cpufreq: sun50i: fix memory leak and remove of_node_put()

[PATCH 1/2] cpufreq: sun50i: fix memory leak in dt_has_supported_hw()

Posted by Javier Carrasco 1 year, 7 months ago

The for_each_child_of_node() loop does not decrement the child node
refcount before the break instruction, even though the node is no
longer required.

This can be avoided with the new for_each_child_of_node_scoped() macro
that removes the need for any of_node_put().

Fixes: fa5aec9561cf ("cpufreq: sun50i: Add support for opp_supported_hw")
Signed-off-by: Javier Carrasco <javier.carrasco.cruz@gmail.com>
---
 drivers/cpufreq/sun50i-cpufreq-nvmem.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/cpufreq/sun50i-cpufreq-nvmem.c b/drivers/cpufreq/sun50i-cpufreq-nvmem.c
index 0b882765cd66..ef83e4bf2639 100644
--- a/drivers/cpufreq/sun50i-cpufreq-nvmem.c
+++ b/drivers/cpufreq/sun50i-cpufreq-nvmem.c
@@ -131,7 +131,7 @@ static const struct of_device_id cpu_opp_match_list[] = {
 static bool dt_has_supported_hw(void)
 {
 	bool has_opp_supported_hw = false;
-	struct device_node *np, *opp;
+	struct device_node *np;
 	struct device *cpu_dev;
 
 	cpu_dev = get_cpu_device(0);
@@ -142,7 +142,7 @@ static bool dt_has_supported_hw(void)
 	if (!np)
 		return false;
 
-	for_each_child_of_node(np, opp) {
+	for_each_child_of_node_scoped(np, opp) {
 		if (of_find_property(opp, "opp-supported-hw", NULL)) {
 			has_opp_supported_hw = true;
 			break;

-- 
2.40.1

Re: [PATCH 1/2] cpufreq: sun50i: fix memory leak in dt_has_supported_hw()

Posted by Andre Przywara 1 year, 7 months ago

On Fri, 03 May 2024 19:52:32 +0200
Javier Carrasco <javier.carrasco.cruz@gmail.com> wrote:

Hi Javier,

> The for_each_child_of_node() loop does not decrement the child node
> refcount before the break instruction, even though the node is no
> longer required.

Ah, thanks for spotting this, there is indeed a leak. Sorry for the
blunder!

> This can be avoided with the new for_each_child_of_node_scoped() macro
> that removes the need for any of_node_put().

Wow, that's the typical convoluted Linux macro, but it looks correct to me.
It would call the put even if the loop ends naturally, but there is a NULL
test in there, so that's fine.

> Fixes: fa5aec9561cf ("cpufreq: sun50i: Add support for opp_supported_hw")
> Signed-off-by: Javier Carrasco <javier.carrasco.cruz@gmail.com>

Reviewed-by: Andre Przywara <andre.przywara@arm.com>

Thanks!
Andre

> ---
>  drivers/cpufreq/sun50i-cpufreq-nvmem.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/cpufreq/sun50i-cpufreq-nvmem.c b/drivers/cpufreq/sun50i-cpufreq-nvmem.c
> index 0b882765cd66..ef83e4bf2639 100644
> --- a/drivers/cpufreq/sun50i-cpufreq-nvmem.c
> +++ b/drivers/cpufreq/sun50i-cpufreq-nvmem.c
> @@ -131,7 +131,7 @@ static const struct of_device_id cpu_opp_match_list[] = {
>  static bool dt_has_supported_hw(void)
>  {
>  	bool has_opp_supported_hw = false;
> -	struct device_node *np, *opp;
> +	struct device_node *np;
>  	struct device *cpu_dev;
>  
>  	cpu_dev = get_cpu_device(0);
> @@ -142,7 +142,7 @@ static bool dt_has_supported_hw(void)
>  	if (!np)
>  		return false;
>  
> -	for_each_child_of_node(np, opp) {
> +	for_each_child_of_node_scoped(np, opp) {
>  		if (of_find_property(opp, "opp-supported-hw", NULL)) {
>  			has_opp_supported_hw = true;
>  			break;
>

Re: [PATCH 1/2] cpufreq: sun50i: fix memory leak in dt_has_supported_hw()

Posted by Viresh Kumar 1 year, 7 months ago

On 10-05-24, 17:49, Andre Przywara wrote:
> On Fri, 03 May 2024 19:52:32 +0200
> Javier Carrasco <javier.carrasco.cruz@gmail.com> wrote:
> > diff --git a/drivers/cpufreq/sun50i-cpufreq-nvmem.c b/drivers/cpufreq/sun50i-cpufreq-nvmem.c
> > index 0b882765cd66..ef83e4bf2639 100644
> > --- a/drivers/cpufreq/sun50i-cpufreq-nvmem.c
> > +++ b/drivers/cpufreq/sun50i-cpufreq-nvmem.c
> > @@ -131,7 +131,7 @@ static const struct of_device_id cpu_opp_match_list[] = {
> >  static bool dt_has_supported_hw(void)
> >  {
> >  	bool has_opp_supported_hw = false;
> > -	struct device_node *np, *opp;
> > +	struct device_node *np;

Why is the opp pointer removed ?

> >  	struct device *cpu_dev;
> >  
> >  	cpu_dev = get_cpu_device(0);
> > @@ -142,7 +142,7 @@ static bool dt_has_supported_hw(void)
> >  	if (!np)
> >  		return false;
> >  
> > -	for_each_child_of_node(np, opp) {
> > +	for_each_child_of_node_scoped(np, opp) {
> >  		if (of_find_property(opp, "opp-supported-hw", NULL)) {
> >  			has_opp_supported_hw = true;
> >  			break;
> > 

-- 
viresh

Re: [PATCH 1/2] cpufreq: sun50i: fix memory leak in dt_has_supported_hw()

Posted by Andre Przywara 1 year, 7 months ago

On Mon, 20 May 2024 13:03:39 +0530
Viresh Kumar <viresh.kumar@linaro.org> wrote:

Hi,

> On 10-05-24, 17:49, Andre Przywara wrote:
> > On Fri, 03 May 2024 19:52:32 +0200
> > Javier Carrasco <javier.carrasco.cruz@gmail.com> wrote:  
> > > diff --git a/drivers/cpufreq/sun50i-cpufreq-nvmem.c b/drivers/cpufreq/sun50i-cpufreq-nvmem.c
> > > index 0b882765cd66..ef83e4bf2639 100644
> > > --- a/drivers/cpufreq/sun50i-cpufreq-nvmem.c
> > > +++ b/drivers/cpufreq/sun50i-cpufreq-nvmem.c
> > > @@ -131,7 +131,7 @@ static const struct of_device_id cpu_opp_match_list[] = {
> > >  static bool dt_has_supported_hw(void)
> > >  {
> > >  	bool has_opp_supported_hw = false;
> > > -	struct device_node *np, *opp;
> > > +	struct device_node *np;  
> 
> Why is the opp pointer removed ?

Because it's now declared *inside* the for_each_child_of_node_scoped loop
below, courtesy of this new macro. The idea is that by doing so, any
"break;" will exit the scope, triggering the cleanup routine. The loop
running till "the end" will also make "opp" exit its scope, triggering the
same routine.

Cheers,
Andre

> 
> > >  	struct device *cpu_dev;
> > >  
> > >  	cpu_dev = get_cpu_device(0);
> > > @@ -142,7 +142,7 @@ static bool dt_has_supported_hw(void)
> > >  	if (!np)
> > >  		return false;
> > >  
> > > -	for_each_child_of_node(np, opp) {
> > > +	for_each_child_of_node_scoped(np, opp) {
> > >  		if (of_find_property(opp, "opp-supported-hw", NULL)) {
> > >  			has_opp_supported_hw = true;
> > >  			break;
> > >   
>

Re: [PATCH 1/2] cpufreq: sun50i: fix memory leak in dt_has_supported_hw()

Posted by Viresh Kumar 1 year, 7 months ago

On 20-05-24, 09:26, Andre Przywara wrote:
> On Mon, 20 May 2024 13:03:39 +0530
> Viresh Kumar <viresh.kumar@linaro.org> wrote:
> 
> Hi,
> 
> > On 10-05-24, 17:49, Andre Przywara wrote:
> > > On Fri, 03 May 2024 19:52:32 +0200
> > > Javier Carrasco <javier.carrasco.cruz@gmail.com> wrote:  
> > > > diff --git a/drivers/cpufreq/sun50i-cpufreq-nvmem.c b/drivers/cpufreq/sun50i-cpufreq-nvmem.c
> > > > index 0b882765cd66..ef83e4bf2639 100644
> > > > --- a/drivers/cpufreq/sun50i-cpufreq-nvmem.c
> > > > +++ b/drivers/cpufreq/sun50i-cpufreq-nvmem.c
> > > > @@ -131,7 +131,7 @@ static const struct of_device_id cpu_opp_match_list[] = {
> > > >  static bool dt_has_supported_hw(void)
> > > >  {
> > > >  	bool has_opp_supported_hw = false;
> > > > -	struct device_node *np, *opp;
> > > > +	struct device_node *np;  
> > 
> > Why is the opp pointer removed ?
> 
> Because it's now declared *inside* the for_each_child_of_node_scoped loop
> below, courtesy of this new macro. The idea is that by doing so, any
> "break;" will exit the scope, triggering the cleanup routine. The loop
> running till "the end" will also make "opp" exit its scope, triggering the
> same routine.

Applied. Thanks.

-- 
viresh