regulator: Fixes for v5.11

The main thing here is a change to make sure that we don't try to double
 resolve the supply of a regulator if we have two probes going on
 simultaneously, plus an incremental fix on top of that to resolve a
 lockdep issue it introduced.
 
 There's also a patch from Dmitry Osipenko adding stubs for some
 functions to avoid build issues in consumers in some configurations.
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Merge tag 'regulator-fix-v5.11-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/broonie/regulator

Pull regulator fixes from Mark Brown:
 "The main thing here is a change to make sure that we don't try to
  double resolve the supply of a regulator if we have two probes going
  on simultaneously, plus an incremental fix on top of that to resolve a
  lockdep issue it introduced.

  There's also a patch from Dmitry Osipenko adding stubs for some
  functions to avoid build issues in consumers in some configurations"

* tag 'regulator-fix-v5.11-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/broonie/regulator:
  regulator: Fix lockdep warning resolving supplies
  regulator: consumer: Add missing stubs to regulator/consumer.h
  regulator: core: avoid regulator_resolve_supply() race condition

drivers/regulator/core.c

@@ -1813,13 +1813,13 @@ static int regulator_resolve_supply(struct regulator_dev *rdev)
 {
 	struct regulator_dev *r;
 	struct device *dev = rdev->dev.parent;
-	int ret;
+	int ret = 0;
 
 	/* No supply to resolve? */
 	if (!rdev->supply_name)
 		return 0;
 
-	/* Supply already resolved? */
+	/* Supply already resolved? (fast-path without locking contention) */
 	if (rdev->supply)
 		return 0;
 
@@ -1829,7 +1829,7 @@ static int regulator_resolve_supply(struct regulator_dev *rdev)
 
 		/* Did the lookup explicitly defer for us? */
 		if (ret == -EPROBE_DEFER)
-			return ret;
+			goto out;
 
 		if (have_full_constraints()) {
 			r = dummy_regulator_rdev;
@@ -1837,15 +1837,18 @@ static int regulator_resolve_supply(struct regulator_dev *rdev)
 		} else {
 			dev_err(dev, "Failed to resolve %s-supply for %s\n",
 				rdev->supply_name, rdev->desc->name);
-			return -EPROBE_DEFER;
+			ret = -EPROBE_DEFER;
+			goto out;
 		}
 	}
 
 	if (r == rdev) {
 		dev_err(dev, "Supply for %s (%s) resolved to itself\n",
 			rdev->desc->name, rdev->supply_name);
-		if (!have_full_constraints())
-			return -EINVAL;
+		if (!have_full_constraints()) {
+			ret = -EINVAL;
+			goto out;
+		}
 		r = dummy_regulator_rdev;
 		get_device(&r->dev);
 	}
@@ -1859,7 +1862,8 @@ static int regulator_resolve_supply(struct regulator_dev *rdev)
 	if (r->dev.parent && r->dev.parent != rdev->dev.parent) {
 		if (!device_is_bound(r->dev.parent)) {
 			put_device(&r->dev);
-			return -EPROBE_DEFER;
+			ret = -EPROBE_DEFER;
+			goto out;
 		}
 	}
 
@@ -1867,15 +1871,32 @@ static int regulator_resolve_supply(struct regulator_dev *rdev)
 	ret = regulator_resolve_supply(r);
 	if (ret < 0) {
 		put_device(&r->dev);
-		return ret;
+		goto out;
+	}
+
+	/*
+	 * Recheck rdev->supply with rdev->mutex lock held to avoid a race
+	 * between rdev->supply null check and setting rdev->supply in
+	 * set_supply() from concurrent tasks.
+	 */
+	regulator_lock(rdev);
+
+	/* Supply just resolved by a concurrent task? */
+	if (rdev->supply) {
+		regulator_unlock(rdev);
+		put_device(&r->dev);
+		goto out;
 	}
 
 	ret = set_supply(rdev, r);
 	if (ret < 0) {
+		regulator_unlock(rdev);
 		put_device(&r->dev);
-		return ret;
+		goto out;
 	}
 
+	regulator_unlock(rdev);
+
 	/*
 	 * In set_machine_constraints() we may have turned this regulator on
 	 * but we couldn't propagate to the supply if it hadn't been resolved
@@ -1886,11 +1907,12 @@ static int regulator_resolve_supply(struct regulator_dev *rdev)
 		if (ret < 0) {
 			_regulator_put(rdev->supply);
 			rdev->supply = NULL;
-			return ret;
+			goto out;
 		}
 	}
 
-	return 0;
+out:
+	return ret;
 }
 
 /* Internal regulator request function */

include/linux/regulator/consumer.h

@@ -331,6 +331,12 @@ regulator_get_exclusive(struct device *dev, const char *id)
 	return ERR_PTR(-ENODEV);
 }
 
+static inline struct regulator *__must_check
+devm_regulator_get_exclusive(struct device *dev, const char *id)
+{
+	return ERR_PTR(-ENODEV);
+}
+
 static inline struct regulator *__must_check
 regulator_get_optional(struct device *dev, const char *id)
 {
@@ -486,6 +492,11 @@ static inline int regulator_get_voltage(struct regulator *regulator)
 	return -EINVAL;
 }
 
+static inline int regulator_sync_voltage(struct regulator *regulator)
+{
+	return -EINVAL;
+}
+
 static inline int regulator_is_supported_voltage(struct regulator *regulator,
 				   int min_uV, int max_uV)
 {
@@ -578,6 +589,25 @@ static inline int devm_regulator_unregister_notifier(struct regulator *regulator
 	return 0;
 }
 
+static inline int regulator_suspend_enable(struct regulator_dev *rdev,
+					   suspend_state_t state)
+{
+	return -EINVAL;
+}
+
+static inline int regulator_suspend_disable(struct regulator_dev *rdev,
+					    suspend_state_t state)
+{
+	return -EINVAL;
+}
+
+static inline int regulator_set_suspend_voltage(struct regulator *regulator,
+						int min_uV, int max_uV,
+						suspend_state_t state)
+{
+	return -EINVAL;
+}
+
 static inline void *regulator_get_drvdata(struct regulator *regulator)
 {
 	return NULL;