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From:   Sherry Sun <sherry.sun@nxp.com>
To:     gregkh@linuxfoundation.org, jirislaby@kernel.org,
        vabhav.sharma@nxp.com
Cc:     linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-imx@nxp.com
Subject: [PATCH] tty: serial: fsl_lpuart: fix potential bug when using both of_alias_get_id and ida_simple_get
Date:   Mon, 21 Mar 2022 19:22:11 +0800
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Now fsl_lpuart driver use both of_alias_get_id() and ida_simple_get() in
.probe(), which has the potential bug. For example, when remove the
lpuart7 alias in dts, of_alias_get_id() will return error, then call
ida_simple_get() to allocate the id 0 for lpuart7, this may confilct
with the lpuart4 which has alias 0.

    aliases {
	...
        serial0 = &lpuart4;
        serial1 = &lpuart5;
        serial2 = &lpuart6;
        serial3 = &lpuart7;
    }

So remove the ida_simple_get() in .probe(), return an error directly
when calling of_alias_get_id() fails, which is consistent with other
uart drivers behavior.

Fixes: 3bc3206e1c0f ("serial: fsl_lpuart: Remove the alias node dependence")
Signed-off-by: Sherry Sun <sherry.sun@nxp.com>
---
 drivers/tty/serial/fsl_lpuart.c | 24 ++++--------------------
 1 file changed, 4 insertions(+), 20 deletions(-)

diff --git a/drivers/tty/serial/fsl_lpuart.c b/drivers/tty/serial/fsl_lpuart.c
index 452a015825ba..40465d23d7ad 100644
--- a/drivers/tty/serial/fsl_lpuart.c
+++ b/drivers/tty/serial/fsl_lpuart.c
@@ -239,8 +239,6 @@
 /* IMX lpuart has four extra unused regs located at the beginning */
 #define IMX_REG_OFF	0x10
 
-static DEFINE_IDA(fsl_lpuart_ida);
-
 enum lpuart_type {
 	VF610_LPUART,
 	LS1021A_LPUART,
@@ -276,7 +274,6 @@ struct lpuart_port {
 	int			rx_dma_rng_buf_len;
 	unsigned int		dma_tx_nents;
 	wait_queue_head_t	dma_wait;
-	bool			id_allocated;
 };
 
 struct lpuart_soc_data {
@@ -2716,23 +2713,18 @@ static int lpuart_probe(struct platform_device *pdev)
 
 	ret = of_alias_get_id(np, "serial");
 	if (ret < 0) {
-		ret = ida_simple_get(&fsl_lpuart_ida, 0, UART_NR, GFP_KERNEL);
-		if (ret < 0) {
-			dev_err(&pdev->dev, "port line is full, add device failed\n");
-			return ret;
-		}
-		sport->id_allocated = true;
+		dev_err(&pdev->dev, "failed to get alias id, errno %d\n", ret);
+		return ret;
 	}
 	if (ret >= ARRAY_SIZE(lpuart_ports)) {
 		dev_err(&pdev->dev, "serial%d out of range\n", ret);
-		ret = -EINVAL;
-		goto failed_out_of_range;
+		return -EINVAL;
 	}
 	sport->port.line = ret;
 
 	ret = lpuart_enable_clks(sport);
 	if (ret)
-		goto failed_clock_enable;
+		return ret;
 	sport->port.uartclk = lpuart_get_baud_clk_rate(sport);
 
 	lpuart_ports[sport->port.line] = sport;
@@ -2781,10 +2773,6 @@ static int lpuart_probe(struct platform_device *pdev)
 failed_attach_port:
 failed_irq_request:
 	lpuart_disable_clks(sport);
-failed_clock_enable:
-failed_out_of_range:
-	if (sport->id_allocated)
-		ida_simple_remove(&fsl_lpuart_ida, sport->port.line);
 	return ret;
 }
 
@@ -2794,9 +2782,6 @@ static int lpuart_remove(struct platform_device *pdev)
 
 	uart_remove_one_port(&lpuart_reg, &sport->port);
 
-	if (sport->id_allocated)
-		ida_simple_remove(&fsl_lpuart_ida, sport->port.line);
-
 	lpuart_disable_clks(sport);
 
 	if (sport->dma_tx_chan)
@@ -2926,7 +2911,6 @@ static int __init lpuart_serial_init(void)
 
 static void __exit lpuart_serial_exit(void)
 {
-	ida_destroy(&fsl_lpuart_ida);
 	platform_driver_unregister(&lpuart_driver);
 	uart_unregister_driver(&lpuart_reg);
 }
-- 
2.17.1