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Subject[PATCH 8/9] x86/smpboot.c: Don't offline BSP if any irq can not be migrated out of it
Date
From: Fenghua Yu <fenghua.yu@intel.com>

Don't offline BSP if any irq can not be migrated out of it.

Call identify_boot_cpu_online() for BSP in smp_callin() and continue to online
BSP in native_cpu_up().

Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
---
arch/x86/kernel/smpboot.c | 43 ++++++++++++++++++++++++++++++++++++-------
1 files changed, 36 insertions(+), 7 deletions(-)

diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index 9f548cb..83838c5 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -136,8 +136,8 @@ EXPORT_PER_CPU_SYMBOL(cpu_info);
atomic_t init_deasserted;

/*
- * Report back to the Boot Processor.
- * Running on AP.
+ * Report back to the Boot Processor during boot time or to the caller processor
+ * during CPU online.
*/
static void __cpuinit smp_callin(void)
{
@@ -224,6 +224,13 @@ static void __cpuinit smp_callin(void)
smp_store_cpu_info(cpuid);

/*
+ * This function won't run on the BSP during boot time. It run
+ * on BSP only when BSP is offlined and onlined again.
+ */
+ if (cpuid == 0)
+ identify_boot_cpu_online();
+
+ /*
* This must be done before setting cpu_online_mask
* or calling notify_cpu_starting.
*/
@@ -839,7 +846,7 @@ int __cpuinit native_cpu_up(unsigned int cpu)

pr_debug("++++++++++++++++++++=_---CPU UP %u\n", cpu);

- if (apicid == BAD_APICID || apicid == boot_cpu_physical_apicid ||
+ if (apicid == BAD_APICID ||
!physid_isset(apicid, phys_cpu_present_map)) {
printk(KERN_ERR "%s: bad cpu %d\n", __func__, cpu);
return -EINVAL;
@@ -1283,12 +1290,34 @@ int native_cpu_disable(void)
* Perhaps use cpufreq to drop frequency, but that could go
* into generic code.
*
- * We won't take down the boot processor on i386 due to some
+ * We won't take down the boot processor on i386 if some
* interrupts only being able to be serviced by the BSP.
- * Especially so if we're not using an IOAPIC -zwane
+ * Especially so if we're not using an IOAPIC
+ * -original comment from zwane, changed by fyu
*/
- if (cpu == 0)
- return -EBUSY;
+ if (cpu == 0) {
+ int irq;
+ struct irq_desc *desc;
+ struct irq_data *data;
+ struct irq_chip *chip;
+
+ for_each_irq_desc(irq, desc) {
+ raw_spin_lock(&desc->lock);
+ if (!irq_has_action(irq)) {
+ raw_spin_unlock(&desc->lock);
+ continue;
+ }
+
+ data = irq_desc_get_irq_data(desc);
+ chip = irq_data_get_irq_chip(data);
+ if (!chip->irq_set_affinity) {
+ pr_debug("irq%d can't move out of BSP\n", irq);
+ raw_spin_unlock(&desc->lock);
+ return -EBUSY;
+ }
+ raw_spin_unlock(&desc->lock);
+ }
+ }

clear_local_APIC();

--
1.6.0.3


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