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

Ben Cheatham
2024-02-21T20:27:31Z

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
>>
>
>