[PATCH v1] opp: Release current OPP properly

[PATCH v1] opp: Release current OPP properly

[Dmitry Osipenko]

The current_opp is released only when whole OPP table is released,
otherwise it's only marked as removed by dev_pm_opp_remove_table().
Functions like dev_pm_opp_put_clkname() and dev_pm_opp_put_supported_hw()
are checking whether OPP table is empty and it's not if current_opp is
set since it holds the refcount of OPP, this produces a noisy warning
from these functions about busy OPP table. Release current_opp when
OPP table is removed to fix it.

Cc: stable@vger.kernel.org
Fixes: 81c4d8a3c414 ("opp: Keep track of currently programmed OPP")
Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
---
 drivers/opp/core.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/drivers/opp/core.c b/drivers/opp/core.c
index b335c077f215..73da968b5c86 100644
--- a/drivers/opp/core.c
+++ b/drivers/opp/core.c
@@ -1378,9 +1378,6 @@ static void _opp_table_kref_release(struct kref *kref)
 	list_del(&opp_table->node);
 	mutex_unlock(&opp_table_lock);
 
-	if (opp_table->current_opp)
-		dev_pm_opp_put(opp_table->current_opp);
-
 	_of_clear_opp_table(opp_table);
 
 	/* Release clk */
@@ -2901,6 +2898,12 @@ void dev_pm_opp_remove_table(struct device *dev)
 	if (_opp_remove_all_static(opp_table))
 		dev_pm_opp_put_opp_table(opp_table);
 
+	/* Drop reference taken by _find_current_opp() */
+	if (opp_table->current_opp) {
+		dev_pm_opp_put(opp_table->current_opp);
+		opp_table->current_opp = NULL;
+	}
+
 	/* Drop reference taken by _find_opp_table() */
 	dev_pm_opp_put_opp_table(opp_table);
 }
-- 
2.32.0

Re: [PATCH v1] opp: Release current OPP properly

[Viresh Kumar]

On 12-08-21, 13:13, Dmitry Osipenko wrote:
> The current_opp is released only when whole OPP table is released,
> otherwise it's only marked as removed by dev_pm_opp_remove_table().
> Functions like dev_pm_opp_put_clkname() and dev_pm_opp_put_supported_hw()
> are checking whether OPP table is empty and it's not if current_opp is
> set since it holds the refcount of OPP, this produces a noisy warning
> from these functions about busy OPP table. Release current_opp when
> OPP table is removed to fix it.
> 
> Cc: stable@vger.kernel.org
> Fixes: 81c4d8a3c414 ("opp: Keep track of currently programmed OPP")
> Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
> ---
>  drivers/opp/core.c | 9 ++++++---
>  1 file changed, 6 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/opp/core.c b/drivers/opp/core.c
> index b335c077f215..73da968b5c86 100644
> --- a/drivers/opp/core.c
> +++ b/drivers/opp/core.c
> @@ -1378,9 +1378,6 @@ static void _opp_table_kref_release(struct kref *kref)
>  	list_del(&opp_table->node);
>  	mutex_unlock(&opp_table_lock);
>  
> -	if (opp_table->current_opp)
> -		dev_pm_opp_put(opp_table->current_opp);
> -
>  	_of_clear_opp_table(opp_table);
>  
>  	/* Release clk */
> @@ -2901,6 +2898,12 @@ void dev_pm_opp_remove_table(struct device *dev)
>  	if (_opp_remove_all_static(opp_table))
>  		dev_pm_opp_put_opp_table(opp_table);
>  
> +	/* Drop reference taken by _find_current_opp() */
> +	if (opp_table->current_opp) {
> +		dev_pm_opp_put(opp_table->current_opp);
> +		opp_table->current_opp = NULL;
> +	}
> +

It is better to drop the reference when the OPP table is really
getting removed.

I think the WARN_ON() in the put_* functions can be dropped. It is
important to check this when the stuff is getting set, like in
dev_pm_opp_set_supported_hw(), but removal is just fine.

-- 
viresh

Re: [PATCH v1] opp: Release current OPP properly

[Dmitry Osipenko]

13.08.2021 07:12, Viresh Kumar пишет:
> On 12-08-21, 13:13, Dmitry Osipenko wrote:
>> The current_opp is released only when whole OPP table is released,
>> otherwise it's only marked as removed by dev_pm_opp_remove_table().
>> Functions like dev_pm_opp_put_clkname() and dev_pm_opp_put_supported_hw()
>> are checking whether OPP table is empty and it's not if current_opp is
>> set since it holds the refcount of OPP, this produces a noisy warning
>> from these functions about busy OPP table. Release current_opp when
>> OPP table is removed to fix it.
>>
>> Cc: stable@vger.kernel.org
>> Fixes: 81c4d8a3c414 ("opp: Keep track of currently programmed OPP")
>> Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
>> ---
>>  drivers/opp/core.c | 9 ++++++---
>>  1 file changed, 6 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/opp/core.c b/drivers/opp/core.c
>> index b335c077f215..73da968b5c86 100644
>> --- a/drivers/opp/core.c
>> +++ b/drivers/opp/core.c
>> @@ -1378,9 +1378,6 @@ static void _opp_table_kref_release(struct kref *kref)
>>  	list_del(&opp_table->node);
>>  	mutex_unlock(&opp_table_lock);
>>  
>> -	if (opp_table->current_opp)
>> -		dev_pm_opp_put(opp_table->current_opp);
>> -
>>  	_of_clear_opp_table(opp_table);
>>  
>>  	/* Release clk */
>> @@ -2901,6 +2898,12 @@ void dev_pm_opp_remove_table(struct device *dev)
>>  	if (_opp_remove_all_static(opp_table))
>>  		dev_pm_opp_put_opp_table(opp_table);
>>  
>> +	/* Drop reference taken by _find_current_opp() */
>> +	if (opp_table->current_opp) {
>> +		dev_pm_opp_put(opp_table->current_opp);
>> +		opp_table->current_opp = NULL;
>> +	}
>> +
> 
> It is better to drop the reference when the OPP table is really
> getting removed.
> 
> I think the WARN_ON() in the put_* functions can be dropped. It is
> important to check this when the stuff is getting set, like in
> dev_pm_opp_set_supported_hw(), but removal is just fine.
> 

Alright, I'll make another patch then.