From: Ashok Raj <ashok.raj@intel.com>
We need to hold call-lock when updating cpu-online-map to ensure the newly
upcoming cpu is excluded in an ongoing smp_call_function.
Signed-off-by: Ashok Raj <ashok.raj@intel.com>
Acked-by: Shaohua Li <shaohua.li@intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
---
arch/i386/kernel/smp.c | 10 ++++++++++
arch/i386/kernel/smpboot.c | 10 ++++++++++
include/asm-i386/smp.h | 2 ++
3 files changed, 22 insertions(+)
diff -puN arch/i386/kernel/smpboot.c~i386-hold-call_lock-when-updating-cpu_online_map arch/i386/kernel/smpboot.c
--- 25/arch/i386/kernel/smpboot.c~i386-hold-call_lock-when-updating-cpu_online_map 2005-06-07 20:58:52.000000000 -0700
+++ 25-akpm/arch/i386/kernel/smpboot.c 2005-06-07 20:58:52.000000000 -0700
@@ -454,7 +454,17 @@ static void __init start_secondary(void
*/
local_flush_tlb();
+ /*
+ * We need to hold call_lock, so there is no inconsistency
+ * between the time smp_call_function() determines number of
+ * IPI receipients, and the time when the determination is made
+ * for which cpus receive the IPI. Holding this
+ * lock helps us to not include this cpu in a currently in progress
+ * smp_call_function().
+ */
+ lock_ipi_call_lock();
cpu_set(smp_processor_id(), cpu_online_map);
+ unlock_ipi_call_lock();
/* We can take interrupts now: we're officially "up". */
local_irq_enable();
diff -puN arch/i386/kernel/smp.c~i386-hold-call_lock-when-updating-cpu_online_map arch/i386/kernel/smp.c
--- 25/arch/i386/kernel/smp.c~i386-hold-call_lock-when-updating-cpu_online_map 2005-06-07 20:58:52.000000000 -0700
+++ 25-akpm/arch/i386/kernel/smp.c 2005-06-07 20:58:52.000000000 -0700
@@ -495,6 +495,16 @@ struct call_data_struct {
int wait;
};
+void lock_ipi_call_lock(void)
+{
+ spin_lock_irq(&call_lock);
+}
+
+void unlock_ipi_call_lock(void)
+{
+ spin_unlock_irq(&call_lock);
+}
+
static struct call_data_struct * call_data;
/*
diff -puN include/asm-i386/smp.h~i386-hold-call_lock-when-updating-cpu_online_map include/asm-i386/smp.h
--- 25/include/asm-i386/smp.h~i386-hold-call_lock-when-updating-cpu_online_map 2005-06-07 20:58:52.000000000 -0700
+++ 25-akpm/include/asm-i386/smp.h 2005-06-07 20:58:52.000000000 -0700
@@ -42,6 +42,8 @@ extern void smp_message_irq(int cpl, voi
extern void smp_invalidate_rcv(void); /* Process an NMI */
extern void (*mtrr_hook) (void);
extern void zap_low_mappings (void);
+extern void lock_ipi_call_lock(void);
+extern void unlock_ipi_call_lock(void);
#define MAX_APICID 256
extern u8 x86_cpu_to_apicid[];
_