1 files changed, 70 insertions, 4 deletions

diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index 57001f8f727a..f743b95d5171 100644
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -418,6 +418,12 @@ static LIST_HEAD(spi_master_list);
  */
 static DEFINE_MUTEX(board_lock);
 
+/*
+ * Prevents addition of devices with same chip select and
+ * addition of devices below an unregistering controller.
+ */
+static DEFINE_MUTEX(spi_add_lock);
+
 /**
  * spi_alloc_device - Allocate a new SPI device
  * @master: Controller to which device is connected
@@ -496,7 +502,6 @@ static int spi_dev_check(struct device *dev, void *data)
  */
 int spi_add_device(struct spi_device *spi)
 {
-	static DEFINE_MUTEX(spi_add_lock);
 	struct spi_master *master = spi->master;
 	struct device *dev = master->dev.parent;
 	int status;
@@ -525,6 +530,13 @@ int spi_add_device(struct spi_device *spi)
 		goto done;
 	}
 
+	/* Controller may unregister concurrently */
+	if (IS_ENABLED(CONFIG_SPI_DYNAMIC) &&
+	    !device_is_registered(&master->dev)) {
+		status = -ENODEV;
+		goto done;
+	}
+
 	if (master->cs_gpios)
 		spi->cs_gpio = master->cs_gpios[spi->chip_select];
 
@@ -1720,6 +1732,47 @@ struct spi_master *spi_alloc_master(struct device *dev, unsigned size)
 }
 EXPORT_SYMBOL_GPL(spi_alloc_master);
 
+static void devm_spi_release_master(struct device *dev, void *master)
+{
+	spi_master_put(*(struct spi_master **)master);
+}
+
+/**
+ * devm_spi_alloc_master - resource-managed spi_alloc_master()
+ * @dev: physical device of SPI master
+ * @size: how much zeroed driver-private data to allocate
+ * Context: can sleep
+ *
+ * Allocate an SPI master and automatically release a reference on it
+ * when @dev is unbound from its driver.  Drivers are thus relieved from
+ * having to call spi_master_put().
+ *
+ * The arguments to this function are identical to spi_alloc_master().
+ *
+ * Return: the SPI master structure on success, else NULL.
+ */
+struct spi_master *devm_spi_alloc_master(struct device *dev, unsigned int size)
+{
+	struct spi_master **ptr, *master;
+
+	ptr = devres_alloc(devm_spi_release_master, sizeof(*ptr),
+			   GFP_KERNEL);
+	if (!ptr)
+		return NULL;
+
+	master = spi_alloc_master(dev, size);
+	if (master) {
+		master->devm_allocated = true;
+		*ptr = master;
+		devres_add(dev, ptr);
+	} else {
+		devres_free(ptr);
+	}
+
+	return master;
+}
+EXPORT_SYMBOL_GPL(devm_spi_alloc_master);
+
 #ifdef CONFIG_OF
 static int of_spi_register_master(struct spi_master *master)
 {
@@ -1917,18 +1970,31 @@ static int __unregister(struct device *dev, void *null)
  */
 void spi_unregister_master(struct spi_master *master)
 {
+	/* Prevent addition of new devices, unregister existing ones */
+	if (IS_ENABLED(CONFIG_SPI_DYNAMIC))
+		mutex_lock(&spi_add_lock);
+
+	device_for_each_child(&master->dev, NULL, __unregister);
+
 	if (master->queued) {
 		if (spi_destroy_queue(master))
 			dev_err(&master->dev, "queue remove failed\n");
 	}
 
-	device_for_each_child(&master->dev, NULL, __unregister);
-
 	mutex_lock(&board_lock);
 	list_del(&master->list);
 	mutex_unlock(&board_lock);
 
-	device_unregister(&master->dev);
+	device_del(&master->dev);
+
+	/* Release the last reference on the master if its driver
+	 * has not yet been converted to devm_spi_alloc_master().
+	 */
+	if (!master->devm_allocated)
+		put_device(&master->dev);
+
+	if (IS_ENABLED(CONFIG_SPI_DYNAMIC))
+		mutex_unlock(&spi_add_lock);
 }
 EXPORT_SYMBOL_GPL(spi_unregister_master);