* Ingo Molnar <mingo@xxxxxxx> [2008-12-27 12:24:50]:
>
> * Kamalesh Babulal <kamalesh@xxxxxxxxxxxxxxxxxx> wrote:
>
> > * Ingo Molnar <mingo@xxxxxxx> [2008-12-27 09:39:36]:
> >
> > >
> > > * Ingo Molnar <mingo@xxxxxxx> wrote:
> > >
> > > > * Yinghai Lu <yinghai@xxxxxxxxxx> wrote:
> > > >
> > > > > +extern int arch_init_chip_data(struct irq_desc *desc, int cpu);
> > > >
> > > > when you change a function declaration's return type, you _must_ double
> > > > check whether you properly updated all instances of that function. In
> > > > this case you forgot about the io_apic.c instance.
> > >
> > > the corrected patch is below.
> > >
> > > Ingo
> > >
> >
> > > --------------->
> > > From d353c528bbb29be434f7688cba9b59781e9151e3 Mon Sep 17 00:00:00 2001
> > > From: Yinghai Lu <yinghai@xxxxxxxxxx>
> > > Date: Fri, 26 Dec 2008 02:05:47 -0800
> > > Subject: [PATCH] sparseirq: work around compiler optimizing away __weak functions
> > >
> > > Impact: fix panic on null pointer with sparseirq
> > >
> > > Some GCC versions seem to inline the weak global function,
> > > when that function is empty.
> > >
> > > Work it around, by making the functions return a (dummy) integer.
> > >
> > > Signed-off-by: Yinghai <yinghai@xxxxxxxxxx>
> > > Signed-off-by: Ingo Molnar <mingo@xxxxxxx>
> > > ---
> > > arch/x86/kernel/io_apic.c | 6 ++++--
> > > include/linux/irq.h | 6 +++---
> > > init/main.c | 7 ++++---
> > > kernel/irq/handle.c | 7 ++++---
> > > 4 files changed, 15 insertions(+), 11 deletions(-)
> > >
> > > diff --git a/arch/x86/kernel/io_apic.c b/arch/x86/kernel/io_apic.c
> > > index 2fe543f..e4d4d19 100644
> > > --- a/arch/x86/kernel/io_apic.c
> > > +++ b/arch/x86/kernel/io_apic.c
> > > @@ -170,7 +170,7 @@ static struct irq_cfg irq_cfgx[NR_IRQS] = {
> > > [15] = { .domain = CPU_MASK_ALL, .vector = IRQ15_VECTOR, },
> > > };
> > >
> > > -void __init arch_early_irq_init(void)
> > > +int __init arch_early_irq_init(void)
> > > {
> > > struct irq_cfg *cfg;
> > > struct irq_desc *desc;
> > > @@ -184,6 +184,8 @@ void __init arch_early_irq_init(void)
> > > desc = irq_to_desc(i);
> > > desc->chip_data = &cfg[i];
> > > }
> > > +
> > > + return 0;
> > > }
> > >
> > > #ifdef CONFIG_SPARSE_IRQ
> > > @@ -212,7 +214,7 @@ static struct irq_cfg *get_one_free_irq_cfg(int cpu)
> > > return cfg;
> > > }
> > >
> > > -void arch_init_chip_data(struct irq_desc *desc, int cpu)
> > > +int arch_init_chip_data(struct irq_desc *desc, int cpu)
> > > {
> > > struct irq_cfg *cfg;
> >
> > the return statement is missing in the patch.
>
> yes, indeed - updated patch below.
>
> Ingo
>
Hi Ingo,
Sorry, for not mentioning that the previous kernel trace, was after
adding the return statement to the arch_init_chip_data().
> --------------->
> From 03f20b9c3b659c191684cb93de66a20386711df4 Mon Sep 17 00:00:00 2001
> From: Yinghai Lu <yinghai@xxxxxxxxxx>
> Date: Fri, 26 Dec 2008 02:05:47 -0800
> Subject: [PATCH] sparseirq: work around compiler optimizing away __weak functions
>
> Impact: fix panic on null pointer with sparseirq
>
> Some GCC versions seem to inline the weak global function,
> when that function is empty.
>
> Work it around, by making the functions return a (dummy) integer.
>
> Signed-off-by: Yinghai <yinghai@xxxxxxxxxx>
> Signed-off-by: Ingo Molnar <mingo@xxxxxxx>
> ---
> arch/x86/kernel/io_apic.c | 8 ++++++--
> include/linux/irq.h | 6 +++---
> init/main.c | 7 ++++---
> kernel/irq/handle.c | 7 ++++---
> 4 files changed, 17 insertions(+), 11 deletions(-)
>
> diff --git a/arch/x86/kernel/io_apic.c b/arch/x86/kernel/io_apic.c
> index 2fe543f..9760393 100644
> --- a/arch/x86/kernel/io_apic.c
> +++ b/arch/x86/kernel/io_apic.c
> @@ -170,7 +170,7 @@ static struct irq_cfg irq_cfgx[NR_IRQS] = {
> [15] = { .domain = CPU_MASK_ALL, .vector = IRQ15_VECTOR, },
> };
>
> -void __init arch_early_irq_init(void)
> +int __init arch_early_irq_init(void)
> {
> struct irq_cfg *cfg;
> struct irq_desc *desc;
> @@ -184,6 +184,8 @@ void __init arch_early_irq_init(void)
> desc = irq_to_desc(i);
> desc->chip_data = &cfg[i];
> }
> +
> + return 0;
> }
>
> #ifdef CONFIG_SPARSE_IRQ
> @@ -212,7 +214,7 @@ static struct irq_cfg *get_one_free_irq_cfg(int cpu)
> return cfg;
> }
>
> -void arch_init_chip_data(struct irq_desc *desc, int cpu)
> +int arch_init_chip_data(struct irq_desc *desc, int cpu)
> {
> struct irq_cfg *cfg;
>
> @@ -224,6 +226,8 @@ void arch_init_chip_data(struct irq_desc *desc, int cpu)
> BUG_ON(1);
> }
> }
> +
> + return 0;
> }
>
> #ifdef CONFIG_NUMA_MIGRATE_IRQ_DESC
> diff --git a/include/linux/irq.h b/include/linux/irq.h
> index 69da275..0e40af4 100644
> --- a/include/linux/irq.h
> +++ b/include/linux/irq.h
> @@ -193,9 +193,9 @@ struct irq_desc {
> const char *name;
> } ____cacheline_internodealigned_in_smp;
>
> -extern void early_irq_init(void);
> -extern void arch_early_irq_init(void);
> -extern void arch_init_chip_data(struct irq_desc *desc, int cpu);
> +extern int early_irq_init(void);
> +extern int arch_early_irq_init(void);
> +extern int arch_init_chip_data(struct irq_desc *desc, int cpu);
> extern void arch_init_copy_chip_data(struct irq_desc *old_desc,
> struct irq_desc *desc, int cpu);
> extern void arch_free_chip_data(struct irq_desc *old_desc, struct irq_desc *desc);
> diff --git a/init/main.c b/init/main.c
> index c1f999a..b541c9a 100644
> --- a/init/main.c
> +++ b/init/main.c
> @@ -539,13 +539,14 @@ void __init __weak thread_info_cache_init(void)
> {
> }
>
> -void __init __weak arch_early_irq_init(void)
> +int __init __weak arch_early_irq_init(void)
> {
> + return 0;
> }
>
> -void __init __weak early_irq_init(void)
> +int __init __weak early_irq_init(void)
> {
> - arch_early_irq_init();
> + return 0;
> }
>
> asmlinkage void __init start_kernel(void)
> diff --git a/kernel/irq/handle.c b/kernel/irq/handle.c
> index 893da67..0bef3ec 100644
> --- a/kernel/irq/handle.c
> +++ b/kernel/irq/handle.c
> @@ -86,8 +86,9 @@ void init_kstat_irqs(struct irq_desc *desc, int cpu, int nr)
> desc->kstat_irqs = (unsigned int *)ptr;
> }
>
> -void __attribute__((weak)) arch_init_chip_data(struct irq_desc *desc, int cpu)
> +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)
> @@ -132,7 +133,7 @@ static struct irq_desc irq_desc_legacy[NR_IRQS_LEGACY] __cacheline_aligned_in_sm
> /* FIXME: use bootmem alloc ...*/
> static unsigned int kstat_irqs_legacy[NR_IRQS_LEGACY][NR_CPUS];
>
> -void __init early_irq_init(void)
> +int __init early_irq_init(void)
> {
> struct irq_desc *desc;
> int legacy_count;
> @@ -151,7 +152,7 @@ void __init early_irq_init(void)
> for (i = legacy_count; i < NR_IRQS; i++)
> irq_desc_ptrs[i] = NULL;
>
> - arch_early_irq_init();
> + return arch_early_irq_init();
> }
>
> struct irq_desc *irq_to_desc(unsigned int irq)
> --
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--
Thanks & Regards,
Kamalesh Babulal,
Linux Technology Center,
IBM, ISTL.
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