err, "ending transaction");
} else
dev->state = state;

- return 0;
+ return err;
}

/**
--
1.9.3