[PATCH] regulator: core: fix use_count leakage when handling boot-on

Rui Zhang
2022-11-22T10:39:01Z

I found a use_count leakage towards supply regulator of rdev with
boot-on option.

┌───────────────────┐ ┌───────────────────┐
│ regulator_dev A │ │ regulator_dev B │
│ (boot-on) │ │ (boot-on) │
│ use_count=0 │◀──supply──│ use_count=1 │
│ │ │ │
└───────────────────┘ └───────────────────┘

In case of rdev(A) configured with `regulator-boot-on', the use_count
of supplying regulator(B) will increment inside
regulator_enable(rdev->supply).

Thus, B will acts like always-on, and further balanced
regulator_enable/disable cannot actually disable it anymore.

However, B was also configured with `regulator-boot-on', we wish it
could be disabled afterwards.

Signed-off-by: Rui Zhang <zr.zhang@vivo.com>
---
drivers/regulator/core.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/regulator/core.c b/drivers/regulator/core.c
index e8c00a884f1f..1cfac32121c0 100644
--- a/drivers/regulator/core.c
+++ b/drivers/regulator/core.c
@@ -1596,7 +1596,13 @@ static int set_machine_constraints(struct regulator_dev *rdev)
if (rdev->supply_name && !rdev->supply)
return -EPROBE_DEFER;

- if (rdev->supply) {
+ /* If supplying regulator has already been enabled,
+ * it's not intended to have use_count increment
+ * when rdev is only boot-on.
+ */
+ if (rdev->supply &&
+ (rdev->constraints->always_on ||
+ !regulator_is_enabled(rdev->supply))) {
ret = regulator_enable(rdev->supply);
if (ret < 0) {
_regulator_put(rdev->supply);
--
2.34.1

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