diff options
Diffstat (limited to 'kernel/futex.c')
| -rw-r--r-- | kernel/futex.c | 116 |
1 files changed, 116 insertions, 0 deletions
diff --git a/kernel/futex.c b/kernel/futex.c index c7130f86106..07ba87de965 100644 --- a/kernel/futex.c +++ b/kernel/futex.c @@ -40,6 +40,7 @@ #include <linux/pagemap.h> #include <linux/syscalls.h> #include <linux/signal.h> +#include <asm/futex.h> #define FUTEX_HASHBITS (CONFIG_BASE_SMALL ? 4 : 8) @@ -327,6 +328,118 @@ out: } /* + * Wake up all waiters hashed on the physical page that is mapped + * to this virtual address: + */ +static int futex_wake_op(unsigned long uaddr1, unsigned long uaddr2, int nr_wake, int nr_wake2, int op) +{ + union futex_key key1, key2; + struct futex_hash_bucket *bh1, *bh2; + struct list_head *head; + struct futex_q *this, *next; + int ret, op_ret, attempt = 0; + +retryfull: + down_read(¤t->mm->mmap_sem); + + ret = get_futex_key(uaddr1, &key1); + if (unlikely(ret != 0)) + goto out; + ret = get_futex_key(uaddr2, &key2); + if (unlikely(ret != 0)) + goto out; + + bh1 = hash_futex(&key1); + bh2 = hash_futex(&key2); + +retry: + if (bh1 < bh2) + spin_lock(&bh1->lock); + spin_lock(&bh2->lock); + if (bh1 > bh2) + spin_lock(&bh1->lock); + + op_ret = futex_atomic_op_inuser(op, (int __user *)uaddr2); + if (unlikely(op_ret < 0)) { + int dummy; + + spin_unlock(&bh1->lock); + if (bh1 != bh2) + spin_unlock(&bh2->lock); + + /* futex_atomic_op_inuser needs to both read and write + * *(int __user *)uaddr2, but we can't modify it + * non-atomically. Therefore, if get_user below is not + * enough, we need to handle the fault ourselves, while + * still holding the mmap_sem. */ + if (attempt++) { + struct vm_area_struct * vma; + struct mm_struct *mm = current->mm; + + ret = -EFAULT; + if (attempt >= 2 || + !(vma = find_vma(mm, uaddr2)) || + vma->vm_start > uaddr2 || + !(vma->vm_flags & VM_WRITE)) + goto out; + + switch (handle_mm_fault(mm, vma, uaddr2, 1)) { + case VM_FAULT_MINOR: + current->min_flt++; + break; + case VM_FAULT_MAJOR: + current->maj_flt++; + break; + default: + goto out; + } + goto retry; + } + + /* If we would have faulted, release mmap_sem, + * fault it in and start all over again. */ + up_read(¤t->mm->mmap_sem); + + ret = get_user(dummy, (int __user *)uaddr2); + if (ret) + return ret; + + goto retryfull; + } + + head = &bh1->chain; + + list_for_each_entry_safe(this, next, head, list) { + if (match_futex (&this->key, &key1)) { + wake_futex(this); + if (++ret >= nr_wake) + break; + } + } + + if (op_ret > 0) { + head = &bh2->chain; + + op_ret = 0; + list_for_each_entry_safe(this, next, head, list) { + if (match_futex (&this->key, &key2)) { + wake_futex(this); + if (++op_ret >= nr_wake2) + break; + } + } + ret += op_ret; + } + + spin_unlock(&bh1->lock); + if (bh1 != bh2) + spin_unlock(&bh2->lock); +out: + up_read(¤t->mm->mmap_sem); + return ret; +} + +/* * Requeue all waiters hashed on one physical page to another * physical page. */ @@ -740,6 +853,9 @@ long do_futex(unsigned long uaddr, int op, int val, unsigned long timeout, case FUTEX_CMP_REQUEUE: ret = futex_requeue(uaddr, uaddr2, val, val2, &val3); break; + case FUTEX_WAKE_OP: + ret = futex_wake_op(uaddr, uaddr2, val, val2, val3); + break; default: ret = -ENOSYS; } |