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-rw-r--r--kernel/futex.c116
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(&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;
}