* Re: [PATCH] arm/mach-omap2/display: fix possible object reference leak
@ 2019-02-19 17:05 ` Tony Lindgren
0 siblings, 0 replies; 11+ messages in thread
From: Tony Lindgren @ 2019-02-19 17:05 UTC (permalink / raw)
To: Peng Hao
Cc: devicetree, Rob Herring, linux-kernel, Julia Lawall,
Tomi Valkeinen, linux-omap, linux-arm-kernel
Hi,
Adding devicetree list, Julia, Rob and Tomi to Cc.
* Peng Hao <peng.hao2@zte.com.cn> [190212 23:11]:
> of_find_device_by_node() takes a reference to the struct device
> when it finds a match via get_device.When returning error we should
> call put_device.
>
> Signed-off-by: Peng Hao <peng.hao2@zte.com.cn>
> ---
> arch/arm/mach-omap2/display.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/arch/arm/mach-omap2/display.c b/arch/arm/mach-omap2/display.c
> index f86b72d..c6aa9ed 100644
> --- a/arch/arm/mach-omap2/display.c
> +++ b/arch/arm/mach-omap2/display.c
> @@ -258,6 +258,7 @@ static int __init omapdss_init_of(void)
> r = of_platform_populate(node, NULL, NULL, &pdev->dev);
> if (r) {
> pr_err("Unable to populate DSS submodule devices\n");
> + put_device(&pdev->dev);
> return r;
> }
In general, if the device tree node is never used afterwards,
should this be just:
r = of_platform_populate(node, NULL, NULL, &pdev->dev);
of_node_put(dev_node);
if (r) {
...
}
If so, Julia might have a Coccinelle recpipe for it?
Regards,
Tony
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
^ permalink raw reply [flat|nested] 11+ messages in thread* Re: [PATCH] arm/mach-omap2/display: fix possible object reference leak
2019-02-19 17:05 ` Tony Lindgren
@ 2019-02-19 17:30 ` Julia Lawall
-1 siblings, 0 replies; 11+ messages in thread
From: Julia Lawall @ 2019-02-19 17:30 UTC (permalink / raw)
To: Tony Lindgren
Cc: Peng Hao, linux-omap, linux-arm-kernel, linux-kernel,
Tomi Valkeinen, Rob Herring, devicetree, wen.yang99
On Tue, 19 Feb 2019, Tony Lindgren wrote:
> Hi,
>
> Adding devicetree list, Julia, Rob and Tomi to Cc.
>
> * Peng Hao <peng.hao2@zte.com.cn> [190212 23:11]:
> > of_find_device_by_node() takes a reference to the struct device
> > when it finds a match via get_device.When returning error we should
> > call put_device.
> >
> > Signed-off-by: Peng Hao <peng.hao2@zte.com.cn>
> > ---
> > arch/arm/mach-omap2/display.c | 1 +
> > 1 file changed, 1 insertion(+)
> >
> > diff --git a/arch/arm/mach-omap2/display.c b/arch/arm/mach-omap2/display.c
> > index f86b72d..c6aa9ed 100644
> > --- a/arch/arm/mach-omap2/display.c
> > +++ b/arch/arm/mach-omap2/display.c
> > @@ -258,6 +258,7 @@ static int __init omapdss_init_of(void)
> > r = of_platform_populate(node, NULL, NULL, &pdev->dev);
> > if (r) {
> > pr_err("Unable to populate DSS submodule devices\n");
> > + put_device(&pdev->dev);
> > return r;
> > }
>
> In general, if the device tree node is never used afterwards,
> should this be just:
>
> r = of_platform_populate(node, NULL, NULL, &pdev->dev);
> of_node_put(dev_node);
Are these solving the same problems? The of_node_put looks clearly
necessary, whether there is a success or failure. I'm not familiar with
put_device. I see that it does a kobject_put, but I don't know what
happens because of that. But it looks like an inconsistency that Peng's
patch only considers the failure case, while your suggestion happens
always.
I guess Peng's patch is motivated by a Coccinelle script that Wen Yang
(also from ZTE) has been working on. Perhaps there is a need to adjust
what is suggested by that script.
[Wen Yang added to CC]
julia
> if (r) {
> ...
> }
>
> If so, Julia might have a Coccinelle recpipe for it?
>
> Regards,
>
> Tony
>
^ permalink raw reply [flat|nested] 11+ messages in thread* Re: [PATCH] arm/mach-omap2/display: fix possible object reference leak
@ 2019-02-19 17:30 ` Julia Lawall
0 siblings, 0 replies; 11+ messages in thread
From: Julia Lawall @ 2019-02-19 17:30 UTC (permalink / raw)
To: Tony Lindgren
Cc: Rob Herring, Peng Hao, devicetree, linux-kernel, Tomi Valkeinen,
linux-omap, wen.yang99, linux-arm-kernel
On Tue, 19 Feb 2019, Tony Lindgren wrote:
> Hi,
>
> Adding devicetree list, Julia, Rob and Tomi to Cc.
>
> * Peng Hao <peng.hao2@zte.com.cn> [190212 23:11]:
> > of_find_device_by_node() takes a reference to the struct device
> > when it finds a match via get_device.When returning error we should
> > call put_device.
> >
> > Signed-off-by: Peng Hao <peng.hao2@zte.com.cn>
> > ---
> > arch/arm/mach-omap2/display.c | 1 +
> > 1 file changed, 1 insertion(+)
> >
> > diff --git a/arch/arm/mach-omap2/display.c b/arch/arm/mach-omap2/display.c
> > index f86b72d..c6aa9ed 100644
> > --- a/arch/arm/mach-omap2/display.c
> > +++ b/arch/arm/mach-omap2/display.c
> > @@ -258,6 +258,7 @@ static int __init omapdss_init_of(void)
> > r = of_platform_populate(node, NULL, NULL, &pdev->dev);
> > if (r) {
> > pr_err("Unable to populate DSS submodule devices\n");
> > + put_device(&pdev->dev);
> > return r;
> > }
>
> In general, if the device tree node is never used afterwards,
> should this be just:
>
> r = of_platform_populate(node, NULL, NULL, &pdev->dev);
> of_node_put(dev_node);
Are these solving the same problems? The of_node_put looks clearly
necessary, whether there is a success or failure. I'm not familiar with
put_device. I see that it does a kobject_put, but I don't know what
happens because of that. But it looks like an inconsistency that Peng's
patch only considers the failure case, while your suggestion happens
always.
I guess Peng's patch is motivated by a Coccinelle script that Wen Yang
(also from ZTE) has been working on. Perhaps there is a need to adjust
what is suggested by that script.
[Wen Yang added to CC]
julia
> if (r) {
> ...
> }
>
> If so, Julia might have a Coccinelle recpipe for it?
>
> Regards,
>
> Tony
>
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
^ permalink raw reply [flat|nested] 11+ messages in thread* Re: [PATCH] arm/mach-omap2/display: fix possible object referenceleak
2019-02-19 17:30 ` Julia Lawall
(?)
@ 2019-02-20 2:41 ` wen.yang99
-1 siblings, 0 replies; 11+ messages in thread
From: wen.yang99 @ 2019-02-20 2:41 UTC (permalink / raw)
To: julia.lawall
Cc: tony, peng.hao2, linux-omap, linux-arm-kernel, linux-kernel,
tomi.valkeinen, robh, devicetree
[-- Attachment #1.1: Type: text/plain, Size: 2489 bytes --]
Hi,
> > Adding devicetree list, Julia, Rob and Tomi to Cc.
> >
> > * Peng Hao <peng.hao2@zte.com.cn> [190212 23:11]:
> > > of_find_device_by_node() takes a reference to the struct device
> > > when it finds a match via get_device.When returning error we should
> > > call put_device.
> > >
> > > Signed-off-by: Peng Hao <peng.hao2@zte.com.cn>
> > > ---
> > > arch/arm/mach-omap2/display.c | 1 +
> > > 1 file changed, 1 insertion(+)
> > >
> > > diff --git a/arch/arm/mach-omap2/display.c b/arch/arm/mach-omap2/display.c
> > > index f86b72d..c6aa9ed 100644
> > > --- a/arch/arm/mach-omap2/display.c
> > > +++ b/arch/arm/mach-omap2/display.c
> > > @@ -258,6 +258,7 @@ static int __init omapdss_init_of(void)
> > > r = of_platform_populate(node, NULL, NULL, &pdev->dev);
> > > if (r) {
> > > pr_err("Unable to populate DSS submodule devices\n");
> > > + put_device(&pdev->dev);
> > > return r;
> > > }
> >
> > In general, if the device tree node is never used afterwards,
> > should this be just:
> >
> > r = of_platform_populate(node, NULL, NULL, &pdev->dev);
> > of_node_put(dev_node);
>
> Are these solving the same problems? The of_node_put looks clearly
> necessary, whether there is a success or failure. I'm not familiar with
> put_device. I see that it does a kobject_put, but I don't know what
> happens because of that. But it looks like an inconsistency that Peng's
> patch only considers the failure case, while your suggestion happens
> always.
>
> I guess Peng's patch is motivated by a Coccinelle script that Wen Yang
> (also from ZTE) has been working on. Perhaps there is a need to adjust
> what is suggested by that script.
Yes, Peng Hao and I belong to the same company.
I found some code issues with this Coccinelle script:
Https://lkml.org/lkml/2019/2/16/107
Our other colleagues are submitting some patches to fix these discovered problems.
For this code(arch/arm/mach-omap2/display.c), there may be two issues:
1, the of_find_device_by_node() takes a reference to the underlying device
structure, we should call put_device() release that reference.
2, of_find_compatible_node/of_find_node_by_name/of_parse_phandle... will
increase the refcount of device_node, we should call of_node_put() to release
the refcount.
The first issue can already be detected by the Coccinelle script described above;
The second issue, we are still looking for ways to develop the corresponding Coccinelle script.
Regards,
Wen
^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: [PATCH] arm/mach-omap2/display: fix possible object reference leak
2019-02-19 17:05 ` Tony Lindgren
@ 2019-02-19 17:33 ` Julia Lawall
-1 siblings, 0 replies; 11+ messages in thread
From: Julia Lawall @ 2019-02-19 17:33 UTC (permalink / raw)
To: Tony Lindgren
Cc: Peng Hao, linux-omap, linux-arm-kernel, linux-kernel,
Tomi Valkeinen, Rob Herring, devicetree, wen.yang99
On Tue, 19 Feb 2019, Tony Lindgren wrote:
> Hi,
>
> Adding devicetree list, Julia, Rob and Tomi to Cc.
>
> * Peng Hao <peng.hao2@zte.com.cn> [190212 23:11]:
> > of_find_device_by_node() takes a reference to the struct device
> > when it finds a match via get_device.When returning error we should
> > call put_device.
> >
> > Signed-off-by: Peng Hao <peng.hao2@zte.com.cn>
> > ---
> > arch/arm/mach-omap2/display.c | 1 +
> > 1 file changed, 1 insertion(+)
> >
> > diff --git a/arch/arm/mach-omap2/display.c b/arch/arm/mach-omap2/display.c
> > index f86b72d..c6aa9ed 100644
> > --- a/arch/arm/mach-omap2/display.c
> > +++ b/arch/arm/mach-omap2/display.c
> > @@ -258,6 +258,7 @@ static int __init omapdss_init_of(void)
> > r = of_platform_populate(node, NULL, NULL, &pdev->dev);
> > if (r) {
> > pr_err("Unable to populate DSS submodule devices\n");
> > + put_device(&pdev->dev);
> > return r;
> > }
>
> In general, if the device tree node is never used afterwards,
> should this be just:
>
> r = of_platform_populate(node, NULL, NULL, &pdev->dev);
> of_node_put(dev_node);
> if (r) {
> ...
> }
>
> If so, Julia might have a Coccinelle recpipe for it?
Unfortunately this is not really an ideal case for Coccinelle, because
node is the result of calling a local function and Coccinelle doesn't by
default do any interprocedural analysis. It is possible to write a rule
that explicitly looks for one function that returns a device node and then
the pattern of its usage in the caller, though.
julia
^ permalink raw reply [flat|nested] 11+ messages in thread* Re: [PATCH] arm/mach-omap2/display: fix possible object reference leak
@ 2019-02-19 17:33 ` Julia Lawall
0 siblings, 0 replies; 11+ messages in thread
From: Julia Lawall @ 2019-02-19 17:33 UTC (permalink / raw)
To: Tony Lindgren
Cc: Rob Herring, Peng Hao, devicetree, linux-kernel, Tomi Valkeinen,
linux-omap, wen.yang99, linux-arm-kernel
On Tue, 19 Feb 2019, Tony Lindgren wrote:
> Hi,
>
> Adding devicetree list, Julia, Rob and Tomi to Cc.
>
> * Peng Hao <peng.hao2@zte.com.cn> [190212 23:11]:
> > of_find_device_by_node() takes a reference to the struct device
> > when it finds a match via get_device.When returning error we should
> > call put_device.
> >
> > Signed-off-by: Peng Hao <peng.hao2@zte.com.cn>
> > ---
> > arch/arm/mach-omap2/display.c | 1 +
> > 1 file changed, 1 insertion(+)
> >
> > diff --git a/arch/arm/mach-omap2/display.c b/arch/arm/mach-omap2/display.c
> > index f86b72d..c6aa9ed 100644
> > --- a/arch/arm/mach-omap2/display.c
> > +++ b/arch/arm/mach-omap2/display.c
> > @@ -258,6 +258,7 @@ static int __init omapdss_init_of(void)
> > r = of_platform_populate(node, NULL, NULL, &pdev->dev);
> > if (r) {
> > pr_err("Unable to populate DSS submodule devices\n");
> > + put_device(&pdev->dev);
> > return r;
> > }
>
> In general, if the device tree node is never used afterwards,
> should this be just:
>
> r = of_platform_populate(node, NULL, NULL, &pdev->dev);
> of_node_put(dev_node);
> if (r) {
> ...
> }
>
> If so, Julia might have a Coccinelle recpipe for it?
Unfortunately this is not really an ideal case for Coccinelle, because
node is the result of calling a local function and Coccinelle doesn't by
default do any interprocedural analysis. It is possible to write a rule
that explicitly looks for one function that returns a device node and then
the pattern of its usage in the caller, though.
julia
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
^ permalink raw reply [flat|nested] 11+ messages in thread* Re: [PATCH] arm/mach-omap2/display: fix possible object reference leak
2019-02-19 17:33 ` Julia Lawall
@ 2019-02-19 17:58 ` Tony Lindgren
-1 siblings, 0 replies; 11+ messages in thread
From: Tony Lindgren @ 2019-02-19 17:58 UTC (permalink / raw)
To: Julia Lawall
Cc: Peng Hao, linux-omap, linux-arm-kernel, linux-kernel,
Tomi Valkeinen, Rob Herring, devicetree, wen.yang99
* Julia Lawall <julia.lawall@lip6.fr> [190219 17:33]:
> On Tue, 19 Feb 2019, Tony Lindgren wrote:
> > In general, if the device tree node is never used afterwards,
> > should this be just:
> >
> > r = of_platform_populate(node, NULL, NULL, &pdev->dev);
> > of_node_put(dev_node);
> > if (r) {
> > ...
> > }
> >
> > If so, Julia might have a Coccinelle recpipe for it?
>
> Unfortunately this is not really an ideal case for Coccinelle, because
> node is the result of calling a local function and Coccinelle doesn't by
> default do any interprocedural analysis. It is possible to write a rule
> that explicitly looks for one function that returns a device node and then
> the pattern of its usage in the caller, though.
OK thanks for the information.
Regards,
Tony
^ permalink raw reply [flat|nested] 11+ messages in thread* Re: [PATCH] arm/mach-omap2/display: fix possible object reference leak
@ 2019-02-19 17:58 ` Tony Lindgren
0 siblings, 0 replies; 11+ messages in thread
From: Tony Lindgren @ 2019-02-19 17:58 UTC (permalink / raw)
To: Julia Lawall
Cc: Rob Herring, Peng Hao, devicetree, linux-kernel, Tomi Valkeinen,
linux-omap, wen.yang99, linux-arm-kernel
* Julia Lawall <julia.lawall@lip6.fr> [190219 17:33]:
> On Tue, 19 Feb 2019, Tony Lindgren wrote:
> > In general, if the device tree node is never used afterwards,
> > should this be just:
> >
> > r = of_platform_populate(node, NULL, NULL, &pdev->dev);
> > of_node_put(dev_node);
> > if (r) {
> > ...
> > }
> >
> > If so, Julia might have a Coccinelle recpipe for it?
>
> Unfortunately this is not really an ideal case for Coccinelle, because
> node is the result of calling a local function and Coccinelle doesn't by
> default do any interprocedural analysis. It is possible to write a rule
> that explicitly looks for one function that returns a device node and then
> the pattern of its usage in the caller, though.
OK thanks for the information.
Regards,
Tony
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
^ permalink raw reply [flat|nested] 11+ messages in thread