How to make context with timeout and retries in Go?

I try to make context with timeout && several retries in Go.
Here is the code example

func readRetry(port io.ReadWriteCloser, timeout, cnt int) []byte {
fmt.Println("IN READ RETRY")
for i := 0; i < cnt; i++ {
fmt.Println("Read attempt:", i)
res := readWithContext(timeout, port)
if res != nil {
return res
}
}
return nil
}
func readWithContext(timeout int, port io.ReadWriteCloser) []byte {
fmt.Println("IN readWithContext")
fmt.Println("Opening channel")
rcvCh := make(chan []byte)
ctx, cancel := context.WithTimeout(context.Background(), time.Duration(time.Second*time.Duration(timeout)))
defer cancel()
go reader(ctx, port, rcvCh)
for {
select {
case <-ctx.Done():
fmt.Println("reader: context cancelled")
return nil
case buf := <-rcvCh:
fmt.Println("reader: got data")
return buf
}
}
}
func reader(ctx context.Context, port io.ReadWriteCloser, rcvCh chan []byte) {
fmt.Println("IN reader")
answ := make([]byte, 1024)
buf := bytes.Buffer{}
var err error
for {
i := 0
i, err = port.Read(answ)
if err != nil && err != io.EOF {
log.Printf("port.Read: %v", err)
}
if i != 0 {
answ = answ[:i]
buf.Write(answ)
if buf.Bytes()[len(buf.Bytes())-1] == delimiter {
fmt.Print("Received: ")
printBuf(buf.Bytes())
rcvCh <- buf.Bytes() //if there is no data in the first attempt, cannot write to the channel here!!
return
}
}
}
}

Then, I call readRetry result := readRetry(port, 2, 5) // 2 seconds timeout, 5 retries. But if data is not ready for the first time, then reader cannot write to rcvCh . It might be full? Why? If I try to close channel at the end of readWithContext execution, there is a collision - write to closed channel. Where is the collision? It think, readWithContext starts every time as a new instance, creates a new instance of rcvCh, and if the reader closes via timeout, all chain of functions with their local variables, including the channel, has been destroyed. But, it seems, I make a mistake. So, how to make retries?
Look, how the log looks like:

IN READ RETRY
Read attempt: 1
IN readWithContext
Opening channel
IN reader
Start reader
Received: 0x01 0x02 0x03 0x04 0x05 0x06 0x07 0x08 0x09 0x0d //<- data is received, but not written to the channel!!
reader: context cancelled

Every retry creates a new reader and a new channel. If readWithContext times out, the reader is still there waiting, and probably eventually reading, but now there's nobody listening on the other end of the channel, so that reader is leaked.

Have a single reader goroutine, and a single channel, use readWithContext to read from it. If the context expires and all retries are exhausted, you have to stop the reader as well.