Hi Dan, thanks for the quick response! Comments inline. On 1/16/24 5:47 PM, 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@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." > That is clearer, I'll change it. >> +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. > Will do. >> + >> 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. > Gotcha, I'll make that change. >> + }, >> +}; >> + >> +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. > Will do. >> + 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 agree. I was trying to not have to use an extra variable for only one line but einj_initialized = platform_driver_probe() == 0; went over the column limit :/. > 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. > My reasoning for this was since this is really a dummy device I didn't want to pollute the platform device in the case the driver failed, but I see the reasoning here and agree with you. > 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. > Alright, will do. >> + 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.