regulator: Fix deadlock during regulator registration

commit a2151374 upstream.

Commit 5e3ca2b3 ("regulator: Try to resolve regulators supplies on
registration") added a call to regulator_resolve_supply() within
regulator_register() where the regulator_list_mutex is held. This causes
a deadlock to occur on the Tegra114 Dalmore board when the palmas PMIC
is registered because regulator_register_resolve_supply() calls
regulator_dev_lookup() which may try to acquire the regulator_list_mutex
again.

Fix this by releasing the mutex before calling
regulator_register_resolve_supply() and update the error exit path to
ensure the mutex is released on an error.

[Made commit message more legible -- broonie]
Signed-off-by: Jon Hunter <jonathanh@nvidia.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/regulator/core.c

@@ -3991,12 +3991,11 @@ regulator_register(const struct regulator_desc *regulator_desc,
 	}
 
 	rdev_init_debugfs(rdev);
+	mutex_unlock(&regulator_list_mutex);
 
 	/* try to resolve regulators supply since a new one was registered */
 	class_for_each_device(&regulator_class, NULL, NULL,
 			      regulator_register_resolve_supply);
-out:
-	mutex_unlock(&regulator_list_mutex);
 	kfree(config);
 	return rdev;
 
@@ -4007,15 +4006,16 @@ regulator_register(const struct regulator_desc *regulator_desc,
 	regulator_ena_gpio_free(rdev);
 	device_unregister(&rdev->dev);
 	/* device core frees rdev */
-	rdev = ERR_PTR(ret);
 	goto out;
 
 wash:
 	regulator_ena_gpio_free(rdev);
 clean:
 	kfree(rdev);
-	rdev = ERR_PTR(ret);
-	goto out;
+out:
+	mutex_unlock(&regulator_list_mutex);
+	kfree(config);
+	return ERR_PTR(ret);
 }
 EXPORT_SYMBOL_GPL(regulator_register);