title: Is static function thread safe in C?
body: <p>I am developing file system on FUSE in C.
  FUSE is event driven system so it matches own opcode to user's callback function.
  As I know static function in C means only scope limitation - i.e. if static function f() was written in foo.c, its symbol's scope is only foo.c not each other source file.
  But my team member said static function is not thread safe, so we should make callback non static.(our system must works in multithreading environment, so it should consider about concurrency.)</p>
  
  <p>I have googled all day long but I could not find it. I want to ask your evidance or opinion about thread safty of static function in C.</p>