K 10 svn:author V 7 davidxu K 8 svn:date V 27 2010-11-07T13:41:17.847779Z K 7 svn:log V 273 Implement robust mutex. userland calls kernel to lock and unlock robust mutex. The kernel remember a list of robust mutexes, and when a thread exits, if its robust mutexes are not unlocked, the kernel will atomatically unlock them and set their robust states to OWNERDEAD. END