Re: [BUG] next-20081216 - WARNING: at kernel/smp.c:333 smp_call_function_mask

Yinghai Lu
2008-12-27T07:40:34Z

Kamalesh Babulal wrote:
> * Ingo Molnar <mingo@elte.hu> [2008-12-26 19:17:34]:
>
>> * Kamalesh Babulal <kamalesh@linux.vnet.ibm.com> wrote:
>>
>>>> how about the patch below, does that work too? (after removing
>>>> Yinghai's patch)
>>> Hi Ingo,
>>>
>>> Kernel crashes with the same trace, after the applying the patch.
>> okay, thanks - does the below cleaner variant of Yinghai's patch solve the
>> problem too?
>>
>> Ingo
>>
>> -------------------->
>> From 9c93fc72ec95dc97d65b840978f9d605f4e5823a Mon Sep 17 00:00:00 2001
>> From: Yinghai Lu <yinghai@kernel.org>
>> 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 putting a barrier into the function.
>>
>> Signed-off-by: Yinghai <yinghai@kernel.org>
>> Signed-off-by: Ingo Molnar <mingo@elte.hu>
>> ---
>> init/main.c | 9 +++++++++
>> kernel/irq/handle.c | 3 ++-
>> 2 files changed, 11 insertions(+), 1 deletions(-)
>>
>> diff --git a/init/main.c b/init/main.c
>> index c1f999a..841d2b2 100644
>> --- a/init/main.c
>> +++ b/init/main.c
>> @@ -531,20 +531,29 @@ static void __init boot_cpu_init(void)
>> cpu_set(cpu, cpu_possible_map);
>> }
>>
>> +/*
>> + * The barriers are needed to keep a GCC bug from optimizing
>> + * away these weak functions:
>> + */
>> +
>> void __init __weak smp_setup_processor_id(void)
>> {
>> + barrier();
>> }
>>
>> void __init __weak thread_info_cache_init(void)
>> {
>> + barrier();
>> }
>>
>> void __init __weak arch_early_irq_init(void)
>> {
>> + barrier();
>> }
>>
>> void __init __weak early_irq_init(void)
>> {
>> + barrier();
>> arch_early_irq_init();
>> }
>>
>> diff --git a/kernel/irq/handle.c b/kernel/irq/handle.c
>> index 06b05a4..a6d16a4 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)
>> +void __weak arch_init_chip_data(struct irq_desc *desc, int cpu)
>> {
>> + barrier();
>> }
>>
>> static void init_one_irq_desc(int irq, struct irq_desc *desc, int cpu)
>> --
>
> Hi Ingo,
>
> Kernel still crashes after applying the patch,

please try it again...

diff --git a/arch/x86/kernel/io_apic.c b/arch/x86/kernel/io_apic.c
index 0fb91df..1f164a1 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] = { .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;
@@ -188,6 +188,8 @@ void __init arch_early_irq_init(void)
if (i < NR_IRQS_LEGACY)
cpumask_setall(cfg[i].domain);
}
+
+ return 0;
}

#ifdef CONFIG_SPARSE_IRQ
diff --git a/include/linux/irq.h b/include/linux/irq.h
index 7bac2d4..8337e58 100644
--- a/include/linux/irq.h
+++ b/include/linux/irq.h
@@ -194,9 +194,9 @@ 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 5149dbd..9e2fafd 100644
--- a/init/main.c
+++ b/init/main.c
@@ -549,15 +549,14 @@ void __init __weak thread_info_cache_init(void)
barrier();
}

-void __init __weak arch_early_irq_init(void)
+int __init __weak arch_early_irq_init(void)
{
- barrier();
+ return 0;
}

-void __init __weak early_irq_init(void)
+int __init __weak early_irq_init(void)
{
- barrier();
- arch_early_irq_init();
+ return arch_early_irq_init();
}

asmlinkage void __init start_kernel(void)
diff --git a/kernel/irq/handle.c b/kernel/irq/handle.c
index 925e36c..0bef3ec 100644
--- a/kernel/irq/handle.c
+++ b/kernel/irq/handle.c
@@ -86,9 +86,9 @@ void init_kstat_irqs(struct irq_desc *desc, int cpu, int nr)
desc->kstat_irqs = (unsigned int *)ptr;
}

-void __weak arch_init_chip_data(struct irq_desc *desc, int cpu)
+int __weak arch_init_chip_data(struct irq_desc *desc, int cpu)
{
- barrier();
+ return 0;
}

static void init_one_irq_desc(int irq, struct irq_desc *desc, int cpu)
@@ -133,7 +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;
@@ -152,7 +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)