Merge branch 'sh/smp'

arch/sh/Kconfig

@@ -706,6 +706,13 @@ config NR_CPUS
 	  This is purely to save memory - each supported CPU adds
 	  approximately eight kilobytes to the kernel image.
 
+config HOTPLUG_CPU
+	bool "Support for hot-pluggable CPUs (EXPERIMENTAL)"
+	depends on SMP && HOTPLUG && EXPERIMENTAL
+	help
+	  Say Y here to experiment with turning CPUs off and on.  CPUs
+	  can be controlled through /sys/devices/system/cpu.
+
 source "kernel/Kconfig.preempt"
 
 config GUSA

arch/sh/boards/board-urquell.c

@@ -24,6 +24,7 @@
 #include <cpu/sh7786.h>
 #include <asm/heartbeat.h>
 #include <asm/sizes.h>
+#include <asm/smp-ops.h>
 
 /*
  * bit  1234 5678
@@ -203,6 +204,8 @@ static void __init urquell_setup(char **cmdline_p)
 	printk(KERN_INFO "Renesas Technology Corp. Urquell support.\n");
 
 	pm_power_off = urquell_power_off;
+
+	register_smp_ops(&shx3_smp_ops);
 }
 
 /*

arch/sh/boards/mach-sdk7786/setup.c

@@ -21,6 +21,7 @@
 #include <asm/heartbeat.h>
 #include <asm/sizes.h>
 #include <asm/reboot.h>
+#include <asm/smp-ops.h>
 
 static struct resource heartbeat_resource = {
 	.start		= 0x07fff8b0,
@@ -189,6 +190,8 @@ static void __init sdk7786_setup(char **cmdline_p)
 
 	machine_ops.restart = sdk7786_restart;
 	pm_power_off = sdk7786_power_off;
+
+	register_smp_ops(&shx3_smp_ops);
 }
 
 /*

arch/sh/boards/mach-x3proto/setup.c

@@ -19,6 +19,7 @@
 #include <linux/usb/r8a66597.h>
 #include <linux/usb/m66592.h>
 #include <asm/ilsel.h>
+#include <asm/smp-ops.h>
 
 static struct resource heartbeat_resources[] = {
 	[0] = {
@@ -152,7 +153,13 @@ static void __init x3proto_init_irq(void)
 	__raw_writel(__raw_readl(0xfe410000) | (1 << 21), 0xfe410000);
 }
 
+static void __init x3proto_setup(char **cmdline_p)
+{
+	register_smp_ops(&shx3_smp_ops);
+}
+
 static struct sh_machine_vector mv_x3proto __initmv = {
 	.mv_name		= "x3proto",
+	.mv_setup		= x3proto_setup,
 	.mv_init_irq		= x3proto_init_irq,
 };

arch/sh/include/asm/irq.h

 #ifndef __ASM_SH_IRQ_H
 #define __ASM_SH_IRQ_H
 
+#include <linux/cpumask.h>
 #include <asm/machvec.h>
 
 /*
@@ -50,6 +51,8 @@ static inline int generic_irq_demux(int irq)
 #define irq_demux(irq)		sh_mv.mv_irq_demux(irq)
 
 void init_IRQ(void);
+void migrate_irqs(void);
+
 asmlinkage int do_IRQ(unsigned int irq, struct pt_regs *regs);
 
 #ifdef CONFIG_IRQSTACKS

arch/sh/include/asm/processor.h

@@ -85,6 +85,10 @@ struct sh_cpuinfo {
 	struct tlb_info itlb;
 	struct tlb_info dtlb;
 
+#ifdef CONFIG_SMP
+	struct task_struct *idle;
+#endif
+
 	unsigned long flags;
 } __attribute__ ((aligned(L1_CACHE_BYTES)));
 

arch/sh/include/asm/smp-ops.h

+#ifndef __ASM_SH_SMP_OPS_H
+#define __ASM_SH_SMP_OPS_H
+
+struct plat_smp_ops {
+	void (*smp_setup)(void);
+	unsigned int (*smp_processor_id)(void);
+	void (*prepare_cpus)(unsigned int max_cpus);
+	void (*start_cpu)(unsigned int cpu, unsigned long entry_point);
+	void (*send_ipi)(unsigned int cpu, unsigned int message);
+	int (*cpu_disable)(unsigned int cpu);
+	void (*cpu_die)(unsigned int cpu);
+	void (*play_dead)(void);
+};
+
+extern struct plat_smp_ops *mp_ops;
+extern struct plat_smp_ops shx3_smp_ops;
+
+#ifdef CONFIG_SMP
+
+static inline void plat_smp_setup(void)
+{
+	BUG_ON(!mp_ops);
+	mp_ops->smp_setup();
+}
+
+static inline void play_dead(void)
+{
+	mp_ops->play_dead();
+}
+
+extern void register_smp_ops(struct plat_smp_ops *ops);
+
+#else
+
+static inline void plat_smp_setup(void)
+{
+	/* UP, nothing to do ... */
+}
+
+static inline void register_smp_ops(struct plat_smp_ops *ops)
+{
+}
+
+static inline void play_dead(void)
+{
+	BUG();
+}
+
+#endif /* CONFIG_SMP */
+
+#endif /* __ASM_SH_SMP_OPS_H */

arch/sh/include/asm/smp.h

@@ -3,15 +3,16 @@
 
 #include <linux/bitops.h>
 #include <linux/cpumask.h>
+#include <asm/smp-ops.h>
 
 #ifdef CONFIG_SMP
 
 #include <linux/spinlock.h>
 #include <asm/atomic.h>
 #include <asm/current.h>
+#include <asm/percpu.h>
 
 #define raw_smp_processor_id()	(current_thread_info()->cpu)
-#define hard_smp_processor_id()	plat_smp_processor_id()
 
 /* Map from cpu id to sequential logical cpu number. */
 extern int __cpu_number_map[NR_CPUS];
@@ -30,20 +31,43 @@ enum {
 	SMP_MSG_NR,	/* must be last */
 };
 
+DECLARE_PER_CPU(int, cpu_state);
+
 void smp_message_recv(unsigned int msg);
 void smp_timer_broadcast(const struct cpumask *mask);
 
 void local_timer_interrupt(void);
 void local_timer_setup(unsigned int cpu);
-
-void plat_smp_setup(void);
-void plat_prepare_cpus(unsigned int max_cpus);
-int plat_smp_processor_id(void);
-void plat_start_cpu(unsigned int cpu, unsigned long entry_point);
-void plat_send_ipi(unsigned int cpu, unsigned int message);
+void local_timer_stop(unsigned int cpu);
 
 void arch_send_call_function_single_ipi(int cpu);
-extern void arch_send_call_function_ipi_mask(const struct cpumask *mask);
+void arch_send_call_function_ipi_mask(const struct cpumask *mask);
+
+void native_play_dead(void);
+void native_cpu_die(unsigned int cpu);
+int native_cpu_disable(unsigned int cpu);
+
+#ifdef CONFIG_HOTPLUG_CPU
+void play_dead_common(void);
+extern int __cpu_disable(void);
+
+static inline void __cpu_die(unsigned int cpu)
+{
+	extern struct plat_smp_ops *mp_ops;     /* private */
+
+	mp_ops->cpu_die(cpu);
+}
+#endif
+
+static inline int hard_smp_processor_id(void)
+{
+	extern struct plat_smp_ops *mp_ops;	/* private */
+
+	if (!mp_ops)
+		return 0;	/* boot CPU */
+
+	return mp_ops->smp_processor_id();
+}
 
 #else
 

arch/sh/kernel/cpu/sh4a/smp-shx3.c

 /*
  * SH-X3 SMP
  *
- *  Copyright (C) 2007 - 2008  Paul Mundt
+ *  Copyright (C) 2007 - 2010  Paul Mundt
  *  Copyright (C) 2007  Magnus Damm
  *
  * This file is subject to the terms and conditions of the GNU General Public
@@ -9,16 +9,22 @@
  * for more details.
  */
 #include <linux/init.h>
+#include <linux/kernel.h>
 #include <linux/cpumask.h>
 #include <linux/smp.h>
 #include <linux/interrupt.h>
 #include <linux/io.h>
+#include <linux/sched.h>
+#include <linux/delay.h>
+#include <linux/cpu.h>
+#include <asm/sections.h>
 
 #define STBCR_REG(phys_id) (0xfe400004 | (phys_id << 12))
 #define RESET_REG(phys_id) (0xfe400008 | (phys_id << 12))
 
 #define STBCR_MSTP	0x00000001
 #define STBCR_RESET	0x00000002
+#define STBCR_SLEEP	0x00000004
 #define STBCR_LTSLP	0x80000000
 
 static irqreturn_t ipi_interrupt_handler(int irq, void *arg)
@@ -37,7 +43,7 @@ static irqreturn_t ipi_interrupt_handler(int irq, void *arg)
 	return IRQ_HANDLED;
 }
 
-void __init plat_smp_setup(void)
+static void shx3_smp_setup(void)
 {
 	unsigned int cpu = 0;
 	int i, num;
@@ -63,7 +69,7 @@ void __init plat_smp_setup(void)
         printk(KERN_INFO "Detected %i available secondary CPU(s)\n", num);
 }
 
-void __init plat_prepare_cpus(unsigned int max_cpus)
+static void shx3_prepare_cpus(unsigned int max_cpus)
 {
 	int i;
 
@@ -74,9 +80,12 @@ void __init plat_prepare_cpus(unsigned int max_cpus)
 	for (i = 0; i < SMP_MSG_NR; i++)
 		request_irq(104 + i, ipi_interrupt_handler,
 			    IRQF_DISABLED | IRQF_PERCPU, "IPI", (void *)(long)i);
+
+	for (i = 0; i < max_cpus; i++)
+		set_cpu_present(i, true);
 }
 
-void plat_start_cpu(unsigned int cpu, unsigned long entry_point)
+static void shx3_start_cpu(unsigned int cpu, unsigned long entry_point)
 {
 	if (__in_29bit_mode())
 		__raw_writel(entry_point, RESET_REG(cpu));
@@ -93,12 +102,12 @@ void plat_start_cpu(unsigned int cpu, unsigned long entry_point)
 	__raw_writel(STBCR_RESET | STBCR_LTSLP, STBCR_REG(cpu));
 }
 
-int plat_smp_processor_id(void)
+static unsigned int shx3_smp_processor_id(void)
 {
 	return __raw_readl(0xff000048); /* CPIDR */
 }
 
-void plat_send_ipi(unsigned int cpu, unsigned int message)
+static void shx3_send_ipi(unsigned int cpu, unsigned int message)
 {
 	unsigned long addr = 0xfe410070 + (cpu * 4);
 
@@ -106,3 +115,52 @@ void plat_send_ipi(unsigned int cpu, unsigned int message)
 
 	__raw_writel(1 << (message << 2), addr); /* C0INTICI..CnINTICI */
 }
+
+static void shx3_update_boot_vector(unsigned int cpu)
+{
+	__raw_writel(STBCR_MSTP, STBCR_REG(cpu));
+	while (!(__raw_readl(STBCR_REG(cpu)) & STBCR_MSTP))
+		cpu_relax();
+	__raw_writel(STBCR_RESET, STBCR_REG(cpu));
+}
+
+static int __cpuinit
+shx3_cpu_callback(struct notifier_block *nfb, unsigned long action, void *hcpu)
+{
+	unsigned int cpu = (unsigned int)hcpu;
+
+	switch (action) {
+	case CPU_UP_PREPARE:
+		shx3_update_boot_vector(cpu);
+		break;
+	case CPU_ONLINE:
+		pr_info("CPU %u is now online\n", cpu);
+		break;
+	case CPU_DEAD:
+		break;
+	}
+
+	return NOTIFY_OK;
+}
+
+static struct notifier_block __cpuinitdata shx3_cpu_notifier = {
+	.notifier_call		= shx3_cpu_callback,
+};
+
+static int __cpuinit register_shx3_cpu_notifier(void)
+{
+	register_hotcpu_notifier(&shx3_cpu_notifier);
+	return 0;
+}
+late_initcall(register_shx3_cpu_notifier);
+
+struct plat_smp_ops shx3_smp_ops = {
+	.smp_setup		= shx3_smp_setup,
+	.prepare_cpus		= shx3_prepare_cpus,
+	.start_cpu		= shx3_start_cpu,
+	.smp_processor_id	= shx3_smp_processor_id,
+	.send_ipi		= shx3_send_ipi,
+	.cpu_die		= native_cpu_die,
+	.cpu_disable		= native_cpu_disable,
+	.play_dead		= native_play_dead,
+};

arch/sh/kernel/idle.c

@@ -19,6 +19,7 @@
 #include <asm/pgalloc.h>
 #include <asm/system.h>
 #include <asm/atomic.h>
+#include <asm/smp.h>
 
 void (*pm_idle)(void) = NULL;
 
@@ -89,10 +90,13 @@ void cpu_idle(void)
 	while (1) {
 		tick_nohz_stop_sched_tick(1);
 
-		while (!need_resched() && cpu_online(cpu)) {
+		while (!need_resched()) {
 			check_pgt_cache();
 			rmb();
 
+			if (cpu_is_offline(cpu))
+				play_dead();
+
 			local_irq_disable();
 			/* Don't trace irqs off for idle */
 			stop_critical_timings();
@@ -133,7 +137,7 @@ static void do_nothing(void *unused)
 void stop_this_cpu(void *unused)
 {
 	local_irq_disable();
-	cpu_clear(smp_processor_id(), cpu_online_map);
+	set_cpu_online(smp_processor_id(), false);
 
 	for (;;)
 		cpu_sleep();

arch/sh/kernel/irq.c

@@ -12,6 +12,7 @@
 #include <linux/kernel_stat.h>
 #include <linux/seq_file.h>
 #include <linux/ftrace.h>
+#include <linux/delay.h>
 #include <asm/processor.h>
 #include <asm/machvec.h>
 #include <asm/uaccess.h>
@@ -292,3 +293,44 @@ int __init arch_probe_nr_irqs(void)
 	return 0;
 }
 #endif
+
+#ifdef CONFIG_HOTPLUG_CPU
+static void route_irq(struct irq_desc *desc, unsigned int irq, unsigned int cpu)
+{
+	printk(KERN_INFO "IRQ%u: moving from cpu%u to cpu%u\n",
+	       irq, desc->node, cpu);
+
+	raw_spin_lock_irq(&desc->lock);
+	desc->chip->set_affinity(irq, cpumask_of(cpu));
+	raw_spin_unlock_irq(&desc->lock);
+}
+
+/*
+ * The CPU has been marked offline.  Migrate IRQs off this CPU.  If
+ * the affinity settings do not allow other CPUs, force them onto any
+ * available CPU.
+ */
+void migrate_irqs(void)
+{
+	struct irq_desc *desc;
+	unsigned int irq, cpu = smp_processor_id();
+
+	for_each_irq_desc(irq, desc) {
+		if (desc->node == cpu) {
+			unsigned int newcpu = cpumask_any_and(desc->affinity,
+							      cpu_online_mask);
+			if (newcpu >= nr_cpu_ids) {
+				if (printk_ratelimit())
+					printk(KERN_INFO "IRQ%u no longer affine to CPU%u\n",
+					       irq, cpu);
+
+				cpumask_setall(desc->affinity);
+				newcpu = cpumask_any_and(desc->affinity,
+							 cpu_online_mask);
+			}
+
+			route_irq(desc, irq, newcpu);
+		}
+	}
+}
+#endif

arch/sh/kernel/localtimer.c

@@ -44,7 +44,7 @@ static void dummy_timer_set_mode(enum clock_event_mode mode,
 {
 }
 
-void __cpuinit local_timer_setup(unsigned int cpu)
+void local_timer_setup(unsigned int cpu)
 {
 	struct clock_event_device *clk = &per_cpu(local_clockevent, cpu);
 
@@ -60,3 +60,7 @@ void __cpuinit local_timer_setup(unsigned int cpu)
 
 	clockevents_register_device(clk);
 }
+
+void local_timer_stop(unsigned int cpu)
+{
+}

arch/sh/kernel/setup.c

@@ -39,6 +39,7 @@
 #include <asm/irq.h>
 #include <asm/setup.h>
 #include <asm/clock.h>
+#include <asm/smp.h>
 #include <asm/mmu_context.h>
 
 /*
@@ -459,9 +460,7 @@ void __init setup_arch(char **cmdline_p)
 	if (likely(sh_mv.mv_setup))
 		sh_mv.mv_setup(cmdline_p);
 
-#ifdef CONFIG_SMP
 	plat_smp_setup();
-#endif
 }
 
 /* processor boot mode configuration */

arch/sh/kernel/smp.c

@@ -3,7 +3,7 @@
  *
  * SMP support for the SuperH processors.
  *
- * Copyright (C) 2002 - 2008 Paul Mundt
+ * Copyright (C) 2002 - 2010 Paul Mundt
  * Copyright (C) 2006 - 2007 Akio Idehara
  *
  * This file is subject to the terms and conditions of the GNU General Public
@@ -31,7 +31,20 @@
 int __cpu_number_map[NR_CPUS];		/* Map physical to logical */
 int __cpu_logical_map[NR_CPUS];		/* Map logical to physical */
 
-static inline void __init smp_store_cpu_info(unsigned int cpu)
+struct plat_smp_ops *mp_ops = NULL;
+
+/* State of each CPU */
+DEFINE_PER_CPU(int, cpu_state) = { 0 };
+
+void __cpuinit register_smp_ops(struct plat_smp_ops *ops)
+{
+	if (mp_ops)
+		printk(KERN_WARNING "Overriding previously set SMP ops\n");
+
+	mp_ops = ops;
+}
+
+static inline void __cpuinit smp_store_cpu_info(unsigned int cpu)
 {
 	struct sh_cpuinfo *c = cpu_data + cpu;
 
@@ -46,14 +59,14 @@ void __init smp_prepare_cpus(unsigned int max_cpus)
 
 	init_new_context(current, &init_mm);
 	current_thread_info()->cpu = cpu;
-	plat_prepare_cpus(max_cpus);
+	mp_ops->prepare_cpus(max_cpus);
 
 #ifndef CONFIG_HOTPLUG_CPU
 	init_cpu_present(&cpu_possible_map);
 #endif
 }
 
-void __devinit smp_prepare_boot_cpu(void)
+void __init smp_prepare_boot_cpu(void)
 {
 	unsigned int cpu = smp_processor_id();
 
@@ -62,37 +75,137 @@ void __devinit smp_prepare_boot_cpu(void)
 
 	set_cpu_online(cpu, true);
 	set_cpu_possible(cpu, true);
+
+	per_cpu(cpu_state, cpu) = CPU_ONLINE;
+}
+
+#ifdef CONFIG_HOTPLUG_CPU
+void native_cpu_die(unsigned int cpu)
+{
+	unsigned int i;
+
+	for (i = 0; i < 10; i++) {
+		smp_rmb();
+		if (per_cpu(cpu_state, cpu) == CPU_DEAD) {
+			if (system_state == SYSTEM_RUNNING)
+				pr_info("CPU %u is now offline\n", cpu);
+
+			return;
+		}
+
+		msleep(100);
+	}
+
+	pr_err("CPU %u didn't die...\n", cpu);
+}
+
+int native_cpu_disable(unsigned int cpu)
+{
+	return cpu == 0 ? -EPERM : 0;
+}
+
+void play_dead_common(void)
+{
+	idle_task_exit();
+	irq_ctx_exit(raw_smp_processor_id());
+	mb();
+
+	__get_cpu_var(cpu_state) = CPU_DEAD;
+	local_irq_disable();
+}
+
+void native_play_dead(void)
+{
+	play_dead_common();
 }
 
+int __cpu_disable(void)
+{
+	unsigned int cpu = smp_processor_id();
+	struct task_struct *p;
+	int ret;
+
+	ret = mp_ops->cpu_disable(cpu);
+	if (ret)
+		return ret;
+
+	/*
+	 * Take this CPU offline.  Once we clear this, we can't return,
+	 * and we must not schedule until we're ready to give up the cpu.
+	 */
+	set_cpu_online(cpu, false);
+
+	/*
+	 * OK - migrate IRQs away from this CPU
+	 */
+	migrate_irqs();
+
+	/*
+	 * Stop the local timer for this CPU.
+	 */
+	local_timer_stop(cpu);
+
+	/*
+	 * Flush user cache and TLB mappings, and then remove this CPU
+	 * from the vm mask set of all processes.
+	 */
+	flush_cache_all();
+	local_flush_tlb_all();
+
+	read_lock(&tasklist_lock);
+	for_each_process(p)
+		if (p->mm)
+			cpumask_clear_cpu(cpu, mm_cpumask(p->mm));
+	read_unlock(&tasklist_lock);
+
+	return 0;
+}
+#else /* ... !CONFIG_HOTPLUG_CPU */
+int native_cpu_disable(void)
+{
+	return -ENOSYS;
+}
+
+void native_cpu_die(unsigned int cpu)
+{
+	/* We said "no" in __cpu_disable */
+	BUG();
+}
+
+void native_play_dead(void)
+{
+	BUG();
+}
+#endif
+
 asmlinkage void __cpuinit start_secondary(void)
 {
-	unsigned int cpu;
+	unsigned int cpu = smp_processor_id();
 	struct mm_struct *mm = &init_mm;
 
 	enable_mmu();
 	atomic_inc(&mm->mm_count);
 	atomic_inc(&mm->mm_users);
 	current->active_mm = mm;
-	BUG_ON(current->mm);
 	enter_lazy_tlb(mm, current);
+	local_flush_tlb_all();
 
 	per_cpu_trap_init();
 
 	preempt_disable();
 
-	notify_cpu_starting(smp_processor_id());
+	notify_cpu_starting(cpu);
 
 	local_irq_enable();
 
-	cpu = smp_processor_id();
-
 	/* Enable local timers */
 	local_timer_setup(cpu);
 	calibrate_delay();
 
 	smp_store_cpu_info(cpu);
 
-	cpu_set(cpu, cpu_online_map);
+	set_cpu_online(cpu, true);
+	per_cpu(cpu_state, cpu) = CPU_ONLINE;
 
 	cpu_idle();
 }
@@ -111,12 +224,19 @@ int __cpuinit __cpu_up(unsigned int cpu)
 	struct task_struct *tsk;
 	unsigned long timeout;
 
-	tsk = fork_idle(cpu);
-	if (IS_ERR(tsk)) {
-		printk(KERN_ERR "Failed forking idle task for cpu %d\n", cpu);
-		return PTR_ERR(tsk);
+	tsk = cpu_data[cpu].idle;
+	if (!tsk) {
+		tsk = fork_idle(cpu);
+		if (IS_ERR(tsk)) {
+			pr_err("Failed forking idle task for cpu %d\n", cpu);
+			return PTR_ERR(tsk);
+		}
+
+		cpu_data[cpu].idle = tsk;
 	}
 
+	per_cpu(cpu_state, cpu) = CPU_UP_PREPARE;
+
 	/* Fill in data in head.S for secondary cpus */
 	stack_start.sp = tsk->thread.sp;
 	stack_start.thread_info = tsk->stack;
@@ -127,7 +247,7 @@ int __cpuinit __cpu_up(unsigned int cpu)
 			   (unsigned long)&stack_start + sizeof(stack_start));
 	wmb();
 
-	plat_start_cpu(cpu, (unsigned long)_stext);
+	mp_ops->start_cpu(cpu, (unsigned long)_stext);
 
 	timeout = jiffies + HZ;
 	while (time_before(jiffies, timeout)) {
@@ -135,6 +255,7 @@ int __cpuinit __cpu_up(unsigned int cpu)
 			break;
 
 		udelay(10);
+		barrier();
 	}
 
 	if (cpu_online(cpu))
@@ -159,7 +280,7 @@ void __init smp_cpus_done(unsigned int max_cpus)
 
 void smp_send_reschedule(int cpu)
 {
-	plat_send_ipi(cpu, SMP_MSG_RESCHEDULE);
+	mp_ops->send_ipi(cpu, SMP_MSG_RESCHEDULE);
 }
 
 void smp_send_stop(void)
@@ -172,12 +293,12 @@ void arch_send_call_function_ipi_mask(const struct cpumask *mask)
 	int cpu;
 
 	for_each_cpu(cpu, mask)
-		plat_send_ipi(cpu, SMP_MSG_FUNCTION);
+		mp_ops->send_ipi(cpu, SMP_MSG_FUNCTION);
 }
 
 void arch_send_call_function_single_ipi(int cpu)
 {
-	plat_send_ipi(cpu, SMP_MSG_FUNCTION_SINGLE);
+	mp_ops->send_ipi(cpu, SMP_MSG_FUNCTION_SINGLE);
 }
 
 void smp_timer_broadcast(const struct cpumask *mask)
@@ -185,7 +306,7 @@ void smp_timer_broadcast(const struct cpumask *mask)
 	int cpu;
 
 	for_each_cpu(cpu, mask)
-		plat_send_ipi(cpu, SMP_MSG_TIMER);
+		mp_ops->send_ipi(cpu, SMP_MSG_TIMER);
 }
 
 static void ipi_timer(void)
@@ -249,7 +370,6 @@ static void flush_tlb_mm_ipi(void *mm)
  * behalf of debugees, kswapd stealing pages from another process etc).
  * Kanoj 07/00.
  */
-
 void flush_tlb_mm(struct mm_struct *mm)
 {
 	preempt_disable();

arch/sh/kernel/topology.c

@@ -52,7 +52,11 @@ static int __init topology_init(void)
 #endif
 
 	for_each_present_cpu(i) {
-		ret = register_cpu(&per_cpu(cpu_devices, i), i);
+		struct cpu *c = &per_cpu(cpu_devices, i);
+
+		c->hotpluggable = 1;
+
+		ret = register_cpu(c, i);
 		if (unlikely(ret))
 			printk(KERN_WARNING "%s: register_cpu %d failed (%d)\n",
 			       __func__, i, ret);