5 files changed, 22 insertions(+), 59 deletions(-)

M carrera/dat.h
M pc/dat.h
M port/proc.c
M port/taslock.c
M power/dat.h

@@ 27,7 27,6 @@ struct Lock
 	ulong	sr;
 	ulong	pc;
 	ulong	pid;
-	int	pri;
 };
 
 struct Label

@@ 30,7 30,6 @@ struct Lock
 	ulong	sr;
 	ulong	pc;
 	ulong	pid;
-	int	pri;
 };
 
 struct Label

@@ 130,21 130,11 @@ enum
 void
 ready(Proc *p)
 {
-	int s, pri, base;
+	int s, pri;
 	Schedq *rq;
 
 	s = splhi();
 
-	/*
-	 *  This interacts with code in taslock().  The intent is to keep the
-	 *  priority of a process trying for a lock lower than the process holding
-	 *  the lock.
-	 */
-	if(p->lockpri)
-		base = p->lockpri;
-	else
-		base = p->basepri;
-
 	/* history counts */
 	if(p->state == Running){
 		p->rt++;


@@ 154,15 144,19 @@ ready(Proc *p)
 		p->rt = 0;
 		pri = p->art/Squantum;
 	}
-	pri = base - pri;
+	pri = p->basepri - pri;
 	if(pri < 0)
 		pri = 0;
 
 	/* the only intersection between the classes is at PriNormal */
-	if(pri < PriNormal && base > PriNormal)
+	if(pri < PriNormal && p->basepri > PriNormal)
 		pri = PriNormal;
-	p->priority = pri;
 
+	/* hack for livelocks due to priority */
+	if(p->lockpri)
+		pri = 0;
+
+	p->priority = pri;
 	rq = &runq[p->priority];
 
 	lock(runq);

@@ 11,59 11,41 @@ lockloop(Lock *l, ulong pc)
 	print("lock loop key 0x%lux pc 0x%lux held by pc 0x%lux proc %d\n",
 		l->key, pc, l->pc, l->pid);
 	dumpaproc(up);
-}
 
-#define LOCKLOOP 100000000	/* to detect a lock loop */
-#define SPINLOOP 10000000	/* to keep tas's off the bus */
+	/* lower priority till we get the lock */
+	if(up && up->state == Running && (getstatus()&IE)){
+		up->lockpri = 1;
+		sched();
+	}
+}
 
 void
 lock(Lock *l)
 {
-	int i, pri, spins;
+	int i;
 	ulong pc, pid;
 
 	pc = getcallerpc(l);
-	if(up){
-		pid = up->pid;
-		pri = up->priority;
-	} else {
-		pid = 0;
-		pri = 0;
-	}
+	pid = up ? up->pid : 0;
 
-	/* quick try, it might work */
 	if(tas(&l->key) == 0){
 		l->pc = pc;
 		l->pid = pid;
-		l->pri = pri;
 		return;
 	}
 
-	spins = 0;
 	for(;;){
 		i = 0;
 		while(l->key)
-			if(i++ > SPINLOOP){
-				/* look for lock loops */
-				if(spins++ > LOCKLOOP/SPINLOOP){
-					spins = 0;
-					lockloop(l, pc);
-				}
-
-				/* possible priority inversion, try switching priority */
-				if(up && up->state == Running)
-				if(getstatus()&IE) {
-print("priority inversion\n");
-					up->lockpri = l->pri;
-					sched();
-				}
+			if(i++ > 100000000){
+				i = 0;
+				lockloop(l, pc);
 			}
-
 		if(tas(&l->key) == 0){
 			l->pc = pc;
 			l->pid = pid;
-			l->pri = pri;
-			up->lockpri = 0;
+			if(up)
+				up->lockpri = 0;
 			return;
 		}
 	}


@@ 83,7 65,6 @@ ilock(Lock *l)
 		l->sr = x;
 		l->pc = pc;
 		l->pid = pid;
-		l->pri = 0;
 		return;
 	}
 


@@ 94,7 75,6 @@ ilock(Lock *l)
 			l->sr = x;
 			l->pc = pc;
 			l->pid = pid;
-			l->pri = 0;
 			return;
 		}
 	}


@@ 107,13 87,7 @@ canlock(Lock *l)
 		return 0;
 
 	l->pc = getcallerpc(l);
-	if(up){
-		l->pid = up->pid;
-		l->pri = up->priority;
-	} else {
-		l->pid = 0;
-		l->pri = 0;
-	}
+	l->pid = up ? up->pid : 0;
 	return 1;
 }
 


@@ 122,7 96,6 @@ unlock(Lock *l)
 {
 	l->key = 0;
 	l->pc = 0;
-	l->pri = 0;
 }
 
 void


@@ 133,6 106,5 @@ iunlock(Lock *l)
 	sr = l->sr;
 	l->key = 0;
 	l->pc = 0;
-	l->pri = 0;
 	splx(sr);
 }

@@ 26,7 26,6 @@ struct Lock
 	ulong	pc;
 	ulong	sr;
 	ulong	pid;
-	int	pri;
 };
 
 struct Label