Re: [PATCH] acpi: Fix hed module initialization order when it is built-in

[Xiaofei Tan]

Hi Jonathan,

在 2024/12/24 3:33, Jonathan Cameron 写道:
> On Mon, 23 Dec 2024 17:31:08 +0800
> Xiaofei Tan <tanxiaofei@xxxxxxxxxx> wrote:
>
> > Hi Rafael,
> >
> > 在 2024/12/11 1:59, Rafael J. Wysocki 写道:
> > > On Fri, Nov 15, 2024 at 4:56 AM Xiaofei Tan <tanxiaofei@xxxxxxxxxx> wrote:
> > > > When the module hed is built-in, the init order is determined by
> > > > Makefile order.
> > > Are you sure?
> > yes
> We had a similar fix in CXL recently (which is why I suggested this approach
> internally when tanxiaofei mentioned the problem).
>
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/drivers/cxl?id=6575b268157f37929948a8d1f3bafb3d7c055bc1
>
> The related discussion for the CXL patch was the first time I'd come across solution
> to load order for built in cases.
Yes :)

> > > > That order violates expectations. Because the module
> > > > hed init is behind evged. RAS records can't be handled in the
> > > > special time window that evged has initialized while hed not.
> > > > If the number of such RAS records is more than the APEI HEST error
> > > > source number, the HEST resources could be occupied all, and then
> > > > could affect subsequent RAS error reporting.
> > > Well, the problem is real, but does the change really prevent it from
> > > happening or does it just increase the likelihood of success?
> > It can be completely solved if the driver used as built-in way. If build HED as a
> > module, it not solved.
> Can we enforce that condition not happening with appropriate Kconfig?
> It's annoying to restrict build options, but if needed to make it work
> then better than not working!

Agree,  i will change ACPI_HED from tristate to bool if there are no other comments, thanks.

> Jonathan
>
>
> > > In the latter case, and generally speaking too, it would be better to
> > > add explicit synchronization between evged and hed.
> > >   
> > > > Reviewed-by: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx>
> > > > Signed-off-by: Xiaofei Tan <tanxiaofei@xxxxxxxxxx>
> > > > ---
> > > >    drivers/acpi/Makefile | 8 +++++++-
> > > >    1 file changed, 7 insertions(+), 1 deletion(-)
> > > >
> > > > diff --git a/drivers/acpi/Makefile b/drivers/acpi/Makefile
> > > > index 61ca4afe83dc..54f60b7922ad 100644
> > > > --- a/drivers/acpi/Makefile
> > > > +++ b/drivers/acpi/Makefile
> > > > @@ -15,6 +15,13 @@ endif
> > > >
> > > >    obj-$(CONFIG_ACPI)             += tables.o
> > > >
> > > > +#
> > > > +# The hed.o needs to be in front of evged.o to avoid the problem that
> > > > +# RAS errors cannot be handled in the special time window of startup
> > > > +# phase that evged has initialized while hed not.
> > > > +#
> > > > +obj-$(CONFIG_ACPI_HED)         += hed.o
> > > > +
> > > >    #
> > > >    # ACPI Core Subsystem (Interpreter)
> > > >    #
> > > > @@ -95,7 +102,6 @@ obj-$(CONFIG_ACPI_HOTPLUG_IOAPIC) += ioapic.o
> > > >    obj-$(CONFIG_ACPI_BATTERY)     += battery.o
> > > >    obj-$(CONFIG_ACPI_SBS)         += sbshc.o
> > > >    obj-$(CONFIG_ACPI_SBS)         += sbs.o
> > > > -obj-$(CONFIG_ACPI_HED)         += hed.o
> > > >    obj-$(CONFIG_ACPI_EC_DEBUGFS)  += ec_sys.o
> > > >    obj-$(CONFIG_ACPI_BGRT)                += bgrt.o
> > > >    obj-$(CONFIG_ACPI_CPPC_LIB)    += cppc_acpi.o
> > > > --
> > > > 2.33.0
> > > >   
> > > .
> .