ape: change tas/sleep locks to cas/semacquire/semrelease locks (from sources)

4 files changed, 85 insertions, 31 deletions

diff --git a/sys/src/ape/lib/ap/power/atom.s b/sys/src/ape/lib/ap/power/atom.s
new file mode 100644
index 000000000..b387300df
--- /dev/null
+++ b/sys/src/ape/lib/ap/power/atom.s
@@ -0,0 +1,63 @@
+TEXT	_xinc(SB),$0	/* void _xinc(long *); */
+TEXT	ainc(SB),$0	/* long ainc(long *); */
+	MOVW	R3, R4
+xincloop:
+	LWAR	(R4), R3
+	ADD	$1, R3
+	DCBT	(R4)				/* fix 405 errata cpu_210 */
+	STWCCC	R3, (R4)
+	BNE	xincloop
+	RETURN
+
+TEXT	_xdec(SB),$0	/* long _xdec(long *); */
+TEXT	adec(SB),$0	/* long adec(long *); */
+	MOVW	R3, R4
+xdecloop:
+	LWAR	(R4), R3
+	ADD	$-1, R3
+	DCBT	(R4)				/* fix 405 errata cpu_210 */
+	STWCCC	R3, (R4)
+	BNE	xdecloop
+	RETURN
+
+TEXT	loadlink(SB), $0
+
+	LWAR	(R3), R3
+	RETURN
+
+TEXT	storecond(SB), $0
+
+	MOVW	val+4(FP), R4
+	DCBT	(R3)				/* fix 405 errata cpu_210 */
+	STWCCC	R4, (R3)
+	BNE	storecondfail
+	MOVW	$1, R3
+	RETURN
+storecondfail:
+	MOVW	$0, R3
+	RETURN
+
+/*
+ * int cas(uint *p, int ov, int nv);
+ * int casp(void **p, void *ov, void *nv);
+ */
+
+TEXT	cas+0(SB),0,$0
+TEXT	casp+0(SB),0,$0
+	MOVW	ov+4(FP),R4
+	MOVW	nv+8(FP),R8
+	LWAR	(R3),R5
+	CMP	R5,R4
+	BNE	fail
+	DCBT	(R3)				/* fix 405 errata cpu_210 */
+	STWCCC	R8,(R3)
+	BNE	fail1
+	MOVW	$1,R3
+	RETURN
+fail:
+	DCBT	(R3)				/* fix 405 errata cpu_210 */
+	STWCCC	R5,(R3)	/* give up exclusive access */
+fail1:
+	MOVW	R0,R3
+	RETURN
+	END
diff --git a/sys/src/ape/lib/ap/power/lock.c b/sys/src/ape/lib/ap/power/lock.c
index 0d17c34d5..65a65df7b 100644
--- a/sys/src/ape/lib/ap/power/lock.c
+++ b/sys/src/ape/lib/ap/power/lock.c
@@ -3,43 +3,33 @@
 #define _LOCK_EXTENSION
 #include <lock.h>
 
-int	tas(int*);
-
 void
-lock(Lock *lk)
+lock(Lock *l)
 {
-	int i;
-
-	/* once fast */
-	if(!tas(&lk->val))
-		return;
-	/* a thousand times pretty fast */
-	for(i=0; i<1000; i++){
-		if(!tas(&lk->val))
-			return;
-		_SLEEP(0);
+	if(ainc(&l->key) == 1)
+		return;	/* changed from 0 -> 1: we hold lock */
+	/* otherwise wait in kernel */
+	while(_SEMACQUIRE(&l->sem, 1) < 0){
+		/* interrupted; try again */
 	}
-	/* now nice and slow */
-	for(i=0; i<1000; i++){
-		if(!tas(&lk->val))
-			return;
-		_SLEEP(100);
-	}
-	/* take your time */
-	while(tas(&lk->val))
-		_SLEEP(1000);
 }
 
-int
-canlock(Lock *lk)
+void
+unlock(Lock *l)
 {
-	if(tas(&lk->val))
-		return 0;
-	return 1;
+	if(adec(&l->key) == 0)
+		return;	/* changed from 1 -> 0: no contention */
+	_SEMRELEASE(&l->sem, 1);
 }
 
-void
-unlock(Lock *lk)
+int
+canlock(Lock *l)
 {
-	lk->val = 0;
+	if(ainc(&l->key) == 1)
+		return 1;	/* changed from 0 -> 1: success */
+	/* Undo increment (but don't miss wakeup) */
+	if(adec(&l->key) == 0)
+		return 0;	/* changed from 1 -> 0: no contention */
+	_SEMRELEASE(&l->sem, 1);
+	return 0;
 }
diff --git a/sys/src/ape/lib/ap/power/main9p.s b/sys/src/ape/lib/ap/power/main9p.s
index 4565b9d06..809ddc451 100644
--- a/sys/src/ape/lib/ap/power/main9p.s
+++ b/sys/src/ape/lib/ap/power/main9p.s
@@ -1,7 +1,7 @@
 #define NPRIVATES	16
 
 GLOBL	_tos(SB), $4
-GLOBAL	_errnoloc(SB), $4
+GLOBL	_errnoloc(SB), $4
 GLOBL	_privates(SB), $4
 GLOBL	_nprivates(SB), $4
 
diff --git a/sys/src/ape/lib/ap/power/mkfile b/sys/src/ape/lib/ap/power/mkfile
index cc546cd84..ab4b35df6 100644
--- a/sys/src/ape/lib/ap/power/mkfile
+++ b/sys/src/ape/lib/ap/power/mkfile
@@ -2,6 +2,7 @@ APE=/sys/src/ape
 <$APE/config
 LIB=/$objtype/lib/ape/libap.a
 OFILES=\
+	atom.$O\
 	cycles.$O\
 	getfcr.$O\
 	lock.$O\