[PATCH net-next v2 1/4] net: pse-pd: scope pse_control regulator handle to kref lifetime

[Carlo Szelinsky <github@szelinsky.de>]

From: Corey Leavitt <corey@leavitt.info>

__pse_control_release() drops psec->ps via devm_regulator_put(), which
only succeeds if the devres entry added by the matching
devm_regulator_get_exclusive() is still present on pcdev->dev at the
time the pse_control's kref hits zero.

In practice that assumption does not hold when the controller is
unbound while any pse_control still has consumers: pcdev->dev's
devres list is released LIFO, so every per-attach regulator-GET
devres runs (and regulator_put()s the underlying regulator) before
pse_controller_unregister() itself is invoked. Any later
pse_control_put() from that unbind path then reads psec->ps as a
dangling pointer inside devm_regulator_put() and WARNs at
drivers/regulator/devres.c:232 (devres_release() fails to find the
already-released match).

The pse_control's consumer handle is logically scoped to the
pse_control's refcount, not to pcdev->dev's devres lifetime. Switch
to the plain regulator_get_exclusive() / regulator_put() pair so
__pse_control_release() does the right put regardless of whether
the controller's devres has already been unwound.

No change to the regulator-framework-visible refcount or lifetime of
the underlying regulator: a single get paired with a single put. The
existing devm_regulator_register() for the per-PI rails is unchanged
(those ARE correctly scoped to the controller's lifetime).

Fixes: d83e13761d5b ("net: pse-pd: Use regulator framework within PSE framework")
Signed-off-by: Corey Leavitt <corey@leavitt.info>
Acked-by: Kory Maincent <kory.maincent@bootlin.com>
Signed-off-by: Carlo Szelinsky <github@szelinsky.de>
---
 drivers/net/pse-pd/pse_core.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/net/pse-pd/pse_core.c b/drivers/net/pse-pd/pse_core.c
index 69dbdbde9d71..a5e6d7b26b9f 100644
--- a/drivers/net/pse-pd/pse_core.c
+++ b/drivers/net/pse-pd/pse_core.c
@@ -1367,7 +1367,7 @@ static void __pse_control_release(struct kref *kref)
 
 	if (psec->pcdev->pi[psec->id].admin_state_enabled)
 		regulator_disable(psec->ps);
-	devm_regulator_put(psec->ps);
+	regulator_put(psec->ps);
 
 	module_put(psec->pcdev->owner);
 
@@ -1436,8 +1436,8 @@ pse_control_get_internal(struct pse_controller_dev *pcdev, unsigned int index,
 		goto free_psec;
 
 	pcdev->pi[index].admin_state_enabled = ret;
-	psec->ps = devm_regulator_get_exclusive(pcdev->dev,
-						rdev_get_name(pcdev->pi[index].rdev));
+	psec->ps = regulator_get_exclusive(pcdev->dev,
+					   rdev_get_name(pcdev->pi[index].rdev));
 	if (IS_ERR(psec->ps)) {
 		ret = PTR_ERR(psec->ps);
 		goto put_module;
-- 
2.43.0