When updating the operating mode as part of regulator enable, the caller has already locked the regulator tree and drms_uA_update() must not try to do the same in order not to trigger a deadlock.
The lock inversion is reported by lockdep as:
====================================================== WARNING: possible circular locking dependency detected 6.1.0-next-20221215 #142 Not tainted ------------------------------------------------------ udevd/154 is trying to acquire lock: ffffc11f123d7e50 (regulator_list_mutex){+.+.}-{3:3}, at: regulator_lock_dependent+0x54/0x280
but task is already holding lock: ffff80000e4c36e8 (regulator_ww_class_acquire){+.+.}-{0:0}, at: regulator_enable+0x34/0x80
which lock already depends on the new lock.
...
Possible unsafe locking scenario:
CPU0 CPU1 ---- ---- lock(regulator_ww_class_acquire); lock(regulator_list_mutex); lock(regulator_ww_class_acquire); lock(regulator_list_mutex);
*** DEADLOCK ***
just before probe of a Qualcomm UFS controller (occasionally) deadlocks when enabling one of its regulators.
Fixes: 9243a195be7a ("regulator: core: Change voltage setting path") Fixes: f8702f9e4aa7 ("regulator: core: Use ww_mutex for regulators locking") Cc: stable@vger.kernel.org # 5.0 Signed-off-by: Johan Hovold johan+linaro@kernel.org --- drivers/regulator/core.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/regulator/core.c b/drivers/regulator/core.c index 729c45393803..ae69e493913d 100644 --- a/drivers/regulator/core.c +++ b/drivers/regulator/core.c @@ -1002,7 +1002,7 @@ static int drms_uA_update(struct regulator_dev *rdev) /* get input voltage */ input_uV = 0; if (rdev->supply) - input_uV = regulator_get_voltage(rdev->supply); + input_uV = regulator_get_voltage_rdev(rdev->supply->rdev); if (input_uV <= 0) input_uV = rdev->constraints->input_uV;