* [PATCH] xen-fbfront: correct return value checks on xenbus_scanf()
@ 2016-07-07 7:48 ` Jan Beulich
0 siblings, 0 replies; 8+ messages in thread
From: Jan Beulich @ 2016-07-07 7:48 UTC (permalink / raw)
To: plagnioj, tomi.valkeinen
Cc: Juergen Gross, xen-devel, Boris Ostrovsky, David Vrabel, linux-fbdev
Only a positive return value indicates success.
Signed-off-by: Jan Beulich <jbeulich@suse.com>
---
drivers/video/fbdev/xen-fbfront.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
--- 4.7-rc6-xenbus_scanf.orig/drivers/video/fbdev/xen-fbfront.c
+++ 4.7-rc6-xenbus_scanf/drivers/video/fbdev/xen-fbfront.c
@@ -658,13 +658,13 @@ InitWait:
goto InitWait; /* no InitWait seen yet, fudge it */
if (xenbus_scanf(XBT_NIL, info->xbdev->otherend,
- "request-update", "%d", &val) < 0)
+ "request-update", "%d", &val) <= 0)
val = 0;
if (val)
info->update_wanted = 1;
if (xenbus_scanf(XBT_NIL, dev->otherend,
- "feature-resize", "%d", &val) < 0)
+ "feature-resize", "%d", &val) <= 0)
val = 0;
info->feature_resize = val;
break;
^ permalink raw reply [flat|nested] 8+ messages in thread
* [PATCH] xen-fbfront: correct return value checks on xenbus_scanf()
@ 2016-07-07 7:48 ` Jan Beulich
0 siblings, 0 replies; 8+ messages in thread
From: Jan Beulich @ 2016-07-07 7:48 UTC (permalink / raw)
To: plagnioj, tomi.valkeinen
Cc: Juergen Gross, xen-devel, Boris Ostrovsky, David Vrabel, linux-fbdev
Only a positive return value indicates success.
Signed-off-by: Jan Beulich <jbeulich@suse.com>
---
drivers/video/fbdev/xen-fbfront.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
--- 4.7-rc6-xenbus_scanf.orig/drivers/video/fbdev/xen-fbfront.c
+++ 4.7-rc6-xenbus_scanf/drivers/video/fbdev/xen-fbfront.c
@@ -658,13 +658,13 @@ InitWait:
goto InitWait; /* no InitWait seen yet, fudge it */
if (xenbus_scanf(XBT_NIL, info->xbdev->otherend,
- "request-update", "%d", &val) < 0)
+ "request-update", "%d", &val) <= 0)
val = 0;
if (val)
info->update_wanted = 1;
if (xenbus_scanf(XBT_NIL, dev->otherend,
- "feature-resize", "%d", &val) < 0)
+ "feature-resize", "%d", &val) <= 0)
val = 0;
info->feature_resize = val;
break;
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^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [Xen-devel] [PATCH] xen-fbfront: correct return value checks on xenbus_scanf()
2016-07-07 7:48 ` Jan Beulich
@ 2016-07-07 9:46 ` David Vrabel
-1 siblings, 0 replies; 8+ messages in thread
From: David Vrabel @ 2016-07-07 9:46 UTC (permalink / raw)
To: Jan Beulich, plagnioj, tomi.valkeinen
Cc: Juergen Gross, xen-devel, Boris Ostrovsky, David Vrabel, linux-fbdev
On 07/07/16 08:48, Jan Beulich wrote:
>
> Signed-off-by: Jan Beulich <jbeulich@suse.com>
> ---
> drivers/video/fbdev/xen-fbfront.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> --- 4.7-rc6-xenbus_scanf.orig/drivers/video/fbdev/xen-fbfront.c
> +++ 4.7-rc6-xenbus_scanf/drivers/video/fbdev/xen-fbfront.c
> @@ -658,13 +658,13 @@ InitWait:
> goto InitWait; /* no InitWait seen yet, fudge it */
>
> if (xenbus_scanf(XBT_NIL, info->xbdev->otherend,
> - "request-update", "%d", &val) < 0)
> + "request-update", "%d", &val) <= 0)
> val = 0;
> if (val)
> info->update_wanted = 1;
>
> if (xenbus_scanf(XBT_NIL, dev->otherend,
> - "feature-resize", "%d", &val) < 0)
> + "feature-resize", "%d", &val) <= 0)
xenbus_scanf() has:
/* Single read and scanf: returns -errno or num scanned. */
...
if (ret = 0)
return -ERANGE;
...
So none of these patches are necessary.
David
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH] xen-fbfront: correct return value checks on xenbus_scanf()
@ 2016-07-07 9:46 ` David Vrabel
0 siblings, 0 replies; 8+ messages in thread
From: David Vrabel @ 2016-07-07 9:46 UTC (permalink / raw)
To: Jan Beulich, plagnioj, tomi.valkeinen
Cc: Juergen Gross, xen-devel, Boris Ostrovsky, David Vrabel, linux-fbdev
On 07/07/16 08:48, Jan Beulich wrote:
>
> Signed-off-by: Jan Beulich <jbeulich@suse.com>
> ---
> drivers/video/fbdev/xen-fbfront.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> --- 4.7-rc6-xenbus_scanf.orig/drivers/video/fbdev/xen-fbfront.c
> +++ 4.7-rc6-xenbus_scanf/drivers/video/fbdev/xen-fbfront.c
> @@ -658,13 +658,13 @@ InitWait:
> goto InitWait; /* no InitWait seen yet, fudge it */
>
> if (xenbus_scanf(XBT_NIL, info->xbdev->otherend,
> - "request-update", "%d", &val) < 0)
> + "request-update", "%d", &val) <= 0)
> val = 0;
> if (val)
> info->update_wanted = 1;
>
> if (xenbus_scanf(XBT_NIL, dev->otherend,
> - "feature-resize", "%d", &val) < 0)
> + "feature-resize", "%d", &val) <= 0)
xenbus_scanf() has:
/* Single read and scanf: returns -errno or num scanned. */
...
if (ret == 0)
return -ERANGE;
...
So none of these patches are necessary.
David
_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xen.org
https://lists.xen.org/xen-devel
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH] xen-fbfront: correct return value checks on xenbus_scanf()
2016-07-07 9:42 ` Juergen Gross
@ 2016-07-07 10:03 ` Jan Beulich
-1 siblings, 0 replies; 8+ messages in thread
From: Jan Beulich @ 2016-07-07 10:03 UTC (permalink / raw)
To: David Vrabel, Juergen Gross
Cc: xen-devel, Boris Ostrovsky, tomi.valkeinen, plagnioj, linux-fbdev
>>> On 07.07.16 at 11:42, <JGross@suse.com> wrote:
> On 07/07/16 09:48, Jan Beulich wrote:
>> Only a positive return value indicates success.
>
> Hmm, I'm not convinced on this change (and the similar others as
> well). From xenbus.h:
>
> /* Single read and scanf: returns -errno or num scanned if > 0. */
>
> There should be no case for xenbus_scanf() returning 0. And looking
> into the functions proofs this is correct.
I don't think it is appropriate for callers to assume a currently
impossible return value indicates success.
Jan
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH] xen-fbfront: correct return value checks on xenbus_scanf()
@ 2016-07-07 10:03 ` Jan Beulich
0 siblings, 0 replies; 8+ messages in thread
From: Jan Beulich @ 2016-07-07 10:03 UTC (permalink / raw)
To: David Vrabel, Juergen Gross
Cc: xen-devel, Boris Ostrovsky, tomi.valkeinen, plagnioj, linux-fbdev
>>> On 07.07.16 at 11:42, <JGross@suse.com> wrote:
> On 07/07/16 09:48, Jan Beulich wrote:
>> Only a positive return value indicates success.
>
> Hmm, I'm not convinced on this change (and the similar others as
> well). From xenbus.h:
>
> /* Single read and scanf: returns -errno or num scanned if > 0. */
>
> There should be no case for xenbus_scanf() returning 0. And looking
> into the functions proofs this is correct.
I don't think it is appropriate for callers to assume a currently
impossible return value indicates success.
Jan
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Xen-devel mailing list
Xen-devel@lists.xen.org
https://lists.xen.org/xen-devel
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH] xen-fbfront: correct return value checks on xenbus_scanf()
[not found] <577E258502000078000FBE6F@suse.com>
@ 2016-07-07 9:42 ` Juergen Gross
0 siblings, 0 replies; 8+ messages in thread
From: Juergen Gross @ 2016-07-07 9:42 UTC (permalink / raw)
To: Jan Beulich, plagnioj, tomi.valkeinen
Cc: xen-devel, Boris Ostrovsky, David Vrabel, linux-fbdev
On 07/07/16 09:48, Jan Beulich wrote:
> Only a positive return value indicates success.
Hmm, I'm not convinced on this change (and the similar others as
well). From xenbus.h:
/* Single read and scanf: returns -errno or num scanned if > 0. */
There should be no case for xenbus_scanf() returning 0. And looking
into the functions proofs this is correct.
Juergen
>
> Signed-off-by: Jan Beulich <jbeulich@suse.com>
> ---
> drivers/video/fbdev/xen-fbfront.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> --- 4.7-rc6-xenbus_scanf.orig/drivers/video/fbdev/xen-fbfront.c
> +++ 4.7-rc6-xenbus_scanf/drivers/video/fbdev/xen-fbfront.c
> @@ -658,13 +658,13 @@ InitWait:
> goto InitWait; /* no InitWait seen yet, fudge it */
>
> if (xenbus_scanf(XBT_NIL, info->xbdev->otherend,
> - "request-update", "%d", &val) < 0)
> + "request-update", "%d", &val) <= 0)
> val = 0;
> if (val)
> info->update_wanted = 1;
>
> if (xenbus_scanf(XBT_NIL, dev->otherend,
> - "feature-resize", "%d", &val) < 0)
> + "feature-resize", "%d", &val) <= 0)
> val = 0;
> info->feature_resize = val;
> break;
>
>
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH] xen-fbfront: correct return value checks on xenbus_scanf()
@ 2016-07-07 9:42 ` Juergen Gross
0 siblings, 0 replies; 8+ messages in thread
From: Juergen Gross @ 2016-07-07 9:42 UTC (permalink / raw)
To: Jan Beulich, plagnioj, tomi.valkeinen
Cc: xen-devel, Boris Ostrovsky, David Vrabel, linux-fbdev
On 07/07/16 09:48, Jan Beulich wrote:
> Only a positive return value indicates success.
Hmm, I'm not convinced on this change (and the similar others as
well). From xenbus.h:
/* Single read and scanf: returns -errno or num scanned if > 0. */
There should be no case for xenbus_scanf() returning 0. And looking
into the functions proofs this is correct.
Juergen
>
> Signed-off-by: Jan Beulich <jbeulich@suse.com>
> ---
> drivers/video/fbdev/xen-fbfront.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> --- 4.7-rc6-xenbus_scanf.orig/drivers/video/fbdev/xen-fbfront.c
> +++ 4.7-rc6-xenbus_scanf/drivers/video/fbdev/xen-fbfront.c
> @@ -658,13 +658,13 @@ InitWait:
> goto InitWait; /* no InitWait seen yet, fudge it */
>
> if (xenbus_scanf(XBT_NIL, info->xbdev->otherend,
> - "request-update", "%d", &val) < 0)
> + "request-update", "%d", &val) <= 0)
> val = 0;
> if (val)
> info->update_wanted = 1;
>
> if (xenbus_scanf(XBT_NIL, dev->otherend,
> - "feature-resize", "%d", &val) < 0)
> + "feature-resize", "%d", &val) <= 0)
> val = 0;
> info->feature_resize = val;
> break;
>
>
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Xen-devel mailing list
Xen-devel@lists.xen.org
https://lists.xen.org/xen-devel
^ permalink raw reply [flat|nested] 8+ messages in thread
end of thread, other threads:[~2016-07-07 10:03 UTC | newest]
Thread overview: 8+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2016-07-07 7:48 [PATCH] xen-fbfront: correct return value checks on xenbus_scanf() Jan Beulich
2016-07-07 7:48 ` Jan Beulich
2016-07-07 9:46 ` [Xen-devel] " David Vrabel
2016-07-07 9:46 ` David Vrabel
[not found] <577E258502000078000FBE6F@suse.com>
2016-07-07 9:42 ` Juergen Gross
2016-07-07 9:42 ` Juergen Gross
2016-07-07 10:03 ` Jan Beulich
2016-07-07 10:03 ` Jan Beulich
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