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 <[email protected]>
Acked-by: Shaohua Li <[email protected]>
-------------------------------------------------
arch/i386/kernel/smp.c | 10 ++++++++++
arch/i386/kernel/smpboot.c | 10 ++++++++++
include/asm-i386/smp.h | 2 ++
3 files changed, 22 insertions(+)
Index: linux-2.6.12-rc6-mm1/arch/i386/kernel/smp.c
===================================================================
--- linux-2.6.12-rc6-mm1.orig/arch/i386/kernel/smp.c
+++ linux-2.6.12-rc6-mm1/arch/i386/kernel/smp.c
@@ -506,6 +506,16 @@ 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;
/*
Index: linux-2.6.12-rc6-mm1/include/asm-i386/smp.h
===================================================================
--- linux-2.6.12-rc6-mm1.orig/include/asm-i386/smp.h
+++ linux-2.6.12-rc6-mm1/include/asm-i386/smp.h
@@ -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[];
Index: linux-2.6.12-rc6-mm1/arch/i386/kernel/smpboot.c
===================================================================
--- linux-2.6.12-rc6-mm1.orig/arch/i386/kernel/smpboot.c
+++ linux-2.6.12-rc6-mm1/arch/i386/kernel/smpboot.c
@@ -503,7 +503,17 @@ static void __devinit start_secondary(vo
set_cpu_sibling_map(raw_smp_processor_id());
wmb();
+ /*
+ * 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();
--
-
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