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

From: Viresh Kumar
Date: Tue Oct 27 2020 - 03:57:14 EST


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@xxxxxxxxx>
Reported-by: Dmitry Osipenko <digetx@xxxxxxxxx>
Signed-off-by: Viresh Kumar <viresh.kumar@xxxxxxxxxx>
---
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)
--
2.25.0.rc1.19.g042ed3e048af