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@xxxxxxx>
> ---
> drivers/acpi/apei/einj.c | 43 ++++++++++++++++++++++++++++++++++++++--
> 1 file changed, 41 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/acpi/apei/einj.c b/drivers/acpi/apei/einj.c
> index 013eb621dc92..10d51cd73fa4 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"
> @@ -136,6 +137,12 @@ static struct apei_exec_ins_type einj_ins_type[] = {
> */
> static DEFINE_MUTEX(einj_mutex);
>
> +/*
> + * Functions called from dependent modules should check this variable
> + * before using any EINJ functionality.
> + */
This reads slightly odd to me, is this clearer?
"Exported APIs use this flag to exit early if einj_probe() failed."
> +static bool einj_initialized;
This can be marked __ro_after_init to make it clear that it is static
for the lifetime of the module.
> +
> static void *einj_param;
>
> static void einj_exec_ctx_init(struct apei_exec_context *ctx)
> @@ -684,7 +691,7 @@ static int einj_check_table(struct acpi_table_einj *einj_tab)
> return 0;
> }
>
> -static int __init einj_init(void)
> +static int einj_probe(struct platform_device *pdev)
This can remain __init since nothing will call this function port
init().
> {
> int rc;
> acpi_status status;
> @@ -782,7 +789,7 @@ static int __init einj_init(void)
> return rc;
> }
>
> -static void __exit einj_exit(void)
> +static void einj_remove(struct platform_device *pdev)
Similarly this can remain __exit.
> {
> struct apei_exec_context ctx;
>
> @@ -801,6 +808,38 @@ 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 = {
> + .remove_new = einj_remove,
> + .driver = {
> + .name = "einj",
Perhaps call this acpi-einj just to preserve the namespace in case a
cross-platform generic "einj" comes along.
> + },
> +};
> +
> +static int __init einj_init(void)
> +{
> + struct platform_device_info einj_dev_info = {
> + .name = "einj",
Ditt "acpi-einj"
> + .id = -1,
> + };
> +
> + einj_dev = platform_device_register_full(&einj_dev_info);
Just return early here if this failed.
> + einj_initialized = !platform_driver_probe(&einj_driver, einj_probe);
Nit, but since platform_driver_probe() does not return bool, I would
prefer this to be more explicit:
err = platform_driver_probe();
einj_initialized = err == 0;
I think it is ok for the platform-device to stick around if einj_probe()
failures as userspace can see that the module is loaded but driver-init
failed.
Similarly it's probably also ok to fail the module load if
platform_device_register_full() fails since something deeper is wrong
with the system if it is starting to fail something so basic.
> + if (!(einj_initialized || IS_ERR_OR_NULL(einj_dev)))
> + platform_device_del(einj_dev);
> +
> + return 0;
> +}
> +
> +static void __exit einj_exit(void)
> +{
> + if (einj_initialized) {
> + platform_driver_unregister(&einj_driver);
> + platform_device_del(einj_dev);
Per above, this device_del can move outside the conditional.
