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Subject[tip:sched/urgent] generic-ipi: Fix kexec boot crash by initializing call_single_queue before enabling interrupts
Commit-ID:  d8ad7d1123a960cc9f276bd499f9325c6f5e1bd1
Gitweb: http://git.kernel.org/tip/d8ad7d1123a960cc9f276bd499f9325c6f5e1bd1
Author: Takao Indoh <indou.takao@jp.fujitsu.com>
AuthorDate: Tue, 29 Mar 2011 12:35:04 -0400
Committer: Ingo Molnar <mingo@elte.hu>
CommitDate: Fri, 17 Jun 2011 10:17:12 +0200

generic-ipi: Fix kexec boot crash by initializing call_single_queue before enabling interrupts

There is a problem that kdump(2nd kernel) sometimes hangs up due
to a pending IPI from 1st kernel. Kernel panic occurs because IPI
comes before call_single_queue is initialized.

To fix the crash, rename init_call_single_data() to call_function_init()
and call it in start_kernel() so that call_single_queue can be
initialized before enabling interrupts.

The details of the crash are:

(1) 2nd kernel boots 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().

Signed-off-by: Takao Indoh <indou.takao@jp.fujitsu.com>
Reviewed-by: WANG Cong <xiyou.wangcong@gmail.com>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Milton Miller <miltonm@bga.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: kexec@lists.infradead.org
Link: http://lkml.kernel.org/r/D6CBEE2F420741indou.takao@jp.fujitsu.com
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
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 7ad824d..8cc38d3 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

/*
@@ -134,7 +137,7 @@ 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 cafba67..d7211fa 100644
--- a/init/main.c
+++ b/init/main.c
@@ -542,6 +542,7 @@ 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

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