runtime/race: tell race detector what memory Read/Write syscalls touch

Fixes #5567.

R=golang-dev, dave, iant
CC=golang-dev
https://golang.org/cl/10085043

src/pkg/runtime/race.c

@@ -330,6 +330,22 @@ runtime·RaceWrite(void *addr)
 	memoryaccess(addr, 0, (uintptr)runtime·getcallerpc(&addr), true);
 }
 
+// func RaceReadRange(addr unsafe.Pointer, len int)
+#pragma textflag 7
+void
+runtime·RaceReadRange(void *addr, intgo len)
+{
+	rangeaccess(addr, len, 1, 0, (uintptr)runtime·getcallerpc(&addr), false);
+}
+
+// func RaceWriteRange(addr unsafe.Pointer, len int)
+#pragma textflag 7
+void
+runtime·RaceWriteRange(void *addr, intgo len)
+{
+	rangeaccess(addr, len, 1, 0, (uintptr)runtime·getcallerpc(&addr), true);
+}
+
 // func RaceDisable()
 void
 runtime·RaceDisable(void)

src/pkg/runtime/race.go

@@ -24,6 +24,8 @@ func RaceReleaseMerge(addr unsafe.Pointer)
 
 func RaceRead(addr unsafe.Pointer)
 func RaceWrite(addr unsafe.Pointer)
+func RaceReadRange(addr unsafe.Pointer, len int)
+func RaceWriteRange(addr unsafe.Pointer, len int)
 
 func RaceSemacquire(s *uint32)
 func RaceSemrelease(s *uint32)

src/pkg/runtime/race/testdata/mop_test.go

@@ -5,8 +5,11 @@
 package race_test
 
 import (
+	"crypto/sha1"
 	"errors"
 	"fmt"
+	"io"
+	"os"
 	"runtime"
 	"sync"
 	"testing"
@@ -1627,3 +1630,43 @@ func TestRaceNestedStruct(t *testing.T) {
 	y.x.y = 42
 	<-c
 }
+
+func TestRaceIssue5567(t *testing.T) {
+	defer runtime.GOMAXPROCS(runtime.GOMAXPROCS(4))
+	in := make(chan []byte)
+	res := make(chan error)
+	go func() {
+		var err error
+		defer func() {
+			close(in)
+			res <- err
+		}()
+		path := "mop_test.go"
+		f, err := os.Open(path)
+		if err != nil {
+			return
+		}
+		defer f.Close()
+		var n, total int
+		b := make([]byte, 17) // the race is on b buffer
+		for err == nil {
+			n, err = f.Read(b)
+			total += n
+			if n > 0 {
+				in <- b[:n]
+			}
+		}
+		if err == io.EOF {
+			err = nil
+		}
+	}()
+	h := sha1.New()
+	for b := range in {
+		h.Write(b)
+	}
+	_ = h.Sum(nil)
+	err := <-res
+	if err != nil {
+		t.Fatal(err)
+	}
+}

src/pkg/syscall/race.go

@@ -20,3 +20,11 @@ func raceAcquire(addr unsafe.Pointer) {
 func raceReleaseMerge(addr unsafe.Pointer) {
 	runtime.RaceReleaseMerge(addr)
 }
+
+func raceReadRange(addr unsafe.Pointer, len int) {
+	runtime.RaceReadRange(addr, len)
+}
+
+func raceWriteRange(addr unsafe.Pointer, len int) {
+	runtime.RaceWriteRange(addr, len)
+}

src/pkg/syscall/race0.go

@@ -17,3 +17,9 @@ func raceAcquire(addr unsafe.Pointer) {
 
 func raceReleaseMerge(addr unsafe.Pointer) {
 }
+
+func raceReadRange(addr unsafe.Pointer, len int) {
+}
+
+func raceWriteRange(addr unsafe.Pointer, len int) {
+}

src/pkg/syscall/syscall_plan9.go

@@ -120,17 +120,10 @@ func Getppid() (ppid int) {
 }
 
 func Read(fd int, p []byte) (n int, err error) {
-	n, err = Pread(fd, p, -1)
-	if raceenabled && err == nil {
-		raceAcquire(unsafe.Pointer(&ioSync))
-	}
-	return
+	return Pread(fd, p, -1)
 }
 
 func Write(fd int, p []byte) (n int, err error) {
-	if raceenabled {
-		raceReleaseMerge(unsafe.Pointer(&ioSync))
-	}
 	return Pwrite(fd, p, -1)
 }
 

src/pkg/syscall/syscall_unix.go

@@ -130,8 +130,13 @@ func (s Signal) String() string {
 
 func Read(fd int, p []byte) (n int, err error) {
 	n, err = read(fd, p)
-	if raceenabled && err == nil {
-		raceAcquire(unsafe.Pointer(&ioSync))
+	if raceenabled {
+		if n > 0 {
+			raceWriteRange(unsafe.Pointer(&p[0]), n)
+		}
+		if err == nil {
+			raceAcquire(unsafe.Pointer(&ioSync))
+		}
 	}
 	return
 }
@@ -140,7 +145,11 @@ func Write(fd int, p []byte) (n int, err error) {
 	if raceenabled {
 		raceReleaseMerge(unsafe.Pointer(&ioSync))
 	}
-	return write(fd, p)
+	n, err = write(fd, p)
+	if raceenabled && n > 0 {
+		raceReadRange(unsafe.Pointer(&p[0]), n)
+	}
+	return
 }
 
 func Sendfile(outfd int, infd int, offset *int64, count int) (written int, err error) {

src/pkg/syscall/syscall_windows.go

@@ -272,6 +272,9 @@ func Read(fd Handle, p []byte) (n int, err error) {
 		return 0, e
 	}
 	if raceenabled {
+		if done > 0 {
+			raceWriteRange(unsafe.Pointer(&p[0]), int(done))
+		}
 		raceAcquire(unsafe.Pointer(&ioSync))
 	}
 	return int(done), nil
@@ -286,6 +289,9 @@ func Write(fd Handle, p []byte) (n int, err error) {
 	if e != nil {
 		return 0, e
 	}
+	if raceenabled && done > 0 {
+		raceReadRange(unsafe.Pointer(&p[0]), int(done))
+	}
 	return int(done), nil
 }