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Message-ID: <003003ae-8f28-931c-3d83-bb33b8e28c1d@gmail.com>
Date:   Fri, 11 Aug 2023 10:55:48 +0400
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Subject: Re: [PATCH 1/3] fpga: bridge: make fpga_bridge_class a static const
 structure
Content-Language: en-US
To:     Xu Yilun <yilun.xu@intel.com>
Cc:     mdf@kernel.org, hao.wu@intel.com, trix@redhat.com,
        linux-fpga@vger.kernel.org, linux-kernel@vger.kernel.org,
        gregkh@linuxfoundation.org
References: <20230810172210.6338-1-ivan.orlov0322@gmail.com>
 <ZNWmhLCeEu07AMPK@yilunxu-OptiPlex-7050>
From:   Ivan Orlov <ivan.orlov0322@gmail.com>
In-Reply-To: <ZNWmhLCeEu07AMPK@yilunxu-OptiPlex-7050>
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On 8/11/23 07:09, Xu Yilun wrote:
> On 2023-08-10 at 21:22:08 +0400, Ivan Orlov wrote:
>> Now that the driver core allows for struct class to be in read-only
>> memory, move the fpga_bridge_class structure to be declared at build
>> time placing it into read-only memory, instead of having to be
>> dynamically allocated at boot time.
>>
>> Suggested-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
>>
>> Signed-off-by: Ivan Orlov <ivan.orlov0322@gmail.com>
>> ---
>>   drivers/fpga/fpga-bridge.c | 106 ++++++++++++++++++-------------------
>>   1 file changed, 52 insertions(+), 54 deletions(-)
>>
>> diff --git a/drivers/fpga/fpga-bridge.c b/drivers/fpga/fpga-bridge.c
>> index a6c25dee9cc1..6e38ddaf16cf 100644
>> --- a/drivers/fpga/fpga-bridge.c
>> +++ b/drivers/fpga/fpga-bridge.c
>> @@ -14,7 +14,6 @@
>>   #include <linux/spinlock.h>
>>   
>>   static DEFINE_IDA(fpga_bridge_ida);
>> -static struct class *fpga_bridge_class;
> 
> Could we still use the forward declaration, to avoid moving too
> much code block.
> 
>>   
>>   /* Lock for adding/removing bridges to linked lists*/
>>   static DEFINE_SPINLOCK(bridge_list_lock);
>> @@ -84,6 +83,53 @@ static struct fpga_bridge *__fpga_bridge_get(struct device *dev,
>>   	return ERR_PTR(ret);
>>   }
>>   
>> +static ssize_t name_show(struct device *dev,
>> +			 struct device_attribute *attr, char *buf)
>> +{
>> +	struct fpga_bridge *bridge = to_fpga_bridge(dev);
>> +
>> +	return sprintf(buf, "%s\n", bridge->name);
>> +}
>> +
>> +static ssize_t state_show(struct device *dev,
>> +			  struct device_attribute *attr, char *buf)
>> +{
>> +	struct fpga_bridge *bridge = to_fpga_bridge(dev);
>> +	int state = 1;
>> +
>> +	if (bridge->br_ops && bridge->br_ops->enable_show) {
>> +		state = bridge->br_ops->enable_show(bridge);
>> +		if (state < 0)
>> +			return state;
>> +	}
>> +
>> +	return sysfs_emit(buf, "%s\n", state ? "enabled" : "disabled");
>> +}
>> +
>> +static DEVICE_ATTR_RO(name);
>> +static DEVICE_ATTR_RO(state);
>> +
>> +static struct attribute *fpga_bridge_attrs[] = {
>> +	&dev_attr_name.attr,
>> +	&dev_attr_state.attr,
>> +	NULL,
>> +};
>> +ATTRIBUTE_GROUPS(fpga_bridge);
>> +
>> +static void fpga_bridge_dev_release(struct device *dev)
>> +{
>> +	struct fpga_bridge *bridge = to_fpga_bridge(dev);
>> +
>> +	ida_free(&fpga_bridge_ida, bridge->dev.id);
>> +	kfree(bridge);
>> +}
>> +
>> +static const struct class fpga_bridge_class = {
>> +	.name = "fpga_bridge",
>> +	.dev_groups = fpga_bridge_groups,
>> +	.dev_release = fpga_bridge_dev_release,
>> +};
> 
> Insert them between __fpga_bridge_get() and of_fpga_bridge_get() is not
> preferred. See below comments.
> 
>> +
>>   /**
>>    * of_fpga_bridge_get - get an exclusive reference to an fpga bridge
>>    *
>> @@ -99,7 +145,7 @@ struct fpga_bridge *of_fpga_bridge_get(struct device_node *np,
>>   {
>>   	struct device *dev;
>>   
>> -	dev = class_find_device_by_of_node(fpga_bridge_class, np);
>> +	dev = class_find_device_by_of_node(&fpga_bridge_class, np);
>>   	if (!dev)
>>   		return ERR_PTR(-ENODEV);
>>   
>> @@ -126,7 +172,7 @@ struct fpga_bridge *fpga_bridge_get(struct device *dev,
>>   {
>>   	struct device *bridge_dev;
>>   
>> -	bridge_dev = class_find_device(fpga_bridge_class, NULL, dev,
>> +	bridge_dev = class_find_device(&fpga_bridge_class, NULL, dev,
>>   				       fpga_bridge_dev_match);
>>   	if (!bridge_dev)
>>   		return ERR_PTR(-ENODEV);
>> @@ -281,39 +327,6 @@ int fpga_bridge_get_to_list(struct device *dev,
>>   }
>>   EXPORT_SYMBOL_GPL(fpga_bridge_get_to_list);
>>   
>> -static ssize_t name_show(struct device *dev,
>> -			 struct device_attribute *attr, char *buf)
>> -{
>> -	struct fpga_bridge *bridge = to_fpga_bridge(dev);
>> -
>> -	return sprintf(buf, "%s\n", bridge->name);
>> -}
>> -
>> -static ssize_t state_show(struct device *dev,
>> -			  struct device_attribute *attr, char *buf)
>> -{
>> -	struct fpga_bridge *bridge = to_fpga_bridge(dev);
>> -	int state = 1;
>> -
>> -	if (bridge->br_ops && bridge->br_ops->enable_show) {
>> -		state = bridge->br_ops->enable_show(bridge);
>> -		if (state < 0)
>> -			return state;
>> -	}
>> -
>> -	return sysfs_emit(buf, "%s\n", state ? "enabled" : "disabled");
>> -}
>> -
>> -static DEVICE_ATTR_RO(name);
>> -static DEVICE_ATTR_RO(state);
>> -
>> -static struct attribute *fpga_bridge_attrs[] = {
>> -	&dev_attr_name.attr,
>> -	&dev_attr_state.attr,
>> -	NULL,
>> -};
>> -ATTRIBUTE_GROUPS(fpga_bridge);
>> -
>>   /**
>>    * fpga_bridge_register - create and register an FPGA Bridge device
>>    * @parent:	FPGA bridge device from pdev
>> @@ -359,7 +372,7 @@ fpga_bridge_register(struct device *parent, const char *name,
>>   	bridge->priv = priv;
>>   
>>   	bridge->dev.groups = br_ops->groups;
>> -	bridge->dev.class = fpga_bridge_class;
>> +	bridge->dev.class = &fpga_bridge_class;
>>   	bridge->dev.parent = parent;
>>   	bridge->dev.of_node = parent->of_node;
>>   	bridge->dev.id = id;
>> @@ -407,29 +420,14 @@ void fpga_bridge_unregister(struct fpga_bridge *bridge)
>>   }
>>   EXPORT_SYMBOL_GPL(fpga_bridge_unregister);
>>   
>> -static void fpga_bridge_dev_release(struct device *dev)
>> -{
>> -	struct fpga_bridge *bridge = to_fpga_bridge(dev);
>> -
>> -	ida_free(&fpga_bridge_ida, bridge->dev.id);
>> -	kfree(bridge);
>> -}
>> -
> 
> How about put the fpga_bridge_class definition here?
> 
> Thanks,
> Yilun

Hi Yilun,

Thank you for the review, I agree that forward declaration is better in 
this case. I'll send you the V2 after making suggested changes.

--
Kind regards,
Ivan Orlov