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)