[PATCH] sched: arch preempt notifier mechanism
This adds a general mechanism whereby a task can request the scheduler to
notify it whenever it is preempted or scheduled back in. This allows the
task to swap any special-purpose registers like the fpu or Intel's VT
registers.
Signed-off-by: Avi Kivity <avi@qumranet.com>
[ mingo@elte.hu: fixes, cleanups ]
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/include/linux/preempt.h b/include/linux/preempt.h
index d0926d6..484988e 100644
--- a/include/linux/preempt.h
+++ b/include/linux/preempt.h
@@ -8,6 +8,7 @@
#include <linux/thread_info.h>
#include <linux/linkage.h>
+#include <linux/list.h>
#ifdef CONFIG_DEBUG_PREEMPT
extern void fastcall add_preempt_count(int val);
@@ -60,4 +61,47 @@
#endif
+#ifdef CONFIG_PREEMPT_NOTIFIERS
+
+struct preempt_notifier;
+
+/**
+ * preempt_ops - notifiers called when a task is preempted and rescheduled
+ * @sched_in: we're about to be rescheduled:
+ * notifier: struct preempt_notifier for the task being scheduled
+ * cpu: cpu we're scheduled on
+ * @sched_out: we've just been preempted
+ * notifier: struct preempt_notifier for the task being preempted
+ * next: the task that's kicking us out
+ */
+struct preempt_ops {
+ void (*sched_in)(struct preempt_notifier *notifier, int cpu);
+ void (*sched_out)(struct preempt_notifier *notifier,
+ struct task_struct *next);
+};
+
+/**
+ * preempt_notifier - key for installing preemption notifiers
+ * @link: internal use
+ * @ops: defines the notifier functions to be called
+ *
+ * Usually used in conjunction with container_of().
+ */
+struct preempt_notifier {
+ struct hlist_node link;
+ struct preempt_ops *ops;
+};
+
+void preempt_notifier_register(struct preempt_notifier *notifier);
+void preempt_notifier_unregister(struct preempt_notifier *notifier);
+
+static inline void preempt_notifier_init(struct preempt_notifier *notifier,
+ struct preempt_ops *ops)
+{
+ INIT_HLIST_NODE(¬ifier->link);
+ notifier->ops = ops;
+}
+
+#endif
+
#endif /* __LINUX_PREEMPT_H */