[PATCH] tty: serial: fsl_lpuart: fix potential bug when using both of_alias_get_id and ida_simple_get

[PATCH] tty: serial: fsl_lpuart: fix potential bug when using both of_alias_get_id and ida_simple_get

[Sherry Sun]

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

RE: [PATCH] tty: serial: fsl_lpuart: fix potential bug when using both of_alias_get_id and ida_simple_get

[Shenwei Wang]

> -----Original Message-----
> From: Sherry Sun <sherry.sun@nxp.com>
> Sent: Monday, March 21, 2022 6:22 AM
> To: gregkh@linuxfoundation.org; jirislaby@kernel.org; Vabhav Sharma
> <vabhav.sharma@nxp.com>
> Cc: linux-serial@vger.kernel.org; linux-kernel@vger.kernel.org; dl-linux-imx
> <linux-imx@nxp.com>
> Subject: [PATCH] tty: serial: fsl_lpuart: fix potential bug when using both
> of_alias_get_id and ida_simple_get
> 
> 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.

The behavior of ida_simple_get() is to allocate an unused alias number. Do you see any conflict when you test?

Regards,
Shenwei

> 
>     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

RE: [PATCH] tty: serial: fsl_lpuart: fix potential bug when using both of_alias_get_id and ida_simple_get

[Sherry Sun]

Hi Shenwei,

> > Subject: [PATCH] tty: serial: fsl_lpuart: fix potential bug when using
> > both of_alias_get_id and ida_simple_get
> >
> > 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.
> 
> The behavior of ida_simple_get() is to allocate an unused alias number. Do
> you see any conflict when you test?
> 

Yes, I have verified this on imx8ulp, I print the port.line value for each uart port.
When I remove the lpuart7 alias, the lpuart7 will get the id 0, same as lpuart4, which caused the lpuart7 probe fail.
ida_simple_get() cannot figure out which id has been used in the uart driver.

[    0.894549] port.line = 0 --> lpuart4
[    0.908148] port.line = 1 --> lpuart5
[    0.939844] port.line = 2 --> lpuart6
[    0.953608] port.line = 0 --> lpuart7

--- a/arch/arm64/boot/dts/freescale/imx8ulp.dtsi
+++ b/arch/arm64/boot/dts/freescale/imx8ulp.dtsi
@@ -25,7 +25,6 @@
                serial0 = &lpuart4;
                serial1 = &lpuart5;
                serial2 = &lpuart6;
-               serial3 = &lpuart7;
        };

Best regards
Sherry

> Regards,
> Shenwei
> 
> >
> >     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

RE: [PATCH] tty: serial: fsl_lpuart: fix potential bug when using both of_alias_get_id and ida_simple_get

[Sherry Sun]

Gentle ping...

> -----Original Message-----
> From: Sherry Sun
> Sent: 2022年3月21日 19:25
> To: gregkh@linuxfoundation.org; jirislaby@kernel.org; Vabhav Sharma
> <vabhav.sharma@nxp.com>
> Cc: linux-serial@vger.kernel.org; linux-kernel@vger.kernel.org; dl-linux-imx
> <linux-imx@nxp.com>
> Subject: [PATCH] tty: serial: fsl_lpuart: fix potential bug when using both
> of_alias_get_id and ida_simple_get
> 
> 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

Re: [PATCH] tty: serial: fsl_lpuart: fix potential bug when using both of_alias_get_id and ida_simple_get

[gregkh]

On Fri, Mar 25, 2022 at 01:27:05AM +0000, Sherry Sun wrote:
> Gentle ping...

It is the middle of the merge window.  I can't do anything with new
changes until after 5.18-rc1 is out.  Please wait until then.

In the meantime, please help out by reviewing other pending patches from
the mailing list.

thanks!

greg k-h

RE: [PATCH] tty: serial: fsl_lpuart: fix potential bug when using both of_alias_get_id and ida_simple_get

[Sherry Sun]

Hi Greg,

> Subject: Re: [PATCH] tty: serial: fsl_lpuart: fix potential bug when using both
> of_alias_get_id and ida_simple_get
> 
> On Fri, Mar 25, 2022 at 01:27:05AM +0000, Sherry Sun wrote:
> > Gentle ping...
> 
> It is the middle of the merge window.  I can't do anything with new
> changes until after 5.18-rc1 is out.  Please wait until then.
> 
> In the meantime, please help out by reviewing other pending patches from
> the mailing list.

Got it, thanks for the info.

Best regards
Sherry

> 
> thanks!
> 
> greg k-h