* [PATCH] xen-kbdfront: correct return value checks on xenbus_scanf()
@ 2016-07-07 7:53 Jan Beulich
2016-07-09 0:33 ` Dmitry Torokhov
0 siblings, 1 reply; 2+ messages in thread
From: Jan Beulich @ 2016-07-07 7:53 UTC (permalink / raw)
To: dmitry.torokhov
Cc: david.vrabel, xen-devel, boris.ostrovsky, Juergen Gross,
linux-input
Only a positive return value indicates success.
Signed-off-by: Jan Beulich <jbeulich@suse.com>
---
drivers/input/misc/xen-kbdfront.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
--- 4.7-rc6-xenbus_scanf.orig/drivers/input/misc/xen-kbdfront.c
+++ 4.7-rc6-xenbus_scanf/drivers/input/misc/xen-kbdfront.c
@@ -127,7 +127,8 @@ static int xenkbd_probe(struct xenbus_de
if (!info->page)
goto error_nomem;
- if (xenbus_scanf(XBT_NIL, dev->otherend, "feature-abs-pointer", "%d", &abs) < 0)
+ if (xenbus_scanf(XBT_NIL, dev->otherend,
+ "feature-abs-pointer", "%d", &abs) <= 0)
abs = 0;
if (abs) {
ret = xenbus_printf(XBT_NIL, dev->nodename,
@@ -324,7 +325,7 @@ static void xenkbd_backend_changed(struc
InitWait:
ret = xenbus_scanf(XBT_NIL, info->xbdev->otherend,
"feature-abs-pointer", "%d", &val);
- if (ret < 0)
+ if (ret <= 0)
val = 0;
if (val) {
ret = xenbus_printf(XBT_NIL, info->xbdev->nodename,
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: [PATCH] xen-kbdfront: correct return value checks on xenbus_scanf()
2016-07-07 7:53 [PATCH] xen-kbdfront: correct return value checks on xenbus_scanf() Jan Beulich
@ 2016-07-09 0:33 ` Dmitry Torokhov
0 siblings, 0 replies; 2+ messages in thread
From: Dmitry Torokhov @ 2016-07-09 0:33 UTC (permalink / raw)
To: Jan Beulich
Cc: david.vrabel, xen-devel, boris.ostrovsky, Juergen Gross,
linux-input
On Thu, Jul 07, 2016 at 01:53:40AM -0600, Jan Beulich wrote:
> Only a positive return value indicates success.
If I am reading this correctly xenbus_scanf() guarantees that it will
not return 0. From include/xen/xenbus.h:
/* Single read and scanf: returns -errno or num scanned if > 0. */
__scanf(4, 5)
int xenbus_scanf(struct xenbus_transaction t,
const char *dir, const char *node, const char *fmt, ...);
and the code matches:
...
/* Distinctive errno. */
if (ret == 0)
return -ERANGE;
return ret;
>
> Signed-off-by: Jan Beulich <jbeulich@suse.com>
> ---
> drivers/input/misc/xen-kbdfront.c | 5 +++--
> 1 file changed, 3 insertions(+), 2 deletions(-)
>
> --- 4.7-rc6-xenbus_scanf.orig/drivers/input/misc/xen-kbdfront.c
> +++ 4.7-rc6-xenbus_scanf/drivers/input/misc/xen-kbdfront.c
> @@ -127,7 +127,8 @@ static int xenkbd_probe(struct xenbus_de
> if (!info->page)
> goto error_nomem;
>
> - if (xenbus_scanf(XBT_NIL, dev->otherend, "feature-abs-pointer", "%d", &abs) < 0)
> + if (xenbus_scanf(XBT_NIL, dev->otherend,
> + "feature-abs-pointer", "%d", &abs) <= 0)
> abs = 0;
> if (abs) {
> ret = xenbus_printf(XBT_NIL, dev->nodename,
> @@ -324,7 +325,7 @@ static void xenkbd_backend_changed(struc
> InitWait:
> ret = xenbus_scanf(XBT_NIL, info->xbdev->otherend,
> "feature-abs-pointer", "%d", &val);
> - if (ret < 0)
> + if (ret <= 0)
> val = 0;
> if (val) {
> ret = xenbus_printf(XBT_NIL, info->xbdev->nodename,
>
>
Thanks.
--
Dmitry
^ permalink raw reply [flat|nested] 2+ messages in thread
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