linux-kernel - Re: [PATCH v3 05/23] ata: libahci_platform: Explicitly set rc on devres

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Date:   Thu, 12 May 2022 12:32:42 +0200
From:   Damien Le Moal <damien.lemoal@...nsource.wdc.com>
To:     Hannes Reinecke <hare@...e.de>,
        Serge Semin <Sergey.Semin@...kalelectronics.ru>,
        Hans de Goede <hdegoede@...hat.com>,
        Jens Axboe <axboe@...nel.dk>
Cc:     Serge Semin <fancer.lancer@...il.com>,
        Alexey Malahov <Alexey.Malahov@...kalelectronics.ru>,
        Pavel Parkhomenko <Pavel.Parkhomenko@...kalelectronics.ru>,
        Rob Herring <robh+dt@...nel.org>, linux-ide@...r.kernel.org,
        linux-kernel@...r.kernel.org, devicetree@...r.kernel.org
Subject: Re: [PATCH v3 05/23] ata: libahci_platform: Explicitly set rc on
 devres_alloc failure

On 2022/05/12 8:27, Hannes Reinecke wrote:
> On 5/12/22 01:17, Serge Semin wrote:
>> It's better for readability and maintainability to explicitly assign an
>> error number to the variable used then as a return value from the method
>> on the cleanup-on-error path. So adding new code in the method we won't
>> have to think whether the overridden rc-variable is set afterward in case
>> of an error. Saving one line of code doesn't worth it especially seeing
>> the rest of the ahci_platform_get_resources() function errors handling
>> blocks do explicitly write errno to rc.
>>
>> Signed-off-by: Serge Semin <Sergey.Semin@...kalelectronics.ru>
>>
>> ---
>>
>> Changelog v2:
>> - Drop rc variable initialization (@Damien)
>> ---
>>   drivers/ata/libahci_platform.c | 6 ++++--
>>   1 file changed, 4 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/ata/libahci_platform.c b/drivers/ata/libahci_platform.c
>> index 32495ae96567..f7f9bfcfc164 100644
>> --- a/drivers/ata/libahci_platform.c
>> +++ b/drivers/ata/libahci_platform.c
>> @@ -389,7 +389,7 @@ struct ahci_host_priv *ahci_platform_get_resources(struct platform_device *pdev,
>>   	struct ahci_host_priv *hpriv;
>>   	struct clk *clk;
>>   	struct device_node *child;
>> -	int i, enabled_ports = 0, rc = -ENOMEM, child_nodes;
>> +	int i, enabled_ports = 0, rc, child_nodes;
>>   	u32 mask_port_map = 0;
>>   
>>   	if (!devres_open_group(dev, NULL, GFP_KERNEL))
>> @@ -397,8 +397,10 @@ struct ahci_host_priv *ahci_platform_get_resources(struct platform_device *pdev,
>>   
>>   	hpriv = devres_alloc(ahci_platform_put_resources, sizeof(*hpriv),
>>   			     GFP_KERNEL);
>> -	if (!hpriv)
>> +	if (!hpriv) {
>> +		rc = -ENOMEM;
>>   		goto err_out;
>> +	}
>>   
>>   	devres_add(dev, hpriv);
>>   
> I disagree.
> As 'rc' is now only initialized within a conditional we're risking 'rc' 
> will be left uninitialized.
> And in the end, it's a matter of style; this patch doesn't change the 
> flow of events and the benefits are hard to see.

Yes. Let's drop this patch. Not improving anything.

> 
> Cheers,
> 
> Hannes


-- 
Damien Le Moal
Western Digital Research