Subject: Re: [PATCH 1/4] drivers/serial/ucc_uart.c: Add of_node_put to avoid memory leak

From: Grant Likely <[email-masked]>
Date: Wed, 8 Sep 2010 13:59:11 -0600

On Tue, Aug 31, 2010 at 05:48:55PM +0200, Julia Lawall wrote:
> Add a call to of_node_put in the error handling code following a call to
> of_find_compatible_node or of_find_node_by_type.
> 
> This patch also substantially reorganizes the error handling code in the
> function, to that it is possible first to jump to code that frees qe_port
> and then to jump to code that also puts np.
> 
> The semantic match that finds this problem is as follows:
> (http://coccinelle.lip6.fr/)
> 
> // <smpl>
> @r exists@
> local idexpression x;
> expression E,E1,E2;
> statement S;
> @@
> 
> *x = 
> (of_find_node_by_path
> |of_find_node_by_name
> |of_find_node_by_phandle
> |of_get_parent
> |of_get_next_parent
> |of_get_next_child
> |of_find_compatible_node
> |of_match_node
> |of_find_node_by_type
> |of_find_node_with_property
> |of_find_matching_node
> |of_parse_phandle
> )(...);
> ...
> if (x == NULL) S
> <... when != x = E
> *if (...) {
>   ... when != of_node_put(x)
>       when != if (...) { ... of_node_put(x); ... }
> (
>   return <+...x...+>;
> |
> *  return ...;
> )
> }
> ...>
> (
> E2 = x;
> |
> of_node_put(x);
> )
> // </smpl>
> 
> Signed-off-by: Julia Lawall <[email-masked]>

Looks good to me.

Acked-by: Grant Likely <[email-masked]>

> 
> ---
>  drivers/serial/ucc_uart.c |   67 ++++++++++++++++++++++++----------------------
>  1 file changed, 35 insertions(+), 32 deletions(-)
> 
> diff --git a/drivers/serial/ucc_uart.c b/drivers/serial/ucc_uart.c
> index 3f4848e..38a5ef0 100644
> --- a/drivers/serial/ucc_uart.c
> +++ b/drivers/serial/ucc_uart.c
> @@ -1270,13 +1270,12 @@ static int ucc_uart_probe(struct platform_device *ofdev,
>  	ret = of_address_to_resource(np, 0, &res);
>  	if (ret) {
>  		dev_err(&ofdev->dev, "missing 'reg' property in device tree\n");
> -		kfree(qe_port);
> -		return ret;
> +		goto out_free;
>  	}
>  	if (!res.start) {
>  		dev_err(&ofdev->dev, "invalid 'reg' property in device tree\n");
> -		kfree(qe_port);
> -		return -EINVAL;
> +		ret = -EINVAL;
> +		goto out_free;
>  	}
>  	qe_port->port.mapbase = res.start;
>  
> @@ -1286,17 +1285,17 @@ static int ucc_uart_probe(struct platform_device *ofdev,
>  	if (!iprop) {
>  		iprop = of_get_property(np, "device-id", NULL);
>  		if (!iprop) {
> -			kfree(qe_port);
>  			dev_err(&ofdev->dev, "UCC is unspecified in "
>  				"device tree\n");
> -			return -EINVAL;
> +			ret = -EINVAL;
> +			goto out_free;
>  		}
>  	}
>  
>  	if ((*iprop < 1) || (*iprop > UCC_MAX_NUM)) {
>  		dev_err(&ofdev->dev, "no support for UCC%u\n", *iprop);
> -		kfree(qe_port);
> -		return -ENODEV;
> +		ret = -ENODEV;
> +		goto out_free;
>  	}
>  	qe_port->ucc_num = *iprop - 1;
>  
> @@ -1310,16 +1309,16 @@ static int ucc_uart_probe(struct platform_device *ofdev,
>  	sprop = of_get_property(np, "rx-clock-name", NULL);
>  	if (!sprop) {
>  		dev_err(&ofdev->dev, "missing rx-clock-name in device tree\n");
> -		kfree(qe_port);
> -		return -ENODEV;
> +		ret = -ENODEV;
> +		goto out_free;
>  	}
>  
>  	qe_port->us_info.rx_clock = qe_clock_source(sprop);
>  	if ((qe_port->us_info.rx_clock < QE_BRG1) ||
>  	    (qe_port->us_info.rx_clock > QE_BRG16)) {
>  		dev_err(&ofdev->dev, "rx-clock-name must be a BRG for UART\n");
> -		kfree(qe_port);
> -		return -ENODEV;
> +		ret = -ENODEV;
> +		goto out_free;
>  	}
>  
>  #ifdef LOOPBACK
> @@ -1329,39 +1328,39 @@ static int ucc_uart_probe(struct platform_device *ofdev,
>  	sprop = of_get_property(np, "tx-clock-name", NULL);
>  	if (!sprop) {
>  		dev_err(&ofdev->dev, "missing tx-clock-name in device tree\n");
> -		kfree(qe_port);
> -		return -ENODEV;
> +		ret = -ENODEV;
> +		goto out_free;
>  	}
>  	qe_port->us_info.tx_clock = qe_clock_source(sprop);
>  #endif
>  	if ((qe_port->us_info.tx_clock < QE_BRG1) ||
>  	    (qe_port->us_info.tx_clock > QE_BRG16)) {
>  		dev_err(&ofdev->dev, "tx-clock-name must be a BRG for UART\n");
> -		kfree(qe_port);
> -		return -ENODEV;
> +		ret = -ENODEV;
> +		goto out_free;
>  	}
>  
>  	/* Get the port number, numbered 0-3 */
>  	iprop = of_get_property(np, "port-number", NULL);
>  	if (!iprop) {
>  		dev_err(&ofdev->dev, "missing port-number in device tree\n");
> -		kfree(qe_port);
> -		return -EINVAL;
> +		ret = -EINVAL;
> +		goto out_free;
>  	}
>  	qe_port->port.line = *iprop;
>  	if (qe_port->port.line >= UCC_MAX_UART) {
>  		dev_err(&ofdev->dev, "port-number must be 0-%u\n",
>  			UCC_MAX_UART - 1);
> -		kfree(qe_port);
> -		return -EINVAL;
> +		ret = -EINVAL;
> +		goto out_free;
>  	}
>  
>  	qe_port->port.irq = irq_of_parse_and_map(np, 0);
>  	if (qe_port->port.irq == NO_IRQ) {
>  		dev_err(&ofdev->dev, "could not map IRQ for UCC%u\n",
>  		       qe_port->ucc_num + 1);
> -		kfree(qe_port);
> -		return -EINVAL;
> +		ret = -EINVAL;
> +		goto out_free;
>  	}
>  
>  	/*
> @@ -1373,8 +1372,8 @@ static int ucc_uart_probe(struct platform_device *ofdev,
>  		np = of_find_node_by_type(NULL, "qe");
>  		if (!np) {
>  			dev_err(&ofdev->dev, "could not find 'qe' node\n");
> -			kfree(qe_port);
> -			return -EINVAL;
> +			ret = -EINVAL;
> +			goto out_free;
>  		}
>  	}
>  
> @@ -1382,8 +1381,8 @@ static int ucc_uart_probe(struct platform_device *ofdev,
>  	if (!iprop) {
>  		dev_err(&ofdev->dev,
>  		       "missing brg-frequency in device tree\n");
> -		kfree(qe_port);
> -		return -EINVAL;
> +		ret = -EINVAL;
> +		goto out_np;
>  	}
>  
>  	if (*iprop)
> @@ -1398,16 +1397,16 @@ static int ucc_uart_probe(struct platform_device *ofdev,
>  		if (!iprop) {
>  			dev_err(&ofdev->dev,
>  				"missing QE bus-frequency in device tree\n");
> -			kfree(qe_port);
> -			return -EINVAL;
> +			ret = -EINVAL;
> +			goto out_np;
>  		}
>  		if (*iprop)
>  			qe_port->port.uartclk = *iprop / 2;
>  		else {
>  			dev_err(&ofdev->dev,
>  				"invalid QE bus-frequency in device tree\n");
> -			kfree(qe_port);
> -			return -EINVAL;
> +			ret = -EINVAL;
> +			goto out_np;
>  		}
>  	}
>  
> @@ -1445,8 +1444,7 @@ static int ucc_uart_probe(struct platform_device *ofdev,
>  	if (ret) {
>  		dev_err(&ofdev->dev, "could not add /dev/ttyQE%u\n",
>  		       qe_port->port.line);
> -		kfree(qe_port);
> -		return ret;
> +		goto out_np;
>  	}
>  
>  	dev_set_drvdata(&ofdev->dev, qe_port);
> @@ -1460,6 +1458,11 @@ static int ucc_uart_probe(struct platform_device *ofdev,
>  	       SERIAL_QE_MINOR + qe_port->port.line);
>  
>  	return 0;
> +out_np:
> +	of_node_put(np);
> +out_free:
> +	kfree(qe_port);
> +	return ret;
>  }
>  
>  static int ucc_uart_remove(struct platform_device *ofdev)
>