[v1] memory: simplify with scoped/cleanup.h for device nodes

[PATCH 1/9] memory: atmel-ebi: use scoped device node handling to simplify error paths

Posted by Krzysztof Kozlowski 1 year, 5 months ago

Obtain the device node reference with scoped/cleanup.h to reduce error
handling and make the code a bit simpler.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
---
 drivers/memory/atmel-ebi.c | 29 ++++++++++-------------------
 1 file changed, 10 insertions(+), 19 deletions(-)

diff --git a/drivers/memory/atmel-ebi.c b/drivers/memory/atmel-ebi.c
index e8bb5f37f5cb..fcbfc2655d8d 100644
--- a/drivers/memory/atmel-ebi.c
+++ b/drivers/memory/atmel-ebi.c
@@ -6,6 +6,7 @@
  * Copyright (C) 2013 Jean-Jacques Hiblot <jjhiblot@traphandler.com>
  */
 
+#include <linux/cleanup.h>
 #include <linux/clk.h>
 #include <linux/io.h>
 #include <linux/mfd/syscon.h>
@@ -517,7 +518,7 @@ static int atmel_ebi_dev_disable(struct atmel_ebi *ebi, struct device_node *np)
 static int atmel_ebi_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
-	struct device_node *child, *np = dev->of_node, *smc_np;
+	struct device_node *child, *np = dev->of_node;
 	struct atmel_ebi *ebi;
 	int ret, reg_cells;
 	struct clk *clk;
@@ -541,30 +542,24 @@ static int atmel_ebi_probe(struct platform_device *pdev)
 
 	ebi->clk = clk;
 
-	smc_np = of_parse_phandle(dev->of_node, "atmel,smc", 0);
+	struct device_node *smc_np __free(device_node) = of_parse_phandle(dev->of_node,
+									  "atmel,smc", 0);
 
 	ebi->smc.regmap = syscon_node_to_regmap(smc_np);
-	if (IS_ERR(ebi->smc.regmap)) {
-		ret = PTR_ERR(ebi->smc.regmap);
-		goto put_node;
-	}
+	if (IS_ERR(ebi->smc.regmap))
+		return PTR_ERR(ebi->smc.regmap);
 
 	ebi->smc.layout = atmel_hsmc_get_reg_layout(smc_np);
-	if (IS_ERR(ebi->smc.layout)) {
-		ret = PTR_ERR(ebi->smc.layout);
-		goto put_node;
-	}
+	if (IS_ERR(ebi->smc.layout))
+		return PTR_ERR(ebi->smc.layout);
 
 	ebi->smc.clk = of_clk_get(smc_np, 0);
 	if (IS_ERR(ebi->smc.clk)) {
-		if (PTR_ERR(ebi->smc.clk) != -ENOENT) {
-			ret = PTR_ERR(ebi->smc.clk);
-			goto put_node;
-		}
+		if (PTR_ERR(ebi->smc.clk) != -ENOENT)
+			return PTR_ERR(ebi->smc.clk);
 
 		ebi->smc.clk = NULL;
 	}
-	of_node_put(smc_np);
 	ret = clk_prepare_enable(ebi->smc.clk);
 	if (ret)
 		return ret;
@@ -615,10 +610,6 @@ static int atmel_ebi_probe(struct platform_device *pdev)
 	}
 
 	return of_platform_populate(np, NULL, NULL, dev);
-
-put_node:
-	of_node_put(smc_np);
-	return ret;
 }
 
 static __maybe_unused int atmel_ebi_resume(struct device *dev)

-- 
2.43.0

Re: [PATCH 1/9] memory: atmel-ebi: use scoped device node handling to simplify error paths

Posted by Jonathan Cameron 1 year, 5 months ago

On Mon, 12 Aug 2024 15:33:55 +0200
Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org> wrote:

> Obtain the device node reference with scoped/cleanup.h to reduce error
> handling and make the code a bit simpler.
> 
> Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>

Hi,

Comments inline.
> ---
>  drivers/memory/atmel-ebi.c | 29 ++++++++++-------------------
>  1 file changed, 10 insertions(+), 19 deletions(-)
> 
> diff --git a/drivers/memory/atmel-ebi.c b/drivers/memory/atmel-ebi.c
> index e8bb5f37f5cb..fcbfc2655d8d 100644
> --- a/drivers/memory/atmel-ebi.c
> +++ b/drivers/memory/atmel-ebi.c
> @@ -6,6 +6,7 @@
>   * Copyright (C) 2013 Jean-Jacques Hiblot <jjhiblot@traphandler.com>
>   */
>  
> +#include <linux/cleanup.h>
>  #include <linux/clk.h>
>  #include <linux/io.h>
>  #include <linux/mfd/syscon.h>
> @@ -517,7 +518,7 @@ static int atmel_ebi_dev_disable(struct atmel_ebi *ebi, struct device_node *np)
>  static int atmel_ebi_probe(struct platform_device *pdev)
>  {
>  	struct device *dev = &pdev->dev;
> -	struct device_node *child, *np = dev->of_node, *smc_np;
> +	struct device_node *child, *np = dev->of_node;
>  	struct atmel_ebi *ebi;
>  	int ret, reg_cells;
>  	struct clk *clk;
> @@ -541,30 +542,24 @@ static int atmel_ebi_probe(struct platform_device *pdev)
>  
>  	ebi->clk = clk;
>  
> -	smc_np = of_parse_phandle(dev->of_node, "atmel,smc", 0);
> +	struct device_node *smc_np __free(device_node) = of_parse_phandle(dev->of_node,
> +									  "atmel,smc", 0);
Trivial:
I'd line break this as
> +	struct device_node *smc_np __free(device_node) =
		of_parse_phandle(dev->of_node, "atmel,smc", 0);

>  
>  	ebi->smc.regmap = syscon_node_to_regmap(smc_np);
> -	if (IS_ERR(ebi->smc.regmap)) {
> -		ret = PTR_ERR(ebi->smc.regmap);
> -		goto put_node;
> -	}
> +	if (IS_ERR(ebi->smc.regmap))
> +		return PTR_ERR(ebi->smc.regmap);
>  
>  	ebi->smc.layout = atmel_hsmc_get_reg_layout(smc_np);
> -	if (IS_ERR(ebi->smc.layout)) {
> -		ret = PTR_ERR(ebi->smc.layout);
> -		goto put_node;
> -	}
> +	if (IS_ERR(ebi->smc.layout))
> +		return PTR_ERR(ebi->smc.layout);
>  
>  	ebi->smc.clk = of_clk_get(smc_np, 0);
>  	if (IS_ERR(ebi->smc.clk)) {
> -		if (PTR_ERR(ebi->smc.clk) != -ENOENT) {
> -			ret = PTR_ERR(ebi->smc.clk);
> -			goto put_node;
> -		}
> +		if (PTR_ERR(ebi->smc.clk) != -ENOENT)
> +			return PTR_ERR(ebi->smc.clk);
>  
>  		ebi->smc.clk = NULL;
>  	}
> -	of_node_put(smc_np);

The large change in scope is a bit inelegant as it now hangs on to
the smc_np much longer than before.

Maybe it's worth pulling out the modified code as a 
atem_eb_probe_smc(struct device_node *smc_np, struct atmel_ebi_smc *smc )

or something like with a struct_group to define the atmel_ebi_smc

That would keep the tight scope for the data and generally simplify it
a bit.

>  	ret = clk_prepare_enable(ebi->smc.clk);
>  	if (ret)
>  		return ret;
> @@ -615,10 +610,6 @@ static int atmel_ebi_probe(struct platform_device *pdev)
>  	}
>  
>  	return of_platform_populate(np, NULL, NULL, dev);
> -
> -put_node:
> -	of_node_put(smc_np);
> -	return ret;
>  }
>  
>  static __maybe_unused int atmel_ebi_resume(struct device *dev)
>

Re: [PATCH 1/9] memory: atmel-ebi: use scoped device node handling to simplify error paths

Posted by Krzysztof Kozlowski 1 year, 5 months ago

On 14/08/2024 18:38, Jonathan Cameron wrote:
> On Mon, 12 Aug 2024 15:33:55 +0200
> Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org> wrote:
> 
>> Obtain the device node reference with scoped/cleanup.h to reduce error
>> handling and make the code a bit simpler.
>>
>> Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
> 
> Hi,
> 
> Comments inline.
>> ---
>>  drivers/memory/atmel-ebi.c | 29 ++++++++++-------------------
>>  1 file changed, 10 insertions(+), 19 deletions(-)
>>
>> diff --git a/drivers/memory/atmel-ebi.c b/drivers/memory/atmel-ebi.c
>> index e8bb5f37f5cb..fcbfc2655d8d 100644
>> --- a/drivers/memory/atmel-ebi.c
>> +++ b/drivers/memory/atmel-ebi.c
>> @@ -6,6 +6,7 @@
>>   * Copyright (C) 2013 Jean-Jacques Hiblot <jjhiblot@traphandler.com>
>>   */
>>  
>> +#include <linux/cleanup.h>
>>  #include <linux/clk.h>
>>  #include <linux/io.h>
>>  #include <linux/mfd/syscon.h>
>> @@ -517,7 +518,7 @@ static int atmel_ebi_dev_disable(struct atmel_ebi *ebi, struct device_node *np)
>>  static int atmel_ebi_probe(struct platform_device *pdev)
>>  {
>>  	struct device *dev = &pdev->dev;
>> -	struct device_node *child, *np = dev->of_node, *smc_np;
>> +	struct device_node *child, *np = dev->of_node;
>>  	struct atmel_ebi *ebi;
>>  	int ret, reg_cells;
>>  	struct clk *clk;
>> @@ -541,30 +542,24 @@ static int atmel_ebi_probe(struct platform_device *pdev)
>>  
>>  	ebi->clk = clk;
>>  
>> -	smc_np = of_parse_phandle(dev->of_node, "atmel,smc", 0);
>> +	struct device_node *smc_np __free(device_node) = of_parse_phandle(dev->of_node,
>> +									  "atmel,smc", 0);
> Trivial:
> I'd line break this as
>> +	struct device_node *smc_np __free(device_node) =
> 		of_parse_phandle(dev->of_node, "atmel,smc", 0);

Yeah, I have troubles with this constructor+destructor syntaxes. They
are way past 80 and 100 column, so maybe indeed should be wrapped at '='.

> 
>>  
>>  	ebi->smc.regmap = syscon_node_to_regmap(smc_np);
>> -	if (IS_ERR(ebi->smc.regmap)) {
>> -		ret = PTR_ERR(ebi->smc.regmap);
>> -		goto put_node;
>> -	}
>> +	if (IS_ERR(ebi->smc.regmap))
>> +		return PTR_ERR(ebi->smc.regmap);
>>  
>>  	ebi->smc.layout = atmel_hsmc_get_reg_layout(smc_np);
>> -	if (IS_ERR(ebi->smc.layout)) {
>> -		ret = PTR_ERR(ebi->smc.layout);
>> -		goto put_node;
>> -	}
>> +	if (IS_ERR(ebi->smc.layout))
>> +		return PTR_ERR(ebi->smc.layout);
>>  
>>  	ebi->smc.clk = of_clk_get(smc_np, 0);
>>  	if (IS_ERR(ebi->smc.clk)) {
>> -		if (PTR_ERR(ebi->smc.clk) != -ENOENT) {
>> -			ret = PTR_ERR(ebi->smc.clk);
>> -			goto put_node;
>> -		}
>> +		if (PTR_ERR(ebi->smc.clk) != -ENOENT)
>> +			return PTR_ERR(ebi->smc.clk);
>>  
>>  		ebi->smc.clk = NULL;
>>  	}
>> -	of_node_put(smc_np);
> 
> The large change in scope is a bit inelegant as it now hangs on to
> the smc_np much longer than before.
> 
> Maybe it's worth pulling out the modified code as a 
> atem_eb_probe_smc(struct device_node *smc_np, struct atmel_ebi_smc *smc )
> 
> or something like with a struct_group to define the atmel_ebi_smc
> 
> That would keep the tight scope for the data and generally simplify it
> a bit.


Are you speaking about any particular code optimization/performance
concerns or readability? Because scope in the latter, I believe, is not
the problem here. The entire point of __free() is that you do not care
about scope of variable or destructor. You know it will be freed, sooner
or later. If it happens later - no problem, anyway we don't have to
"think" about this variable or cleaning up because of __free().

Best regards,
Krzysztof