1 files changed, 79 insertions, 125 deletions

diff --git a/arch/blackfin/mach-common/smp.c b/arch/blackfin/mach-common/smp.c
index a17107a700d5..9f251406a76a 100644
--- a/arch/blackfin/mach-common/smp.c
+++ b/arch/blackfin/mach-common/smp.c
@@ -19,6 +19,7 @@
 #include <linux/mm.h>
 #include <linux/cpu.h>
 #include <linux/smp.h>
+#include <linux/cpumask.h>
 #include <linux/seq_file.h>
 #include <linux/irq.h>
 #include <linux/slab.h>
@@ -43,12 +44,6 @@ void __cpuinitdata *init_retx_coreb, *init_saved_retx_coreb,
 	*init_saved_seqstat_coreb, *init_saved_icplb_fault_addr_coreb,
 	*init_saved_dcplb_fault_addr_coreb;
 
-cpumask_t cpu_possible_map;
-EXPORT_SYMBOL(cpu_possible_map);
-
-cpumask_t cpu_online_map;
-EXPORT_SYMBOL(cpu_online_map);
-
 #define BFIN_IPI_RESCHEDULE   0
 #define BFIN_IPI_CALL_FUNC    1
 #define BFIN_IPI_CPU_STOP     2
@@ -65,8 +60,7 @@ struct smp_call_struct {
 	void (*func)(void *info);
 	void *info;
 	int wait;
-	cpumask_t pending;
-	cpumask_t waitmask;
+	cpumask_t *waitmask;
 };
 
 static struct blackfin_flush_data smp_flush_data;
@@ -74,15 +68,19 @@ static struct blackfin_flush_data smp_flush_data;
 static DEFINE_SPINLOCK(stop_lock);
 
 struct ipi_message {
-	struct list_head list;
 	unsigned long type;
 	struct smp_call_struct call_struct;
 };
 
+/* A magic number - stress test shows this is safe for common cases */
+#define BFIN_IPI_MSGQ_LEN 5
+
+/* Simple FIFO buffer, overflow leads to panic */
 struct ipi_message_queue {
-	struct list_head head;
 	spinlock_t lock;
 	unsigned long count;
+	unsigned long head; /* head of the queue */
+	struct ipi_message ipi_message[BFIN_IPI_MSGQ_LEN];
 };
 
 static DEFINE_PER_CPU(struct ipi_message_queue, ipi_msg_queue);
@@ -121,7 +119,6 @@ static void ipi_call_function(unsigned int cpu, struct ipi_message *msg)
 	func = msg->call_struct.func;
 	info = msg->call_struct.info;
 	wait = msg->call_struct.wait;
-	cpu_clear(cpu, msg->call_struct.pending);
 	func(info);
 	if (wait) {
 #ifdef __ARCH_SYNC_CORE_DCACHE
@@ -132,51 +129,57 @@ static void ipi_call_function(unsigned int cpu, struct ipi_message *msg)
 		 */
 		resync_core_dcache();
 #endif
-		cpu_clear(cpu, msg->call_struct.waitmask);
-	} else
-		kfree(msg);
+		cpu_clear(cpu, *msg->call_struct.waitmask);
+	}
+}
+
+/* Use IRQ_SUPPLE_0 to request reschedule.
+ * When returning from interrupt to user space,
+ * there is chance to reschedule */
+static irqreturn_t ipi_handler_int0(int irq, void *dev_instance)
+{
+	unsigned int cpu = smp_processor_id();
+
+	platform_clear_ipi(cpu, IRQ_SUPPLE_0);
+	return IRQ_HANDLED;
 }
 
-static irqreturn_t ipi_handler(int irq, void *dev_instance)
+static irqreturn_t ipi_handler_int1(int irq, void *dev_instance)
 {
 	struct ipi_message *msg;
 	struct ipi_message_queue *msg_queue;
 	unsigned int cpu = smp_processor_id();
+	unsigned long flags;
 
-	platform_clear_ipi(cpu);
+	platform_clear_ipi(cpu, IRQ_SUPPLE_1);
 
 	msg_queue = &__get_cpu_var(ipi_msg_queue);
-	msg_queue->count++;
 
-	spin_lock(&msg_queue->lock);
-	while (!list_empty(&msg_queue->head)) {
-		msg = list_entry(msg_queue->head.next, typeof(*msg), list);
-		list_del(&msg->list);
+	spin_lock_irqsave(&msg_queue->lock, flags);
+
+	while (msg_queue->count) {
+		msg = &msg_queue->ipi_message[msg_queue->head];
 		switch (msg->type) {
-		case BFIN_IPI_RESCHEDULE:
-			/* That's the easiest one; leave it to
-			 * return_from_int. */
-			kfree(msg);
-			break;
 		case BFIN_IPI_CALL_FUNC:
-			spin_unlock(&msg_queue->lock);
+			spin_unlock_irqrestore(&msg_queue->lock, flags);
 			ipi_call_function(cpu, msg);
-			spin_lock(&msg_queue->lock);
+			spin_lock_irqsave(&msg_queue->lock, flags);
 			break;
 		case BFIN_IPI_CPU_STOP:
-			spin_unlock(&msg_queue->lock);
+			spin_unlock_irqrestore(&msg_queue->lock, flags);
 			ipi_cpu_stop(cpu);
-			spin_lock(&msg_queue->lock);
-			kfree(msg);
+			spin_lock_irqsave(&msg_queue->lock, flags);
 			break;
 		default:
 			printk(KERN_CRIT "CPU%u: Unknown IPI message 0x%lx\n",
 			       cpu, msg->type);
-			kfree(msg);
 			break;
 		}
+		msg_queue->head++;
+		msg_queue->head %= BFIN_IPI_MSGQ_LEN;
+		msg_queue->count--;
 	}
-	spin_unlock(&msg_queue->lock);
+	spin_unlock_irqrestore(&msg_queue->lock, flags);
 	return IRQ_HANDLED;
 }
 
@@ -186,48 +189,47 @@ static void ipi_queue_init(void)
 	struct ipi_message_queue *msg_queue;
 	for_each_possible_cpu(cpu) {
 		msg_queue = &per_cpu(ipi_msg_queue, cpu);
-		INIT_LIST_HEAD(&msg_queue->head);
 		spin_lock_init(&msg_queue->lock);
 		msg_queue->count = 0;
+		msg_queue->head = 0;
 	}
 }
 
-int smp_call_function(void (*func)(void *info), void *info, int wait)
+static inline void smp_send_message(cpumask_t callmap, unsigned long type,
+					void (*func) (void *info), void *info, int wait)
 {
 	unsigned int cpu;
-	cpumask_t callmap;
-	unsigned long flags;
 	struct ipi_message_queue *msg_queue;
 	struct ipi_message *msg;
-
-	callmap = cpu_online_map;
-	cpu_clear(smp_processor_id(), callmap);
-	if (cpus_empty(callmap))
-		return 0;
-
-	msg = kmalloc(sizeof(*msg), GFP_ATOMIC);
-	if (!msg)
-		return -ENOMEM;
-	INIT_LIST_HEAD(&msg->list);
-	msg->call_struct.func = func;
-	msg->call_struct.info = info;
-	msg->call_struct.wait = wait;
-	msg->call_struct.pending = callmap;
-	msg->call_struct.waitmask = callmap;
-	msg->type = BFIN_IPI_CALL_FUNC;
+	unsigned long flags, next_msg;
+	cpumask_t waitmask = callmap; /* waitmask is shared by all cpus */
 
 	for_each_cpu_mask(cpu, callmap) {
 		msg_queue = &per_cpu(ipi_msg_queue, cpu);
 		spin_lock_irqsave(&msg_queue->lock, flags);
-		list_add_tail(&msg->list, &msg_queue->head);
+		if (msg_queue->count < BFIN_IPI_MSGQ_LEN) {
+			next_msg = (msg_queue->head + msg_queue->count)
+					% BFIN_IPI_MSGQ_LEN;
+			msg = &msg_queue->ipi_message[next_msg];
+			msg->type = type;
+			if (type == BFIN_IPI_CALL_FUNC) {
+				msg->call_struct.func = func;
+				msg->call_struct.info = info;
+				msg->call_struct.wait = wait;
+				msg->call_struct.waitmask = &waitmask;
+			}
+			msg_queue->count++;
+		} else
+			panic("IPI message queue overflow\n");
 		spin_unlock_irqrestore(&msg_queue->lock, flags);
-		platform_send_ipi_cpu(cpu);
+		platform_send_ipi_cpu(cpu, IRQ_SUPPLE_1);
 	}
+
 	if (wait) {
-		while (!cpus_empty(msg->call_struct.waitmask))
+		while (!cpus_empty(waitmask))
 			blackfin_dcache_invalidate_range(
-				(unsigned long)(&msg->call_struct.waitmask),
-				(unsigned long)(&msg->call_struct.waitmask));
+				(unsigned long)(&waitmask),
+				(unsigned long)(&waitmask));
 #ifdef __ARCH_SYNC_CORE_DCACHE
 		/*
 		 * Invalidate D cache in case shared data was changed by
@@ -235,8 +237,20 @@ int smp_call_function(void (*func)(void *info), void *info, int wait)
 		 */
 		resync_core_dcache();
 #endif
-		kfree(msg);
 	}
+}
+
+int smp_call_function(void (*func)(void *info), void *info, int wait)
+{
+	cpumask_t callmap;
+
+	callmap = cpu_online_map;
+	cpu_clear(smp_processor_id(), callmap);
+	if (cpus_empty(callmap))
+		return 0;
+
+	smp_send_message(callmap, BFIN_IPI_CALL_FUNC, func, info, wait);
+
 	return 0;
 }
 EXPORT_SYMBOL_GPL(smp_call_function);
@@ -246,100 +260,39 @@ int smp_call_function_single(int cpuid, void (*func) (void *info), void *info,
 {
 	unsigned int cpu = cpuid;
 	cpumask_t callmap;
-	unsigned long flags;
-	struct ipi_message_queue *msg_queue;
-	struct ipi_message *msg;
 
 	if (cpu_is_offline(cpu))
 		return 0;
 	cpus_clear(callmap);
 	cpu_set(cpu, callmap);
 
-	msg = kmalloc(sizeof(*msg), GFP_ATOMIC);
-	if (!msg)
-		return -ENOMEM;
-	INIT_LIST_HEAD(&msg->list);
-	msg->call_struct.func = func;
-	msg->call_struct.info = info;
-	msg->call_struct.wait = wait;
-	msg->call_struct.pending = callmap;
-	msg->call_struct.waitmask = callmap;
-	msg->type = BFIN_IPI_CALL_FUNC;
-
-	msg_queue = &per_cpu(ipi_msg_queue, cpu);
-	spin_lock_irqsave(&msg_queue->lock, flags);
-	list_add_tail(&msg->list, &msg_queue->head);
-	spin_unlock_irqrestore(&msg_queue->lock, flags);
-	platform_send_ipi_cpu(cpu);
+	smp_send_message(callmap, BFIN_IPI_CALL_FUNC, func, info, wait);
 
-	if (wait) {
-		while (!cpus_empty(msg->call_struct.waitmask))
-			blackfin_dcache_invalidate_range(
-				(unsigned long)(&msg->call_struct.waitmask),
-				(unsigned long)(&msg->call_struct.waitmask));
-#ifdef __ARCH_SYNC_CORE_DCACHE
-		/*
-		 * Invalidate D cache in case shared data was changed by
-		 * other processors to ensure cache coherence.
-		 */
-		resync_core_dcache();
-#endif
-		kfree(msg);
-	}
 	return 0;
 }
 EXPORT_SYMBOL_GPL(smp_call_function_single);
 
 void smp_send_reschedule(int cpu)
 {
-	unsigned long flags;
-	struct ipi_message_queue *msg_queue;
-	struct ipi_message *msg;
-
+	/* simply trigger an ipi */
 	if (cpu_is_offline(cpu))
 		return;
-
-	msg = kzalloc(sizeof(*msg), GFP_ATOMIC);
-	if (!msg)
-		return;
-	INIT_LIST_HEAD(&msg->list);
-	msg->type = BFIN_IPI_RESCHEDULE;
-
-	msg_queue = &per_cpu(ipi_msg_queue, cpu);
-	spin_lock_irqsave(&msg_queue->lock, flags);
-	list_add_tail(&msg->list, &msg_queue->head);
-	spin_unlock_irqrestore(&msg_queue->lock, flags);
-	platform_send_ipi_cpu(cpu);
+	platform_send_ipi_cpu(cpu, IRQ_SUPPLE_0);
 
 	return;
 }
 
 void smp_send_stop(void)
 {
-	unsigned int cpu;
 	cpumask_t callmap;
-	unsigned long flags;
-	struct ipi_message_queue *msg_queue;
-	struct ipi_message *msg;
 
 	callmap = cpu_online_map;
 	cpu_clear(smp_processor_id(), callmap);
 	if (cpus_empty(callmap))
 		return;
 
-	msg = kzalloc(sizeof(*msg), GFP_ATOMIC);
-	if (!msg)
-		return;
-	INIT_LIST_HEAD(&msg->list);
-	msg->type = BFIN_IPI_CPU_STOP;
+	smp_send_message(callmap, BFIN_IPI_CPU_STOP, NULL, NULL, 0);
 
-	for_each_cpu_mask(cpu, callmap) {
-		msg_queue = &per_cpu(ipi_msg_queue, cpu);
-		spin_lock_irqsave(&msg_queue->lock, flags);
-		list_add_tail(&msg->list, &msg_queue->head);
-		spin_unlock_irqrestore(&msg_queue->lock, flags);
-		platform_send_ipi_cpu(cpu);
-	}
 	return;
 }
 
@@ -446,7 +399,8 @@ void __init smp_prepare_cpus(unsigned int max_cpus)
 {
 	platform_prepare_cpus(max_cpus);
 	ipi_queue_init();
-	platform_request_ipi(&ipi_handler);
+	platform_request_ipi(IRQ_SUPPLE_0, ipi_handler_int0);
+	platform_request_ipi(IRQ_SUPPLE_1, ipi_handler_int1);
 }
 
 void __init smp_cpus_done(unsigned int max_cpus)