linux-kernel - [PATCH v3 2/2] regulator: check that dummy regulator has been probed before using it

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Message-ID: <20250313103051.32430-3-ceggers@arri.de>
Date: Thu, 13 Mar 2025 11:27:39 +0100
From: Christian Eggers <ceggers@...i.de>
To: Liam Girdwood <lgirdwood@...il.com>, Mark Brown <broonie@...nel.org>,
	Douglas Anderson <dianders@...omium.org>
CC: <linux-kernel@...r.kernel.org>, Christian Eggers <ceggers@...i.de>,
	<stable@...r.kernel.org>
Subject: [PATCH v3 2/2] regulator: check that dummy regulator has been probed before using it

Due to asynchronous driver probing there is a chance that the dummy
regulator hasn't already been probed when first accessing it.

Cc: stable@...r.kernel.org
Signed-off-by: Christian Eggers <ceggers@...i.de>
---
v2:
- return -EPROBE_DEFER rather than using BUG_ON()

v3:
- move dev_warn() below returning -EPROBE_DEFER

 drivers/regulator/core.c | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/drivers/regulator/core.c b/drivers/regulator/core.c
index 4ddf0efead68..4d0f13899e6b 100644
--- a/drivers/regulator/core.c
+++ b/drivers/regulator/core.c
@@ -2069,6 +2069,10 @@ static int regulator_resolve_supply(struct regulator_dev *rdev)
 
 		if (have_full_constraints()) {
 			r = dummy_regulator_rdev;
+			if (!r) {
+				ret = -EPROBE_DEFER;
+				goto out;
+			}
 			get_device(&r->dev);
 		} else {
 			dev_err(dev, "Failed to resolve %s-supply for %s\n",
@@ -2086,6 +2090,10 @@ static int regulator_resolve_supply(struct regulator_dev *rdev)
 			goto out;
 		}
 		r = dummy_regulator_rdev;
+		if (!r) {
+			ret = -EPROBE_DEFER;
+			goto out;
+		}
 		get_device(&r->dev);
 	}
 
@@ -2211,8 +2219,10 @@ struct regulator *_regulator_get_common(struct regulator_dev *rdev, struct devic
 			 * enabled, even if it isn't hooked up, and just
 			 * provide a dummy.
 			 */
-			dev_warn(dev, "supply %s not found, using dummy regulator\n", id);
 			rdev = dummy_regulator_rdev;
+			if (!rdev)
+				return ERR_PTR(-EPROBE_DEFER);
+			dev_warn(dev, "supply %s not found, using dummy regulator\n", id);
 			get_device(&rdev->dev);
 			break;
 
-- 
2.44.1