[PATCH] some irq_chip variables initiate end to point to NULL

[PATCH] some irq_chip variables initiate end to point to NULL

[Zhang, Yanmin]

I got an oops when booting 2.6.19-rc5-mm1 on my ia64 machine.

Below is the log.

Oops 11012296146944 [1]
Modules linked in: binfmt_misc dm_mirror dm_multipath dm_mod thermal processor f
an container button sg eepro100 e100 mii

Pid: 0, CPU 0, comm:              swapper
psr : 0000121008022038 ifs : 800000000000040b ip  : [<a0000001000e1411>]    Not
tainted
ip is at __do_IRQ+0x371/0x3e0
unat: 0000000000000000 pfs : 000000000000040b rsc : 0000000000000003
rnat: 656960155aa56aa5 bsps: a00000010058b890 pr  : 656960155aa55a65
ldrs: 0000000000000000 ccv : 0000000000000000 fpsr: 0009804c0270033f
csd : 0000000000000000 ssd : 0000000000000000
b0  : a0000001000e1390 b6  : a0000001005beac0 b7  : e00000007f01aa00
f6  : 000000000000000000000 f7  : 0ffe69090000000000000
f8  : 1000a9090000000000000 f9  : 0ffff8000000000000000
f10 : 1000a908ffffff6f70000 f11 : 1003e0000000000000909
r1  : a000000100fbbff0 r2  : 0000000000010002 r3  : 0000000000010001
r8  : fffffffffffbffff r9  : a000000100bd8060 r10 : a000000100dd83b8
r11 : fffffffffffeffff r12 : a000000100bcbbb0 r13 : a000000100bc4000
r14 : 0000000000010000 r15 : 0000000000010000 r16 : a000000100c01aa8
r17 : a000000100d2c350 r18 : 0000000000000000 r19 : a000000100d2c300
r20 : a000000100c01a88 r21 : 0000000080010100 r22 : a000000100c01ac0
r23 : a0000001000108e0 r24 : e000000477980004 r25 : 0000000000000000
r26 : 0000000000000000 r27 : e00000000913400c r28 : e0000004799ee51c
r29 : e0000004778b87f0 r30 : a000000100d2c300 r31 : a00000010005c7e0

Call Trace:
 [<a000000100014600>] show_stack+0x40/0xa0
                                sp 00000100bcb760 bsp 00000100bc4f40
 [<a000000100014f00>] show_regs+0x840/0x880
                                sp 00000100bcb930 bsp 00000100bc4ee8
 [<a000000100037fb0>] die+0x250/0x320
                                sp 00000100bcb930 bsp 00000100bc4ea0
 [<a00000010005e5f0>] ia64_do_page_fault+0x8d0/0xa20
                                sp 00000100bcb950 bsp 00000100bc4e50
 [<a00000010000caa0>] ia64_leave_kernel+0x0/0x290
                                sp 00000100bcb9e0 bsp 00000100bc4e50
 [<a0000001000e1410>] __do_IRQ+0x370/0x3e0
                                sp 00000100bcbbb0 bsp 00000100bc4df0
 [<a000000100011f50>] ia64_handle_irq+0x170/0x220
                                sp 00000100bcbbb0 bsp 00000100bc4dc0
 [<a00000010000caa0>] ia64_leave_kernel+0x0/0x290
                                sp 00000100bcbbb0 bsp 00000100bc4dc0
 [<a000000100012390>] ia64_pal_call_static+0x90/0xc0
                                sp 00000100bcbd80 bsp 00000100bc4d78
 [<a000000100015630>] default_idle+0x90/0x160
                                sp 00000100bcbd80 bsp 00000100bc4d58
 [<a000000100014290>] cpu_idle+0x1f0/0x440
                                sp 00000100bcbe20 bsp 00000100bc4d18
 [<a000000100009980>] rest_init+0xc0/0xe0
                                sp 00000100bcbe20 bsp 00000100bc4d00
 [<a0000001009f8ea0>] start_kernel+0x6a0/0x6c0
                                sp 00000100bcbe20 bsp 00000100bc4ca0
 [<a0000001000089f0>] __end_ivt_text+0x6d0/0x6f0
                                sp 00000100bcbe30 bsp 00000100bc4c00
 <0>Kernel panic - not syncing: Aiee, killing interrupt handler!


The root cause is that some irq_chip variables, especially ia64_msi_chip,
initiate their memeber end to point to NULL. __do_IRQ doesn't check
if irq_chip->end is null and just calls it after processing the interrupt.

As irq_chip->end is called at many places, so I fix it by reinitiating
irq_chip->end to dummy_irq_chip.end, e.g., a noop function.

Below patch against 2.6.19-rc5-mm1 fixes it.

Signed-off-by: Zhang Yanmin <yanmin.zhang@intel.com>

---

--- linux-2.6.19-rc5-mm1/kernel/irq/chip.c	2006-11-14 14:16:16.000000000 +0800
+++ linux-2.6.19-rc5-mm1_fix/kernel/irq/chip.c	2006-11-14 14:14:25.000000000 +0800
@@ -233,6 +233,8 @@ void irq_chip_set_defaults(struct irq_ch
 		chip->shutdown = chip->disable;
 	if (!chip->name)
 		chip->name = chip->typename;
+	if (!chip->end)
+		chip->end = dummy_irq_chip.end;
 }
 
 static inline void mask_ack_irq(struct irq_desc *desc, int irq)

Re: [PATCH] some irq_chip variables initiate end to point to NULL

[Andrew Morton]

On Tue, 14 Nov 2006 17:08:10 +0800
"Zhang, Yanmin" <yanmin_zhang@linux.intel.com> wrote:

> I got an oops when booting 2.6.19-rc5-mm1 on my ia64 machine.
> 
> Below is the log.
> 
> Oops 11012296146944 [1]
> Modules linked in: binfmt_misc dm_mirror dm_multipath dm_mod thermal processor f
> an container button sg eepro100 e100 mii
> 
> Pid: 0, CPU 0, comm:              swapper
> psr : 0000121008022038 ifs : 800000000000040b ip  : [<a0000001000e1411>]    Not
> tainted
> ip is at __do_IRQ+0x371/0x3e0
> unat: 0000000000000000 pfs : 000000000000040b rsc : 0000000000000003
> rnat: 656960155aa56aa5 bsps: a00000010058b890 pr  : 656960155aa55a65
> ldrs: 0000000000000000 ccv : 0000000000000000 fpsr: 0009804c0270033f
> csd : 0000000000000000 ssd : 0000000000000000
> b0  : a0000001000e1390 b6  : a0000001005beac0 b7  : e00000007f01aa00
> f6  : 000000000000000000000 f7  : 0ffe69090000000000000
> f8  : 1000a9090000000000000 f9  : 0ffff8000000000000000
> f10 : 1000a908ffffff6f70000 f11 : 1003e0000000000000909
> r1  : a000000100fbbff0 r2  : 0000000000010002 r3  : 0000000000010001
> r8  : fffffffffffbffff r9  : a000000100bd8060 r10 : a000000100dd83b8
> r11 : fffffffffffeffff r12 : a000000100bcbbb0 r13 : a000000100bc4000
> r14 : 0000000000010000 r15 : 0000000000010000 r16 : a000000100c01aa8
> r17 : a000000100d2c350 r18 : 0000000000000000 r19 : a000000100d2c300
> r20 : a000000100c01a88 r21 : 0000000080010100 r22 : a000000100c01ac0
> r23 : a0000001000108e0 r24 : e000000477980004 r25 : 0000000000000000
> r26 : 0000000000000000 r27 : e00000000913400c r28 : e0000004799ee51c
> r29 : e0000004778b87f0 r30 : a000000100d2c300 r31 : a00000010005c7e0
> 
> Call Trace:
>  [<a000000100014600>] show_stack+0x40/0xa0
>                                 sp 00000100bcb760 bsp 00000100bc4f40
>  [<a000000100014f00>] show_regs+0x840/0x880
>                                 sp 00000100bcb930 bsp 00000100bc4ee8
>  [<a000000100037fb0>] die+0x250/0x320
>                                 sp 00000100bcb930 bsp 00000100bc4ea0
>  [<a00000010005e5f0>] ia64_do_page_fault+0x8d0/0xa20
>                                 sp 00000100bcb950 bsp 00000100bc4e50
>  [<a00000010000caa0>] ia64_leave_kernel+0x0/0x290
>                                 sp 00000100bcb9e0 bsp 00000100bc4e50
>  [<a0000001000e1410>] __do_IRQ+0x370/0x3e0
>                                 sp 00000100bcbbb0 bsp 00000100bc4df0
>  [<a000000100011f50>] ia64_handle_irq+0x170/0x220
>                                 sp 00000100bcbbb0 bsp 00000100bc4dc0
>  [<a00000010000caa0>] ia64_leave_kernel+0x0/0x290
>                                 sp 00000100bcbbb0 bsp 00000100bc4dc0
>  [<a000000100012390>] ia64_pal_call_static+0x90/0xc0
>                                 sp 00000100bcbd80 bsp 00000100bc4d78
>  [<a000000100015630>] default_idle+0x90/0x160
>                                 sp 00000100bcbd80 bsp 00000100bc4d58
>  [<a000000100014290>] cpu_idle+0x1f0/0x440
>                                 sp 00000100bcbe20 bsp 00000100bc4d18
>  [<a000000100009980>] rest_init+0xc0/0xe0
>                                 sp 00000100bcbe20 bsp 00000100bc4d00
>  [<a0000001009f8ea0>] start_kernel+0x6a0/0x6c0
>                                 sp 00000100bcbe20 bsp 00000100bc4ca0
>  [<a0000001000089f0>] __end_ivt_text+0x6d0/0x6f0
>                                 sp 00000100bcbe30 bsp 00000100bc4c00
>  <0>Kernel panic - not syncing: Aiee, killing interrupt handler!
> 
> 
> The root cause is that some irq_chip variables, especially ia64_msi_chip,
> initiate their memeber end to point to NULL. __do_IRQ doesn't check
> if irq_chip->end is null and just calls it after processing the interrupt.
> 
> As irq_chip->end is called at many places, so I fix it by reinitiating
> irq_chip->end to dummy_irq_chip.end, e.g., a noop function.
> 
> Below patch against 2.6.19-rc5-mm1 fixes it.
> 
> Signed-off-by: Zhang Yanmin <yanmin.zhang@intel.com>
> 
> ---
> 
> --- linux-2.6.19-rc5-mm1/kernel/irq/chip.c	2006-11-14 14:16:16.000000000 +0800
> +++ linux-2.6.19-rc5-mm1_fix/kernel/irq/chip.c	2006-11-14 14:14:25.000000000 +0800
> @@ -233,6 +233,8 @@ void irq_chip_set_defaults(struct irq_ch
>  		chip->shutdown = chip->disable;
>  	if (!chip->name)
>  		chip->name = chip->typename;
> +	if (!chip->end)
> +		chip->end = dummy_irq_chip.end;
>  }
>  

The same bug should be hitting in mainline, shouldn't it?

[patch] ia64: use generic_handle_irq()

[Ingo Molnar]

* Andrew Morton <akpm@osdl.org> wrote:

> On Tue, 14 Nov 2006 17:08:10 +0800
> "Zhang, Yanmin" <yanmin_zhang@linux.intel.com> wrote:
> 
> > I got an oops when booting 2.6.19-rc5-mm1 on my ia64 machine.
> > 
> > Below is the log.
> > 
> > Oops 11012296146944 [1]
> > Modules linked in: binfmt_misc dm_mirror dm_multipath dm_mod thermal processor f
> > an container button sg eepro100 e100 mii
> > 
> > Pid: 0, CPU 0, comm:              swapper
> > psr : 0000121008022038 ifs : 800000000000040b ip  : [<a0000001000e1411>]    Not
> > tainted
> > ip is at __do_IRQ+0x371/0x3e0
> > unat: 0000000000000000 pfs : 000000000000040b rsc : 0000000000000003
> > rnat: 656960155aa56aa5 bsps: a00000010058b890 pr  : 656960155aa55a65
> > ldrs: 0000000000000000 ccv : 0000000000000000 fpsr: 0009804c0270033f
> > csd : 0000000000000000 ssd : 0000000000000000
> > b0  : a0000001000e1390 b6  : a0000001005beac0 b7  : e00000007f01aa00
> > f6  : 000000000000000000000 f7  : 0ffe69090000000000000
> > f8  : 1000a9090000000000000 f9  : 0ffff8000000000000000
> > f10 : 1000a908ffffff6f70000 f11 : 1003e0000000000000909
> > r1  : a000000100fbbff0 r2  : 0000000000010002 r3  : 0000000000010001
> > r8  : fffffffffffbffff r9  : a000000100bd8060 r10 : a000000100dd83b8
> > r11 : fffffffffffeffff r12 : a000000100bcbbb0 r13 : a000000100bc4000
> > r14 : 0000000000010000 r15 : 0000000000010000 r16 : a000000100c01aa8
> > r17 : a000000100d2c350 r18 : 0000000000000000 r19 : a000000100d2c300
> > r20 : a000000100c01a88 r21 : 0000000080010100 r22 : a000000100c01ac0
> > r23 : a0000001000108e0 r24 : e000000477980004 r25 : 0000000000000000
> > r26 : 0000000000000000 r27 : e00000000913400c r28 : e0000004799ee51c
> > r29 : e0000004778b87f0 r30 : a000000100d2c300 r31 : a00000010005c7e0
> > 
> > Call Trace:
> >  [<a000000100014600>] show_stack+0x40/0xa0
> >                                 sp 00000100bcb760 bsp 00000100bc4f40
> >  [<a000000100014f00>] show_regs+0x840/0x880
> >                                 sp 00000100bcb930 bsp 00000100bc4ee8
> >  [<a000000100037fb0>] die+0x250/0x320
> >                                 sp 00000100bcb930 bsp 00000100bc4ea0
> >  [<a00000010005e5f0>] ia64_do_page_fault+0x8d0/0xa20
> >                                 sp 00000100bcb950 bsp 00000100bc4e50
> >  [<a00000010000caa0>] ia64_leave_kernel+0x0/0x290
> >                                 sp 00000100bcb9e0 bsp 00000100bc4e50
> >  [<a0000001000e1410>] __do_IRQ+0x370/0x3e0
> >                                 sp 00000100bcbbb0 bsp 00000100bc4df0
> >  [<a000000100011f50>] ia64_handle_irq+0x170/0x220
> >                                 sp 00000100bcbbb0 bsp 00000100bc4dc0
> >  [<a00000010000caa0>] ia64_leave_kernel+0x0/0x290
> >                                 sp 00000100bcbbb0 bsp 00000100bc4dc0
> >  [<a000000100012390>] ia64_pal_call_static+0x90/0xc0
> >                                 sp 00000100bcbd80 bsp 00000100bc4d78
> >  [<a000000100015630>] default_idle+0x90/0x160
> >                                 sp 00000100bcbd80 bsp 00000100bc4d58
> >  [<a000000100014290>] cpu_idle+0x1f0/0x440
> >                                 sp 00000100bcbe20 bsp 00000100bc4d18
> >  [<a000000100009980>] rest_init+0xc0/0xe0
> >                                 sp 00000100bcbe20 bsp 00000100bc4d00
> >  [<a0000001009f8ea0>] start_kernel+0x6a0/0x6c0
> >                                 sp 00000100bcbe20 bsp 00000100bc4ca0
> >  [<a0000001000089f0>] __end_ivt_text+0x6d0/0x6f0
> >                                 sp 00000100bcbe30 bsp 00000100bc4c00
> >  <0>Kernel panic - not syncing: Aiee, killing interrupt handler!
> > 
> > 
> > The root cause is that some irq_chip variables, especially ia64_msi_chip,
> > initiate their memeber end to point to NULL. __do_IRQ doesn't check
> > if irq_chip->end is null and just calls it after processing the interrupt.
> > 
> > As irq_chip->end is called at many places, so I fix it by reinitiating
> > irq_chip->end to dummy_irq_chip.end, e.g., a noop function.
> > 
> > Below patch against 2.6.19-rc5-mm1 fixes it.
> > 
> > Signed-off-by: Zhang Yanmin <yanmin.zhang@intel.com>
> > 
> > ---
> > 
> > --- linux-2.6.19-rc5-mm1/kernel/irq/chip.c	2006-11-14 14:16:16.000000000 +0800
> > +++ linux-2.6.19-rc5-mm1_fix/kernel/irq/chip.c	2006-11-14 14:14:25.000000000 +0800
> > @@ -233,6 +233,8 @@ void irq_chip_set_defaults(struct irq_ch
> >  		chip->shutdown = chip->disable;
> >  	if (!chip->name)
> >  		chip->name = chip->typename;
> > +	if (!chip->end)
> > +		chip->end = dummy_irq_chip.end;
> >  }
> >  
> 
> The same bug should be hitting in mainline, shouldn't it?

correct.

this bug comes from a 'mixed' IRQ setup on ia64: half of it is still 
old-style, half of it (the MSI stuff) is new-style irqchip code. But the 
ia64 lowlevel code unconditionally calls __do_IRQ(), which is a bug.

the genirq code has all the right helpers for such a mixed situation: so 
a better fix might be the one below: use generic_handle_irq() instead of 
unconditionally calling into __do_IRQ(). But i have not tested it - 
Yanmin, can you confirm this too fixes your bug?

similarly, any architecture that makes use of the new generic MSI 
infrastructure should not be calling __do_IRQ() directly. (but i'm not 
aware of any other besides ia64 - i386 and x86_64 is now fully irq-chip 
converted.)

Eric, do you agree?

	Ingo

----------------->
From: Ingo Molnar <mingo@elte.hu>
Subject: ia64: use generic_handle_irq()

use generic_handle_irq() to handle mixed-type irq handling.

Signed-off-by: Ingo Molnar <mingo@elte.hu>

Index: linux/arch/ia64/kernel/irq.c
=================================--- linux.orig/arch/ia64/kernel/irq.c
+++ linux/arch/ia64/kernel/irq.c
@@ -197,7 +197,7 @@ void fixup_irqs(void)
 			struct pt_regs *old_regs = set_irq_regs(NULL);
 
 			vectors_in_migration[irq]=0;
-			__do_IRQ(irq);
+			generic_handle_irq(irq);
 			set_irq_regs(old_regs);
 		}
 	}
Index: linux/arch/ia64/kernel/irq_ia64.c
=================================--- linux.orig/arch/ia64/kernel/irq_ia64.c
+++ linux/arch/ia64/kernel/irq_ia64.c
@@ -186,7 +186,7 @@ ia64_handle_irq (ia64_vector vector, str
 			ia64_setreg(_IA64_REG_CR_TPR, vector);
 			ia64_srlz_d();
 
-			__do_IRQ(local_vector_to_irq(vector));
+			generic_handle_irq(local_vector_to_irq(vector));
 
 			/*
 			 * Disable interrupts and send EOI:

Re: [patch] ia64: use generic_handle_irq()

[Eric W. Biederman]

Ingo Molnar <mingo@elte.hu> writes:

> * Andrew Morton <akpm@osdl.org> wrote:
>
>> On Tue, 14 Nov 2006 17:08:10 +0800
>> "Zhang, Yanmin" <yanmin_zhang@linux.intel.com> wrote:
>> 
>> > I got an oops when booting 2.6.19-rc5-mm1 on my ia64 machine.
>> > 
>> > 
>> > The root cause is that some irq_chip variables, especially ia64_msi_chip,
>> > initiate their memeber end to point to NULL. __do_IRQ doesn't check
>> > if irq_chip->end is null and just calls it after processing the interrupt.
>> > 
>> > As irq_chip->end is called at many places, so I fix it by reinitiating
>> > irq_chip->end to dummy_irq_chip.end, e.g., a noop function.
>> > 
>> > Below patch against 2.6.19-rc5-mm1 fixes it.
>> > 
>> > Signed-off-by: Zhang Yanmin <yanmin.zhang@intel.com>
>> > 
>> > ---
>> > 
>> > --- linux-2.6.19-rc5-mm1/kernel/irq/chip.c 2006-11-14 14:16:16.000000000
> +0800
>> > +++ linux-2.6.19-rc5-mm1_fix/kernel/irq/chip.c 2006-11-14 14:14:25.000000000
> +0800
>> > @@ -233,6 +233,8 @@ void irq_chip_set_defaults(struct irq_ch
>> >  		chip->shutdown = chip->disable;
>> >  	if (!chip->name)
>> >  		chip->name = chip->typename;
>> > +	if (!chip->end)
>> > +		chip->end = dummy_irq_chip.end;
>> >  }
>> >  
>> 
>> The same bug should be hitting in mainline, shouldn't it?
>
> correct.
>
> this bug comes from a 'mixed' IRQ setup on ia64: half of it is still 
> old-style, half of it (the MSI stuff) is new-style irqchip code. But the 
> ia64 lowlevel code unconditionally calls __do_IRQ(), which is a bug.

Now that we hare half converted yes it is a bug.

> the genirq code has all the right helpers for such a mixed situation: so 
> a better fix might be the one below: use generic_handle_irq() instead of 
> unconditionally calling into __do_IRQ(). But i have not tested it - 
> Yanmin, can you confirm this too fixes your bug?
>
> similarly, any architecture that makes use of the new generic MSI 
> infrastructure should not be calling __do_IRQ() directly. (but i'm not 
> aware of any other besides ia64 - i386 and x86_64 is now fully irq-chip 
> converted.)
>
> Eric, do you agree?
>

This is true in practice.  It isn't necessarily true, as all of irq_chip
structures are arch specific.  It would be silly to start using msi interrupts
without converting to genirq though.  So I think this covers it for ia64.

Your patch only fixes 2 spots and there is a third in irq_ia64.c that
needs to be fixed as well.  At least in linus's tree.

>
> Index: linux/arch/ia64/kernel/irq.c
> =================================> --- linux.orig/arch/ia64/kernel/irq.c
> +++ linux/arch/ia64/kernel/irq.c
> @@ -197,7 +197,7 @@ void fixup_irqs(void)
>  			struct pt_regs *old_regs = set_irq_regs(NULL);
>  
>  			vectors_in_migration[irq]=0;
> -			__do_IRQ(irq);
> +			generic_handle_irq(irq);
>  			set_irq_regs(old_regs);
>  		}
>  	}
> Index: linux/arch/ia64/kernel/irq_ia64.c
> =================================> --- linux.orig/arch/ia64/kernel/irq_ia64.c
> +++ linux/arch/ia64/kernel/irq_ia64.c
> @@ -186,7 +186,7 @@ ia64_handle_irq (ia64_vector vector, str
>  			ia64_setreg(_IA64_REG_CR_TPR, vector);
>  			ia64_srlz_d();
>  
> -			__do_IRQ(local_vector_to_irq(vector));
> +			generic_handle_irq(local_vector_to_irq(vector));
>  
>  			/*
>  			 * Disable interrupts and send EOI:

Re: [patch] ia64: use generic_handle_irq()

[Zhang, Yanmin]

On Wed, 2006-11-15 at 02:08, Eric W. Biederman wrote:
> Ingo Molnar <mingo@elte.hu> writes:
> 
> > * Andrew Morton <akpm@osdl.org> wrote:
> >
> >> On Tue, 14 Nov 2006 17:08:10 +0800
> >> "Zhang, Yanmin" <yanmin_zhang@linux.intel.com> wrote:
> >> 
> >> > I got an oops when booting 2.6.19-rc5-mm1 on my ia64 machine.
> >> > 
> >> > 
> >> > The root cause is that some irq_chip variables, especially ia64_msi_chip,
> >> > initiate their memeber end to point to NULL. __do_IRQ doesn't check
> >> > if irq_chip->end is null and just calls it after processing the interrupt.
> >> > 
> >> > As irq_chip->end is called at many places, so I fix it by reinitiating
> >> > irq_chip->end to dummy_irq_chip.end, e.g., a noop function.
> >> > 
> >> > Below patch against 2.6.19-rc5-mm1 fixes it.
> >> > 
> >> > Signed-off-by: Zhang Yanmin <yanmin.zhang@intel.com>
> >> > 
> >> > ---
> >> > 
> >> > --- linux-2.6.19-rc5-mm1/kernel/irq/chip.c 2006-11-14 14:16:16.000000000
> > +0800
> >> > +++ linux-2.6.19-rc5-mm1_fix/kernel/irq/chip.c 2006-11-14 14:14:25.000000000
> > +0800
> >> > @@ -233,6 +233,8 @@ void irq_chip_set_defaults(struct irq_ch
> >> >  		chip->shutdown = chip->disable;
> >> >  	if (!chip->name)
> >> >  		chip->name = chip->typename;
> >> > +	if (!chip->end)
> >> > +		chip->end = dummy_irq_chip.end;
> >> >  }
> >> >  
> >> 
> >> The same bug should be hitting in mainline, shouldn't it?
> >
> > correct.
> >
> > this bug comes from a 'mixed' IRQ setup on ia64: half of it is still 
> > old-style, half of it (the MSI stuff) is new-style irqchip code. But the 
> > ia64 lowlevel code unconditionally calls __do_IRQ(), which is a bug.
> 
> Now that we hare half converted yes it is a bug.
> 
> > the genirq code has all the right helpers for such a mixed situation: so 
> > a better fix might be the one below: use generic_handle_irq() instead of 
> > unconditionally calling into __do_IRQ(). But i have not tested it - 
> > Yanmin, can you confirm this too fixes your bug?
> >
> > similarly, any architecture that makes use of the new generic MSI 
> > infrastructure should not be calling __do_IRQ() directly. (but i'm not 
> > aware of any other besides ia64 - i386 and x86_64 is now fully irq-chip 
> > converted.)
> >
> > Eric, do you agree?
> >
> 
> This is true in practice.  It isn't necessarily true, as all of irq_chip
> structures are arch specific.  It would be silly to start using msi interrupts
> without converting to genirq though.  So I think this covers it for ia64.
> 
> Your patch only fixes 2 spots and there is a third in irq_ia64.c that
> needs to be fixed as well.  At least in linus's tree.
Based on Eric's comments, I added a new change into Ingo's patch, and tested
on my ia64 machine. It does fix the bug and works well. I still think
my original patch to initilate null end to dummy_irq_chip.end is useful, at
least to prevent potential errors.

---

--- linux-2.6.19-rc5-mm1/arch/ia64/kernel/irq.c	2006-11-14 14:16:12.000000000 +0800
+++ linux-2.6.19-rc5-mm1_fix/arch/ia64/kernel/irq.c	2006-11-15 09:56:01.000000000 +0800
@@ -197,7 +197,7 @@ void fixup_irqs(void)
 			struct pt_regs *old_regs = set_irq_regs(NULL);
 
 			vectors_in_migration[irq]=0;
-			__do_IRQ(irq);
+			generic_handle_irq(irq);
 			set_irq_regs(old_regs);
 		}
 	}
--- linux-2.6.19-rc5-mm1/arch/ia64/kernel/irq_ia64.c	2006-11-14 14:16:12.000000000 +0800
+++ linux-2.6.19-rc5-mm1_fix/arch/ia64/kernel/irq_ia64.c	2006-11-15 09:56:51.000000000 +0800
@@ -186,7 +186,7 @@ ia64_handle_irq (ia64_vector vector, str
 			ia64_setreg(_IA64_REG_CR_TPR, vector);
 			ia64_srlz_d();
 
-			__do_IRQ(local_vector_to_irq(vector));
+			generic_handle_irq(local_vector_to_irq(vector));
 
 			/*
 			 * Disable interrupts and send EOI:
@@ -242,7 +242,7 @@ void ia64_process_pending_intr(void)
 			 * Probably could shared code.
 			 */
 			vectors_in_migration[local_vector_to_irq(vector)]=0;
-			__do_IRQ(local_vector_to_irq(vector));
+			generic_handle_irq(local_vector_to_irq(vector));
 			set_irq_regs(old_regs);
 
 			/*