linux-kernel - Re: [PATCH v2 5/6] vfio: platform: use list of registered reset function

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Date:	Thu, 22 Oct 2015 13:46:27 +0200
From:	Eric Auger <eric.auger@...aro.org>
To:	Arnd Bergmann <arnd@...db.de>
Cc:	eric.auger@...com, alex.williamson@...hat.com,
	b.reynal@...tualopensystems.com,
	linux-arm-kernel@...ts.infradead.org, kvmarm@...ts.cs.columbia.edu,
	kvm@...r.kernel.org, christoffer.dall@...aro.org,
	linux-kernel@...r.kernel.org, patches@...aro.org
Subject: Re: [PATCH v2 5/6] vfio: platform: use list of registered reset
 function

On 10/22/2015 12:19 PM, Arnd Bergmann wrote:
> On Thursday 22 October 2015 11:42:01 Eric Auger wrote:
>> Remove the static lookup table and use the dynamic list of registered
>> reset functions instead. Also load the reset module through its alias.
>> The reset struct module pointer is stored in vfio_platform_device.
>>
>> We also remove the useless struct device pointer parameter in
>> vfio_platform_get_reset.
>>
>> This patch fixes the issue related to the usage of __symbol_get, which
>> besides from being moot, prevented compilation with CONFIG_MODULES
>> disabled.
>>
>> Also usage of MODULE_ALIAS makes possible to add a new reset module
>> without needing to update the framework. This was suggested by Arnd.
>>
>> Signed-off-by: Eric Auger <eric.auger@...aro.org>
>> Reported-by: Arnd Bergmann <arnd@...db.de>
> 
> Looks good, just small style issues:
> 
>>
>> -			}
>> +	mutex_lock(&reset_lock);
>> +	list_for_each_entry(iter, &reset_list, link) {
>> +		if (!strcmp(iter->compat, compat) &&
>> +			try_module_get(iter->owner)) {
>> +			*module = iter->owner;
>> +			mutex_unlock(&reset_lock);
>> +			return iter->reset;
>>  		}
>>  	}
>> +
>> +	mutex_unlock(&reset_lock);
>> +	return NULL;
> 
> Better use 'break' to have a single mutex_unlock and return  statement.
OK
> 
>> +
>>  
>>  static void vfio_platform_put_reset(struct vfio_platform_device *vdev)
>>  {
>> -	if (vdev->reset)
>> -		symbol_put_addr(vdev->reset);
>> +	if (vdev->reset) {
>> +		module_put(vdev->reset_module);
>> +		vdev->reset_module = NULL;
>> +		vdev->reset = NULL;
>> +	}
>>  }
> 
> This gets called from the remove callback. No need to clear those
> struct members immediately before the kfree().
I should have added those assignments in next patch actually. This
latter moves the vfio_platform_put_reset call in the release function.

Best Regards

Eric
> 
> 	Arnd
> 

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