- in _can_int_tx if can driver sendmsg do not return RT_EOK,
   it will repeat until sendmsg return RT_EOK
 - if error occur on can bus(wire broken or EMI), all threads that
   have lower priority will not be executed
 - we should let application layer to determine if resend is appropriate
   when send fail, besides in data link layer, can already implemented
   auto resend in hardware