This is a note to let you know that I've just added the patch titled
regulator: core: fix use_count leakage when handling boot-on
to the 5.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
regulator-core-fix-use_count-leakage-when-handling-b.patch
and it can be found in the queue-5.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit e59c5cf1b56d040d448d1409894048d5ef0d187c
Author: Rui Zhang <zr.zhang@xxxxxxxx>
Date: Thu Dec 1 11:38:06 2022 +0800
regulator: core: fix use_count leakage when handling boot-on
[ Upstream commit 0591b14ce0398125439c759f889647369aa616a0 ]
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@xxxxxxxx>
Link: https://lore.kernel.org/r/20221201033806.2567812-1-zr.zhang@xxxxxxxx
Signed-off-by: Mark Brown <broonie@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/regulator/core.c b/drivers/regulator/core.c
index 5dd17a341577..f2214e7c75b3 100644
--- a/drivers/regulator/core.c
+++ b/drivers/regulator/core.c
@@ -1387,7 +1387,13 @@ 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);
