Revert "runtime/trace: add missing events for the locked g in extra M."

This reverts commit ea9c3fd42d.

Reason for revert: break linux/ricsv64, openbsd/arm, illumos/amd64 builders

Change-Id: I98479a8f63e76eed89a0e8846acf2c73e8441377
Reviewed-on: https://go-review.googlesource.com/c/go/+/423437
Reviewed-by: Than McIntosh <thanm@google.com>
Auto-Submit: Michael Pratt <mpratt@google.com>
Reviewed-by: Michael Pratt <mpratt@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Cuong Manh Le <cuong.manhle.vn@gmail.com>

src/internal/trace/goroutines.go

@@ -187,7 +187,7 @@ func GoroutineStats(events []*Event) map[uint64]*GDesc {
 			gs[g.ID] = g
 		case EvGoStart, EvGoStartLabel:
 			g := gs[ev.G]
-			if g.PC == 0 && len(ev.Stk) > 0 {
+			if g.PC == 0 {
 				g.PC = ev.Stk[0].PC
 				g.Name = ev.Stk[0].Fn
 			}
@@ -353,6 +353,5 @@ func RelatedGoroutines(events []*Event, goid uint64) map[uint64]bool {
 func IsSystemGoroutine(entryFn string) bool {
 	// This mimics runtime.isSystemGoroutine as closely as
 	// possible.
-	// Also, locked g in extra M (with empty entryFn) is system goroutine.
-	return entryFn == "" || entryFn != "runtime.main" && strings.HasPrefix(entryFn, "runtime.")
+	return entryFn != "runtime.main" && strings.HasPrefix(entryFn, "runtime.")
 }

src/runtime/crash_cgo_test.go

@@ -710,16 +710,3 @@ func TestCgoTracebackGoroutineProfile(t *testing.T) {
 		t.Fatalf("want %s, got %s\n", want, output)
 	}
 }
-
-func TestCgoTraceParser(t *testing.T) {
-	// Test issue 29707.
-	switch runtime.GOOS {
-	case "windows", "plan9":
-		t.Skipf("skipping cgo trace parser test on %s", runtime.GOOS)
-	}
-	output := runTestProg(t, "testprogcgo", "CgoTraceParser")
-	want := "OK\n"
-	if output != want {
-		t.Fatalf("want %s, got %s\n", want, output)
-	}
-}

src/runtime/proc.go

@@ -1917,7 +1917,6 @@ func oneNewExtraM() {
 	casgstatus(gp, _Gidle, _Gdead)
 	gp.m = mp
 	mp.curg = gp
-	mp.isextra = true
 	mp.lockedInt++
 	mp.lockedg.set(gp)
 	gp.lockedm.set(mp)
@@ -1925,14 +1924,6 @@ func oneNewExtraM() {
 	if raceenabled {
 		gp.racectx = racegostart(abi.FuncPCABIInternal(newextram) + sys.PCQuantum)
 	}
-	if trace.enabled {
-		// trigger two trace events for the locked g in the extra m,
-		// since the next event of the g will be traceEvGoSysExit in exitsyscall,
-		// while calling from C thread to Go.
-		traceGoCreate(gp, 0) // no start pc
-		gp.traceseq++
-		traceEvent(traceEvGoInSyscall, -1, gp.goid)
-	}
 	// put on allg for garbage collector
 	allgadd(gp)
 

src/runtime/runtime2.go

@@ -546,7 +546,6 @@ type m struct {
 	newSigstack   bool // minit on C thread called sigaltstack
 	printlock     int8
 	incgo         bool   // m is executing a cgo call
-	isextra       bool   // m is an extra m
 	freeWait      uint32 // if == 0, safe to free g0 and delete m (atomic)
 	fastrand      uint64
 	needextram    bool

src/runtime/testdata/testprogcgo/issue29707.go

@@ -1,58 +0,0 @@
-// Copyright 2011 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-//go:build !plan9 && !windows
-// +build !plan9,!windows
-
-// This is for issue #29707
-
-package main
-
-/*
-#include <pthread.h>
-
-extern void* callback(void*);
-typedef void* (*cb)(void*);
-
-static void testCallback(cb cb) {
-	pthread_t thread_id;
-	pthread_create(&thread_id, NULL, cb, NULL);
-	pthread_join(thread_id, NULL);
-}
-*/
-import "C"
-
-import (
-	"bytes"
-	"fmt"
-	traceparser "internal/trace"
-	"runtime/trace"
-	"time"
-	"unsafe"
-)
-
-func init() {
-	register("CgoTraceParser", CgoTraceParser)
-}
-
-//export callback
-func callback(unsafe.Pointer) unsafe.Pointer {
-	time.Sleep(time.Millisecond)
-	return nil
-}
-
-func CgoTraceParser() {
-	buf := new(bytes.Buffer)
-
-	trace.Start(buf)
-	C.testCallback(C.cb(C.callback))
-	trace.Stop()
-
-	_, err := traceparser.Parse(buf, "")
-	if err != nil {
-		fmt.Println("Parse error: ", err)
-	} else {
-		fmt.Println("OK")
-	}
-}

src/runtime/trace.go

@@ -272,17 +272,6 @@ func StartTrace() error {
 		if status == _Gsyscall {
 			gp.traceseq++
 			traceEvent(traceEvGoInSyscall, -1, gp.goid)
-		} else if status == _Gdead && gp.m != nil && gp.m.isextra {
-			// trigger two trace events for the dead g in the extra m,
-			// since the next event of the g will be traceEvGoSysExit in exitsyscall,
-			// while calling from C thread to Go.
-			gp.traceseq = 0
-			gp.tracelastp = getg().m.p
-			// +PCQuantum because traceFrameForPC expects return PCs and subtracts PCQuantum.
-			id := trace.stackTab.put([]uintptr{startPCforTrace(0) + sys.PCQuantum}) // no start pc
-			traceEvent(traceEvGoCreate, -1, gp.goid, uint64(id), stackID)
-			gp.traceseq++
-			traceEvent(traceEvGoInSyscall, -1, gp.goid)
 		} else {
 			gp.sysblocktraced = false
 		}
@@ -1566,7 +1555,7 @@ func trace_userLog(id uint64, category, message string) {
 func startPCforTrace(pc uintptr) uintptr {
 	f := findfunc(pc)
 	if !f.valid() {
-		return pc // may happen for locked g in extra M since its pc is 0.
+		return pc // should not happen, but don't care
 	}
 	w := funcdata(f, _FUNCDATA_WrapInfo)
 	if w == nil {