From d7437fc0d8291181debe032671a289b6bd93f46f Mon Sep 17 00:00:00 2001
From: Wolfram Sang <wsa+renesas@sang-engineering.com>
Date: Thu, 8 Aug 2019 21:54:17 +0200
Subject: [PATCH] i2c: emev2: avoid race when unregistering slave client
Git-commit: d7437fc0d8291181debe032671a289b6bd93f46f
Patch-mainline: v5.3-rc5
References: bsc#1051510

After we disabled interrupts, there might still be an active one
running. Sync before clearing the pointer to the slave device.

Fixes: c31d0a00021d ("i2c: emev2: add slave support")
Reported-by: Krzysztof Adamski <krzysztof.adamski@nokia.com>
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Reviewed-by: Krzysztof Adamski <krzysztof.adamski@nokia.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/i2c/busses/i2c-emev2.c | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/drivers/i2c/busses/i2c-emev2.c b/drivers/i2c/busses/i2c-emev2.c
index 35b302d983e0..959d4912ec0d 100644
--- a/drivers/i2c/busses/i2c-emev2.c
+++ b/drivers/i2c/busses/i2c-emev2.c
@@ -69,6 +69,7 @@ struct em_i2c_device {
 	struct completion msg_done;
 	struct clk *sclk;
 	struct i2c_client *slave;
+	int irq;
 };
 
 static inline void em_clear_set_bit(struct em_i2c_device *priv, u8 clear, u8 set, u8 reg)
@@ -339,6 +340,12 @@ static int em_i2c_unreg_slave(struct i2c_client *slave)
 
 	writeb(0, priv->base + I2C_OFS_SVA0);
 
+	/*
+	 * Wait for interrupt to finish. New slave irqs cannot happen because we
+	 * cleared the slave address and, thus, only extension codes will be
+	 * detected which do not use the slave ptr.
+	 */
+	synchronize_irq(priv->irq);
 	priv->slave = NULL;
 
 	return 0;
@@ -355,7 +362,7 @@ static int em_i2c_probe(struct platform_device *pdev)
 {
 	struct em_i2c_device *priv;
 	struct resource *r;
-	int irq, ret;
+	int ret;
 
 	priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
 	if (!priv)
@@ -390,8 +397,8 @@ static int em_i2c_probe(struct platform_device *pdev)
 
 	em_i2c_reset(&priv->adap);
 
-	irq = platform_get_irq(pdev, 0);
-	ret = devm_request_irq(&pdev->dev, irq, em_i2c_irq_handler, 0,
+	priv->irq = platform_get_irq(pdev, 0);
+	ret = devm_request_irq(&pdev->dev, priv->irq, em_i2c_irq_handler, 0,
 				"em_i2c", priv);
 	if (ret)
 		goto err_clk;
@@ -401,7 +408,8 @@ static int em_i2c_probe(struct platform_device *pdev)
 	if (ret)
 		goto err_clk;
 
-	dev_info(&pdev->dev, "Added i2c controller %d, irq %d\n", priv->adap.nr, irq);
+	dev_info(&pdev->dev, "Added i2c controller %d, irq %d\n", priv->adap.nr,
+		 priv->irq);
 
 	return 0;
 
-- 
2.16.4