Index: kern/kern_resource.c
===================================================================
RCS file: /home/aggelos/imports/vcs/dcvs/src/sys/kern/kern_resource.c,v
retrieving revision 1.31
diff -u -u -r1.31 kern_resource.c
--- kern/kern_resource.c	3 Feb 2007 17:05:58 -0000	1.31
+++ kern/kern_resource.c	28 Apr 2007 20:24:55 -0000
@@ -261,6 +261,98 @@
 	return (0);
 }
 
+int
+sys_lwp_rtprio(struct lwp_rtprio_args *uap)
+{
+	struct proc *p = curproc;
+	struct lwp *lp;
+	struct rtprio rtp;
+	struct ucred *cr = p->p_ucred;
+	int error;
+
+	error = copyin(uap->rtp, &rtp, sizeof(struct rtprio));
+	if (error)
+		return error;
+
+	if (uap->pid < 0) {
+		return EINVAL;
+	} else if (uap->pid == 0) {
+		/* curproc already loaded on p */
+	} else {
+		p = pfind(uap->pid);
+	}
+
+	if (p == 0) {
+		return ESRCH;
+	}
+
+	if (uap->tid < -1) {
+		return EINVAL;
+	} else if (uap->tid == -1) {
+		/*
+		 * sadly, tid can be 0 so we can't use 0 here
+		 * like sys_rtprio()
+		 */
+		lp = curthread->td_lwp;
+	} else {
+		FOREACH_LWP_IN_PROC(lp, p) {
+			if (lp->lwp_tid == uap->tid) {
+				break;
+			}
+		}
+		if (!lp) {
+			return ESRCH;
+		}
+	}
+
+	switch (uap->function) {
+	case RTP_LOOKUP:
+		return (copyout(&lp->lwp_rtprio, uap->rtp,
+				sizeof(struct rtprio)));
+	case RTP_SET:
+		if (cr->cr_uid && cr->cr_ruid &&
+		    cr->cr_uid != p->p_ucred->cr_uid &&
+		    cr->cr_ruid != p->p_ucred->cr_uid) {
+			return EPERM;
+		}
+		/* disallow setting rtprio in most cases if not superuser */
+		if (suser_cred(cr, 0)) {
+			/* can't set someone else's */
+			if (uap->pid) { /* XXX */
+				return EPERM;
+			}
+			/* can't set realtime priority */
+/*
+ * Realtime priority has to be restricted for reasons which should be
+ * obvious. However, for idle priority, there is a potential for
+ * system deadlock if an idleprio process gains a lock on a resource
+ * that other processes need (and the idleprio process can't run
+ * due to a CPU-bound normal process). Fix me! XXX
+ */
+ 			if (RTP_PRIO_IS_REALTIME(rtp.type)) {
+				return EPERM;
+			}
+		}
+		switch (rtp.type) {
+#ifdef RTP_PRIO_FIFO
+		case RTP_PRIO_FIFO:
+#endif
+		case RTP_PRIO_REALTIME:
+		case RTP_PRIO_NORMAL:
+		case RTP_PRIO_IDLE:
+			if (rtp.prio > RTP_PRIO_MAX)
+				return EINVAL;
+			lp->lwp_rtprio = rtp;
+			return 0;
+		default:
+			return EINVAL;
+		}
+	default:
+		return EINVAL;
+	}
+	panic("can't get here");
+}
+
 /*
  * Set realtime priority
  */
Index: kern/syscalls.master
===================================================================
RCS file: /home/aggelos/imports/vcs/dcvs/src/sys/kern/syscalls.master,v
retrieving revision 1.54
diff -u -u -r1.54 syscalls.master
--- kern/syscalls.master	22 Apr 2007 00:59:25 -0000	1.54
+++ kern/syscalls.master	28 Apr 2007 12:01:48 -0000
@@ -680,3 +680,4 @@
 495	STD	BSD	{ int lwp_create(struct lwp_params *params); }
 496	STD	BSD	{ lwpid_t lwp_gettid(void); }
 497	STD	BSD	{ int lwp_kill(pid_t pid, lwpid_t tid, int signum); }
+498	STD	BSD	{ int lwp_rtprio(int function, pid_t pid, lwpid_t tid, struct rtprio *rtp); }
Index: sys/rtprio.h
===================================================================
RCS file: /home/aggelos/imports/vcs/dcvs/src/sys/sys/rtprio.h,v
retrieving revision 1.5
diff -u -u -r1.5 rtprio.h
--- sys/rtprio.h	20 May 2006 02:42:13 -0000	1.5
+++ sys/rtprio.h	28 Apr 2007 17:38:22 -0000
@@ -81,6 +81,7 @@
 
 __BEGIN_DECLS
 int	rtprio (int, pid_t, struct rtprio *);
+int	lwp_rtprio (int, pid_t, lwpid_t, struct rtprio *);
 __END_DECLS
 #endif	/* !_KERNEL */
 #endif	/* !_SYS_RTPRIO_H_ */