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// Copyright 2016 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 linux && race
package race_test
import (
"sync/atomic"
"syscall"
"testing"
"unsafe"
)
func TestAtomicMmap(t *testing.T) {
// Test that atomic operations work on "external" memory. Previously they crashed (#16206).
// Also do a sanity correctness check: under race detector atomic operations
// are implemented inside of race runtime.
mem, err := syscall.Mmap(-1, 0, 1<<20, syscall.PROT_READ|syscall.PROT_WRITE, syscall.MAP_ANON|syscall.MAP_PRIVATE)
if err != nil {
t.Fatalf("mmap failed: %v", err)
}
defer syscall.Munmap(mem)
a := (*uint64)(unsafe.Pointer(&mem[0]))
if *a != 0 {
t.Fatalf("bad atomic value: %v, want 0", *a)
}
atomic.AddUint64(a, 1)
if *a != 1 {
t.Fatalf("bad atomic value: %v, want 1", *a)
}
atomic.AddUint64(a, 1)
if *a != 2 {
t.Fatalf("bad atomic value: %v, want 2", *a)
}
}
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