From 963e5d3b76d657f1ebcf3561446d2ba1872bbfa2 Mon Sep 17 00:00:00 2001
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Date: Tue, 29 Mar 2011 14:51:10 +1100
Subject: powerpc: Make decrementer interrupt robust against offlined CPUs

With some implementations, it is possible that a timer interrupt
occurs every few seconds on an offline CPU. In this case, just
re-arm the decrementer and return immediately

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
---
 arch/powerpc/kernel/time.c | 15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)

(limited to 'arch')

diff --git a/arch/powerpc/kernel/time.c b/arch/powerpc/kernel/time.c
index aa9269600ca2..375480c56eb9 100644
--- a/arch/powerpc/kernel/time.c
+++ b/arch/powerpc/kernel/time.c
@@ -577,14 +577,21 @@ void timer_interrupt(struct pt_regs * regs)
 	struct clock_event_device *evt = &decrementer->event;
 	u64 now;
 
+	/* Ensure a positive value is written to the decrementer, or else
+	 * some CPUs will continue to take decrementer exceptions.
+	 */
+	set_dec(DECREMENTER_MAX);
+
+	/* Some implementations of hotplug will get timer interrupts while
+	 * offline, just ignore these
+	 */
+	if (!cpu_online(smp_processor_id()))
+		return;
+
 	trace_timer_interrupt_entry(regs);
 
 	__get_cpu_var(irq_stat).timer_irqs++;
 
-	/* Ensure a positive value is written to the decrementer, or else
-	 * some CPUs will continuue to take decrementer exceptions */
-	set_dec(DECREMENTER_MAX);
-
 #if defined(CONFIG_PPC32) && defined(CONFIG_PMAC)
 	if (atomic_read(&ppc_n_lost_interrupts) != 0)
 		do_IRQ(regs);
-- 
cgit v1.2.3


From fa3f82c8bb7acbe049ea71f258b3ae0a33d9d40b Mon Sep 17 00:00:00 2001
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Date: Thu, 10 Feb 2011 18:45:24 +1100
Subject: powerpc/smp: soft-replugged CPUs must go back to start_secondary

Various thing are torn down when a CPU is hot-unplugged. That CPU
is expected to go back to start_secondary when re-plugged to re
initialize everything, such as clock sources, maps, ...

Some implementations just return from cpu_die() callback
in the idle loop when the CPU is "re-plugged". This is not enough.

We fix it using a little asm trampoline which resets the stack
and calls back into start_secondary as if we were all fresh from
boot. The trampoline already existed on ppc64, but we add it for
ppc32

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
---
 arch/powerpc/include/asm/smp.h                  | 1 +
 arch/powerpc/kernel/head_32.S                   | 9 +++++++++
 arch/powerpc/kernel/smp.c                       | 9 +++++++--
 arch/powerpc/platforms/pseries/offline_states.h | 2 --
 4 files changed, 17 insertions(+), 4 deletions(-)

(limited to 'arch')

diff --git a/arch/powerpc/include/asm/smp.h b/arch/powerpc/include/asm/smp.h
index 66e237bbe15f..1de0e97a394f 100644
--- a/arch/powerpc/include/asm/smp.h
+++ b/arch/powerpc/include/asm/smp.h
@@ -36,6 +36,7 @@ extern void cpu_die(void);
 
 extern void smp_send_debugger_break(int cpu);
 extern void smp_message_recv(int);
+extern void start_secondary_resume(void);
 
 DECLARE_PER_CPU(unsigned int, cpu_pvr);
 
diff --git a/arch/powerpc/kernel/head_32.S b/arch/powerpc/kernel/head_32.S
index 98c4b29a56f4..c5c24beb8387 100644
--- a/arch/powerpc/kernel/head_32.S
+++ b/arch/powerpc/kernel/head_32.S
@@ -890,6 +890,15 @@ __secondary_start:
 	mtspr	SPRN_SRR1,r4
 	SYNC
 	RFI
+
+_GLOBAL(start_secondary_resume)
+	/* Reset stack */
+	rlwinm	r1,r1,0,0,(31-THREAD_SHIFT)	/* current_thread_info() */
+	addi	r1,r1,THREAD_SIZE-STACK_FRAME_OVERHEAD
+	li	r3,0
+	std	r3,0(r1)		/* Zero the stack frame pointer	*/
+	bl	start_secondary
+	b	.
 #endif /* CONFIG_SMP */
 
 #ifdef CONFIG_KVM_BOOK3S_HANDLER
diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c
index 981360509172..1c9956c43801 100644
--- a/arch/powerpc/kernel/smp.c
+++ b/arch/powerpc/kernel/smp.c
@@ -502,7 +502,7 @@ static struct device_node *cpu_to_l2cache(int cpu)
 }
 
 /* Activate a secondary processor. */
-int __devinit start_secondary(void *unused)
+void __devinit start_secondary(void *unused)
 {
 	unsigned int cpu = smp_processor_id();
 	struct device_node *l2_cache;
@@ -558,7 +558,8 @@ int __devinit start_secondary(void *unused)
 	local_irq_enable();
 
 	cpu_idle();
-	return 0;
+
+	BUG();
 }
 
 int setup_profiling_timer(unsigned int multiplier)
@@ -660,5 +661,9 @@ void cpu_die(void)
 {
 	if (ppc_md.cpu_die)
 		ppc_md.cpu_die();
+
+	/* If we return, we re-enter start_secondary */
+	start_secondary_resume();
 }
+
 #endif
diff --git a/arch/powerpc/platforms/pseries/offline_states.h b/arch/powerpc/platforms/pseries/offline_states.h
index 75a6f480d931..08672d9136ab 100644
--- a/arch/powerpc/platforms/pseries/offline_states.h
+++ b/arch/powerpc/platforms/pseries/offline_states.h
@@ -34,6 +34,4 @@ static inline void set_default_offline_state(int cpu)
 #endif
 
 extern enum cpu_state_vals get_preferred_offline_state(int cpu);
-extern int start_secondary(void);
-extern void start_secondary_resume(void);
 #endif
-- 
cgit v1.2.3


From 4fcb8833af3355065bd8bffcd338eabc6f3a38a0 Mon Sep 17 00:00:00 2001
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Date: Thu, 10 Feb 2011 18:46:50 +1100
Subject: powerpc/smp: Fix generic_mach_cpu_die()

This is used by some "soft" hotplug implementations. I needs to
call idle_task_exit() when the CPU is going away, and we remove
the now no-longer needed set_cpu_online() and local_irq_enable()
which are handled by the return to start_secondary

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
---
 arch/powerpc/kernel/smp.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

(limited to 'arch')

diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c
index 1c9956c43801..3c0fab5e1e16 100644
--- a/arch/powerpc/kernel/smp.c
+++ b/arch/powerpc/kernel/smp.c
@@ -362,14 +362,13 @@ void generic_mach_cpu_die(void)
 	unsigned int cpu;
 
 	local_irq_disable();
+	idle_task_exit();
 	cpu = smp_processor_id();
 	printk(KERN_DEBUG "CPU%d offline\n", cpu);
 	__get_cpu_var(cpu_state) = CPU_DEAD;
 	smp_wmb();
 	while (__get_cpu_var(cpu_state) != CPU_UP_PREPARE)
 		cpu_relax();
-	set_cpu_online(cpu, true);
-	local_irq_enable();
 }
 #endif
 
-- 
cgit v1.2.3


From b527d07114fdab83f39040c69b4b0a4b1b232c16 Mon Sep 17 00:00:00 2001
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Date: Fri, 11 Feb 2011 12:46:41 +1100
Subject: powerpc/smp: Remove unused generic_cpu_enable()

Nobody uses it, besides we should always use the normal __cpu_up
path anyways

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
---
 arch/powerpc/include/asm/smp.h |  1 -
 arch/powerpc/kernel/smp.c      | 22 ----------------------
 2 files changed, 23 deletions(-)

(limited to 'arch')

diff --git a/arch/powerpc/include/asm/smp.h b/arch/powerpc/include/asm/smp.h
index 1de0e97a394f..a629b6fef882 100644
--- a/arch/powerpc/include/asm/smp.h
+++ b/arch/powerpc/include/asm/smp.h
@@ -43,7 +43,6 @@ DECLARE_PER_CPU(unsigned int, cpu_pvr);
 #ifdef CONFIG_HOTPLUG_CPU
 extern void fixup_irqs(const struct cpumask *map);
 int generic_cpu_disable(void);
-int generic_cpu_enable(unsigned int cpu);
 void generic_cpu_die(unsigned int cpu);
 void generic_mach_cpu_die(void);
 #endif
diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c
index 3c0fab5e1e16..19d0c2576282 100644
--- a/arch/powerpc/kernel/smp.c
+++ b/arch/powerpc/kernel/smp.c
@@ -322,28 +322,6 @@ int generic_cpu_disable(void)
 	return 0;
 }
 
-int generic_cpu_enable(unsigned int cpu)
-{
-	/* Do the normal bootup if we haven't
-	 * already bootstrapped. */
-	if (system_state != SYSTEM_RUNNING)
-		return -ENOSYS;
-
-	/* get the target out of it's holding state */
-	per_cpu(cpu_state, cpu) = CPU_UP_PREPARE;
-	smp_wmb();
-
-	while (!cpu_online(cpu))
-		cpu_relax();
-
-#ifdef CONFIG_PPC64
-	fixup_irqs(cpu_online_mask);
-	/* counter the irq disable in fixup_irqs */
-	local_irq_enable();
-#endif
-	return 0;
-}
-
 void generic_cpu_die(unsigned int cpu)
 {
 	int i;
-- 
cgit v1.2.3


From 7a53a4fe707a93a33f6c5d42173bf213cb6ff71d Mon Sep 17 00:00:00 2001
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Date: Fri, 11 Feb 2011 12:49:01 +1100
Subject: powerpc/smp: Remove unused smp_ops->cpu_enable()

Remove the last remnants of cpu_enable(), everybody uses the normal
__cpu_up() path now

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
---
 arch/powerpc/include/asm/machdep.h    |  1 -
 arch/powerpc/kernel/smp.c             | 10 ----------
 arch/powerpc/platforms/powermac/smp.c |  2 --
 3 files changed, 13 deletions(-)

(limited to 'arch')

diff --git a/arch/powerpc/include/asm/machdep.h b/arch/powerpc/include/asm/machdep.h
index fe56a23e1ff0..bcfc0da2cef1 100644
--- a/arch/powerpc/include/asm/machdep.h
+++ b/arch/powerpc/include/asm/machdep.h
@@ -37,7 +37,6 @@ struct smp_ops_t {
 	void  (*setup_cpu)(int nr);
 	void  (*take_timebase)(void);
 	void  (*give_timebase)(void);
-	int   (*cpu_enable)(unsigned int nr);
 	int   (*cpu_disable)(void);
 	void  (*cpu_die)(unsigned int nr);
 	int   (*cpu_bootable)(unsigned int nr);
diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c
index 19d0c2576282..be7d7282341c 100644
--- a/arch/powerpc/kernel/smp.c
+++ b/arch/powerpc/kernel/smp.c
@@ -350,21 +350,11 @@ void generic_mach_cpu_die(void)
 }
 #endif
 
-static int __devinit cpu_enable(unsigned int cpu)
-{
-	if (smp_ops && smp_ops->cpu_enable)
-		return smp_ops->cpu_enable(cpu);
-
-	return -ENOSYS;
-}
-
 int __cpuinit __cpu_up(unsigned int cpu)
 {
 	int c;
 
 	secondary_ti = current_set[cpu];
-	if (!cpu_enable(cpu))
-		return 0;
 
 	if (smp_ops == NULL ||
 	    (smp_ops->cpu_bootable && !smp_ops->cpu_bootable(cpu)))
diff --git a/arch/powerpc/platforms/powermac/smp.c b/arch/powerpc/platforms/powermac/smp.c
index c95215f4f8b6..ebd2b7e037f0 100644
--- a/arch/powerpc/platforms/powermac/smp.c
+++ b/arch/powerpc/platforms/powermac/smp.c
@@ -923,8 +923,6 @@ struct smp_ops_t core99_smp_ops = {
 # if defined(CONFIG_PPC64)
 	.cpu_disable	= generic_cpu_disable,
 	.cpu_die	= generic_cpu_die,
-	/* intentionally do *NOT* assign cpu_enable,
-	 * the generic code will use kick_cpu then! */
 # endif
 #endif
 };
-- 
cgit v1.2.3


From fb49f864c3c3f8ac5b68563774171fe43634ffeb Mon Sep 17 00:00:00 2001
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Date: Fri, 11 Feb 2011 14:09:32 +1100
Subject: powerpc/pmac/smp: Fix 32-bit PowerMac cpu_die

Use generic cpu_state, call idle_task_exit() properly, and
remove smp_core99_cpu_die() which isn't useful, the generic
function does the job just fine.
---
 arch/powerpc/include/asm/smp.h        |  1 +
 arch/powerpc/platforms/powermac/smp.c | 25 +++++--------------------
 2 files changed, 6 insertions(+), 20 deletions(-)

(limited to 'arch')

diff --git a/arch/powerpc/include/asm/smp.h b/arch/powerpc/include/asm/smp.h
index a629b6fef882..9fe559785b39 100644
--- a/arch/powerpc/include/asm/smp.h
+++ b/arch/powerpc/include/asm/smp.h
@@ -45,6 +45,7 @@ extern void fixup_irqs(const struct cpumask *map);
 int generic_cpu_disable(void);
 void generic_cpu_die(unsigned int cpu);
 void generic_mach_cpu_die(void);
+DECLARE_PER_CPU(int, cpu_state);
 #endif
 
 #ifdef CONFIG_PPC64
diff --git a/arch/powerpc/platforms/powermac/smp.c b/arch/powerpc/platforms/powermac/smp.c
index ebd2b7e037f0..e0ac7bb77f29 100644
--- a/arch/powerpc/platforms/powermac/smp.c
+++ b/arch/powerpc/platforms/powermac/smp.c
@@ -880,31 +880,17 @@ int smp_core99_cpu_disable(void)
 	return 0;
 }
 
-static int cpu_dead[NR_CPUS];
-
 void pmac32_cpu_die(void)
 {
 	local_irq_disable();
-	cpu_dead[smp_processor_id()] = 1;
+	idle_task_exit();
+	printk(KERN_DEBUG "CPU%d offline\n", smp_processor_id());
+	__get_cpu_var(cpu_state) = CPU_DEAD;
+	smp_wmb();
 	mb();
 	low_cpu_die();
 }
 
-void smp_core99_cpu_die(unsigned int cpu)
-{
-	int timeout;
-
-	timeout = 1000;
-	while (!cpu_dead[cpu]) {
-		if (--timeout == 0) {
-			printk("CPU %u refused to die!\n", cpu);
-			break;
-		}
-		msleep(1);
-	}
-	cpu_dead[cpu] = 0;
-}
-
 #endif /* CONFIG_HOTPLUG_CPU && CONFIG_PP32 */
 
 /* Core99 Macs (dual G4s and G5s) */
@@ -918,12 +904,11 @@ struct smp_ops_t core99_smp_ops = {
 #if defined(CONFIG_HOTPLUG_CPU)
 # if defined(CONFIG_PPC32)
 	.cpu_disable	= smp_core99_cpu_disable,
-	.cpu_die	= smp_core99_cpu_die,
 # endif
 # if defined(CONFIG_PPC64)
 	.cpu_disable	= generic_cpu_disable,
-	.cpu_die	= generic_cpu_die,
 # endif
+	.cpu_die	= generic_cpu_die,
 #endif
 };
 
-- 
cgit v1.2.3


From 1c91cc570576dfd0f288d664c095d64d11aaace4 Mon Sep 17 00:00:00 2001
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Date: Fri, 11 Feb 2011 13:05:17 +1100
Subject: powerpc/pmac/smp: Rename fixup_irqs() to migrate_irqs() and use it on
 ppc32

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
---
 arch/powerpc/include/asm/smp.h | 2 +-
 arch/powerpc/kernel/irq.c      | 3 ++-
 arch/powerpc/kernel/smp.c      | 2 +-
 3 files changed, 4 insertions(+), 3 deletions(-)

(limited to 'arch')

diff --git a/arch/powerpc/include/asm/smp.h b/arch/powerpc/include/asm/smp.h
index 9fe559785b39..7e997715bf1e 100644
--- a/arch/powerpc/include/asm/smp.h
+++ b/arch/powerpc/include/asm/smp.h
@@ -41,7 +41,7 @@ extern void start_secondary_resume(void);
 DECLARE_PER_CPU(unsigned int, cpu_pvr);
 
 #ifdef CONFIG_HOTPLUG_CPU
-extern void fixup_irqs(const struct cpumask *map);
+extern void migrate_irqs(void);
 int generic_cpu_disable(void);
 void generic_cpu_die(unsigned int cpu);
 void generic_mach_cpu_die(void);
diff --git a/arch/powerpc/kernel/irq.c b/arch/powerpc/kernel/irq.c
index 63625e0650b5..f621b7d2d869 100644
--- a/arch/powerpc/kernel/irq.c
+++ b/arch/powerpc/kernel/irq.c
@@ -246,12 +246,13 @@ u64 arch_irq_stat_cpu(unsigned int cpu)
 }
 
 #ifdef CONFIG_HOTPLUG_CPU
-void fixup_irqs(const struct cpumask *map)
+void migrate_irqs(void)
 {
 	struct irq_desc *desc;
 	unsigned int irq;
 	static int warned;
 	cpumask_var_t mask;
+	const struct cpumask *map = cpu_online_mask;
 
 	alloc_cpumask_var(&mask, GFP_KERNEL);
 
diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c
index be7d7282341c..f6cc5c19c6ac 100644
--- a/arch/powerpc/kernel/smp.c
+++ b/arch/powerpc/kernel/smp.c
@@ -317,8 +317,8 @@ int generic_cpu_disable(void)
 	set_cpu_online(cpu, false);
 #ifdef CONFIG_PPC64
 	vdso_data->processorCount--;
-	fixup_irqs(cpu_online_mask);
 #endif
+	migrate_irqs();
 	return 0;
 }
 
-- 
cgit v1.2.3


From 45e07fd045153c0049c99b0cf6cf7254c164d37b Mon Sep 17 00:00:00 2001
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Date: Mon, 21 Feb 2011 16:31:49 +1100
Subject: powerpc/pmac/smp: Fixup smp_core99_cpu_disable() and use it on 64-bit

Use the generic code, just add the MPIC priority setting,

I don't see any use in mucking around with the decrementer,
as 32-bit will have EE off all along, and 64-bit will be able
to deal with it.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
---
 arch/powerpc/platforms/powermac/smp.c | 17 +++++------------
 1 file changed, 5 insertions(+), 12 deletions(-)

(limited to 'arch')

diff --git a/arch/powerpc/platforms/powermac/smp.c b/arch/powerpc/platforms/powermac/smp.c
index e0ac7bb77f29..eda470913291 100644
--- a/arch/powerpc/platforms/powermac/smp.c
+++ b/arch/powerpc/platforms/powermac/smp.c
@@ -867,16 +867,14 @@ static void __devinit smp_core99_setup_cpu(int cpu_nr)
 
 #if defined(CONFIG_HOTPLUG_CPU) && defined(CONFIG_PPC32)
 
-int smp_core99_cpu_disable(void)
+static int smp_core99_cpu_disable(void)
 {
-	set_cpu_online(smp_processor_id(), false);
+	int rc = generic_cpu_disable();
+	if (rc)
+		return rc;
 
-	/* XXX reset cpu affinity here */
 	mpic_cpu_set_priority(0xf);
-	asm volatile("mtdec %0" : : "r" (0x7fffffff));
-	mb();
-	udelay(20);
-	asm volatile("mtdec %0" : : "r" (0x7fffffff));
+
 	return 0;
 }
 
@@ -902,12 +900,7 @@ struct smp_ops_t core99_smp_ops = {
 	.give_timebase	= smp_core99_give_timebase,
 	.take_timebase	= smp_core99_take_timebase,
 #if defined(CONFIG_HOTPLUG_CPU)
-# if defined(CONFIG_PPC32)
 	.cpu_disable	= smp_core99_cpu_disable,
-# endif
-# if defined(CONFIG_PPC64)
-	.cpu_disable	= generic_cpu_disable,
-# endif
 	.cpu_die	= generic_cpu_die,
 #endif
 };
-- 
cgit v1.2.3


From 4c6130d9bba78e7ac44584378660a1204c5297d1 Mon Sep 17 00:00:00 2001
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Date: Fri, 11 Feb 2011 14:03:20 +1100
Subject: powerpc/pmac/smp: Consolidate 32-bit and 64-bit PowerMac cpu_die in
 one file

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
---
 arch/powerpc/platforms/powermac/pmac.h  |  1 -
 arch/powerpc/platforms/powermac/setup.c | 56 -------------------------------
 arch/powerpc/platforms/powermac/smp.c   | 58 +++++++++++++++++++++++++++++++--
 3 files changed, 55 insertions(+), 60 deletions(-)

(limited to 'arch')

diff --git a/arch/powerpc/platforms/powermac/pmac.h b/arch/powerpc/platforms/powermac/pmac.h
index f0bc08f6c1f0..20468f49aec0 100644
--- a/arch/powerpc/platforms/powermac/pmac.h
+++ b/arch/powerpc/platforms/powermac/pmac.h
@@ -33,7 +33,6 @@ extern void pmac_setup_pci_dma(void);
 extern void pmac_check_ht_link(void);
 
 extern void pmac_setup_smp(void);
-extern void pmac32_cpu_die(void);
 extern void low_cpu_die(void) __attribute__((noreturn));
 
 extern int pmac_nvram_init(void);
diff --git a/arch/powerpc/platforms/powermac/setup.c b/arch/powerpc/platforms/powermac/setup.c
index d5aceb7fb125..aa45281bd296 100644
--- a/arch/powerpc/platforms/powermac/setup.c
+++ b/arch/powerpc/platforms/powermac/setup.c
@@ -650,51 +650,6 @@ static int pmac_pci_probe_mode(struct pci_bus *bus)
 		return PCI_PROBE_NORMAL;
 	return PCI_PROBE_DEVTREE;
 }
-
-#ifdef CONFIG_HOTPLUG_CPU
-/* access per cpu vars from generic smp.c */
-DECLARE_PER_CPU(int, cpu_state);
-
-static void pmac64_cpu_die(void)
-{
-	/*
-	 * turn off as much as possible, we'll be
-	 * kicked out as this will only be invoked
-	 * on core99 platforms for now ...
-	 */
-
-	printk(KERN_INFO "CPU#%d offline\n", smp_processor_id());
-	__get_cpu_var(cpu_state) = CPU_DEAD;
-	smp_wmb();
-
-	/*
-	 * during the path that leads here preemption is disabled,
-	 * reenable it now so that when coming up preempt count is
-	 * zero correctly
-	 */
-	preempt_enable();
-
-	/*
-	 * hard-disable interrupts for the non-NAP case, the NAP code
-	 * needs to re-enable interrupts (but soft-disables them)
-	 */
-	hard_irq_disable();
-
-	while (1) {
-		/* let's not take timer interrupts too often ... */
-		set_dec(0x7fffffff);
-
-		/* should always be true at this point */
-		if (cpu_has_feature(CPU_FTR_CAN_NAP))
-			power4_cpu_offline_powersave();
-		else {
-			HMT_low();
-			HMT_very_low();
-		}
-	}
-}
-#endif /* CONFIG_HOTPLUG_CPU */
-
 #endif /* CONFIG_PPC64 */
 
 define_machine(powermac) {
@@ -726,15 +681,4 @@ define_machine(powermac) {
 	.pcibios_after_init	= pmac_pcibios_after_init,
 	.phys_mem_access_prot	= pci_phys_mem_access_prot,
 #endif
-#ifdef CONFIG_HOTPLUG_CPU
-#ifdef CONFIG_PPC64
-	.cpu_die		= pmac64_cpu_die,
-#endif
-#ifdef CONFIG_PPC32
-	.cpu_die		= pmac32_cpu_die,
-#endif
-#endif
-#if defined(CONFIG_HOTPLUG_CPU) && defined(CONFIG_PPC32)
-	.cpu_die		= generic_mach_cpu_die,
-#endif
 };
diff --git a/arch/powerpc/platforms/powermac/smp.c b/arch/powerpc/platforms/powermac/smp.c
index eda470913291..50e15b43ffad 100644
--- a/arch/powerpc/platforms/powermac/smp.c
+++ b/arch/powerpc/platforms/powermac/smp.c
@@ -865,7 +865,7 @@ static void __devinit smp_core99_setup_cpu(int cpu_nr)
 }
 
 
-#if defined(CONFIG_HOTPLUG_CPU) && defined(CONFIG_PPC32)
+#ifdef CONFIG_HOTPLUG_CPU
 
 static int smp_core99_cpu_disable(void)
 {
@@ -878,7 +878,9 @@ static int smp_core99_cpu_disable(void)
 	return 0;
 }
 
-void pmac32_cpu_die(void)
+#ifdef CONFIG_PPC32
+
+static void pmac_cpu_die(void)
 {
 	local_irq_disable();
 	idle_task_exit();
@@ -889,7 +891,52 @@ void pmac32_cpu_die(void)
 	low_cpu_die();
 }
 
-#endif /* CONFIG_HOTPLUG_CPU && CONFIG_PP32 */
+#else /* CONFIG_PPC32 */
+
+static void pmac_cpu_die(void)
+{
+	local_irq_disable();
+	idle_task_exit();
+
+	/*
+	 * turn off as much as possible, we'll be
+	 * kicked out as this will only be invoked
+	 * on core99 platforms for now ...
+	 */
+
+	printk(KERN_INFO "CPU#%d offline\n", smp_processor_id());
+	__get_cpu_var(cpu_state) = CPU_DEAD;
+	smp_wmb();
+
+	/*
+	 * during the path that leads here preemption is disabled,
+	 * reenable it now so that when coming up preempt count is
+	 * zero correctly
+	 */
+	preempt_enable();
+
+	/*
+	 * hard-disable interrupts for the non-NAP case, the NAP code
+	 * needs to re-enable interrupts (but soft-disables them)
+	 */
+	hard_irq_disable();
+
+	while (1) {
+		/* let's not take timer interrupts too often ... */
+		set_dec(0x7fffffff);
+
+		/* should always be true at this point */
+		if (cpu_has_feature(CPU_FTR_CAN_NAP))
+			power4_cpu_offline_powersave();
+		else {
+			HMT_low();
+			HMT_very_low();
+		}
+	}
+}
+
+#endif /* else CONFIG_PPC32 */
+#endif /* CONFIG_HOTPLUG_CPU */
 
 /* Core99 Macs (dual G4s and G5s) */
 struct smp_ops_t core99_smp_ops = {
@@ -933,5 +980,10 @@ void __init pmac_setup_smp(void)
 		smp_ops = &psurge_smp_ops;
 	}
 #endif /* CONFIG_PPC32 */
+
+#ifdef CONFIG_HOTPLUG_CPU
+	ppc_md.cpu_die = pmac_cpu_die;
+#endif
 }
 
+
-- 
cgit v1.2.3


From e872e41b79f61dbc22f85577613925a4a7de1c1a Mon Sep 17 00:00:00 2001
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Date: Fri, 11 Feb 2011 14:55:42 +1100
Subject: powerpc/pmac/smp: Remove HMT changes for PowerMac offline code

Those instructions do nothing on non-threaded processors such
as 970's used on those machines.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
---
 arch/powerpc/platforms/powermac/smp.c | 4 ----
 1 file changed, 4 deletions(-)

(limited to 'arch')

diff --git a/arch/powerpc/platforms/powermac/smp.c b/arch/powerpc/platforms/powermac/smp.c
index 50e15b43ffad..53bee660ff3d 100644
--- a/arch/powerpc/platforms/powermac/smp.c
+++ b/arch/powerpc/platforms/powermac/smp.c
@@ -928,10 +928,6 @@ static void pmac_cpu_die(void)
 		/* should always be true at this point */
 		if (cpu_has_feature(CPU_FTR_CAN_NAP))
 			power4_cpu_offline_powersave();
-		else {
-			HMT_low();
-			HMT_very_low();
-		}
 	}
 }
 
-- 
cgit v1.2.3


From 62cc67b9df273be18fcb09a071592dedf751c90a Mon Sep 17 00:00:00 2001
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Date: Mon, 21 Feb 2011 16:49:58 +1100
Subject: powerpc/pmac/smp: Properly NAP offlined CPU on G5

The current code soft-disables, and then goes to NAP mode which
turns interrupts on. That means that if an interrupt occurs, we
will hit the masked interrupt code path which isn't what we want,
as it will return with EE off, which will either get us out of
NAP mode, or fail to enter it (according to spec).

Instead, let's just rely on the fact that it is safe to take
decrementer interrupts on an offline CPU and leave interrupts
enabled. We can also get rid of the special case in asm for
power4_cpu_offline_powersave() and just use power4_idle().

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
---
 arch/powerpc/include/asm/machdep.h    |  1 -
 arch/powerpc/kernel/head_64.S         |  7 +++++++
 arch/powerpc/kernel/idle_power4.S     | 21 ---------------------
 arch/powerpc/platforms/powermac/smp.c | 14 ++++++++------
 4 files changed, 15 insertions(+), 28 deletions(-)

(limited to 'arch')

diff --git a/arch/powerpc/include/asm/machdep.h b/arch/powerpc/include/asm/machdep.h
index bcfc0da2cef1..578d3309e109 100644
--- a/arch/powerpc/include/asm/machdep.h
+++ b/arch/powerpc/include/asm/machdep.h
@@ -266,7 +266,6 @@ struct machdep_calls {
 
 extern void e500_idle(void);
 extern void power4_idle(void);
-extern void power4_cpu_offline_powersave(void);
 extern void ppc6xx_idle(void);
 extern void book3e_idle(void);
 
diff --git a/arch/powerpc/kernel/head_64.S b/arch/powerpc/kernel/head_64.S
index 782f23df7c85..271140b38b6f 100644
--- a/arch/powerpc/kernel/head_64.S
+++ b/arch/powerpc/kernel/head_64.S
@@ -536,6 +536,13 @@ _GLOBAL(pmac_secondary_start)
 	add	r13,r13,r4		/* for this processor.		*/
 	mtspr	SPRN_SPRG_PACA,r13	/* Save vaddr of paca in an SPRG*/
 
+	/* Mark interrupts soft and hard disabled (they might be enabled
+	 * in the PACA when doing hotplug)
+	 */
+	li	r0,0
+	stb	r0,PACASOFTIRQEN(r13)
+	stb	r0,PACAHARDIRQEN(r13)
+
 	/* Create a temp kernel stack for use before relocation is on.	*/
 	ld	r1,PACAEMERGSP(r13)
 	subi	r1,r1,STACK_FRAME_OVERHEAD
diff --git a/arch/powerpc/kernel/idle_power4.S b/arch/powerpc/kernel/idle_power4.S
index 5328709eeedc..ba3195478600 100644
--- a/arch/powerpc/kernel/idle_power4.S
+++ b/arch/powerpc/kernel/idle_power4.S
@@ -53,24 +53,3 @@ END_FTR_SECTION_IFSET(CPU_FTR_ALTIVEC)
 	isync
 	b	1b
 
-_GLOBAL(power4_cpu_offline_powersave)
-	/* Go to NAP now */
-	mfmsr	r7
-	rldicl	r0,r7,48,1
-	rotldi	r0,r0,16
-	mtmsrd	r0,1			/* hard-disable interrupts */
-	li	r0,1
-	li	r6,0
-	stb	r0,PACAHARDIRQEN(r13)	/* we'll hard-enable shortly */
-	stb	r6,PACASOFTIRQEN(r13)	/* soft-disable irqs */
-BEGIN_FTR_SECTION
-	DSSALL
-	sync
-END_FTR_SECTION_IFSET(CPU_FTR_ALTIVEC)
-	ori	r7,r7,MSR_EE
-	oris	r7,r7,MSR_POW@h
-	sync
-	isync
-	mtmsrd	r7
-	isync
-	blr
diff --git a/arch/powerpc/platforms/powermac/smp.c b/arch/powerpc/platforms/powermac/smp.c
index 53bee660ff3d..837989e72ca1 100644
--- a/arch/powerpc/platforms/powermac/smp.c
+++ b/arch/powerpc/platforms/powermac/smp.c
@@ -916,18 +916,20 @@ static void pmac_cpu_die(void)
 	preempt_enable();
 
 	/*
-	 * hard-disable interrupts for the non-NAP case, the NAP code
-	 * needs to re-enable interrupts (but soft-disables them)
+	 * Re-enable interrupts. The NAP code needs to enable them
+	 * anyways, do it now so we deal with the case where one already
+	 * happened while soft-disabled.
+	 * We shouldn't get any external interrupts, only decrementer, and the
+	 * decrementer handler is safe for use on offline CPUs
 	 */
-	hard_irq_disable();
+	local_irq_enable();
 
 	while (1) {
 		/* let's not take timer interrupts too often ... */
 		set_dec(0x7fffffff);
 
-		/* should always be true at this point */
-		if (cpu_has_feature(CPU_FTR_CAN_NAP))
-			power4_cpu_offline_powersave();
+		/* Enter NAP mode */
+		power4_idle();
 	}
 }
 
-- 
cgit v1.2.3


From d72944457bb7d5c4be43aa1b741cb93c69484c20 Mon Sep 17 00:00:00 2001
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Date: Tue, 8 Mar 2011 13:50:37 +1100
Subject: powerpc/smp: Add a smp_ops->bringup_up() done callback

This allows us to stop abusing smp_ops->setup_cpu() for cleanup
tasks that have to take place after the initial boot time CPU
bringup.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
---
 arch/powerpc/include/asm/machdep.h | 1 +
 arch/powerpc/kernel/smp.c          | 4 ++++
 2 files changed, 5 insertions(+)

(limited to 'arch')

diff --git a/arch/powerpc/include/asm/machdep.h b/arch/powerpc/include/asm/machdep.h
index 578d3309e109..e4f01915fbb0 100644
--- a/arch/powerpc/include/asm/machdep.h
+++ b/arch/powerpc/include/asm/machdep.h
@@ -35,6 +35,7 @@ struct smp_ops_t {
 	int   (*probe)(void);
 	void  (*kick_cpu)(int nr);
 	void  (*setup_cpu)(int nr);
+	void  (*bringup_done)(void);
 	void  (*take_timebase)(void);
 	void  (*give_timebase)(void);
 	int   (*cpu_disable)(void);
diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c
index f6cc5c19c6ac..df3739713edd 100644
--- a/arch/powerpc/kernel/smp.c
+++ b/arch/powerpc/kernel/smp.c
@@ -553,7 +553,11 @@ void __init smp_cpus_done(unsigned int max_cpus)
 
 	free_cpumask_var(old_mask);
 
+	if (smp_ops && smp_ops->bringup_done)
+		smp_ops->bringup_done();
+
 	dump_numa_cpu_topology();
+
 }
 
 int arch_sd_sibling_asym_packing(void)
-- 
cgit v1.2.3


From 734796f12351f9a0f38c47b981414f82d852f222 Mon Sep 17 00:00:00 2001
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Date: Tue, 8 Mar 2011 13:54:50 +1100
Subject: powerpc/pmac/smp: Fix CPU hotplug crashes on some machines

On some machines that use i2c to synchronize the timebases (such
as PowerMac7,2/7,3 G5 machines), hotplug CPU would crash when
putting back a new CPU online due to the underlying i2c bus being
closed.

This uses the newly added bringup_done() callback to move the close
along with other housekeeping calls, and adds a CPU notifier to
re-open the i2c bus around subsequent hotplug operations

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
---
 arch/powerpc/platforms/powermac/smp.c | 71 +++++++++++++++++++++++++++--------
 1 file changed, 55 insertions(+), 16 deletions(-)

(limited to 'arch')

diff --git a/arch/powerpc/platforms/powermac/smp.c b/arch/powerpc/platforms/powermac/smp.c
index 837989e72ca1..74a43c652041 100644
--- a/arch/powerpc/platforms/powermac/smp.c
+++ b/arch/powerpc/platforms/powermac/smp.c
@@ -840,30 +840,68 @@ static void __devinit smp_core99_setup_cpu(int cpu_nr)
 
 	/* Setup openpic */
 	mpic_setup_this_cpu();
+}
 
-	if (cpu_nr == 0) {
-#ifdef CONFIG_PPC64
-		extern void g5_phy_disable_cpu1(void);
+#ifdef CONFIG_HOTPLUG_CPU
+static int smp_core99_cpu_notify(struct notifier_block *self,
+				 unsigned long action, void *hcpu)
+{
+	int rc;
 
-		/* Close i2c bus if it was used for tb sync */
+	switch(action) {
+	case CPU_UP_PREPARE:
+	case CPU_UP_PREPARE_FROZEN:
+		/* Open i2c bus if it was used for tb sync */
 		if (pmac_tb_clock_chip_host) {
-			pmac_i2c_close(pmac_tb_clock_chip_host);
-			pmac_tb_clock_chip_host	= NULL;
+			rc = pmac_i2c_open(pmac_tb_clock_chip_host, 1);
+			if (rc) {
+				pr_err("Failed to open i2c bus for time sync\n");
+				return notifier_from_errno(rc);
+			}
 		}
+		break;
+	case CPU_ONLINE:
+	case CPU_UP_CANCELED:
+		/* Close i2c bus if it was used for tb sync */
+		if (pmac_tb_clock_chip_host)
+			pmac_i2c_close(pmac_tb_clock_chip_host);
+		break;
+	default:
+		break;
+	}
+	return NOTIFY_OK;
+}
 
-		/* If we didn't start the second CPU, we must take
-		 * it off the bus
-		 */
-		if (of_machine_is_compatible("MacRISC4") &&
-		    num_online_cpus() < 2)		
-			g5_phy_disable_cpu1();
-#endif /* CONFIG_PPC64 */
+static struct notifier_block __cpuinitdata smp_core99_cpu_nb = {
+	.notifier_call	= smp_core99_cpu_notify,
+};
+#endif /* CONFIG_HOTPLUG_CPU */
 
-		if (ppc_md.progress)
-			ppc_md.progress("core99_setup_cpu 0 done", 0x349);
+static void __init smp_core99_bringup_done(void)
+{
+#ifdef CONFIG_PPC64
+	extern void g5_phy_disable_cpu1(void);
+
+	/* Close i2c bus if it was used for tb sync */
+	if (pmac_tb_clock_chip_host)
+		pmac_i2c_close(pmac_tb_clock_chip_host);
+
+	/* If we didn't start the second CPU, we must take
+	 * it off the bus.
+	 */
+	if (of_machine_is_compatible("MacRISC4") &&
+	    num_online_cpus() < 2) {
+		set_cpu_present(1, false);
+		g5_phy_disable_cpu1();
 	}
-}
+#endif /* CONFIG_PPC64 */
 
+#ifdef CONFIG_HOTPLUG_CPU
+	register_cpu_notifier(&smp_core99_cpu_nb);
+#endif
+	if (ppc_md.progress)
+		ppc_md.progress("smp_core99_bringup_done", 0x349);
+}
 
 #ifdef CONFIG_HOTPLUG_CPU
 
@@ -940,6 +978,7 @@ static void pmac_cpu_die(void)
 struct smp_ops_t core99_smp_ops = {
 	.message_pass	= smp_mpic_message_pass,
 	.probe		= smp_core99_probe,
+	.bringup_done	= smp_core99_bringup_done,
 	.kick_cpu	= smp_core99_kick_cpu,
 	.setup_cpu	= smp_core99_setup_cpu,
 	.give_timebase	= smp_core99_give_timebase,
-- 
cgit v1.2.3


From 105765f451d3ff007bb4ae3761e825686d9615db Mon Sep 17 00:00:00 2001
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Date: Fri, 1 Apr 2011 09:23:37 +1100
Subject: powerpc/smp: Don't expose per-cpu "cpu_state" array

Instead, keep it static, expose an accessor and use that from
the PowerMac code. Avoids easy namespace collisions and will
make it easier to consolidate with other implementations.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
---
 arch/powerpc/include/asm/smp.h        |  2 +-
 arch/powerpc/kernel/smp.c             |  7 ++++++-
 arch/powerpc/platforms/powermac/smp.c | 12 ++++++++----
 3 files changed, 15 insertions(+), 6 deletions(-)

(limited to 'arch')

diff --git a/arch/powerpc/include/asm/smp.h b/arch/powerpc/include/asm/smp.h
index 7e997715bf1e..a902a0d3ae0d 100644
--- a/arch/powerpc/include/asm/smp.h
+++ b/arch/powerpc/include/asm/smp.h
@@ -45,7 +45,7 @@ extern void migrate_irqs(void);
 int generic_cpu_disable(void);
 void generic_cpu_die(unsigned int cpu);
 void generic_mach_cpu_die(void);
-DECLARE_PER_CPU(int, cpu_state);
+void generic_set_cpu_dead(unsigned int cpu);
 #endif
 
 #ifdef CONFIG_PPC64
diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c
index df3739713edd..d7f8cc18ae05 100644
--- a/arch/powerpc/kernel/smp.c
+++ b/arch/powerpc/kernel/smp.c
@@ -305,7 +305,7 @@ void __devinit smp_prepare_boot_cpu(void)
 
 #ifdef CONFIG_HOTPLUG_CPU
 /* State of each CPU during hotplug phases */
-DEFINE_PER_CPU(int, cpu_state) = { 0 };
+static DEFINE_PER_CPU(int, cpu_state) = { 0 };
 
 int generic_cpu_disable(void)
 {
@@ -348,6 +348,11 @@ void generic_mach_cpu_die(void)
 	while (__get_cpu_var(cpu_state) != CPU_UP_PREPARE)
 		cpu_relax();
 }
+
+void generic_set_cpu_dead(unsigned int cpu)
+{
+	per_cpu(cpu_state, cpu) = CPU_DEAD;
+}
 #endif
 
 int __cpuinit __cpu_up(unsigned int cpu)
diff --git a/arch/powerpc/platforms/powermac/smp.c b/arch/powerpc/platforms/powermac/smp.c
index 74a43c652041..ce5b4f53aacb 100644
--- a/arch/powerpc/platforms/powermac/smp.c
+++ b/arch/powerpc/platforms/powermac/smp.c
@@ -920,10 +920,12 @@ static int smp_core99_cpu_disable(void)
 
 static void pmac_cpu_die(void)
 {
+	int cpu = smp_processor_id();
+
 	local_irq_disable();
 	idle_task_exit();
-	printk(KERN_DEBUG "CPU%d offline\n", smp_processor_id());
-	__get_cpu_var(cpu_state) = CPU_DEAD;
+	pr_debug("CPU%d offline\n", cpu);
+	generic_set_cpu_dead(cpu);
 	smp_wmb();
 	mb();
 	low_cpu_die();
@@ -933,6 +935,8 @@ static void pmac_cpu_die(void)
 
 static void pmac_cpu_die(void)
 {
+	int cpu = smp_processor_id();
+
 	local_irq_disable();
 	idle_task_exit();
 
@@ -942,8 +946,8 @@ static void pmac_cpu_die(void)
 	 * on core99 platforms for now ...
 	 */
 
-	printk(KERN_INFO "CPU#%d offline\n", smp_processor_id());
-	__get_cpu_var(cpu_state) = CPU_DEAD;
+	printk(KERN_INFO "CPU#%d offline\n", cpu);
+	generic_set_cpu_dead(cpu);
 	smp_wmb();
 
 	/*
-- 
cgit v1.2.3


From c56e58537d504706954a06570b4034c04e5b7500 Mon Sep 17 00:00:00 2001
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Date: Tue, 8 Mar 2011 14:40:04 +1100
Subject: powerpc/smp: Create idle threads on demand and properly reset them

Instead of creating idle threads at boot for all possible CPUs, we
create them on demand, like x86 or ARM, and we properly call init_idle
to re-initialize an idle thread when a CPU was unplugged and is now
re-plugged.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
---
 arch/powerpc/kernel/smp.c | 100 ++++++++++++++++++++++++++++++++++++----------
 1 file changed, 78 insertions(+), 22 deletions(-)

(limited to 'arch')

diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c
index d7f8cc18ae05..54faff91b805 100644
--- a/arch/powerpc/kernel/smp.c
+++ b/arch/powerpc/kernel/smp.c
@@ -57,6 +57,25 @@
 #define DBG(fmt...)
 #endif
 
+
+/* Store all idle threads, this can be reused instead of creating
+* a new thread. Also avoids complicated thread destroy functionality
+* for idle threads.
+*/
+#ifdef CONFIG_HOTPLUG_CPU
+/*
+ * Needed only for CONFIG_HOTPLUG_CPU because __cpuinitdata is
+ * removed after init for !CONFIG_HOTPLUG_CPU.
+ */
+static DEFINE_PER_CPU(struct task_struct *, idle_thread_array);
+#define get_idle_for_cpu(x)      (per_cpu(idle_thread_array, x))
+#define set_idle_for_cpu(x, p)   (per_cpu(idle_thread_array, x) = (p))
+#else
+static struct task_struct *idle_thread_array[NR_CPUS] __cpuinitdata ;
+#define get_idle_for_cpu(x)      (idle_thread_array[(x)])
+#define set_idle_for_cpu(x, p)   (idle_thread_array[(x)] = (p))
+#endif
+
 struct thread_info *secondary_ti;
 
 DEFINE_PER_CPU(cpumask_var_t, cpu_sibling_map);
@@ -238,23 +257,6 @@ static void __devinit smp_store_cpu_info(int id)
 	per_cpu(cpu_pvr, id) = mfspr(SPRN_PVR);
 }
 
-static void __init smp_create_idle(unsigned int cpu)
-{
-	struct task_struct *p;
-
-	/* create a process for the processor */
-	p = fork_idle(cpu);
-	if (IS_ERR(p))
-		panic("failed fork for CPU %u: %li", cpu, PTR_ERR(p));
-#ifdef CONFIG_PPC64
-	paca[cpu].__current = p;
-	paca[cpu].kstack = (unsigned long) task_thread_info(p)
-		+ THREAD_SIZE - STACK_FRAME_OVERHEAD;
-#endif
-	current_set[cpu] = task_thread_info(p);
-	task_thread_info(p)->cpu = cpu;
-}
-
 void __init smp_prepare_cpus(unsigned int max_cpus)
 {
 	unsigned int cpu;
@@ -288,10 +290,6 @@ void __init smp_prepare_cpus(unsigned int max_cpus)
 			max_cpus = NR_CPUS;
 	else
 		max_cpus = 1;
-
-	for_each_possible_cpu(cpu)
-		if (cpu != boot_cpuid)
-			smp_create_idle(cpu);
 }
 
 void __devinit smp_prepare_boot_cpu(void)
@@ -355,9 +353,62 @@ void generic_set_cpu_dead(unsigned int cpu)
 }
 #endif
 
+struct create_idle {
+	struct work_struct work;
+	struct task_struct *idle;
+	struct completion done;
+	int cpu;
+};
+
+static void __cpuinit do_fork_idle(struct work_struct *work)
+{
+	struct create_idle *c_idle =
+		container_of(work, struct create_idle, work);
+
+	c_idle->idle = fork_idle(c_idle->cpu);
+	complete(&c_idle->done);
+}
+
+static int __cpuinit create_idle(unsigned int cpu)
+{
+	struct thread_info *ti;
+	struct create_idle c_idle = {
+		.cpu	= cpu,
+		.done	= COMPLETION_INITIALIZER_ONSTACK(c_idle.done),
+	};
+	INIT_WORK_ONSTACK(&c_idle.work, do_fork_idle);
+
+	c_idle.idle = get_idle_for_cpu(cpu);
+
+	/* We can't use kernel_thread since we must avoid to
+	 * reschedule the child. We use a workqueue because
+	 * we want to fork from a kernel thread, not whatever
+	 * userspace process happens to be trying to online us.
+	 */
+	if (!c_idle.idle) {
+		schedule_work(&c_idle.work);
+		wait_for_completion(&c_idle.done);
+	} else
+		init_idle(c_idle.idle, cpu);
+	if (IS_ERR(c_idle.idle)) {		
+		pr_err("Failed fork for CPU %u: %li", cpu, PTR_ERR(c_idle.idle));
+		return PTR_ERR(c_idle.idle);
+	}
+	ti = task_thread_info(c_idle.idle);
+
+#ifdef CONFIG_PPC64
+	paca[cpu].__current = c_idle.idle;
+	paca[cpu].kstack = (unsigned long)ti + THREAD_SIZE - STACK_FRAME_OVERHEAD;
+#endif
+	ti->cpu = cpu;
+	current_set[cpu] = ti;
+
+	return 0;
+}
+
 int __cpuinit __cpu_up(unsigned int cpu)
 {
-	int c;
+	int rc, c;
 
 	secondary_ti = current_set[cpu];
 
@@ -365,6 +416,11 @@ int __cpuinit __cpu_up(unsigned int cpu)
 	    (smp_ops->cpu_bootable && !smp_ops->cpu_bootable(cpu)))
 		return -EINVAL;
 
+	/* Make sure we have an idle thread */
+	rc = create_idle(cpu);
+	if (rc)
+		return rc;
+
 	/* Make sure callin-map entry is 0 (can be leftover a CPU
 	 * hotplug
 	 */
-- 
cgit v1.2.3


From aeeafbfa7a5692c68d306043878aa2dd785e5230 Mon Sep 17 00:00:00 2001
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Date: Tue, 8 Mar 2011 14:49:33 +1100
Subject: powerpc/smp: Increase vdso_data->processorCount, not just decrease it

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
---
 arch/powerpc/kernel/smp.c | 4 ++++
 1 file changed, 4 insertions(+)

(limited to 'arch')

diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c
index 54faff91b805..cbdbb14be4b0 100644
--- a/arch/powerpc/kernel/smp.c
+++ b/arch/powerpc/kernel/smp.c
@@ -551,6 +551,10 @@ void __devinit start_secondary(void *unused)
 
 	secondary_cpu_time_init();
 
+#ifdef CONFIG_PPC64
+	if (system_state == SYSTEM_RUNNING)
+		vdso_data->processorCount++;
+#endif
 	ipi_call_lock();
 	notify_cpu_starting(cpu);
 	set_cpu_online(cpu, true);
-- 
cgit v1.2.3


From 76d479a7caff58b1e5f31d80805f7f65f9177696 Mon Sep 17 00:00:00 2001
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Date: Tue, 8 Mar 2011 14:57:26 +1100
Subject: powerpc/pmac/smp: Remove no-longer needed preempt workaround

The generic code properly re-initializes the preempt count in the
idle thread now

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
---
 arch/powerpc/platforms/powermac/smp.c | 7 -------
 1 file changed, 7 deletions(-)

(limited to 'arch')

diff --git a/arch/powerpc/platforms/powermac/smp.c b/arch/powerpc/platforms/powermac/smp.c
index ce5b4f53aacb..a830c5e80657 100644
--- a/arch/powerpc/platforms/powermac/smp.c
+++ b/arch/powerpc/platforms/powermac/smp.c
@@ -950,13 +950,6 @@ static void pmac_cpu_die(void)
 	generic_set_cpu_dead(cpu);
 	smp_wmb();
 
-	/*
-	 * during the path that leads here preemption is disabled,
-	 * reenable it now so that when coming up preempt count is
-	 * zero correctly
-	 */
-	preempt_enable();
-
 	/*
 	 * Re-enable interrupts. The NAP code needs to enable them
 	 * anyways, do it now so we deal with the case where one already
-- 
cgit v1.2.3