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    SubjectRe: [PATCH v2] generic-ipi: Initialize call_single_queue before enabling interrupt
    On Tue, Mar 29, 2011 at 12:35:04PM -0400, Takao Indoh wrote:
    > Hi all,
    >
    > This patch renames init_call_single_data() to call_function_init() and
    > calls it in start_kernel() so that call_single_queue can be initialized
    > before enabling interrupt.
    >
    > There is a problem that kdump(2nd kernel) sometimes hangs up due to
    > pending IPI from 1st kernel. Kernel panic occurs because IPI comes
    > before call_single_queue is initialized. The details are as follows.
    > (1) 2nd kernel boot up
    > (2) A pending IPI from 1st kernel comes when irqs are first enabled
    > in start_kernel().
    > (3) Kernel tries to handle the interrupt, but call_single_queue is not
    > initialized yet at this point. As a result, in the
    > generic_smp_call_function_single_interrupt(), NULL pointer
    > dereference occurs when list_replace_init() tries to access
    > &q->list.next.
    > Therefore this patch changes the name of init_call_single_data() to
    > call_function_init() and calls it before local_irq_enable() in
    > start_kernel().
    >
    > v2:
    > - Rename init_call_single_data() to call_function_init() and calls it in
    > start_kernel()
    > - Change insert position in start_kernel().
    > - Adjust for CONFIG_SMP/CONFIG_USE_GENERIC_SMP_HELPERS options
    > - Rebased to Linus's latest tree
    >
    > v1:
    > https://lkml.org/lkml/2011/3/25/317
    > - Divide init_call_single_data() into two functions,
    > o init_call_single_data: initialize call_single_queue
    > o init_hotplug_cfd: initialize hotplug_cfd_notifier
    > And call init_call_single_data before local_irq_enable() in
    > start_kernel().
    >
    > v0:
    > https://lkml.org/lkml/2011/3/23/417
    > - In generic_smp_call_function_single_interrupt(), check if
    > call_single_queue was initialized or not, and just return if not
    > initialized.
    >
    > Signed-off-by: Takao Indoh <indou.takao@jp.fujitsu.com>
    > ---
    > include/linux/smp.h | 5 ++++-
    > init/main.c | 1 +
    > kernel/smp.c | 5 +----
    > 3 files changed, 6 insertions(+), 5 deletions(-)
    >
    > diff --git a/include/linux/smp.h b/include/linux/smp.h
    > index 74243c8..4fb3eac 100644
    > --- a/include/linux/smp.h
    > +++ b/include/linux/smp.h
    > @@ -85,12 +85,15 @@ int smp_call_function_any(const struct cpumask *mask,
    > * Generic and arch helpers
    > */
    > #ifdef CONFIG_USE_GENERIC_SMP_HELPERS
    > +void __init call_function_init(void);
    > void generic_smp_call_function_single_interrupt(void);
    > void generic_smp_call_function_interrupt(void);
    > void ipi_call_lock(void);
    > void ipi_call_unlock(void);
    > void ipi_call_lock_irq(void);
    > void ipi_call_unlock_irq(void);
    > +#else
    > +static inline void call_function_init(void) { }
    > #endif
    >
    > /*
    > @@ -144,7 +147,7 @@ static inline void smp_send_reschedule(int cpu) { }
    > #define smp_prepare_boot_cpu() do {} while (0)
    > #define smp_call_function_many(mask, func, info, wait) \
    > (up_smp_call_function(func, info))
    > -static inline void init_call_single_data(void) { }
    > +static inline void call_function_init(void) { }
    >
    > static inline int
    > smp_call_function_any(const struct cpumask *mask, smp_call_func_t func,
    > diff --git a/init/main.c b/init/main.c
    > index 4a9479e..12821d1 100644
    > --- a/init/main.c
    > +++ b/init/main.c
    > @@ -539,6 +539,7 @@ asmlinkage void __init start_kernel(void)
    > timekeeping_init();
    > time_init();
    > profile_init();
    > + call_function_init();
    > if (!irqs_disabled())
    > printk(KERN_CRIT "start_kernel(): bug: interrupts were "
    > "enabled early\n");
    > diff --git a/kernel/smp.c b/kernel/smp.c
    > index 73a1951..fb67dfa 100644
    > --- a/kernel/smp.c
    > +++ b/kernel/smp.c
    > @@ -74,7 +74,7 @@ static struct notifier_block __cpuinitdata hotplug_cfd_notifier = {
    > .notifier_call = hotplug_cfd,
    > };
    >
    > -static int __cpuinit init_call_single_data(void)
    > +void __init call_function_init(void)
    > {
    > void *cpu = (void *)(long)smp_processor_id();
    > int i;
    > @@ -88,10 +88,7 @@ static int __cpuinit init_call_single_data(void)
    >
    > hotplug_cfd(&hotplug_cfd_notifier, CPU_UP_PREPARE, cpu);
    > register_cpu_notifier(&hotplug_cfd_notifier);
    > -
    > - return 0;
    > }
    > -early_initcall(init_call_single_data);
    >
    > /*
    > * csd_lock/csd_unlock used to serialize access to per-cpu csd resources
    >
    Acked-by: Neil Horman <nhorman@tuxdriver.com>

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