diff mbox series

opp: Reduce the size of critical section in _opp_table_kref_release()

Message ID e0df59de670b48a923246fae1f972317b84b2764.1603785323.git.viresh.kumar@linaro.org
State Accepted
Commit e0df59de670b48a923246fae1f972317b84b2764
Headers show
Series opp: Reduce the size of critical section in _opp_table_kref_release() | expand

Commit Message

Viresh Kumar Oct. 27, 2020, 7:57 a.m. UTC
There is a lot of stuff here which can be done outside of the big
opp_table_lock, do that. This helps avoiding few circular dependency
lockdeps around debugfs and interconnects.

Reported-by: Rob Clark <robdclark@gmail.com>
Reported-by: Dmitry Osipenko <digetx@gmail.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
---
Rob: I know this only fixes the issue partially for you and I am still
looking into that. I just wanted to get this merged in early as this
fixes lockdep for other users as well.

 drivers/opp/core.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

Comments

Stephen Boyd Oct. 28, 2020, 11:32 p.m. UTC | #1
Quoting Viresh Kumar (2020-10-27 00:57:06)
> There is a lot of stuff here which can be done outside of the big
> opp_table_lock, do that. This helps avoiding few circular dependency
> lockdeps around debugfs and interconnects.
> 
> Reported-by: Rob Clark <robdclark@gmail.com>
> Reported-by: Dmitry Osipenko <digetx@gmail.com>
> Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
> ---

Any Fixes tag?

Reviewed-by: Stephen Boyd <sboyd@kernel.org>
Viresh Kumar Oct. 29, 2020, 4:10 a.m. UTC | #2
On 28-10-20, 16:32, Stephen Boyd wrote:
> Quoting Viresh Kumar (2020-10-27 00:57:06)

> > There is a lot of stuff here which can be done outside of the big

> > opp_table_lock, do that. This helps avoiding few circular dependency

> > lockdeps around debugfs and interconnects.

> > 

> > Reported-by: Rob Clark <robdclark@gmail.com>

> > Reported-by: Dmitry Osipenko <digetx@gmail.com>

> > Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>

> > ---

> 

> Any Fixes tag?


The circular dependency lockdep appears with 5.11 stuff and so we
don't need to fix it in any of the earlier releases. And so I didn't
wanted to bother with the fixes tag, as the code had been like this
for ever.

> Reviewed-by: Stephen Boyd <sboyd@kernel.org>


Thanks a lot. I was a bit worried about the crazy idea I had to solve
this :)

-- 
viresh
Dmitry Osipenko Oct. 29, 2020, 2:38 p.m. UTC | #3
27.10.2020 10:57, Viresh Kumar пишет:
> There is a lot of stuff here which can be done outside of the big

> opp_table_lock, do that. This helps avoiding few circular dependency

> lockdeps around debugfs and interconnects.

> 

> Reported-by: Rob Clark <robdclark@gmail.com>

> Reported-by: Dmitry Osipenko <digetx@gmail.com>

> Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>

> ---

> Rob: I know this only fixes the issue partially for you and I am still

> looking into that. I just wanted to get this merged in early as this

> fixes lockdep for other users as well.

> 

>  drivers/opp/core.c | 7 ++++---

>  1 file changed, 4 insertions(+), 3 deletions(-)

> 

> diff --git a/drivers/opp/core.c b/drivers/opp/core.c

> index 4ac4e7ce6b8b..0e0a5269dc82 100644

> --- a/drivers/opp/core.c

> +++ b/drivers/opp/core.c

> @@ -1181,6 +1181,10 @@ static void _opp_table_kref_release(struct kref *kref)

>  	struct opp_device *opp_dev, *temp;

>  	int i;

>  

> +	/* Drop the lock as soon as we can */

> +	list_del(&opp_table->node);

> +	mutex_unlock(&opp_table_lock);

> +

>  	_of_clear_opp_table(opp_table);

>  

>  	/* Release clk */

> @@ -1208,10 +1212,7 @@ static void _opp_table_kref_release(struct kref *kref)

>  

>  	mutex_destroy(&opp_table->genpd_virt_dev_lock);

>  	mutex_destroy(&opp_table->lock);

> -	list_del(&opp_table->node);

>  	kfree(opp_table);

> -

> -	mutex_unlock(&opp_table_lock);

>  }

>  

>  void dev_pm_opp_put_opp_table(struct opp_table *opp_table)

> 


Fixes the NVIDIA Tegra devfreq driver lockup using WIP ICC patches, thanks.

Tested-by: Dmitry Osipenko <digetx@gmail.com>
Viresh Kumar Oct. 30, 2020, 4:20 a.m. UTC | #4
On 29-10-20, 09:40, Viresh Kumar wrote:
> Thanks a lot. I was a bit worried about the crazy idea I had to solve
> this :)

Hmm, I thought this is the other patch where I had that crazy idea.
This one was quite straight forward :)
Stephen Boyd Oct. 31, 2020, 2:53 a.m. UTC | #5
Quoting Viresh Kumar (2020-10-29 21:20:00)
> On 29-10-20, 09:40, Viresh Kumar wrote:
> > Thanks a lot. I was a bit worried about the crazy idea I had to solve
> > this :)
> 
> Hmm, I thought this is the other patch where I had that crazy idea.
> This one was quite straight forward :)
> 

What's the other crazy idea patch?
Viresh Kumar Nov. 2, 2020, 5:23 a.m. UTC | #6
On 30-10-20, 19:53, Stephen Boyd wrote:
> Quoting Viresh Kumar (2020-10-29 21:20:00)

> > On 29-10-20, 09:40, Viresh Kumar wrote:

> > > Thanks a lot. I was a bit worried about the crazy idea I had to solve

> > > this :)

> > 

> > Hmm, I thought this is the other patch where I had that crazy idea.

> > This one was quite straight forward :)

> > 

> 

> What's the other crazy idea patch?


Surprisingly I never sent it properly, just shared in another email thread with
Rob Clark to test it out.

Sent that now.

-- 
viresh
diff mbox series

Patch

diff --git a/drivers/opp/core.c b/drivers/opp/core.c
index 4ac4e7ce6b8b..0e0a5269dc82 100644
--- a/drivers/opp/core.c
+++ b/drivers/opp/core.c
@@ -1181,6 +1181,10 @@  static void _opp_table_kref_release(struct kref *kref)
 	struct opp_device *opp_dev, *temp;
 	int i;
 
+	/* Drop the lock as soon as we can */
+	list_del(&opp_table->node);
+	mutex_unlock(&opp_table_lock);
+
 	_of_clear_opp_table(opp_table);
 
 	/* Release clk */
@@ -1208,10 +1212,7 @@  static void _opp_table_kref_release(struct kref *kref)
 
 	mutex_destroy(&opp_table->genpd_virt_dev_lock);
 	mutex_destroy(&opp_table->lock);
-	list_del(&opp_table->node);
 	kfree(opp_table);
-
-	mutex_unlock(&opp_table_lock);
 }
 
 void dev_pm_opp_put_opp_table(struct opp_table *opp_table)