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| Started by | Insu Yun <wuninsu@gmail.com> |
|---|---|
| First post | 2015-10-15 18:30 +0200 |
| Last post | 2015-10-15 20:30 +0200 |
| Articles | 3 — 3 participants |
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[PATCH] xen: check return value of xenbus_printf Insu Yun <wuninsu@gmail.com> - 2015-10-15 18:30 +0200
Re: [PATCH] xen: check return value of xenbus_printf David Vrabel <david.vrabel@citrix.com> - 2015-10-15 18:50 +0200
Re: [PATCH] xen: check return value of xenbus_printf Julien Grall <julien.grall@citrix.com> - 2015-10-15 20:30 +0200
| From | Insu Yun <wuninsu@gmail.com> |
|---|---|
| Date | 2015-10-15 18:30 +0200 |
| Subject | [PATCH] xen: check return value of xenbus_printf |
| Message-ID | <qjTzI-3md-9@gated-at.bofh.it> |
Internally, xenbus_printf uses memory allocation, so it can be failed in
memory pressure.Therefore, xenbus_printf's return should be checked
and properly handled.
Signed-off-by: Insu Yun <wuninsu@gmail.com>
---
drivers/input/misc/xen-kbdfront.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/drivers/input/misc/xen-kbdfront.c b/drivers/input/misc/xen-kbdfront.c
index 23d0549..a3b0940 100644
--- a/drivers/input/misc/xen-kbdfront.c
+++ b/drivers/input/misc/xen-kbdfront.c
@@ -129,8 +129,11 @@ static int xenkbd_probe(struct xenbus_device *dev,
if (xenbus_scanf(XBT_NIL, dev->otherend, "feature-abs-pointer", "%d", &abs) < 0)
abs = 0;
- if (abs)
- xenbus_printf(XBT_NIL, dev->nodename, "request-abs-pointer", "1");
+ if (abs) {
+ ret = xenbus_printf(XBT_NIL, dev->nodename, "request-abs-pointer", "1");
+ if (ret)
+ pr_warning("xenkbd: can't request abs-pointer");
+ }
/* keyboard */
kbd = input_allocate_device();
--
1.9.1
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| From | David Vrabel <david.vrabel@citrix.com> |
|---|---|
| Date | 2015-10-15 18:50 +0200 |
| Message-ID | <qjTT4-3IL-15@gated-at.bofh.it> |
| In reply to | #1247972 |
On 15/10/15 17:25, Insu Yun wrote:
> Internally, xenbus_printf uses memory allocation, so it can be failed in
> memory pressure.Therefore, xenbus_printf's return should be checked
> and properly handled.
[...]
> --- a/drivers/input/misc/xen-kbdfront.c
> +++ b/drivers/input/misc/xen-kbdfront.c
> @@ -129,8 +129,11 @@ static int xenkbd_probe(struct xenbus_device *dev,
>
> if (xenbus_scanf(XBT_NIL, dev->otherend, "feature-abs-pointer", "%d", &abs) < 0)
> abs = 0;
> - if (abs)
> - xenbus_printf(XBT_NIL, dev->nodename, "request-abs-pointer", "1");
> + if (abs) {
> + ret = xenbus_printf(XBT_NIL, dev->nodename, "request-abs-pointer", "1");
> + if (ret)
> + pr_warning("xenkbd: can't request abs-pointer");
I think you want abs = 0 here or input device will be configured as
absolute but the backend will supply relative coordinates.
David
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| From | Julien Grall <julien.grall@citrix.com> |
|---|---|
| Date | 2015-10-15 20:30 +0200 |
| Message-ID | <qjVrQ-65I-7@gated-at.bofh.it> |
| In reply to | #1248001 |
Hi Insu,
On 15/10/15 19:12, Insu Yun wrote:
>
>
> On Thu, Oct 15, 2015 at 12:40 PM, David Vrabel <david.vrabel@citrix.com
> <mailto:david.vrabel@citrix.com>> wrote:
>
> On 15/10/15 17:25, Insu Yun wrote:
> > Internally, xenbus_printf uses memory allocation, so it can be failed in
> > memory pressure.Therefore, xenbus_printf's return should be checked
> > and properly handled.
> [...]
> > --- a/drivers/input/misc/xen-kbdfront.c
> > +++ b/drivers/input/misc/xen-kbdfront.c
> > @@ -129,8 +129,11 @@ static int xenkbd_probe(struct xenbus_device *dev,
> >
> > if (xenbus_scanf(XBT_NIL, dev->otherend, "feature-abs-pointer", "%d", &abs) < 0)
> > abs = 0;
> > - if (abs)
> > - xenbus_printf(XBT_NIL, dev->nodename, "request-abs-pointer", "1");
> > + if (abs) {
> > + ret = xenbus_printf(XBT_NIL, dev->nodename, "request-abs-pointer", "1");
> > + if (ret)
>
> > + pr_warning("xenkbd: can't request abs-pointer");
>
>
> This error handling is from other code .
> I am not sure that it is right error handling.
>
>
>
> I think you want abs = 0 here or input device will be configured as
> absolute but the backend will supply relative coordinates.
>
>
> I cannot understand
If the frontend is not able to write the node "request-abs-pointer" in
the xenstore, the backend will always supply relative coordinates.
Although, as abs = 1, the frontend will be configured to handle absolute
coordinate. So the backend and frontend won't be able to understand each
other.
So you have to set abs to 0 if xebus_printf fails.
Regards,
--
Julien Grall
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