futex: get_futex_key, get_key_refs and drop_key_refs
lguest uses the convenient futex infrastructure for inter-domain I/O, so
expose get_futex_key, get_key_refs (renamed get_futex_key_refs) and
drop_key_refs (renamed drop_futex_key_refs). Also means we need to expose the
union that these use.
No code changes.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/include/linux/futex.h b/include/linux/futex.h
index 3f153b4..820125c 100644
--- a/include/linux/futex.h
+++ b/include/linux/futex.h
@@ -100,6 +100,35 @@
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);