Module Name: src
Committed By: riastradh
Date: Sun Dec 19 11:45:42 UTC 2021
Modified Files:
src/sys/external/bsd/drm2/include/linux: rbtree.h
Log Message:
linux/rbtree: Hack up constiness.
To generate a diff of this commit:
cvs rdiff -u -r1.13 -r1.14 src/sys/external/bsd/drm2/include/linux/rbtree.h
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/sys/external/bsd/drm2/include/linux/rbtree.h
diff -u src/sys/external/bsd/drm2/include/linux/rbtree.h:1.13 src/sys/external/bsd/drm2/include/linux/rbtree.h:1.14
--- src/sys/external/bsd/drm2/include/linux/rbtree.h:1.13 Sun Dec 19 11:45:13 2021
+++ src/sys/external/bsd/drm2/include/linux/rbtree.h Sun Dec 19 11:45:41 2021
@@ -1,4 +1,4 @@
-/* $NetBSD: rbtree.h,v 1.13 2021/12/19 11:45:13 riastradh Exp $ */
+/* $NetBSD: rbtree.h,v 1.14 2021/12/19 11:45:41 riastradh Exp $ */
/*-
* Copyright (c) 2013 The NetBSD Foundation, Inc.
@@ -51,17 +51,30 @@ struct rb_root_cached {
__p ? container_of(__p, T, F) : NULL; \
})
+/*
+ * Several of these functions take const inputs and return non-const
+ * outputs. That is a deliberate choice. It would be better if these
+ * functions could be const-polymorphic -- return const if given const,
+ * return non-const if given non-const -- but C doesn't let us express
+ * that. We are using them to adapt Linux code that is defined in
+ * terms of token-substitution macros, without types of their own,
+ * which happen to work out with both const and non-const variants.
+ * Presumably the Linux code compiles upstream and has some level of
+ * const type-checking in Linux, so this abuse of __UNCONST does not
+ * carry substantial risk over to this code here.
+ */
+
static inline bool
-RB_EMPTY_ROOT(struct rb_root *root)
+RB_EMPTY_ROOT(const struct rb_root *root)
{
- return RB_TREE_MIN(&root->rbr_tree) == NULL;
+ return RB_TREE_MIN(__UNCONST(&root->rbr_tree)) == NULL;
}
static inline struct rb_node *
-rb_first(struct rb_root *root)
+rb_first(const struct rb_root *root)
{
- char *vnode = RB_TREE_MIN(&root->rbr_tree);
+ char *vnode = RB_TREE_MIN(__UNCONST(&root->rbr_tree));
if (vnode)
vnode += root->rbr_tree.rbt_ops->rbto_node_offset;
@@ -69,18 +82,18 @@ rb_first(struct rb_root *root)
}
static inline struct rb_node *
-rb_next2(struct rb_root *root, struct rb_node *rbnode)
+rb_next2(const struct rb_root *root, const struct rb_node *rbnode)
{
- char *vnode = (char *)rbnode;
+ char *vnode = (char *)__UNCONST(rbnode);
vnode -= root->rbr_tree.rbt_ops->rbto_node_offset;
- return RB_TREE_NEXT(&root->rbr_tree, vnode);
+ return RB_TREE_NEXT(__UNCONST(&root->rbr_tree), vnode);
}
static inline struct rb_node *
-rb_last(struct rb_root *root)
+rb_last(const struct rb_root *root)
{
- char *vnode = RB_TREE_MAX(&root->rbr_tree);
+ char *vnode = RB_TREE_MAX(__UNCONST(&root->rbr_tree));
if (vnode)
vnode += root->rbr_tree.rbt_ops->rbto_node_offset;
@@ -88,7 +101,7 @@ rb_last(struct rb_root *root)
}
static inline struct rb_node *
-rb_first_cached(struct rb_root_cached *root)
+rb_first_cached(const struct rb_root_cached *root)
{
return rb_first(&root->rb_root);
}
