code: 9ferno

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the same codee as in 9front

--- a/os/port/taslock.c

+++ b/os/port/taslock.c

@@ -50,7 +50,12 @@

 		dumpaproc(p);

 }

-/* if looped to obtain a lock, return 1. Else, return 0 */

+/*

+	if looped to obtain a lock, return 1. else, return 0

+	Why not have a sched() in the waiting loop to give up the processor?

+	< ori> the idea is that going through the scheduler takes more time than

+	waiting for the other cpu to do the few protected instructions

+ */

 int

 lock(Lock *l)

 {

@@ -63,11 +68,8 @@

 	if(up)

 		up->nlocks++;	/* prevent being scheded */

 	if(tas(&l->key) == 0){ /* got the lock on the 1st attempt, done */

-		if(up){

-				up->lastlock = l;

-				l->priority = up->priority;

-				up->priority = PriLock;

-			}

+		if(up)

+			up->lastlock = l;

 		l->pc = pc;

 		l->p = up;

 		l->m = MACHP(m->machno);

@@ -85,15 +87,14 @@

 		lockstats.inglare++;

 		i = 0;

 		while(l->key){

-			if(conf.nmach < 2 && up && up->state == Running && islo()

-				/* && up->edf && (up->edf->flags & Admitted)*/){

+			if(conf.nmach < 2 && up && up->edf && (up->edf->flags & Admitted)){

 				/*

 				 * Priority inversion, yield on a uniprocessor; on a

 				 * multiprocessor, the other processor will unlock

 				 */

-				print("inversion %#p pc %#p proc %zud held by pc %#p proc %zud\n",

+				print("inversion %#p pc %#p proc %ud held by pc %#p proc %ud\n",

 					l, pc, up != nil ? up->pid : 0, l->pc, l->p != nil ? ((Proc*)l->p)->pid : 0);

-				/* up->edf->d = todget(nil);*/	/* yield to process with lock */

+				up->edf->d = todget(nil);	/* yield to process with lock */

 				up->pc = pc;

 				sched();

 			}

@@ -105,11 +106,8 @@

 		if(up)

 			up->nlocks++;

 		if(tas(&l->key) == 0){

-			if(up){

+			if(up)

 				up->lastlock = l;

-				l->priority = up->priority;

-				up->priority = PriLock;

-			}

 			l->pc = pc;

 			l->p = up;

 			l->m = MACHP(m->machno);

@@ -136,10 +134,6 @@

 	x = splhi();

 	if(tas(&l->key) != 0){

 		lockstats.glare++;

-		if(conf.nmach < 2)

-			panic("ilock: no way out: pc 0x%zux:"

-					" lock 0x%p held by pc 0x%zux",

-					pc, l, l->pc);

 		/*

 		 * Cannot also check l->pc, l->m, or l->isilock here

 		 * because they might just not be set yet, or

@@ -198,7 +192,6 @@

 void

 unlock(Lock *l)

 {

-	int pri;

 #ifdef LOCKCYCLES

 	l->lockcycles += lcycles();

 	cumlockcycles += l->lockcycles;

@@ -220,23 +213,16 @@

 		dumpaproc(l->p);

 		dumpaproc(up);

 	}

-	pri = l->priority;

-	l->pc = 0;

-	l->p = nil;

 	l->m = nil;

 	coherence();

 	l->key = 0;

-	if(up){

-		up->priority = pri;

-		up->lastlock = nil;

-		if(--up->nlocks == 0 && up->delaysched && islo()){

-			/*

-			 * Call sched if the need arose while locks were held

-			 * But, don't do it from interrupt routines, hence the islo() test

-			 */

-			sched();

-		}

+	if(up && --up->nlocks >= 0 && up->delaysched && islo()){

+		/*

+		 * Call sched if the need arose while locks were held

+		 * But, don't do it from interrupt routines, hence the islo() test

+		 */

+		sched();

 	}

 }

@@ -266,9 +252,6 @@

 		print("iunlock(%#p) while lo: pc %#p, held by %#p\n", l, getcallerpc(&l), l->pc);

 	sr = l->sr;

-	l->sr = 0;

-	l->pc = 0;

-	l->p = nil;

 	l->m = nil;

 	coherence();

 	l->key = 0;