On 26-10-20, 01:17, Dmitry Osipenko wrote:
This patch fixes lockup which happens when OPP table is released if interconnect provider uses OPP in the icc_provider->set() callback and bandwidth of the ICC path is set to 0 by the ICC core when path is released. The icc_put() doesn't need the opp_table_lock protection, hence let's move it outside of the lock in order to resolve the problem.
In particular this fixes tegra-devfreq driver lockup on trying to unload the driver module. The devfreq driver uses OPP-bandwidth API and its ICC provider also uses OPP for DVFS, hence they both take same opp_table_lock when OPP table of the devfreq is released.
Signed-off-by: Dmitry Osipenko digetx@gmail.com
drivers/opp/core.c | 21 ++++++++++++++------- 1 file changed, 14 insertions(+), 7 deletions(-)
diff --git a/drivers/opp/core.c b/drivers/opp/core.c index 2483e765318a..1134df360fe0 100644 --- a/drivers/opp/core.c +++ b/drivers/opp/core.c @@ -1187,12 +1187,6 @@ static void _opp_table_kref_release(struct kref *kref) if (!IS_ERR(opp_table->clk)) clk_put(opp_table->clk);
if (opp_table->paths) {
for (i = 0; i < opp_table->path_count; i++)icc_put(opp_table->paths[i]);kfree(opp_table->paths);}
WARN_ON(!list_empty(&opp_table->opp_list));
list_for_each_entry_safe(opp_dev, temp, &opp_table->dev_list, node) {
@@ -1209,9 +1203,22 @@ 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);
- /*
* Interconnect provider may use OPP too, hence icc_put() needs to be* invoked outside of the opp_table_lock in order to prevent nested* locking which happens when bandwidth of the ICC path is set to 0* by ICC core on release of the path.*/- if (opp_table->paths) {
for (i = 0; i < opp_table->path_count; i++)icc_put(opp_table->paths[i]);kfree(opp_table->paths);- }
- kfree(opp_table);
}
Never make such _fixes_ part of such a big patchset. Always send them separately.
Having said that, I already have a patch with me which shall fix it for you as well:
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)