Address review comments

unix/example_sysvshm_test.go

@@ -2,23 +2,18 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build (darwin && amd64) || linux
-// +build darwin,amd64 linux
+//go:build (darwin && amd64) || (linux && !android)
+// +build darwin,amd64 linux,!android
 
 package unix_test
 
 import (
 	"log"
-	"runtime"
 
 	"golang.org/x/sys/unix"
 )
 
 func ExampleSysvShmGet() {
-	// sysv shared memory isn't implemented on Android
-	if runtime.GOOS == "android" {
-		return
-	}
 
 	// create shared memory region of 1024 bytes
 	id, err := unix.SysvShmGet(unix.IPC_PRIVATE, 1024, unix.IPC_CREAT|unix.IPC_EXCL|0o600)

unix/syscall_linux.go

@@ -2318,6 +2318,7 @@ type RemoteIovec struct {
 
 //sys	PidfdOpen(pid int, flags int) (fd int, err error) = SYS_PIDFD_OPEN
 //sys	PidfdGetfd(pidfd int, targetfd int, flags int) (fd int, err error) = SYS_PIDFD_GETFD
+
 //sys	shmat(id int, addr uintptr, flag int) (ret uintptr, err error)
 //sys	shmctl(id int, cmd int, buf *SysvShmDesc) (result int, err error)
 //sys	shmdt(addr uintptr) (err error)

unix/sysvshm_unix.go

@@ -47,7 +47,7 @@ func SysvShmAttach(id int, addr uintptr, flag int) ([]byte, error) {
 //
 // It is not safe to use the slice after calling this function.
 func SysvShmDetach(data []byte) error {
-	if data == nil {
+	if len(data) == 0 {
 		return EINVAL
 	}