From 435806d31b24866b50e3d30ba323ae3a5ca05a44 Mon Sep 17 00:00:00 2001
From: David Xu <davidxu@FreeBSD.org>
Date: Tue, 11 Dec 2007 08:25:36 +0000
Subject: Fix LOR of thread lock and umtx's priority propagation mutex due to
 the reworking of scheduler lock.

MFC: after 3 days
---
 sys/kern/kern_resource.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

(limited to 'sys/kern/kern_resource.c')

diff --git a/sys/kern/kern_resource.c b/sys/kern/kern_resource.c
index 5086a5921a9c..4e22054c34bc 100644
--- a/sys/kern/kern_resource.c
+++ b/sys/kern/kern_resource.c
@@ -56,6 +56,7 @@ __FBSDID("$FreeBSD$");
 #include <sys/syscallsubr.h>
 #include <sys/sysent.h>
 #include <sys/time.h>
+#include <sys/umtx.h>
 
 #include <vm/vm.h>
 #include <vm/vm_param.h>
@@ -482,6 +483,7 @@ int
 rtp_to_pri(struct rtprio *rtp, struct thread *td)
 {
 	u_char	newpri;
+	u_char	oldpri;
 
 	if (rtp->prio > RTP_PRIO_MAX)
 		return (EINVAL);
@@ -501,10 +503,15 @@ rtp_to_pri(struct rtprio *rtp, struct thread *td)
 		return (EINVAL);
 	}
 	sched_class(td, rtp->type);	/* XXX fix */
+	oldpri = td->td_user_pri;
 	sched_user_prio(td, newpri);
 	if (curthread == td)
 		sched_prio(curthread, td->td_user_pri); /* XXX dubious */
-	thread_unlock(td);
+	if (TD_ON_UPILOCK(td) && oldpri != newpri) {
+		thread_unlock(td);
+		umtx_pi_adjust(td, oldpri);
+	} else
+		thread_unlock(td);
 	return (0);
 }
 
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