1 files changed, 166 insertions, 98 deletions

diff --git a/kernel/smp.c b/kernel/smp.c
index 6ecf4b9895d4..7a0ce25829dc 100644
--- a/kernel/smp.c
+++ b/kernel/smp.c
@@ -10,23 +10,28 @@
 #include <linux/rcupdate.h>
 #include <linux/rculist.h>
 #include <linux/smp.h>
+#include <linux/cpu.h>
 
 static DEFINE_PER_CPU(struct call_single_queue, call_single_queue);
-static LIST_HEAD(call_function_queue);
-__cacheline_aligned_in_smp DEFINE_SPINLOCK(call_function_lock);
+
+static struct {
+	struct list_head	queue;
+	spinlock_t		lock;
+} call_function __cacheline_aligned_in_smp = {
+	.queue = LIST_HEAD_INIT(call_function.queue),
+	.lock  = __SPIN_LOCK_UNLOCKED(call_function.lock),
+};
 
 enum {
 	CSD_FLAG_WAIT		= 0x01,
-	CSD_FLAG_ALLOC		= 0x02,
-	CSD_FLAG_LOCK		= 0x04,
+	CSD_FLAG_LOCK		= 0x02,
 };
 
 struct call_function_data {
 	struct call_single_data csd;
 	spinlock_t lock;
 	unsigned int refs;
-	struct rcu_head rcu_head;
-	unsigned long cpumask_bits[];
+	cpumask_var_t cpumask;
 };
 
 struct call_single_queue {
@@ -34,8 +39,45 @@ struct call_single_queue {
 	spinlock_t lock;
 };
 
+static DEFINE_PER_CPU(struct call_function_data, cfd_data) = {
+	.lock = __SPIN_LOCK_UNLOCKED(cfd_data.lock),
+};
+
+static int
+hotplug_cfd(struct notifier_block *nfb, unsigned long action, void *hcpu)
+{
+	long cpu = (long)hcpu;
+	struct call_function_data *cfd = &per_cpu(cfd_data, cpu);
+
+	switch (action) {
+	case CPU_UP_PREPARE:
+	case CPU_UP_PREPARE_FROZEN:
+		if (!alloc_cpumask_var_node(&cfd->cpumask, GFP_KERNEL,
+				cpu_to_node(cpu)))
+			return NOTIFY_BAD;
+		break;
+
+#ifdef CONFIG_CPU_HOTPLUG
+	case CPU_UP_CANCELED:
+	case CPU_UP_CANCELED_FROZEN:
+
+	case CPU_DEAD:
+	case CPU_DEAD_FROZEN:
+		free_cpumask_var(cfd->cpumask);
+		break;
+#endif
+	};
+
+	return NOTIFY_OK;
+}
+
+static struct notifier_block __cpuinitdata hotplug_cfd_notifier = {
+	.notifier_call = hotplug_cfd,
+};
+
 static int __cpuinit init_call_single_data(void)
 {
+	void *cpu = (void *)(long)smp_processor_id();
 	int i;
 
 	for_each_possible_cpu(i) {
@@ -44,18 +86,69 @@ static int __cpuinit init_call_single_data(void)
 		spin_lock_init(&q->lock);
 		INIT_LIST_HEAD(&q->list);
 	}
+
+	hotplug_cfd(&hotplug_cfd_notifier, CPU_UP_PREPARE, cpu);
+	register_cpu_notifier(&hotplug_cfd_notifier);
+
 	return 0;
 }
 early_initcall(init_call_single_data);
 
-static void csd_flag_wait(struct call_single_data *data)
+/*
+ * csd_wait/csd_complete are used for synchronous ipi calls
+ */
+static void csd_wait_prepare(struct call_single_data *data)
 {
-	/* Wait for response */
-	do {
-		if (!(data->flags & CSD_FLAG_WAIT))
-			break;
+	data->flags |= CSD_FLAG_WAIT;
+}
+
+static void csd_complete(struct call_single_data *data)
+{
+	if (data->flags & CSD_FLAG_WAIT) {
+		/*
+		 * ensure we're all done before saying we are
+		 */
+		smp_mb();
+		data->flags &= ~CSD_FLAG_WAIT;
+	}
+}
+
+static void csd_wait(struct call_single_data *data)
+{
+	while (data->flags & CSD_FLAG_WAIT)
 		cpu_relax();
-	} while (1);
+}
+
+/*
+ * csd_lock/csd_unlock used to serialize access to per-cpu csd resources
+ *
+ * For non-synchronous ipi calls the csd can still be in use by the previous
+ * function call. For multi-cpu calls its even more interesting as we'll have
+ * to ensure no other cpu is observing our csd.
+ */
+static void csd_lock(struct call_single_data *data)
+{
+	while (data->flags & CSD_FLAG_LOCK)
+		cpu_relax();
+	data->flags = CSD_FLAG_LOCK;
+
+	/*
+	 * prevent CPU from reordering the above assignment to ->flags
+	 * with any subsequent assignments to other fields of the
+	 * specified call_single_data structure.
+	 */
+
+	smp_mb();
+}
+
+static void csd_unlock(struct call_single_data *data)
+{
+	WARN_ON(!(data->flags & CSD_FLAG_LOCK));
+	/*
+	 * ensure we're all done before releasing data
+	 */
+	smp_mb();
+	data->flags &= ~CSD_FLAG_LOCK;
 }
 
 /*
@@ -89,16 +182,7 @@ static void generic_exec_single(int cpu, struct call_single_data *data)
 		arch_send_call_function_single_ipi(cpu);
 
 	if (wait)
-		csd_flag_wait(data);
-}
-
-static void rcu_free_call_data(struct rcu_head *head)
-{
-	struct call_function_data *data;
-
-	data = container_of(head, struct call_function_data, rcu_head);
-
-	kfree(data);
+		csd_wait(data);
 }
 
 /*
@@ -122,41 +206,35 @@ void generic_smp_call_function_interrupt(void)
 	 * It's ok to use list_for_each_rcu() here even though we may delete
 	 * 'pos', since list_del_rcu() doesn't clear ->next
 	 */
-	rcu_read_lock();
-	list_for_each_entry_rcu(data, &call_function_queue, csd.list) {
+	list_for_each_entry_rcu(data, &call_function.queue, csd.list) {
 		int refs;
 
-		if (!cpumask_test_cpu(cpu, to_cpumask(data->cpumask_bits)))
+		spin_lock(&data->lock);
+		if (!cpumask_test_cpu(cpu, data->cpumask)) {
+			spin_unlock(&data->lock);
 			continue;
+		}
+		cpumask_clear_cpu(cpu, data->cpumask);
+		spin_unlock(&data->lock);
 
 		data->csd.func(data->csd.info);
 
 		spin_lock(&data->lock);
-		cpumask_clear_cpu(cpu, to_cpumask(data->cpumask_bits));
 		WARN_ON(data->refs == 0);
-		data->refs--;
-		refs = data->refs;
+		refs = --data->refs;
+		if (!refs) {
+			spin_lock(&call_function.lock);
+			list_del_rcu(&data->csd.list);
+			spin_unlock(&call_function.lock);
+		}
 		spin_unlock(&data->lock);
 
 		if (refs)
 			continue;
 
-		spin_lock(&call_function_lock);
-		list_del_rcu(&data->csd.list);
-		spin_unlock(&call_function_lock);
-
-		if (data->csd.flags & CSD_FLAG_WAIT) {
-			/*
-			 * serialize stores to data with the flag clear
-			 * and wakeup
-			 */
-			smp_wmb();
-			data->csd.flags &= ~CSD_FLAG_WAIT;
-		}
-		if (data->csd.flags & CSD_FLAG_ALLOC)
-			call_rcu(&data->rcu_head, rcu_free_call_data);
+		csd_complete(&data->csd);
+		csd_unlock(&data->csd);
 	}
-	rcu_read_unlock();
 
 	put_cpu();
 }
@@ -192,14 +270,14 @@ void generic_smp_call_function_single_interrupt(void)
 
 		data->func(data->info);
 
-		if (data_flags & CSD_FLAG_WAIT) {
-			smp_wmb();
-			data->flags &= ~CSD_FLAG_WAIT;
-		} else if (data_flags & CSD_FLAG_LOCK) {
-			smp_wmb();
-			data->flags &= ~CSD_FLAG_LOCK;
-		} else if (data_flags & CSD_FLAG_ALLOC)
-			kfree(data);
+		if (data_flags & CSD_FLAG_WAIT)
+			csd_complete(data);
+
+		/*
+		 * Unlocked CSDs are valid through generic_exec_single()
+		 */
+		if (data_flags & CSD_FLAG_LOCK)
+			csd_unlock(data);
 	}
 }
 
@@ -218,7 +296,9 @@ static DEFINE_PER_CPU(struct call_single_data, csd_data);
 int smp_call_function_single(int cpu, void (*func) (void *info), void *info,
 			     int wait)
 {
-	struct call_single_data d;
+	struct call_single_data d = {
+		.flags = 0,
+	};
 	unsigned long flags;
 	/* prevent preemption and reschedule on another processor,
 	   as well as CPU removal */
@@ -239,13 +319,11 @@ int smp_call_function_single(int cpu, void (*func) (void *info), void *info,
 			/*
 			 * We are calling a function on a single CPU
 			 * and we are not going to wait for it to finish.
-			 * We first try to allocate the data, but if we
-			 * fail, we fall back to use a per cpu data to pass
-			 * the information to that CPU. Since all callers
-			 * of this code will use the same data, we must
-			 * synchronize the callers to prevent a new caller
-			 * from corrupting the data before the callee
-			 * can access it.
+			 * We use a per cpu data to pass the information to
+			 * that CPU. Since all callers of this code will
+			 * use the same data, we must synchronize the
+			 * callers to prevent a new caller from corrupting
+			 * the data before the callee can access it.
 			 *
 			 * The CSD_FLAG_LOCK is used to let us know when
 			 * the IPI handler is done with the data.
@@ -255,18 +333,11 @@ int smp_call_function_single(int cpu, void (*func) (void *info), void *info,
 			 * will make sure the callee is done with the
 			 * data before a new caller will use it.
 			 */
-			data = kmalloc(sizeof(*data), GFP_ATOMIC);
-			if (data)
-				data->flags = CSD_FLAG_ALLOC;
-			else {
-				data = &per_cpu(csd_data, me);
-				while (data->flags & CSD_FLAG_LOCK)
-					cpu_relax();
-				data->flags = CSD_FLAG_LOCK;
-			}
+			data = &__get_cpu_var(csd_data);
+			csd_lock(data);
 		} else {
 			data = &d;
-			data->flags = CSD_FLAG_WAIT;
+			csd_wait_prepare(data);
 		}
 
 		data->func = func;
@@ -326,14 +397,14 @@ void smp_call_function_many(const struct cpumask *mask,
 {
 	struct call_function_data *data;
 	unsigned long flags;
-	int cpu, next_cpu;
+	int cpu, next_cpu, me = smp_processor_id();
 
 	/* Can deadlock when called with interrupts disabled */
 	WARN_ON(irqs_disabled());
 
 	/* So, what's a CPU they want?  Ignoring this one. */
 	cpu = cpumask_first_and(mask, cpu_online_mask);
-	if (cpu == smp_processor_id())
+	if (cpu == me)
 		cpu = cpumask_next_and(cpu, mask, cpu_online_mask);
 	/* No online cpus?  We're done. */
 	if (cpu >= nr_cpu_ids)
@@ -341,7 +412,7 @@ void smp_call_function_many(const struct cpumask *mask,
 
 	/* Do we have another CPU which isn't us? */
 	next_cpu = cpumask_next_and(cpu, mask, cpu_online_mask);
-	if (next_cpu == smp_processor_id())
+	if (next_cpu == me)
 		next_cpu = cpumask_next_and(next_cpu, mask, cpu_online_mask);
 
 	/* Fastpath: do that cpu by itself. */
@@ -350,31 +421,28 @@ void smp_call_function_many(const struct cpumask *mask,
 		return;
 	}
 
-	data = kmalloc(sizeof(*data) + cpumask_size(), GFP_ATOMIC);
-	if (unlikely(!data)) {
-		/* Slow path. */
-		for_each_online_cpu(cpu) {
-			if (cpu == smp_processor_id())
-				continue;
-			if (cpumask_test_cpu(cpu, mask))
-				smp_call_function_single(cpu, func, info, wait);
-		}
-		return;
-	}
+	data = &__get_cpu_var(cfd_data);
+	csd_lock(&data->csd);
 
-	spin_lock_init(&data->lock);
-	data->csd.flags = CSD_FLAG_ALLOC;
+	spin_lock_irqsave(&data->lock, flags);
 	if (wait)
-		data->csd.flags |= CSD_FLAG_WAIT;
+		csd_wait_prepare(&data->csd);
+
 	data->csd.func = func;
 	data->csd.info = info;
-	cpumask_and(to_cpumask(data->cpumask_bits), mask, cpu_online_mask);
-	cpumask_clear_cpu(smp_processor_id(), to_cpumask(data->cpumask_bits));
-	data->refs = cpumask_weight(to_cpumask(data->cpumask_bits));
+	cpumask_and(data->cpumask, mask, cpu_online_mask);
+	cpumask_clear_cpu(me, data->cpumask);
+	data->refs = cpumask_weight(data->cpumask);
 
-	spin_lock_irqsave(&call_function_lock, flags);
-	list_add_tail_rcu(&data->csd.list, &call_function_queue);
-	spin_unlock_irqrestore(&call_function_lock, flags);
+	spin_lock(&call_function.lock);
+	/*
+	 * Place entry at the _HEAD_ of the list, so that any cpu still
+	 * observing the entry in generic_smp_call_function_interrupt() will
+	 * not miss any other list entries.
+	 */
+	list_add_rcu(&data->csd.list, &call_function.queue);
+	spin_unlock(&call_function.lock);
+	spin_unlock_irqrestore(&data->lock, flags);
 
 	/*
 	 * Make the list addition visible before sending the ipi.
@@ -384,11 +452,11 @@ void smp_call_function_many(const struct cpumask *mask,
 	smp_mb();
 
 	/* Send a message to all CPUs in the map */
-	arch_send_call_function_ipi_mask(to_cpumask(data->cpumask_bits));
+	arch_send_call_function_ipi_mask(data->cpumask);
 
 	/* optionally wait for the CPUs to complete */
 	if (wait)
-		csd_flag_wait(&data->csd);
+		csd_wait(&data->csd);
 }
 EXPORT_SYMBOL(smp_call_function_many);
 
@@ -418,20 +486,20 @@ EXPORT_SYMBOL(smp_call_function);
 
 void ipi_call_lock(void)
 {
-	spin_lock(&call_function_lock);
+	spin_lock(&call_function.lock);
 }
 
 void ipi_call_unlock(void)
 {
-	spin_unlock(&call_function_lock);
+	spin_unlock(&call_function.lock);
 }
 
 void ipi_call_lock_irq(void)
 {
-	spin_lock_irq(&call_function_lock);
+	spin_lock_irq(&call_function.lock);
 }
 
 void ipi_call_unlock_irq(void)
 {
-	spin_unlock_irq(&call_function_lock);
+	spin_unlock_irq(&call_function.lock);
 }