[PATCH] ACPI / WMI: Call acpi_wmi_init() later

[PATCH] ACPI / WMI: Call acpi_wmi_init() later

[Rafael J. Wysocki]

From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Calling acpi_wmi_init() at the subsys_initcall() level causes ordering
issues to appear on some systems and they are difficult to reproduce,
because there is no guaranteed ordering between subsys_initcall()
calls, so they may occur in different orders on different systems.

In particular, commit 86d9f48534e8 (mm/slab: fix kmemcg cache
creation delayed issue) exposed one of these issues where genl_init()
and acpi_wmi_init() are both called at the same initcall level, but
the former must run before the latter so as to avoid a NULL pointer
dereference.

For this reason, move the acpi_wmi_init() invocation to the
initcall_sync level which should still be early enough for things
to work correctly in the WMI land.

Link: https://marc.info/?t=151274596700002&r=1&w=2
Reported-by: Jonathan McDowell <noodles@earth.li>
Reported-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Tested-by: Jonathan McDowell <noodles@earth.li>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---
 drivers/platform/x86/wmi.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Index: linux-pm/drivers/platform/x86/wmi.c
===================================================================
--- linux-pm.orig/drivers/platform/x86/wmi.c
+++ linux-pm/drivers/platform/x86/wmi.c
@@ -1458,5 +1458,5 @@ static void __exit acpi_wmi_exit(void)
 	class_unregister(&wmi_bus_class);
 }
 
-subsys_initcall(acpi_wmi_init);
+subsys_initcall_sync(acpi_wmi_init);
 module_exit(acpi_wmi_exit);

Re: [PATCH] ACPI / WMI: Call acpi_wmi_init() later

[Rafael J. Wysocki]

On Wed, Jan 3, 2018 at 12:49 PM, Rafael J. Wysocki <rjw@rjwysocki.net> wrote:
> From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
>
> Calling acpi_wmi_init() at the subsys_initcall() level causes ordering
> issues to appear on some systems and they are difficult to reproduce,
> because there is no guaranteed ordering between subsys_initcall()
> calls, so they may occur in different orders on different systems.
>
> In particular, commit 86d9f48534e8 (mm/slab: fix kmemcg cache
> creation delayed issue) exposed one of these issues where genl_init()
> and acpi_wmi_init() are both called at the same initcall level, but
> the former must run before the latter so as to avoid a NULL pointer
> dereference.
>
> For this reason, move the acpi_wmi_init() invocation to the
> initcall_sync level which should still be early enough for things
> to work correctly in the WMI land.
>
> Link: https://marc.info/?t=151274596700002&r=1&w=2
> Reported-by: Jonathan McDowell <noodles@earth.li>
> Reported-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
> Tested-by: Jonathan McDowell <noodles@earth.li>
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Guys, this fixes a crash on boot.

If there are no concerns/objections I will just take it through the ACPI tree.

> ---
>  drivers/platform/x86/wmi.c |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> Index: linux-pm/drivers/platform/x86/wmi.c
> ===================================================================
> --- linux-pm.orig/drivers/platform/x86/wmi.c
> +++ linux-pm/drivers/platform/x86/wmi.c
> @@ -1458,5 +1458,5 @@ static void __exit acpi_wmi_exit(void)
>         class_unregister(&wmi_bus_class);
>  }
>
> -subsys_initcall(acpi_wmi_init);
> +subsys_initcall_sync(acpi_wmi_init);
>  module_exit(acpi_wmi_exit);
>
> --

Re: [PATCH] ACPI / WMI: Call acpi_wmi_init() later

[Darren Hart]

On Sat, Jan 06, 2018 at 12:30:23AM +0100, Rafael J. Wysocki wrote:
> On Wed, Jan 3, 2018 at 12:49 PM, Rafael J. Wysocki <rjw@rjwysocki.net> wrote:
> > From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> >
> > Calling acpi_wmi_init() at the subsys_initcall() level causes ordering
> > issues to appear on some systems and they are difficult to reproduce,
> > because there is no guaranteed ordering between subsys_initcall()
> > calls, so they may occur in different orders on different systems.
> >
> > In particular, commit 86d9f48534e8 (mm/slab: fix kmemcg cache
> > creation delayed issue) exposed one of these issues where genl_init()
> > and acpi_wmi_init() are both called at the same initcall level, but
> > the former must run before the latter so as to avoid a NULL pointer
> > dereference.
> >
> > For this reason, move the acpi_wmi_init() invocation to the
> > initcall_sync level which should still be early enough for things
> > to work correctly in the WMI land.
> >
> > Link: https://marc.info/?t=151274596700002&r=1&w=2
> > Reported-by: Jonathan McDowell <noodles@earth.li>
> > Reported-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
> > Tested-by: Jonathan McDowell <noodles@earth.li>
> > Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> 
> Guys, this fixes a crash on boot.
> 
> If there are no concerns/objections I will just take it through the ACPI tree.

Queued up and running through tests now. I'll have it in for-next as soon as
those complete assuming to issues.

-- 
Darren Hart
VMware Open Source Technology Center

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Re: [PATCH] ACPI / WMI: Call acpi_wmi_init() later

[Jonathan McDowell]

On Sat, Jan 06, 2018 at 12:30:23AM +0100, Rafael J. Wysocki wrote:
> On Wed, Jan 3, 2018 at 12:49 PM, Rafael J. Wysocki <rjw@rjwysocki.net> wrote:
> > From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> >
> > Calling acpi_wmi_init() at the subsys_initcall() level causes ordering
> > issues to appear on some systems and they are difficult to reproduce,
> > because there is no guaranteed ordering between subsys_initcall()
> > calls, so they may occur in different orders on different systems.
> >
> > In particular, commit 86d9f48534e8 (mm/slab: fix kmemcg cache
> > creation delayed issue) exposed one of these issues where genl_init()
> > and acpi_wmi_init() are both called at the same initcall level, but
> > the former must run before the latter so as to avoid a NULL pointer
> > dereference.
> >
> > For this reason, move the acpi_wmi_init() invocation to the
> > initcall_sync level which should still be early enough for things
> > to work correctly in the WMI land.
> >
> > Link: https://marc.info/?t=151274596700002&r=1&w=2
> > Reported-by: Jonathan McDowell <noodles@earth.li>
> > Reported-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
> > Tested-by: Jonathan McDowell <noodles@earth.li>
> > Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> 
> Guys, this fixes a crash on boot.
> 
> If there are no concerns/objections I will just take it through the ACPI tree.

Note that I first started seeing it in v4.9 so would ideally hit the
appropriate stable trees too.

> > ---
> >  drivers/platform/x86/wmi.c |    2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > Index: linux-pm/drivers/platform/x86/wmi.c
> > ===================================================================
> > --- linux-pm.orig/drivers/platform/x86/wmi.c
> > +++ linux-pm/drivers/platform/x86/wmi.c
> > @@ -1458,5 +1458,5 @@ static void __exit acpi_wmi_exit(void)
> >         class_unregister(&wmi_bus_class);
> >  }
> >
> > -subsys_initcall(acpi_wmi_init);
> > +subsys_initcall_sync(acpi_wmi_init);
> >  module_exit(acpi_wmi_exit);
> >
> > --

J.

-- 
/-\                             | 101 things you can't have too much
|@/  Debian GNU/Linux Developer |    of : 36 - Spare video tapes.
\-                              |

Re: [PATCH] ACPI / WMI: Call acpi_wmi_init() later

[Darren Hart]

On Sat, Jan 06, 2018 at 11:02:27AM +0000, Jonathan McDowell wrote:
> On Sat, Jan 06, 2018 at 12:30:23AM +0100, Rafael J. Wysocki wrote:
> > On Wed, Jan 3, 2018 at 12:49 PM, Rafael J. Wysocki <rjw@rjwysocki.net> wrote:
> > > From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> > >
> > > Calling acpi_wmi_init() at the subsys_initcall() level causes ordering
> > > issues to appear on some systems and they are difficult to reproduce,
> > > because there is no guaranteed ordering between subsys_initcall()
> > > calls, so they may occur in different orders on different systems.
> > >
> > > In particular, commit 86d9f48534e8 (mm/slab: fix kmemcg cache
> > > creation delayed issue) exposed one of these issues where genl_init()
> > > and acpi_wmi_init() are both called at the same initcall level, but
> > > the former must run before the latter so as to avoid a NULL pointer
> > > dereference.
> > >
> > > For this reason, move the acpi_wmi_init() invocation to the
> > > initcall_sync level which should still be early enough for things
> > > to work correctly in the WMI land.
> > >
> > > Link: https://marc.info/?t=151274596700002&r=1&w=2
> > > Reported-by: Jonathan McDowell <noodles@earth.li>
> > > Reported-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
> > > Tested-by: Jonathan McDowell <noodles@earth.li>
> > > Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> > 
> > Guys, this fixes a crash on boot.
> > 
> > If there are no concerns/objections I will just take it through the ACPI tree.
> 
> Note that I first started seeing it in v4.9 so would ideally hit the
> appropriate stable trees too.

Thanks, I'll take care of that.

-- 
Darren Hart
VMware Open Source Technology Center