diff options
Diffstat (limited to 'src/thread/__lock.c')
| -rw-r--r-- | src/thread/__lock.c | 33 |
1 files changed, 27 insertions, 6 deletions
diff --git a/src/thread/__lock.c b/src/thread/__lock.c index d1717956..d1734096 100644 --- a/src/thread/__lock.c +++ b/src/thread/__lock.c @@ -1,11 +1,32 @@ #include "pthread_impl.h" +void __lock_2(volatile int *l) +{ + if (!__syscall(SYS_futex, l, FUTEX_LOCK_PI, 0, 0)) + return; + int old, tid = __pthread_self()->tid; + while ((old = a_cas(l, 0, tid))) { + a_cas(l, old, old|INT_MIN); + __syscall(SYS_futex, l, FUTEX_WAIT, old|INT_MIN, 0); + } +} + void __lock(volatile int *l) { - int spins=10000; - /* Do not use futexes because we insist that unlocking is a simple - * assignment to optimize non-pathological code with no contention. */ - while (a_swap(l, 1)) - if (spins) spins--, a_spin(); - else __syscall(SYS_sched_yield); + if (a_cas(l, 0, __pthread_self()->tid)) __lock_2(l); +} + +void __unlock_2(volatile int *l) +{ + if (__syscall(SYS_futex, l, FUTEX_UNLOCK_PI)) { + *l = 0; + __syscall(SYS_futex, l, FUTEX_WAKE, 1); + } +} + +void __unlock(volatile int *l) +{ + int old = *l; + if (!(old & INT_MIN) && a_cas(l, old, 0)==old) return; + __unlock_2(l); } |