diff options
Diffstat (limited to 'kernel/futex.c')
| -rw-r--r-- | kernel/futex.c | 42 |
1 files changed, 29 insertions, 13 deletions
diff --git a/kernel/futex.c b/kernel/futex.c index 08ec814ad9d2..6801b3751a95 100644 --- a/kernel/futex.c +++ b/kernel/futex.c @@ -157,7 +157,9 @@ * enqueue. */ +#ifndef CONFIG_HAVE_FUTEX_CMPXCHG int __read_mostly futex_cmpxchg_enabled; +#endif /* * Futex flags used to encode options to functions and preserve them across @@ -1450,6 +1452,7 @@ retry: hb2 = hash_futex(&key2); retry_private: + hb_waiters_inc(hb2); double_lock_hb(hb1, hb2); if (likely(cmpval != NULL)) { @@ -1459,6 +1462,7 @@ retry_private: if (unlikely(ret)) { double_unlock_hb(hb1, hb2); + hb_waiters_dec(hb2); ret = get_user(curval, uaddr1); if (ret) @@ -1508,6 +1512,7 @@ retry_private: break; case -EFAULT: double_unlock_hb(hb1, hb2); + hb_waiters_dec(hb2); put_futex_key(&key2); put_futex_key(&key1); ret = fault_in_user_writeable(uaddr2); @@ -1517,6 +1522,7 @@ retry_private: case -EAGAIN: /* The owner was exiting, try again. */ double_unlock_hb(hb1, hb2); + hb_waiters_dec(hb2); put_futex_key(&key2); put_futex_key(&key1); cond_resched(); @@ -1592,6 +1598,7 @@ retry_private: out_unlock: double_unlock_hb(hb1, hb2); + hb_waiters_dec(hb2); /* * drop_futex_key_refs() must be called outside the spinlocks. During @@ -2875,9 +2882,28 @@ SYSCALL_DEFINE6(futex, u32 __user *, uaddr, int, op, u32, val, return do_futex(uaddr, op, val, tp, uaddr2, val2, val3); } -static int __init futex_init(void) +static void __init futex_detect_cmpxchg(void) { +#ifndef CONFIG_HAVE_FUTEX_CMPXCHG u32 curval; + + /* + * This will fail and we want it. Some arch implementations do + * runtime detection of the futex_atomic_cmpxchg_inatomic() + * functionality. We want to know that before we call in any + * of the complex code paths. Also we want to prevent + * registration of robust lists in that case. NULL is + * guaranteed to fault and we get -EFAULT on functional + * implementation, the non-functional ones will return + * -ENOSYS. + */ + if (cmpxchg_futex_value_locked(&curval, NULL, 0, 0) == -EFAULT) + futex_cmpxchg_enabled = 1; +#endif +} + +static int __init futex_init(void) +{ unsigned int futex_shift; unsigned long i; @@ -2893,18 +2919,8 @@ static int __init futex_init(void) &futex_shift, NULL, futex_hashsize, futex_hashsize); futex_hashsize = 1UL << futex_shift; - /* - * This will fail and we want it. Some arch implementations do - * runtime detection of the futex_atomic_cmpxchg_inatomic() - * functionality. We want to know that before we call in any - * of the complex code paths. Also we want to prevent - * registration of robust lists in that case. NULL is - * guaranteed to fault and we get -EFAULT on functional - * implementation, the non-functional ones will return - * -ENOSYS. - */ - if (cmpxchg_futex_value_locked(&curval, NULL, 0, 0) == -EFAULT) - futex_cmpxchg_enabled = 1; + + futex_detect_cmpxchg(); for (i = 0; i < futex_hashsize; i++) { atomic_set(&futex_queues[i].waiters, 0); |
