kernel/cpu.c: create a CPU_STARTING cpu_chain notifier

Right now, there is no notifier that is called on a new cpu, before the new
cpu begins processing interrupts/softirqs.
Various kernel function would need that notification, e.g. kvm works around
by calling smp_call_function_single(), rcu polls cpu_online_map.

The patch adds a CPU_STARTING notification. It also adds a helper function
that sends the message to all cpu_chain handlers.

Tested on x86-64.
All other archs are untested. Especially on sparc, I'm not sure if I got
it right.

Signed-off-by: Manfred Spraul <manfred@colorfullife.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

diff --git a/arch/alpha/kernel/smp.c b/arch/alpha/kernel/smp.c
index 83df541..06b6fda 100644 (file)
--- a/arch/alpha/kernel/smp.c
+++ b/arch/alpha/kernel/smp.c
@@ -149,6 +149,9 @@ smp_callin(void)
        atomic_inc(&init_mm.mm_count);
        current->active_mm = &init_mm;
 
+       /* inform the notifiers about the new cpu */
+       notify_cpu_starting(cpuid);
+
        /* Must have completely accurate bogos.  */
        local_irq_enable();
 

diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c
index e9842f6..e42a749 100644 (file)
--- a/arch/arm/kernel/smp.c
+++ b/arch/arm/kernel/smp.c
@@ -277,6 +277,7 @@ asmlinkage void __cpuinit secondary_start_kernel(void)
        /*
         * Enable local interrupts.
         */
+       notify_cpu_starting(cpu);
        local_irq_enable();
        local_fiq_enable();
 

diff --git a/arch/cris/arch-v32/kernel/smp.c b/arch/cris/arch-v32/kernel/smp.c
index 952a24b..52e16c6 100644 (file)
--- a/arch/cris/arch-v32/kernel/smp.c
+++ b/arch/cris/arch-v32/kernel/smp.c
@@ -178,6 +178,7 @@ void __init smp_callin(void)
        unmask_irq(IPI_INTR_VECT);
        unmask_irq(TIMER0_INTR_VECT);
        preempt_disable();
+       notify_cpu_starting(cpu);
        local_irq_enable();
 
        cpu_set(cpu, cpu_online_map);

diff --git a/arch/ia64/kernel/smpboot.c b/arch/ia64/kernel/smpboot.c
index bcea81e..333b58f 100644 (file)
--- a/arch/ia64/kernel/smpboot.c
+++ b/arch/ia64/kernel/smpboot.c
@@ -401,6 +401,7 @@ smp_callin (void)
        spin_lock(&vector_lock);
        /* Setup the per cpu irq handling data structures */
        __setup_vector_irq(cpuid);
+       notify_cpu_starting(cpuid);
        cpu_set(cpuid, cpu_online_map);
        per_cpu(cpu_state, cpuid) = CPU_ONLINE;
        spin_unlock(&vector_lock);

diff --git a/arch/m32r/kernel/smpboot.c b/arch/m32r/kernel/smpboot.c
index 2c03ac1..fc29948 100644 (file)
--- a/arch/m32r/kernel/smpboot.c
+++ b/arch/m32r/kernel/smpboot.c
@@ -498,6 +498,8 @@ static void __init smp_online(void)
 {
        int cpu_id = smp_processor_id();
 
+       notify_cpu_starting(cpu_id);
+
        local_irq_enable();
 
        /* Get our bogomips. */

diff --git a/arch/mips/kernel/smp.c b/arch/mips/kernel/smp.c
index 4410f17..7b59cfb 100644 (file)
--- a/arch/mips/kernel/smp.c
+++ b/arch/mips/kernel/smp.c
@@ -121,6 +121,8 @@ asmlinkage __cpuinit void start_secondary(void)
        cpu = smp_processor_id();
        cpu_data[cpu].udelay_val = loops_per_jiffy;
 
+       notify_cpu_starting(cpu);
+
        mp_ops->smp_finish();
        set_cpu_sibling_map(cpu);
 

diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c
index 5337ca7..c27b10a 100644 (file)
--- a/arch/powerpc/kernel/smp.c
+++ b/arch/powerpc/kernel/smp.c
@@ -453,6 +453,7 @@ int __devinit start_secondary(void *unused)
        secondary_cpu_time_init();
 
        ipi_call_lock();
+       notify_cpu_starting(cpu);
        cpu_set(cpu, cpu_online_map);
        /* Update sibling maps */
        base = cpu_first_thread_in_core(cpu);

diff --git a/arch/s390/kernel/smp.c b/arch/s390/kernel/smp.c
index 00b9b4d..9e8b1f9 100644 (file)
--- a/arch/s390/kernel/smp.c
+++ b/arch/s390/kernel/smp.c
@@ -585,6 +585,8 @@ int __cpuinit start_secondary(void *cpuvoid)
        /* Enable pfault pseudo page faults on this cpu. */
        pfault_init();
 
+       /* call cpu notifiers */
+       notify_cpu_starting(smp_processor_id());
        /* Mark this cpu as online */
        spin_lock(&call_lock);
        cpu_set(smp_processor_id(), cpu_online_map);

diff --git a/arch/sh/kernel/smp.c b/arch/sh/kernel/smp.c
index 60c5084..001778f 100644 (file)
--- a/arch/sh/kernel/smp.c
+++ b/arch/sh/kernel/smp.c
@@ -82,6 +82,8 @@ asmlinkage void __cpuinit start_secondary(void)
 
        preempt_disable();
 
+       notify_cpu_starting(smp_processor_id());
+
        local_irq_enable();
 
        calibrate_delay();

diff --git a/arch/sparc/kernel/sun4d_smp.c b/arch/sparc/kernel/sun4d_smp.c
index 6959640..446767e 100644 (file)
--- a/arch/sparc/kernel/sun4d_smp.c
+++ b/arch/sparc/kernel/sun4d_smp.c
@@ -88,6 +88,7 @@ void __init smp4d_callin(void)
        local_flush_cache_all();
        local_flush_tlb_all();
 
+       notify_cpu_starting(cpuid);
        /*
         * Unblock the master CPU _only_ when the scheduler state
         * of all secondary CPUs will be up-to-date, so after

diff --git a/arch/sparc/kernel/sun4m_smp.c b/arch/sparc/kernel/sun4m_smp.c
index a14a76a..9964890 100644 (file)
--- a/arch/sparc/kernel/sun4m_smp.c
+++ b/arch/sparc/kernel/sun4m_smp.c
@@ -71,6 +71,8 @@ void __cpuinit smp4m_callin(void)
        local_flush_cache_all();
        local_flush_tlb_all();
 
+       notify_cpu_starting(cpuid);
+
        /* Get our local ticker going. */
        smp_setup_percpu_timer();
 

diff --git a/arch/um/kernel/smp.c b/arch/um/kernel/smp.c
index be2d50c..0457721 100644 (file)
--- a/arch/um/kernel/smp.c
+++ b/arch/um/kernel/smp.c
@@ -85,6 +85,7 @@ static int idle_proc(void *cpup)
        while (!cpu_isset(cpu, smp_commenced_mask))
                cpu_relax();
 
+       notify_cpu_starting(cpu);
        cpu_set(cpu, cpu_online_map);
        default_idle();
        return 0;

diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index 7985c5b..0b8261c 100644 (file)
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -257,6 +257,7 @@ static void __cpuinit smp_callin(void)
        end_local_APIC_setup();
        map_cpu_to_logical_apicid();
 
+       notify_cpu_starting(cpuid);
        /*
         * Get our bogomips.
         *

diff --git a/arch/x86/mach-voyager/voyager_smp.c b/arch/x86/mach-voyager/voyager_smp.c
index ee0fba0..199a5f4 100644 (file)
--- a/arch/x86/mach-voyager/voyager_smp.c
+++ b/arch/x86/mach-voyager/voyager_smp.c
@@ -448,6 +448,8 @@ static void __init start_secondary(void *unused)
 
        VDEBUG(("VOYAGER SMP: CPU%d, stack at about %p\n", cpuid, &cpuid));
 
+       notify_cpu_starting(cpuid);
+
        /* enable interrupts */
        local_irq_enable();
 

diff --git a/include/linux/cpu.h b/include/linux/cpu.h
index d7faf88..c2747ac 100644 (file)
--- a/include/linux/cpu.h
+++ b/include/linux/cpu.h
@@ -69,6 +69,7 @@ static inline void unregister_cpu_notifier(struct notifier_block *nb)
 #endif
 
 int cpu_up(unsigned int cpu);
+void notify_cpu_starting(unsigned int cpu);
 extern void cpu_hotplug_init(void);
 extern void cpu_maps_update_begin(void);
 extern void cpu_maps_update_done(void);

diff --git a/include/linux/notifier.h b/include/linux/notifier.h
index da2698b..b86fa2f 100644 (file)
--- a/include/linux/notifier.h
+++ b/include/linux/notifier.h
@@ -213,9 +213,16 @@ static inline int notifier_to_errno(int ret)
 #define CPU_DOWN_FAILED                0x0006 /* CPU (unsigned)v NOT going down */
 #define CPU_DEAD               0x0007 /* CPU (unsigned)v dead */
 #define CPU_DYING              0x0008 /* CPU (unsigned)v not running any task,
-                                       * not handling interrupts, soon dead */
+                                       * not handling interrupts, soon dead.
+                                       * Called on the dying cpu, interrupts
+                                       * are already disabled. Must not
+                                       * sleep, must not fail */
 #define CPU_POST_DEAD          0x0009 /* CPU (unsigned)v dead, cpu_hotplug
                                        * lock is dropped */
+#define CPU_STARTING           0x000A /* CPU (unsigned)v soon running.
+                                       * Called on the new cpu, just before
+                                       * enabling interrupts. Must not sleep,
+                                       * must not fail */
 
 /* Used for CPU hotplug events occuring while tasks are frozen due to a suspend
  * operation in progress
@@ -229,6 +236,7 @@ static inline int notifier_to_errno(int ret)
 #define CPU_DOWN_FAILED_FROZEN (CPU_DOWN_FAILED | CPU_TASKS_FROZEN)
 #define CPU_DEAD_FROZEN                (CPU_DEAD | CPU_TASKS_FROZEN)
 #define CPU_DYING_FROZEN       (CPU_DYING | CPU_TASKS_FROZEN)
+#define CPU_STARTING_FROZEN    (CPU_STARTING | CPU_TASKS_FROZEN)
 
 /* Hibernation and suspend events */
 #define PM_HIBERNATION_PREPARE 0x0001 /* Going to hibernate */

diff --git a/kernel/cpu.c b/kernel/cpu.c
index f17e985..dc45f24 100644 (file)
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -453,6 +453,25 @@ out:
 }
 #endif /* CONFIG_PM_SLEEP_SMP */
 
+/**
+ * notify_cpu_starting(cpu) - call the CPU_STARTING notifiers
+ * @cpu: cpu that just started
+ *
+ * This function calls the cpu_chain notifiers with CPU_STARTING.
+ * It must be called by the arch code on the new cpu, before the new cpu
+ * enables interrupts and before the "boot" cpu returns from __cpu_up().
+ */
+void notify_cpu_starting(unsigned int cpu)
+{
+       unsigned long val = CPU_STARTING;
+
+#ifdef CONFIG_PM_SLEEP_SMP
+       if (cpu_isset(cpu, frozen_cpus))
+               val = CPU_STARTING_FROZEN;
+#endif /* CONFIG_PM_SLEEP_SMP */
+       raw_notifier_call_chain(&cpu_chain, val, (void *)(long)cpu);
+}
+
 #endif /* CONFIG_SMP */
 
 /*