2018-06-12 03:52:26

by Zhouyang Jia

Subject: [PATCH] xen: add error handling for xenbus_printf

When xenbus_printf fails, the lack of error-handling code may
cause unexpected results.

This patch adds error-handling code after calling xenbus_printf.

Signed-off-by: Zhouyang Jia <[email protected]>
---
drivers/xen/manage.c | 17 ++++++++++++++---
1 file changed, 14 insertions(+), 3 deletions(-)

diff --git a/drivers/xen/manage.c b/drivers/xen/manage.c
index 8835065..159694d 100644
--- a/drivers/xen/manage.c
+++ b/drivers/xen/manage.c
@@ -289,8 +289,15 @@ static void sysrq_handler(struct xenbus_watch *watch, const char *path,
return;
}

- if (sysrq_key != '\0')
- xenbus_printf(xbt, "control", "sysrq", "%c", '\0');
+ if (sysrq_key != '\0') {
+ err = xenbus_printf(xbt, "control", "sysrq", "%c", '\0');
+ if (err) {
+ pr_err("Error %d writing sysrq code in control/sysrq\n",
+ err);
+ xenbus_transaction_end(xbt, 1);
+ return;
+ }
+ }

err = xenbus_transaction_end(xbt, 0);
if (err == -EAGAIN)
@@ -342,7 +349,11 @@ static int setup_shutdown_watcher(void)
continue;
snprintf(node, FEATURE_PATH_SIZE, "feature-%s",
shutdown_handlers[idx].command);
- xenbus_printf(XBT_NIL, "control", node, "%u", 1);
+ err = xenbus_printf(XBT_NIL, "control", node, "%u", 1);
+ if (err) {
+ pr_err("Error %d writing %s\n", err, node);
+ return err;
+ }
}

return 0;
--
2.7.4

2018-06-14 21:59:11

by Boris Ostrovsky

Subject: Re: [PATCH] xen: add error handling for xenbus_printf

On 06/11/2018 11:44 PM, Zhouyang Jia wrote:
> When xenbus_printf fails, the lack of error-handling code may
> cause unexpected results.
>
> This patch adds error-handling code after calling xenbus_printf.
>
> Signed-off-by: Zhouyang Jia <[email protected]>
> ---
> drivers/xen/manage.c | 17 ++++++++++++++---
> 1 file changed, 14 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/xen/manage.c b/drivers/xen/manage.c
> index 8835065..159694d 100644
> --- a/drivers/xen/manage.c
> +++ b/drivers/xen/manage.c
> @@ -289,8 +289,15 @@ static void sysrq_handler(struct xenbus_watch *watch, const char *path,
> return;
> }
>
> - if (sysrq_key != '\0')
> - xenbus_printf(xbt, "control", "sysrq", "%c", '\0');
> + if (sysrq_key != '\0') {
> + err = xenbus_printf(xbt, "control", "sysrq", "%c", '\0');
> + if (err) {
> + pr_err("Error %d writing sysrq code in control/sysrq\n",
> + err);
> + xenbus_transaction_end(xbt, 1);
> + return;
> + }
> + }
>
> err = xenbus_transaction_end(xbt, 0);
> if (err == -EAGAIN)
> @@ -342,7 +349,11 @@ static int setup_shutdown_watcher(void)
> continue;
> snprintf(node, FEATURE_PATH_SIZE, "feature-%s",
> shutdown_handlers[idx].command);
> - xenbus_printf(XBT_NIL, "control", node, "%u", 1);
> + err = xenbus_printf(XBT_NIL, "control", node, "%u", 1);
> + if (err) {
> + pr_err("Error %d writing %s\n", err, node);


Adding __func__ will make it it easier trying to understand where the
error is coming from. And for consistency, I'd add it to the one above
as well.


-boris

2018-06-14 23:35:54

by Zhouyang Jia

Subject: [PATCH v2] xen: add error handling for xenbus_printf

When xenbus_printf fails, the lack of error-handling code may
cause unexpected results.

This patch adds error-handling code after calling xenbus_printf.

Signed-off-by: Zhouyang Jia <[email protected]>
---
v1->v2:
- Add __func__.
---
drivers/xen/manage.c | 18 +++++++++++++++---
1 file changed, 15 insertions(+), 3 deletions(-)

diff --git a/drivers/xen/manage.c b/drivers/xen/manage.c
index 8835065..c93d8ef 100644
--- a/drivers/xen/manage.c
+++ b/drivers/xen/manage.c
@@ -289,8 +289,15 @@ static void sysrq_handler(struct xenbus_watch *watch, const char *path,
return;
}

- if (sysrq_key != '\0')
- xenbus_printf(xbt, "control", "sysrq", "%c", '\0');
+ if (sysrq_key != '\0') {
+ err = xenbus_printf(xbt, "control", "sysrq", "%c", '\0');
+ if (err) {
+ pr_err("%s: Error %d writing sysrq in control/sysrq\n",
+ __func__, err);
+ xenbus_transaction_end(xbt, 1);
+ return;
+ }
+ }

err = xenbus_transaction_end(xbt, 0);
if (err == -EAGAIN)
@@ -342,7 +349,12 @@ static int setup_shutdown_watcher(void)
continue;
snprintf(node, FEATURE_PATH_SIZE, "feature-%s",
shutdown_handlers[idx].command);
- xenbus_printf(XBT_NIL, "control", node, "%u", 1);
+ err = xenbus_printf(XBT_NIL, "control", node, "%u", 1);
+ if (err) {
+ pr_err("%s: Error %d writing %s\n", __func__,
+ err, node);
+ return err;
+ }
}

return 0;
--
2.7.4

2018-06-15 12:55:29

by Boris Ostrovsky

Subject: Re: [PATCH v2] xen: add error handling for xenbus_printf

On 06/14/2018 07:34 PM, Zhouyang Jia wrote:
> When xenbus_printf fails, the lack of error-handling code may
> cause unexpected results.
>
> This patch adds error-handling code after calling xenbus_printf.
>
> Signed-off-by: Zhouyang Jia <[email protected]>

Reviewed-by: Boris Ostrovsky <[email protected]>

(I wasn't asking you to use xenbus_dev_error() for this patch. Only for
the other two patches --- for scsi front and back).

2018-06-19 13:04:32

by Juergen Gross

Subject: Re: [PATCH v2] xen: add error handling for xenbus_printf

On 15/06/18 01:34, Zhouyang Jia wrote:
> When xenbus_printf fails, the lack of error-handling code may
> cause unexpected results.
>
> This patch adds error-handling code after calling xenbus_printf.
>
> Signed-off-by: Zhouyang Jia <[email protected]>

Pushed to xen/tip.git for-linus-4.18


Juergen