netdev - Re: [PATCH v2 net-next 1/2] lan743x: Add main source files for new lan743x driver

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Date:   Thu, 22 Feb 2018 13:43:30 -0800
From:   Florian Fainelli <f.fainelli@...il.com>
To:     Bryan.Whitehead@...rochip.com, andrew@...n.ch
Cc:     davem@...emloft.net, UNGLinuxDriver@...rochip.com,
        netdev@...r.kernel.org
Subject: Re: [PATCH v2 net-next 1/2] lan743x: Add main source files for new
 lan743x driver

On 02/22/2018 01:31 PM, Bryan.Whitehead@...rochip.com wrote:
>>> +static void lan743x_intr_unregister_isr(struct lan743x_adapter *adapter,
>>> +					int vector_index)
>>> +{
>>> +	struct lan743x_vector *vector = &adapter->intr.vector_list
>>> +					[vector_index];
>>> +
>>> +	devm_free_irq(&adapter->pci.pdev->dev, vector->irq, vector);
>>
>> Hu Bryan
>>
>> The point of devm_ is that you don't need to free resources you have
>> allocated using devm_. The core will release them when the device is
>> removed.
> 
> Hi Andrew,
> 
> When I remove the call devm_free_irq, I get a segmentation fault on close
> in pci_disable_msix. Did I do something else wrong?
> 
> Also I'm allocating interrupt resources on interface up, and freeing resources
> on interface down. So if there is an up, down, up sequence then the driver
> will allocate resources twice. In order for devm to work properly, should I
> move all resource allocation into the probe function?

No, most network drivers request their interrupt line in the open
function and free it in the close function. Because you are balancing
each devm_request_irq() with a devm_free_irq(), just don't just devm_*
functions, just the normal request_irq() and free_irq() functions.
-- 
Florian