linux-kernel - [PATCH v2] generic-ipi: Initialize call_single

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Date:	Tue, 29 Mar 2011 12:35:04 -0400
From:	Takao Indoh <indou.takao@...fujitsu.com>
To:	linux-kernel@...r.kernel.org, kexec@...ts.infradead.org
Cc:	Milton Miller <miltonm@....com>, Jens Axboe <axboe@...nel.dk>,
	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
	Ingo Molnar <mingo@...e.hu>, Vivek Goyal <vgoyal@...hat.com>,
	WANG Cong <xiyou.wangcong@...il.com>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>
Subject: [PATCH v2] generic-ipi: Initialize call_single_queue before enabling interrupt

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@...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
--
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