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Message-ID: <003003ae-8f28-931c-3d83-bb33b8e28c1d@gmail.com>
Date: Fri, 11 Aug 2023 10:55:48 +0400
From: Ivan Orlov <ivan.orlov0322@...il.com>
To: Xu Yilun <yilun.xu@...el.com>
Cc: mdf@...nel.org, hao.wu@...el.com, trix@...hat.com,
linux-fpga@...r.kernel.org, linux-kernel@...r.kernel.org,
gregkh@...uxfoundation.org
Subject: Re: [PATCH 1/3] fpga: bridge: make fpga_bridge_class a static const
structure
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@...uxfoundation.org>
>>
>> Signed-off-by: Ivan Orlov <ivan.orlov0322@...il.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
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