runtime: change lockedg/lockedm to guintptr/muintptr

This change has no real effect in itself. This is to prepare for a
followup change that will call lockOSThread during a cgo callback when
there is no p assigned, and therefore when lockOSThread can not use a
write barrier.

Change-Id: Ia122d41acf54191864bcb68f393f2ed3b2f87abc
Reviewed-on: https://go-review.googlesource.com/63630
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Crawshaw <crawshaw@golang.org>
Reviewed-by: Austin Clements <austin@google.com>

src/runtime/proc.go

@@ -429,7 +429,7 @@ func badctxt() {
 
 func lockedOSThread() bool {
 	gp := getg()
-	return gp.lockedm != nil && gp.m.lockedg != nil
+	return gp.lockedm != 0 && gp.m.lockedg != 0
 }
 
 var (
@@ -1504,8 +1504,8 @@ func oneNewExtraM() {
 	gp.m = mp
 	mp.curg = gp
 	mp.locked = _LockInternal
-	mp.lockedg = gp
-	gp.lockedm = mp
+	mp.lockedg.set(gp)
+	gp.lockedm.set(mp)
 	gp.goid = int64(atomic.Xadd64(&sched.goidgen, 1))
 	if raceenabled {
 		gp.racectx = racegostart(funcPC(newextram) + sys.PCQuantum)
@@ -1819,7 +1819,7 @@ func wakep() {
 func stoplockedm() {
 	_g_ := getg()
 
-	if _g_.m.lockedg == nil || _g_.m.lockedg.lockedm != _g_.m {
+	if _g_.m.lockedg == 0 || _g_.m.lockedg.ptr().lockedm.ptr() != _g_.m {
 		throw("stoplockedm: inconsistent locking")
 	}
 	if _g_.m.p != 0 {
@@ -1831,7 +1831,7 @@ func stoplockedm() {
 	// Wait until another thread schedules lockedg again.
 	notesleep(&_g_.m.park)
 	noteclear(&_g_.m.park)
-	status := readgstatus(_g_.m.lockedg)
+	status := readgstatus(_g_.m.lockedg.ptr())
 	if status&^_Gscan != _Grunnable {
 		print("runtime:stoplockedm: g is not Grunnable or Gscanrunnable\n")
 		dumpgstatus(_g_)
@@ -1847,7 +1847,7 @@ func stoplockedm() {
 func startlockedm(gp *g) {
 	_g_ := getg()
 
-	mp := gp.lockedm
+	mp := gp.lockedm.ptr()
 	if mp == _g_.m {
 		throw("startlockedm: locked to me")
 	}
@@ -2214,9 +2214,9 @@ func schedule() {
 		throw("schedule: holding locks")
 	}
 
-	if _g_.m.lockedg != nil {
+	if _g_.m.lockedg != 0 {
 		stoplockedm()
-		execute(_g_.m.lockedg, false) // Never returns.
+		execute(_g_.m.lockedg.ptr(), false) // Never returns.
 	}
 
 top:
@@ -2267,7 +2267,7 @@ top:
 		resetspinning()
 	}
 
-	if gp.lockedm != nil {
+	if gp.lockedm != 0 {
 		// Hands off own p to the locked m,
 		// then blocks waiting for a new p.
 		startlockedm(gp)
@@ -2386,8 +2386,8 @@ func goexit0(gp *g) {
 		atomic.Xadd(&sched.ngsys, -1)
 	}
 	gp.m = nil
-	gp.lockedm = nil
-	_g_.m.lockedg = nil
+	gp.lockedm = 0
+	_g_.m.lockedg = 0
 	gp.paniconfault = false
 	gp._defer = nil // should be true already but just in case.
 	gp._panic = nil // non-nil for Goexit during panic. points at stack-allocated data.
@@ -2815,7 +2815,7 @@ func exitsyscall0(gp *g) {
 		acquirep(_p_)
 		execute(gp, false) // Never returns.
 	}
-	if _g_.m.lockedg != nil {
+	if _g_.m.lockedg != 0 {
 		// Wait until another thread schedules gp and so m again.
 		stoplockedm()
 		execute(gp, false) // Never returns.
@@ -3165,8 +3165,8 @@ func Breakpoint() {
 //go:nosplit
 func dolockOSThread() {
 	_g_ := getg()
-	_g_.m.lockedg = _g_
-	_g_.lockedm = _g_.m
+	_g_.m.lockedg.set(_g_)
+	_g_.lockedm.set(_g_.m)
 }
 
 //go:nosplit
@@ -3194,8 +3194,8 @@ func dounlockOSThread() {
 	if _g_.m.locked != 0 {
 		return
 	}
-	_g_.m.lockedg = nil
-	_g_.lockedm = nil
+	_g_.m.lockedg = 0
+	_g_.lockedm = 0
 }
 
 //go:nosplit
@@ -4102,7 +4102,7 @@ func schedtrace(detailed bool) {
 	for mp := allm; mp != nil; mp = mp.alllink {
 		_p_ := mp.p.ptr()
 		gp := mp.curg
-		lockedg := mp.lockedg
+		lockedg := mp.lockedg.ptr()
 		id1 := int32(-1)
 		if _p_ != nil {
 			id1 = _p_.id
@@ -4122,7 +4122,7 @@ func schedtrace(detailed bool) {
 	for gi := 0; gi < len(allgs); gi++ {
 		gp := allgs[gi]
 		mp := gp.m
-		lockedm := gp.lockedm
+		lockedm := gp.lockedm.ptr()
 		id1 := int32(-1)
 		if mp != nil {
 			id1 = mp.id

src/runtime/runtime2.go

@@ -357,7 +357,7 @@ type g struct {
 	sysexitticks   int64    // cputicks when syscall has returned (for tracing)
 	traceseq       uint64   // trace event sequencer
 	tracelastp     puintptr // last P emitted an event for this goroutine
-	lockedm        *m
+	lockedm        muintptr
 	sig            uint32
 	writebuf       []byte
 	sigcode0       uintptr
@@ -423,7 +423,7 @@ type m struct {
 	alllink       *m // on allm
 	schedlink     muintptr
 	mcache        *mcache
-	lockedg       *g
+	lockedg       guintptr
 	createstack   [32]uintptr // stack that created this thread.
 	freglo        [16]uint32  // d[i] lsb and f[i]
 	freghi        [16]uint32  // d[i] msb and f[i+16]

src/runtime/signal_sighandler.go

@@ -88,9 +88,9 @@ func sighandler(sig uint32, info *siginfo, ctxt unsafe.Pointer, gp *g) {
 	}
 
 	print("PC=", hex(c.sigpc()), " m=", _g_.m.id, " sigcode=", c.sigcode(), "\n")
-	if _g_.m.lockedg != nil && _g_.m.ncgo > 0 && gp == _g_.m.g0 {
+	if _g_.m.lockedg != 0 && _g_.m.ncgo > 0 && gp == _g_.m.g0 {
 		print("signal arrived during cgo execution\n")
-		gp = _g_.m.lockedg
+		gp = _g_.m.lockedg.ptr()
 	}
 	print("\n")
 

src/runtime/signal_windows.go

@@ -126,11 +126,11 @@ func lastcontinuehandler(info *exceptionrecord, r *context, gp *g) int32 {
 	print("Exception ", hex(info.exceptioncode), " ", hex(info.exceptioninformation[0]), " ", hex(info.exceptioninformation[1]), " ", hex(r.ip()), "\n")
 
 	print("PC=", hex(r.ip()), "\n")
-	if _g_.m.lockedg != nil && _g_.m.ncgo > 0 && gp == _g_.m.g0 {
+	if _g_.m.lockedg != 0 && _g_.m.ncgo > 0 && gp == _g_.m.g0 {
 		if iscgo {
 			print("signal arrived during external code execution\n")
 		}
-		gp = _g_.m.lockedg
+		gp = _g_.m.lockedg.ptr()
 	}
 	print("\n")
 

src/runtime/traceback.go

@@ -795,7 +795,7 @@ func goroutineheader(gp *g) {
 	if waitfor >= 1 {
 		print(", ", waitfor, " minutes")
 	}
-	if gp.lockedm != nil {
+	if gp.lockedm != 0 {
 		print(", locked to thread")
 	}
 	print("]:\n")