Re: [PATCH 01/27] driver core: Constify driver API device_find_child()

[quic_zijuhu <quic_zijuhu@quicinc.com>]

On 8/13/2024 5:48 PM, Greg Kroah-Hartman wrote:
> On Sun, Aug 11, 2024 at 10:24:52AM +0800, Zijun Hu wrote:
>> From: Zijun Hu <quic_zijuhu@quicinc.com>
>>
>> Constify the following driver API:
>> struct device *device_find_child(struct device *dev, void *data,
>> 		int (*match)(struct device *dev, void *data));
>> to
>> struct device *device_find_child(struct device *dev, const void *data,
>>                                  device_match_t match);
>> typedef int (*device_match_t)(struct device *dev, const void *data);
>> Since it should not modify caller's match data @*data.
>>
>> Signed-off-by: Zijun Hu <quic_zijuhu@quicinc.com>
>> ---
>>  drivers/base/core.c    | 11 +++--------
>>  include/linux/device.h |  4 ++--
>>  2 files changed, 5 insertions(+), 10 deletions(-)
>>
>> diff --git a/drivers/base/core.c b/drivers/base/core.c
>> index 3f3ebdb5aa0b..f152e0f8fb03 100644
>> --- a/drivers/base/core.c
>> +++ b/drivers/base/core.c
>> @@ -4062,8 +4062,8 @@ EXPORT_SYMBOL_GPL(device_for_each_child_reverse);
>>   *
>>   * NOTE: you will need to drop the reference with put_device() after use.
>>   */
>> -struct device *device_find_child(struct device *parent, void *data,
>> -				 int (*match)(struct device *dev, void *data))
>> +struct device *device_find_child(struct device *parent, const void *data,
>> +				 device_match_t match)
>>  {
>>  	struct klist_iter i;
>>  	struct device *child;
>> @@ -4108,11 +4108,6 @@ struct device *device_find_child_by_name(struct device *parent,
>>  }
>>  EXPORT_SYMBOL_GPL(device_find_child_by_name);
>>  
>> -static int match_any(struct device *dev, void *unused)
>> -{
>> -	return 1;
>> -}
>> -
>>  /**
>>   * device_find_any_child - device iterator for locating a child device, if any.
>>   * @parent: parent struct device
>> @@ -4124,7 +4119,7 @@ static int match_any(struct device *dev, void *unused)
>>   */
>>  struct device *device_find_any_child(struct device *parent)
>>  {
>> -	return device_find_child(parent, NULL, match_any);
>> +	return device_find_child(parent, NULL, device_match_any);
>>  }
>>  EXPORT_SYMBOL_GPL(device_find_any_child);
>>  
>> diff --git a/include/linux/device.h b/include/linux/device.h
>> index b2423fca3d45..76f10bdbb4ea 100644
>> --- a/include/linux/device.h
>> +++ b/include/linux/device.h
>> @@ -1073,8 +1073,8 @@ int device_for_each_child(struct device *dev, void *data,
>>  			  int (*fn)(struct device *dev, void *data));
>>  int device_for_each_child_reverse(struct device *dev, void *data,
>>  				  int (*fn)(struct device *dev, void *data));
>> -struct device *device_find_child(struct device *dev, void *data,
>> -				 int (*match)(struct device *dev, void *data));
>> +struct device *device_find_child(struct device *dev, const void *data,
>> +				 device_match_t match);
>>  struct device *device_find_child_by_name(struct device *parent,
>>  					 const char *name);
>>  struct device *device_find_any_child(struct device *parent);
>>
>> -- 
>> 2.34.1
>>
> 
> This patch breaks the build:
> 
> ./include/linux/device.h:1077:6: error: unknown type name 'device_match_t'
>  1077 |                                  device_match_t match);
>       |                                  ^
> 1 error generated.
> make[2]: *** [scripts/Makefile.build:117: arch/x86/kernel/asm-offsets.s] Error 1
> make[1]: *** [/mnt/fast_t2/linux/work/driver-core/Makefile:1193: prepare0] Error 2
> 
> How did you test it?
> 
> And as you are changing the parameters here, doesn't the build break
> also because of that?
> 

it seems these dependency patches listed within [PATCH 00/27] are not
picked up.

let me summarize my recently patch serials

A)
Subject: [PATCH v2] drivers/base: Introduce device_match_t for device
finding APIs
https://lore.kernel.org/all/20240811-dev_match_api-v2-1-dd22ff555a30@quicinc.com/

B)
[PATCH 0/5] driver core: Prevent device_find_child() from modifying
caller's match data
https://lore.kernel.org/all/20240811-const_dfc_prepare-v1-0-d67cc416b3d3@quicinc.com/

C)  // this depends on both A) and B)
Subject: [PATCH 00/27] driver core: Make device_find_child()'s match
function take a const pointer
https://lore.kernel.org/all/20240811-const_dfc_done-v1-0-9d85e3f943cb@quicinc.com/

D)
Subject: [PATCH v2] driver core: Simplify driver API
device_find_child_by_name() implementation
https://lore.kernel.org/all/20240811-simply_api_dfcbn-v2-1-d0398acdc366@quicinc.com/


ALL these patch serials are based on driver-core tree with branch
driver-core-next, ALL of them can be built PASS.

> thanks,
> 
> greg k-h