1 #include "stdio_impl.h"
2 #include "pthread_impl.h"
4 #define MAYBE_WAITERS 0x40000000
6 int __lockfile(FILE *f)
8 int owner = f->lock, tid = __pthread_self()->tid;
9 if ((owner & ~MAYBE_WAITERS) == tid)
12 owner = a_cas(&f->lock, 0, tid);
14 if (a_cas(&f->lock, owner, owner|MAYBE_WAITERS)==owner) break;
16 while ((owner = a_cas(&f->lock, 0, tid|MAYBE_WAITERS)))
17 __futexwait(&f->lock, owner, 1);
21 void __unlockfile(FILE *f)
23 if (a_swap(&f->lock, 0) & MAYBE_WAITERS)
24 __wake(&f->lock, 1, 1);