netdev - Re:Re: [PATCH] ftgmac100: Hold reference returned by of_get_child_by

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Date:   Wed, 6 Jul 2022 16:55:37 +0800 (CST)
From:   "Liang He" <windhl@....com>
To:     "Jakub Kicinski" <kuba@...nel.org>
Cc:     davem@...emloft.net, edumazet@...gle.com, pabeni@...hat.com,
        netdev@...r.kernel.org
Subject: Re:Re: [PATCH] ftgmac100: Hold reference returned by
 of_get_child_by_name()




At 2022-07-06 09:48:05, "Jakub Kicinski" <kuba@...nel.org> wrote:
>On Mon,  4 Jul 2022 23:18:19 +0800 Liang He wrote:
>> In ftgmac100_probe(), we should hold the refernece returned by
>> of_get_child_by_name() and use it to call of_node_put() for
>> reference balance.
>> 
>> Signed-off-by: Liang He <windhl@....com>
>> ---
>>  drivers/net/ethernet/faraday/ftgmac100.c | 6 ++++--
>>  1 file changed, 4 insertions(+), 2 deletions(-)
>> 
>> diff --git a/drivers/net/ethernet/faraday/ftgmac100.c b/drivers/net/ethernet/faraday/ftgmac100.c
>> index 5231818943c6..e50bd7beb09b 100644
>> --- a/drivers/net/ethernet/faraday/ftgmac100.c
>> +++ b/drivers/net/ethernet/faraday/ftgmac100.c
>> @@ -1770,7 +1770,7 @@ static int ftgmac100_probe(struct platform_device *pdev)
>>  	int irq;
>>  	struct net_device *netdev;
>>  	struct ftgmac100 *priv;
>> -	struct device_node *np;
>> +	struct device_node *np, *child_np;
>>  	int err = 0;
>>  
>>  	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>> @@ -1883,7 +1883,7 @@ static int ftgmac100_probe(struct platform_device *pdev)
>>  
>>  		/* Display what we found */
>>  		phy_attached_info(phy);
>> -	} else if (np && !of_get_child_by_name(np, "mdio")) {
>> +	} else if (np && !(child_np = of_get_child_by_name(np, "mdio"))) {
>>  		/* Support legacy ASPEED devicetree descriptions that decribe a
>>  		 * MAC with an embedded MDIO controller but have no "mdio"
>>  		 * child node. Automatically scan the MDIO bus for available
>> @@ -1901,6 +1901,8 @@ static int ftgmac100_probe(struct platform_device *pdev)
>>  		}
>>  
>>  	}
>> +	if (child_np)
>> +		of_node_put(child_np);
>
>Since we don't care about the value of the node we should add a helper
>which checks for presence of the node and releases the reference,
>rather than have to do that in this large function.
>
>Please also add a Fixes tag.


Hi, Jakub,

Can you tell me where to add such helper?

you mean add a helper in of.h for common usasge or just add it in this file?

Thanks,

Liang