[PATCH] x86, i8259: Only register sysdev for real PIC

[PATCH] x86, i8259: Only register sysdev for real PIC

[Adam Lackorzynski]

Do not register the sysdev function when the null_legacy_pic is used so
that the i8259 resume, suspend and shutdown functions are not called.

Signed-off-by: Adam Lackorzynski <adam@os.inf.tu-dresden.de>
---
 arch/x86/kernel/i8259.c |   26 ++++++++++++++++----------
 1 files changed, 16 insertions(+), 10 deletions(-)

diff --git a/arch/x86/kernel/i8259.c b/arch/x86/kernel/i8259.c
index 7c9f02c..dfadc74 100644
--- a/arch/x86/kernel/i8259.c
+++ b/arch/x86/kernel/i8259.c
@@ -276,16 +276,6 @@ static struct sys_device device_i8259A = {
 	.cls	= &i8259_sysdev_class,
 };
 
-static int __init i8259A_init_sysfs(void)
-{
-	int error = sysdev_class_register(&i8259_sysdev_class);
-	if (!error)
-		error = sysdev_register(&device_i8259A);
-	return error;
-}
-
-device_initcall(i8259A_init_sysfs);
-
 static void mask_8259A(void)
 {
 	unsigned long flags;
@@ -407,3 +397,19 @@ struct legacy_pic default_legacy_pic = {
 };
 
 struct legacy_pic *legacy_pic = &default_legacy_pic;
+
+static int __init i8259A_init_sysfs(void)
+{
+	int error;
+
+	if (legacy_pic != &default_legacy_pic)
+		return 0;
+
+	error = sysdev_class_register(&i8259_sysdev_class);
+	if (!error)
+		error = sysdev_register(&device_i8259A);
+	return error;
+}
+
+device_initcall(i8259A_init_sysfs);
+
-- 
1.5.6.5

Re: [PATCH] x86, i8259: Only register sysdev for real PIC

[Andrew Morton]

On Wed, 2 Jun 2010 13:31:50 +0200 Adam Lackorzynski <adam@os.inf.tu-dresden.de> wrote:

> Do not register the sysdev function when the null_legacy_pic is used so
> that the i8259 resume, suspend and shutdown functions are not called.

What are the effects of this change?  Does it fix an oops or a hang, or
nothing at all, or...?

Re: [PATCH] x86, i8259: Only register sysdev for real PIC

[Adam Lackorzynski]

On Wed Jun 02, 2010 at 18:18:14 -0700, Andrew Morton wrote:
> On Wed, 2 Jun 2010 13:31:50 +0200 Adam Lackorzynski <adam@os.inf.tu-dresden.de> wrote:
> 
> > Do not register the sysdev function when the null_legacy_pic is used so
> > that the i8259 resume, suspend and shutdown functions are not called.
> 
> What are the effects of this change?  Does it fix an oops or a hang, or
> nothing at all, or...?
 
My platform makes use of the null_legacy_pic choice and oopses when
doing a shutdown as the shutdown code goes through all the registered
sysdevs and calls their shutdown method which in my case poke on a
non-existing i8259. Imho the i8259 specific sysdev should only be
registered if the i8259 is actually there.


Adam

Re: [PATCH] x86, i8259: Only register sysdev for real PIC

[Andrew Morton]

On Thu, 3 Jun 2010 11:01:41 +0200 Adam Lackorzynski <adam@os.inf.tu-dresden.de> wrote:

> 
> On Wed Jun 02, 2010 at 18:18:14 -0700, Andrew Morton wrote:
> > On Wed, 2 Jun 2010 13:31:50 +0200 Adam Lackorzynski <adam@os.inf.tu-dresden.de> wrote:
> > 
> > > Do not register the sysdev function when the null_legacy_pic is used so
> > > that the i8259 resume, suspend and shutdown functions are not called.
> > 
> > What are the effects of this change?  Does it fix an oops or a hang, or
> > nothing at all, or...?
>  
> My platform makes use of the null_legacy_pic choice and oopses when
> doing a shutdown as the shutdown code goes through all the registered
> sysdevs and calls their shutdown method which in my case poke on a
> non-existing i8259. Imho the i8259 specific sysdev should only be
> registered if the i8259 is actually there.

OK, thanks.  Important info, that.  I'd say that makes it something we
should fix in 2.6.34.x and perhaps earlier.