Merge pull request #2020 from kinvolk/alban/fix-getWalkedProcPid

procspy: use a Reader to copy the background reader buffer

probe/endpoint/procspy/background_reader_linux.go

@@ -46,7 +46,10 @@ func (br *backgroundReader) getWalkedProcPid(buf *bytes.Buffer) (map[uint64]*Pro
 	br.mtx.Lock()
 	defer br.mtx.Unlock()
 
-	_, err := io.Copy(buf, br.latestBuf)
+	// Don't access latestBuf directly but create a reader. In this way,
+	// the buffer will not be empty in the next call of getWalkedProcPid
+	// and it can be copied again.
+	_, err := io.Copy(buf, bytes.NewReader(br.latestBuf.Bytes()))
 
 	return br.latestSockets, err
 }