[ Upstream commit 063773011d33bb36588a90385aa9eb75d13c6d80 ]
Lockdep reports the following issue on my setup:
Possible unsafe locking scenario:
CPU0 CPU1 ---- ---- lock((work_completion)(&(&rdev->disable_work)->work)); lock(regulator_list_mutex); lock((work_completion)(&(&rdev->disable_work)->work)); lock(regulator_list_mutex);
The problem is that regulator_unregister takes the regulator_list_mutex and then calls flush_work on disable_work. But regulator_disable_work calls regulator_lock_dependent which will also take the regulator_list_mutex. Resulting in a deadlock if the flush_work call actually needs to flush the work.
Fix this issue by moving the flush_work outside of the regulator_list_mutex. The list mutex is not used to guard the point at which the delayed work is queued, so its use adds no additional safety.
Fixes: f8702f9e4aa7 ("regulator: core: Use ww_mutex for regulators locking") Signed-off-by: Charles Keepax ckeepax@opensource.cirrus.com Reviewed-by: Dmitry Osipenko digetx@gmail.com Signed-off-by: Mark Brown broonie@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/regulator/core.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/regulator/core.c b/drivers/regulator/core.c index 6da41207e479a..35a7d020afecd 100644 --- a/drivers/regulator/core.c +++ b/drivers/regulator/core.c @@ -5062,10 +5062,11 @@ void regulator_unregister(struct regulator_dev *rdev) regulator_put(rdev->supply); }
+ flush_work(&rdev->disable_work.work); + mutex_lock(®ulator_list_mutex);
debugfs_remove_recursive(rdev->debugfs); - flush_work(&rdev->disable_work.work); WARN_ON(rdev->open_count); regulator_remove_coupling(rdev); unset_regulator_supplies(rdev);