[PATCH 5.10 1/2] fsl_lpuart: Don't enable interrupts too early

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From: Indan Zupancic <Indan.Zupancic@xxxxxxxxxxxx>

[ Upstream commit 401fb66a355eb0f22096cf26864324f8e63c7d78 ]

If an irq is pending when devm_request_irq() is called, the irq
handler will cause a NULL pointer access because initialisation
is not done yet.

Fixes: 9d7ee0e28da59 ("tty: serial: lpuart: avoid report NULL interrupt")
Cc: stable <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Indan Zupancic <Indan.Zupancic@xxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20220505114750.45423-1-Indan.Zupancic@xxxxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
[5.10 did not have lpuart_global_reset or anything after
uart_add_one_port(), so add the remove call in cleanup manually]
Signed-off-by: Dominique Martinet <dominique.martinet@xxxxxxxxxxxxxxxxx>
---
This was originally intended as a prerequirement to backport the patch
submitted in [1] for 5.10, but even with that part of the patch gone it
makes sense as a fix on its own.

[1] https://lkml.kernel.org/r/20221222114414.1886632-1-linux@xxxxxxxxxxxxxxxxxx

 drivers/tty/serial/fsl_lpuart.c | 18 ++++++++++--------
 1 file changed, 10 insertions(+), 8 deletions(-)

diff --git a/drivers/tty/serial/fsl_lpuart.c b/drivers/tty/serial/fsl_lpuart.c
index 43aca5a2ef0f..223695947b65 100644
--- a/drivers/tty/serial/fsl_lpuart.c
+++ b/drivers/tty/serial/fsl_lpuart.c
@@ -2586,6 +2586,7 @@ static int lpuart_probe(struct platform_device *pdev)
 	struct device_node *np = pdev->dev.of_node;
 	struct lpuart_port *sport;
 	struct resource *res;
+	irq_handler_t handler;
 	int ret;
 
 	sport = devm_kzalloc(&pdev->dev, sizeof(*sport), GFP_KERNEL);
@@ -2658,17 +2659,12 @@ static int lpuart_probe(struct platform_device *pdev)
 
 	if (lpuart_is_32(sport)) {
 		lpuart_reg.cons = LPUART32_CONSOLE;
-		ret = devm_request_irq(&pdev->dev, sport->port.irq, lpuart32_int, 0,
-					DRIVER_NAME, sport);
+		handler = lpuart32_int;
 	} else {
 		lpuart_reg.cons = LPUART_CONSOLE;
-		ret = devm_request_irq(&pdev->dev, sport->port.irq, lpuart_int, 0,
-					DRIVER_NAME, sport);
+		handler = lpuart_int;
 	}
 
-	if (ret)
-		goto failed_irq_request;
-
 	ret = uart_get_rs485_mode(&sport->port);
 	if (ret)
 		goto failed_get_rs485;
@@ -2684,11 +2680,17 @@ static int lpuart_probe(struct platform_device *pdev)
 	if (ret)
 		goto failed_attach_port;
 
+	ret = devm_request_irq(&pdev->dev, sport->port.irq, handler, 0,
+				DRIVER_NAME, sport);
+	if (ret)
+		goto failed_irq_request;
+
 	return 0;
 
+failed_irq_request:
+	uart_remove_one_port(&lpuart_reg, &sport->port);
 failed_get_rs485:
 failed_attach_port:
-failed_irq_request:
 	lpuart_disable_clks(sport);
 	return ret;
 }
-- 
2.35.1





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