futex: get_futex_key, get_key_refs and drop_key_refs

[firefly-linux-kernel-4.4.55.git] / include / linux / futex.h

diff --git a/include/linux/futex.h b/include/linux/futex.h
index 3f153b4e156c4e9be16c70570276c02d3aecba8c..820125c628c1364478cfcc513275214aa9da628a 100644 (file)
--- a/include/linux/futex.h
+++ b/include/linux/futex.h
@@ -100,6 +100,35 @@ long do_futex(u32 __user *uaddr, int op, u32 val, unsigned long timeout,
 extern int
 handle_futex_death(u32 __user *uaddr, struct task_struct *curr, int pi);
 
+/*
+ * Futexes are matched on equal values of this key.
+ * The key type depends on whether it's a shared or private mapping.
+ * Don't rearrange members without looking at hash_futex().
+ *
+ * offset is aligned to a multiple of sizeof(u32) (== 4) by definition.
+ * We set bit 0 to indicate if it's an inode-based key.
+ */
+union futex_key {
+       struct {
+               unsigned long pgoff;
+               struct inode *inode;
+               int offset;
+       } shared;
+       struct {
+               unsigned long address;
+               struct mm_struct *mm;
+               int offset;
+       } private;
+       struct {
+               unsigned long word;
+               void *ptr;
+               int offset;
+       } both;
+};
+int get_futex_key(u32 __user *uaddr, union futex_key *key);
+void get_futex_key_refs(union futex_key *key);
+void drop_futex_key_refs(union futex_key *key);
+
 #ifdef CONFIG_FUTEX
 extern void exit_robust_list(struct task_struct *curr);
 extern void exit_pi_state_list(struct task_struct *curr);