runtime: dump the full stack of a throwing goroutine

Useful for debugging of runtime bugs.
+ Do not print "stack segment boundary" unless GOTRACEBACK>1.
+ Do not traceback system goroutines unless GOTRACEBACK>1.

R=rsc, minux.ma
CC=golang-dev
https://golang.org/cl/7098050

src/pkg/runtime/panic.c

@@ -454,6 +454,8 @@ runtime·throwinit(void)
 void
 runtime·throw(int8 *s)
 {
+	if(m->throwing == 0)
+		m->throwing = 1;
 	runtime·startpanic();
 	runtime·printf("fatal error: %s\n", s);
 	runtime·dopanic(0);

src/pkg/runtime/proc.c

@@ -242,6 +242,7 @@ runtime·main(void)
 	setmcpumax(runtime·gomaxprocs);
 	runtime·sched.init = true;
 	scvg = runtime·newproc1((byte*)runtime·MHeap_Scavenger, nil, 0, 0, runtime·main);
+	scvg->issystem = true;
 	main·init();
 	runtime·sched.init = false;
 	if(!runtime·sched.lockmain)
@@ -325,10 +326,14 @@ void
 runtime·tracebackothers(G *me)
 {
 	G *gp;
+	int32 traceback;
 
+	traceback = runtime·gotraceback();
 	for(gp = runtime·allg; gp != nil; gp = gp->alllink) {
 		if(gp == me || gp->status == Gdead)
 			continue;
+		if(gp->issystem && traceback < 2)
+			continue;
 		runtime·printf("\n");
 		runtime·goroutineheader(gp);
 		runtime·traceback(gp->sched.pc, (byte*)gp->sched.sp, 0, gp);
@@ -624,6 +629,7 @@ top:
 	if((scvg == nil && runtime·sched.grunning == 0) ||
 	   (scvg != nil && runtime·sched.grunning == 1 && runtime·sched.gwait == 0 &&
 	    (scvg->status == Grunning || scvg->status == Gsyscall))) {
+		m->throwing = -1;  // do not dump full stacks
 		runtime·throw("all goroutines are asleep - deadlock!");
 	}
 

src/pkg/runtime/runtime.h

@@ -219,6 +219,7 @@ struct	G
 	G*	schedlink;
 	bool	readyonstop;
 	bool	ispanic;
+	bool	issystem;
 	int8	raceignore; // ignore race detection events
 	M*	m;		// for debuggers, but offset not hard-coded
 	M*	lockedm;
@@ -252,6 +253,7 @@ struct	M
 	G*	curg;		// current running goroutine
 	int32	id;
 	int32	mallocing;
+	int32	throwing;
 	int32	gcing;
 	int32	locks;
 	int32	nomemprof;
@@ -865,7 +867,7 @@ Hmap*	runtime·makemap_c(MapType*, int64);
 Hchan*	runtime·makechan_c(ChanType*, int64);
 void	runtime·chansend(ChanType*, Hchan*, byte*, bool*, void*);
 void	runtime·chanrecv(ChanType*, Hchan*, byte*, bool*, bool*);
-bool	runtime·showframe(Func*);
+bool	runtime·showframe(Func*, bool);
 
 void	runtime·ifaceE2I(InterfaceType*, Eface, Iface*);
 

src/pkg/runtime/symtab.c

@@ -559,11 +559,13 @@ contains(String s, int8 *p)
 }
 
 bool
-runtime·showframe(Func *f)
+runtime·showframe(Func *f, bool current)
 {
 	static int32 traceback = -1;
 
+	if(current && m->throwing > 0)
+		return 1;
 	if(traceback < 0)
 		traceback = runtime·gotraceback();
-	return traceback > 1 || contains(f->name, ".") && !hasprefix(f->name, "runtime.");
+	return traceback > 1 || f != nil && contains(f->name, ".") && !hasprefix(f->name, "runtime.");
 }

src/pkg/runtime/time.goc

@@ -108,8 +108,10 @@ addtimer(Timer *t)
 			runtime·ready(timers.timerproc);
 		}
 	}
-	if(timers.timerproc == nil)
+	if(timers.timerproc == nil) {
 		timers.timerproc = runtime·newproc1((byte*)timerproc, nil, 0, 0, addtimer);
+		timers.timerproc->issystem = true;
+	}
 }
 
 // Delete timer t from the heap.

src/pkg/runtime/traceback_arm.c

@@ -60,7 +60,7 @@ runtime·gentraceback(byte *pc0, byte *sp, byte *lr0, G *gp, int32 skip, uintptr
 			sp = (byte*)stk->gobuf.sp;
 			lr = 0;
 			fp = nil;
-			if(pcbuf == nil)
+			if(pcbuf == nil && runtime·showframe(nil, gp == m->curg))
 				runtime·printf("----- stack segment boundary -----\n");
 			stk = (Stktop*)stk->stackbase;
 			continue;
@@ -118,7 +118,7 @@ runtime·gentraceback(byte *pc0, byte *sp, byte *lr0, G *gp, int32 skip, uintptr
 		else if(pcbuf != nil)
 			pcbuf[n++] = pc;
 		else {
-			if(runtime·showframe(f)) {
+			if(runtime·showframe(f, gp == m->curg)) {
 				// Print during crash.
 				//	main(0x1, 0x2, 0x3)
 				//		/home/rsc/go/src/runtime/x.go:23 +0xf
@@ -184,7 +184,8 @@ runtime·gentraceback(byte *pc0, byte *sp, byte *lr0, G *gp, int32 skip, uintptr
 			sp += 12;
 	}
 	
-	if(pcbuf == nil && (pc = gp->gopc) != 0 && (f = runtime·findfunc(pc)) != nil && gp->goid != 1) {
+	if(pcbuf == nil && (pc = gp->gopc) != 0 && (f = runtime·findfunc(pc)) != nil
+			&& runtime·showframe(f, gp == m->curg) && gp->goid != 1) {
 		runtime·printf("created by %S\n", f->name);
 		tracepc = pc;	// back up to CALL instruction for funcline.
 		if(n > 0 && pc > f->entry)

src/pkg/runtime/traceback_x86.c

@@ -77,7 +77,7 @@ runtime·gentraceback(byte *pc0, byte *sp, byte *lr0, G *gp, int32 skip, uintptr
 			sp = (byte*)stk->gobuf.sp;
 			lr = 0;
 			fp = nil;
-			if(pcbuf == nil)
+			if(pcbuf == nil && runtime·showframe(nil, gp == m->curg))
 				runtime·printf("----- stack segment boundary -----\n");
 			stk = (Stktop*)stk->stackbase;
 			continue;
@@ -126,7 +126,7 @@ runtime·gentraceback(byte *pc0, byte *sp, byte *lr0, G *gp, int32 skip, uintptr
 		else if(pcbuf != nil)
 			pcbuf[n++] = pc;
 		else {
-			if(runtime·showframe(f)) {
+			if(runtime·showframe(f, gp == m->curg)) {
 				// Print during crash.
 				//	main(0x1, 0x2, 0x3)
 				//		/home/rsc/go/src/runtime/x.go:23 +0xf
@@ -196,7 +196,8 @@ runtime·gentraceback(byte *pc0, byte *sp, byte *lr0, G *gp, int32 skip, uintptr
 	}
 	
 	// Show what created goroutine, except main goroutine (goid 1).
-	if(pcbuf == nil && (pc = gp->gopc) != 0 && (f = runtime·findfunc(pc)) != nil && gp->goid != 1) {
+	if(pcbuf == nil && (pc = gp->gopc) != 0 && (f = runtime·findfunc(pc)) != nil
+			&& runtime·showframe(f, gp == m->curg) && gp->goid != 1) {
 		runtime·printf("created by %S\n", f->name);
 		tracepc = pc;	// back up to CALL instruction for funcline.
 		if(n > 0 && pc > f->entry)