mailbox: mailbox-test: initialize struct earlier

[ Upstream commit bbcf9af ]

The waitqueue must be initialized before the debugfs files are created
because from that time, requests from userspace can already be made.
Similarily, drvdata and spinlock needs to be initialized before we
request the channel, otherwise dangling irqs might run into problems
like a NULL pointer exception.

Fixes: 8ea4484 ("mailbox: Add generic mechanism for testing Mailbox Controllers")
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Jassi Brar <jassisinghbrar@gmail.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

Author: Wolfram Sang

drivers/mailbox/mailbox-test.c

@@ -366,6 +366,12 @@ static int mbox_test_probe(struct platform_device *pdev)
 	if (!tdev)
 		return -ENOMEM;
 
+	tdev->dev = &pdev->dev;
+	spin_lock_init(&tdev->lock);
+	mutex_init(&tdev->mutex);
+	init_waitqueue_head(&tdev->waitq);
+	platform_set_drvdata(pdev, tdev);
+
 	/* It's okay for MMIO to be NULL */
 	tdev->tx_mmio = devm_platform_get_and_ioremap_resource(pdev, 0, &res);
 	if (PTR_ERR(tdev->tx_mmio) == -EBUSY) {
@@ -395,12 +401,6 @@ static int mbox_test_probe(struct platform_device *pdev)
 	if (!tdev->rx_channel && (tdev->rx_mmio != tdev->tx_mmio))
 		tdev->rx_channel = tdev->tx_channel;
 
-	tdev->dev = &pdev->dev;
-	platform_set_drvdata(pdev, tdev);
-
-	spin_lock_init(&tdev->lock);
-	mutex_init(&tdev->mutex);
-
 	if (tdev->rx_channel) {
 		tdev->rx_buffer = devm_kzalloc(&pdev->dev,
 					       MBOX_MAX_MSG_LEN, GFP_KERNEL);
@@ -414,7 +414,6 @@ static int mbox_test_probe(struct platform_device *pdev)
 	if (ret)
 		goto err_free_chans;
 
-	init_waitqueue_head(&tdev->waitq);
 	dev_info(&pdev->dev, "Successfully registered\n");
 
 	return 0;