linux-kernel - [PATCH 4.4 029/101] spi: Fix controller unregister order

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Date:   Fri, 19 Jun 2020 16:32:18 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Lukas Wunner <lukas@...ner.de>,
        Linus Walleij <linus.walleij@...aro.org>,
        Mark Brown <broonie@...nel.org>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 4.4 029/101] spi: Fix controller unregister order

From: Lukas Wunner <lukas@...ner.de>

[ 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 ffbbdd21329f ("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: ffbbdd21329f ("spi: create a message queueing infrastructure")
Signed-off-by: Lukas Wunner <lukas@...ner.de>
Cc: stable@...r.kernel.org # v3.4+
Cc: Linus Walleij <linus.walleij@...aro.org>
Link: https://lore.kernel.org/r/8aaf9d44c153fe233b17bc2dec4eb679898d7e7b.1589557526.git.lukas@wunner.de
Signed-off-by: Mark Brown <broonie@...nel.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/spi/spi.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index e5460d84ed08..57001f8f727a 100644
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -1922,11 +1922,12 @@ void spi_unregister_master(struct spi_master *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_for_each_child(&master->dev, NULL, __unregister);
 	device_unregister(&master->dev);
 }
 EXPORT_SYMBOL_GPL(spi_unregister_master);
-- 
2.25.1