spi: Fix controller unregister order

[ Upstream commit 84855678add8aba927faf76bc2f130a40f94b6f7 ]

When an SPI controller unregisters, it unbinds all its slave devices.
For this, their drivers may need to access the SPI bus, e.g. to quiesce
interrupts.

However since commit ffbbdd21 ("spi: create a message queueing
infrastructure"), spi_destroy_queue() is executed before unbinding the
slaves.  It sets ctlr->running = false, thereby preventing SPI bus
access and causing unbinding of slave devices to fail.

Fix by unbinding slaves before calling spi_destroy_queue().

Fixes: ffbbdd21 ("spi: create a message queueing infrastructure")
Signed-off-by: NLukas Wunner <lukas@wunner.de>
Cc: stable@vger.kernel.org # v3.4+
Cc: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/8aaf9d44c153fe233b17bc2dec4eb679898d7e7b.1589557526.git.lukas@wunner.deSigned-off-by: NMark Brown <broonie@kernel.org>
Signed-off-by: NSasha Levin <sashal@kernel.org>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>

drivers/spi/spi.c

@@ -2306,6 +2306,8 @@ void spi_unregister_controller(struct spi_controller *ctlr)
 	struct spi_controller *found;
 	int id = ctlr->bus_num;
 
+	device_for_each_child(&ctlr->dev, NULL, __unregister);
+
 	/* First make sure that this controller was ever added */
 	mutex_lock(&board_lock);
 	found = idr_find(&spi_master_idr, id);
@@ -2318,7 +2320,6 @@ void spi_unregister_controller(struct spi_controller *ctlr)
 	list_del(&ctlr->list);
 	mutex_unlock(&board_lock);
 
-	device_for_each_child(&ctlr->dev, NULL, __unregister);
 	device_unregister(&ctlr->dev);
 	/* free bus id */
 	mutex_lock(&board_lock);