[CELL] oprofile: enable SPU switch notification to detect currently active SPU tasks

From: Maynard Johnson <mpjohn@us.ibm.com>

This patch adds to the capability of spu_switch_event_register so that
the caller is also notified of currently active SPU tasks.
Exports spu_switch_event_register and spu_switch_event_unregister so
that OProfile can get access to the notifications provided.

Signed-off-by: Maynard Johnson <mpjohn@us.ibm.com>
Signed-off-by: Carl Love <carll@us.ibm.com>
Signed-off-by: Bob Nelson <rrnelson@us.ibm.com>
Signed-off-by: Arnd Bergmann <arnd.bergmann@de.ibm.com>
Acked-by: Paul Mackerras <paulus@samba.org>
diff --git a/arch/powerpc/platforms/cell/spufs/sched.c b/arch/powerpc/platforms/cell/spufs/sched.c
index 49b8f68..88ec333 100644
--- a/arch/powerpc/platforms/cell/spufs/sched.c
+++ b/arch/powerpc/platforms/cell/spufs/sched.c
@@ -204,21 +204,51 @@
 
 static BLOCKING_NOTIFIER_HEAD(spu_switch_notifier);
 
-static void spu_switch_notify(struct spu *spu, struct spu_context *ctx)
+void spu_switch_notify(struct spu *spu, struct spu_context *ctx)
 {
 	blocking_notifier_call_chain(&spu_switch_notifier,
 			    ctx ? ctx->object_id : 0, spu);
 }
 
+static void notify_spus_active(void)
+{
+	int node;
+
+	/*
+	 * Wake up the active spu_contexts.
+	 *
+	 * When the awakened processes see their "notify_active" flag is set,
+	 * they will call spu_switch_notify();
+	 */
+	for_each_online_node(node) {
+		struct spu *spu;
+		mutex_lock(&spu_prio->active_mutex[node]);
+		list_for_each_entry(spu, &spu_prio->active_list[node], list) {
+			struct spu_context *ctx = spu->ctx;
+			set_bit(SPU_SCHED_NOTIFY_ACTIVE, &ctx->sched_flags);
+			mb();	/* make sure any tasks woken up below */
+				/* can see the bit(s) set above */
+			wake_up_all(&ctx->stop_wq);
+		}
+		mutex_unlock(&spu_prio->active_mutex[node]);
+	}
+}
+
 int spu_switch_event_register(struct notifier_block * n)
 {
-	return blocking_notifier_chain_register(&spu_switch_notifier, n);
+	int ret;
+	ret = blocking_notifier_chain_register(&spu_switch_notifier, n);
+	if (!ret)
+		notify_spus_active();
+	return ret;
 }
+EXPORT_SYMBOL_GPL(spu_switch_event_register);
 
 int spu_switch_event_unregister(struct notifier_block * n)
 {
 	return blocking_notifier_chain_unregister(&spu_switch_notifier, n);
 }
+EXPORT_SYMBOL_GPL(spu_switch_event_unregister);
 
 /**
  * spu_bind_context - bind spu context to physical spu