1 files changed, 116 insertions, 0 deletions

diff --git a/kernel/futex.c b/kernel/futex.c
index c7130f86106c..07ba87de9658 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(&current->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(&current->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(&current->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;
         }