code clean

Signed-off-by: Thynson <lanxingcan@gmail.com>
error checking

Signed-off-by: Thynson <lanxingcan@gmail.com>
Fix not set non-blocking mode

Signed-off-by: Thynson <lanxingcan@gmail.com>
fix bugs

Signed-off-by: Thynson <lanxingcan@gmail.com>
Remove unnecessary return value of callback

Signed-off-by: Thynson <lanxingcan@gmail.com>
util functions

Signed-off-by: Thynson <lanxingcan@gmail.com>
correct poll target design

Signed-off-by: Thynson <lanxingcan@gmail.com>