Re: [git pull] sparseirq / irq updates for v2.6.29

Yinghai Lu
2008-12-29T00:53:50Z

Yinghai Lu wrote:
> Ingo Molnar wrote:
>> * Ingo Molnar <mingo@elte.hu> wrote:
>>
>>> b2e2fe9: sparseirq: work around __weak alias bug
>> here's that fix, standalone too. Kamalesh, i think this should finally fix
>> the crash you are seeing.
>>
>> Ingo
>>
>> ---------------->
>> >From b2e2fe99628c4f944c3075258e536197b5a4f3f8 Mon Sep 17 00:00:00 2001
>> From: Ingo Molnar <mingo@elte.hu>
>> Date: Mon, 29 Dec 2008 00:16:45 +0100
>> Subject: [PATCH] sparseirq: work around __weak alias bug
>>
>> Impact: fix boot crash if the kernel is built with certain GCC versions
>>
>> GCC has a bug with __weak alias functions: if the functions are in
>> the same compilation unit as their call site, GCC can decide to
>> inline them - and thus rob the linker of the opportunity to override
>> the weak alias with the real thing.
>>
>> This can lead to the boot crash reported by Kamalesh Babulal:
>>
>> ACPI: Core revision 20080926
>> Setting APIC routing to flat
>> BUG: unable to handle kernel NULL pointer dereference at
>> 0000000000000000
>> IP: [<ffffffff8021f9a8>] add_pin_to_irq_cpu+0x14/0x74
>> PGD 0
>> Oops: 0000 [#1] SMP
>> [...]
>>
>> So move the arch_init_chip_data() function from handle.c to manage.c.
>
> that is not enough.
>
> need
>
>

or this one

[PATCH] sparseirq: move weak function to chip.c v2

Impact: fix panic

some gcc compiler will remove the weak global blank function
Linus noted that we could move those function to other unit to workaround it.

try to workaround it:
1. one time path: add printk
2. multi time path: move to chip.c

Signed-off-by: Yinghai Lu <yinghai@kernel.org>

---
init/main.c | 4 ++++
kernel/irq/chip.c | 5 +++++
kernel/irq/handle.c | 5 -----
3 files changed, 9 insertions(+), 5 deletions(-)

Index: linux-2.6/init/main.c
===================================================================
--- linux-2.6.orig/init/main.c
+++ linux-2.6/init/main.c
@@ -544,11 +544,15 @@ void __init __weak thread_info_cache_ini

int __init __weak arch_early_irq_init(void)
{
+ printk(KERN_DEBUG "calling __weak arch_early_irq_init()\n");
+
return 0;
}

int __init __weak early_irq_init(void)
{
+ printk(KERN_DEBUG "calling __weak early_irq_init()\n");
+
return arch_early_irq_init();
}

Index: linux-2.6/kernel/irq/chip.c
===================================================================
--- linux-2.6.orig/kernel/irq/chip.c
+++ linux-2.6/kernel/irq/chip.c
@@ -18,6 +18,11 @@

#include "internals.h"

+int __weak arch_init_chip_data(struct irq_desc *desc, int cpu)
+{
+ return 0;
+}
+
/**
* dynamic_irq_init - initialize a dynamically allocated irq
* @irq: irq number to initialize
Index: linux-2.6/kernel/irq/handle.c
===================================================================
--- linux-2.6.orig/kernel/irq/handle.c
+++ linux-2.6/kernel/irq/handle.c
@@ -86,11 +86,6 @@ void init_kstat_irqs(struct irq_desc *de
desc->kstat_irqs = (unsigned int *)ptr;
}

-int __weak arch_init_chip_data(struct irq_desc *desc, int cpu)
-{
- return 0;
-}
-
static void init_one_irq_desc(int irq, struct irq_desc *desc, int cpu)
{
memcpy(desc, &irq_desc_init, sizeof(struct irq_desc));