Re: [PATCH v13 1/4] EINJ: Migrate to a platform driver

[Ben Cheatham <benjamin.cheatham@amd.com>]

Thanks for taking a look Dan, responses inline.

On 2/21/24 12:18 AM, Dan Williams wrote:
> Ben Cheatham wrote:
>> Change the EINJ module to install a platform device/driver on module
>> init and move the module init() and exit() functions to driver probe and
>> remove. This change allows the EINJ module to load regardless of whether
>> setting up EINJ succeeds, which allows dependent modules to still load
>> (i.e. the CXL core).
>>
>> Since EINJ may no longer be initialized when the module loads, any
>> functions that are called from dependent/external modules should check
>> the einj_initialized variable before calling any EINJ functions.
>>
>> Signed-off-by: Ben Cheatham <Benjamin.Cheatham@amd.com>
>> ---
>>  drivers/acpi/apei/einj.c | 46 +++++++++++++++++++++++++++++++++++++---
>>  1 file changed, 43 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/acpi/apei/einj.c b/drivers/acpi/apei/einj.c
>> index 89fb9331c611..6ea323b9d8ef 100644
>> --- a/drivers/acpi/apei/einj.c
>> +++ b/drivers/acpi/apei/einj.c
>> @@ -21,6 +21,7 @@
>>  #include <linux/nmi.h>
>>  #include <linux/delay.h>
>>  #include <linux/mm.h>
>> +#include <linux/platform_device.h>
>>  #include <asm/unaligned.h>
>>  
>>  #include "apei-internal.h"
>> @@ -137,6 +138,11 @@ static struct apei_exec_ins_type einj_ins_type[] = {
>>   */
>>  static DEFINE_MUTEX(einj_mutex);
>>  
>> +/*
>> + * Exported APIs use this flag to exit early if einj_probe() failed.
>> + */
>> +static bool einj_initialized __ro_after_init;
>> +
>>  static void *einj_param;
>>  
>>  static void einj_exec_ctx_init(struct apei_exec_context *ctx)
>> @@ -703,7 +709,7 @@ static int einj_check_table(struct acpi_table_einj *einj_tab)
>>  	return 0;
>>  }
>>  
>> -static int __init einj_init(void)
>> +static int __init einj_probe(struct platform_device *pdev)
>>  {
>>  	int rc;
>>  	acpi_status status;
>> @@ -717,7 +723,7 @@ static int __init einj_init(void)
>>  	status = acpi_get_table(ACPI_SIG_EINJ, 0,
>>  				(struct acpi_table_header **)&einj_tab);
>>  	if (status == AE_NOT_FOUND) {
>> -		pr_warn("EINJ table not found.\n");
>> +		pr_info("EINJ table not found.\n");
> 
> Per comment on cover letter this should be pr_debug() to hide it given
> that this module is no longer only loaded manually.
> 

Alright sounds good.

>>  		return -ENODEV;
>>  	} else if (ACPI_FAILURE(status)) {
>>  		pr_err("Failed to get EINJ table: %s\n",
>> @@ -805,7 +811,7 @@ static int __init einj_init(void)
>>  	return rc;
>>  }
>>  
>> -static void __exit einj_exit(void)
>> +static void __exit einj_remove(struct platform_device *pdev)
>>  {
>>  	struct apei_exec_context ctx;
>>  
>> @@ -826,6 +832,40 @@ static void __exit einj_exit(void)
>>  	acpi_put_table((struct acpi_table_header *)einj_tab);
>>  }
>>  
>> +static struct platform_device *einj_dev;
>> +struct platform_driver einj_driver = {
> 
> This can be static.
> 

Will change.

>> +	.remove_new = einj_remove,
>> +	.driver = {
>> +		.name = "acpi-einj",
>> +	},
>> +};
>> +
>> +static int __init einj_init(void)
>> +{
>> +	struct platform_device_info einj_dev_info = {
>> +		.name = "acpi-einj",
>> +		.id = -1,
>> +	};
>> +	int rc;
>> +
>> +	einj_dev = platform_device_register_full(&einj_dev_info);
>> +	if (IS_ERR_OR_NULL(einj_dev))
> 
> Given that platform_device_register_full() never returns NULL, this
> should be IS_ERR().
> 

Sure thing.

>> +		return PTR_ERR(einj_dev);
>> +
>> +	rc = platform_driver_probe(&einj_driver, einj_probe);
>> +	einj_initialized = rc == 0;
>> +
>> +	return 0;
>> +}
>> +
>> +static void __exit einj_exit(void)
>> +{
>> +	if (einj_initialized)
>> +		platform_driver_unregister(&einj_driver);
>> +
>> +	platform_device_del(einj_dev);
>> +}
>> +
>>  module_init(einj_init);
>>  module_exit(einj_exit);
>>  
>> -- 
>> 2.34.1
>>
> 
>