Introduce two flags to control upcall behaviour:

o KMF_NOUPCALL
	Ask kse_release to not return to userland upcall entry, but instead
	direct returns to userland by using current thread's stack and return
	address on stack. This flags is intended to be used by UTS in critical
	region to wait another UTS thread to leave critical region, by using
	kse_release with this flag to avoid spinnng and burning CPU. Also this
	flags can be used by UTS to poll completed context when there is nothing
	to do in userland and needn't restart from its entry like normal upcall.

o KMF_NOCOMPLETED
	Ask kernel to not bring completed thread contexts back to userland when
	doing upcall, this flags is intend to be used with above flag when an
	upcall thread is in critical region and can not process completed contexts
	at that time.

Tested by: deischen

1 files changed, 4 insertions, 0 deletions

diff --git a/sys/sys/kse.h b/sys/sys/kse.h
index 8e96525d71e9..a69adcdcde88 100644
--- a/sys/sys/kse.h
+++ b/sys/sys/kse.h
@@ -85,6 +85,10 @@ struct kse_mailbox {
 #define	KSE_VER_0	0
 #define	KSE_VERSION	KSE_VER_0
 
+/* These flags are kept in km_flags */
+#define	KMF_NOUPCALL		0x01
+#define	KMF_NOCOMPLETED		0x02
+
 #ifndef _KERNEL
 int	kse_create(struct kse_mailbox *, int);
 int	kse_exit(void);