This introduces the following .config variables:
DEBUG_GRBTREE
DEBUG_GRBTREE_VALIDATE
DEBUG_GRBTREE will enable the use of the following new flags in struct
rb_relationship's flags member. When DEBUG_GRBTREE is not enabled in the
config, these flags will evaluate to zero.
RB_VERIFY_USAGE - Perform additional checks to assure that nodes are not
inserted into more than one tree by mistake, but adds the requirement
that nodes are initialized (rb_debug_clear_node) prior to insertion.
RB_VERIFY_INTEGRITY - Perform exhaustive integrity checks on tree during
most manipulation & access functions (high run-time overhead)
Finally, the DEBUG_GRBTREE_VALIDATE .config variable will force-enable
the RB_VERIFY_INTEGRITY behavior on all trees.
Signed-off-by: Daniel Santos <daniel.santos@xxxxxxxxx>
---
include/linux/rbtree.h | 153 ++++++++++++++++++++++++++++++++++++++++++++---
lib/Kconfig.debug | 22 +++++++-
2 files changed, 164 insertions(+), 11 deletions(-)
diff --git a/include/linux/rbtree.h b/include/linux/rbtree.h
index 48e325f..5f10915 100644
--- a/include/linux/rbtree.h
+++ b/include/linux/rbtree.h
@@ -85,7 +85,6 @@ static inline void rb_link_node(struct rb_node * node, struct rb_node * parent,
*rb_link = node;
}
-
#define __JUNK junk,
#define _iff_empty(test_or_junk, t, f) __iff_empty(test_or_junk, t, f)
#define __iff_empty(__ignored1, __ignored2, result, ...) result
@@ -134,6 +133,18 @@ static inline void rb_link_node(struct rb_node * node, struct rb_node * parent,
*/
#define OPT_OFFSETOF(type, member) IFF_EMPTY(member, 0, offsetof(type, member))
+
+#define GRBTREE_DEBUG IS_ENABLED(DEBUG_GRBTREE)
+#define GRBTREE_VALIDATE IS_ENABLED(DEBUG_GRBTREE_VALIDATE)
+
+/* keep disabled debug code out of older compilers that fail to optimize out
+ * const struct member values */
+#if GRBTREE_DEBUG
+# define __RB_DEBUG_ENABLE_MASK 0xffffffff
+#else
+# define __RB_DEBUG_ENABLE_MASK 0
+#endif
+
/**
* enum rb_flags - values for strct rb_relationship's flags
* @RB_HAS_LEFTMOST: The container has a struct rb_node *leftmost member
@@ -147,18 +158,47 @@ static inline void rb_link_node(struct rb_node * node, struct rb_node * parent,
* @RB_INSERT_REPLACES: When set, the rb_insert() will replace a value if it
* matches the supplied one (valid only when
* RB_UNIQUE_KEYS is set).
+ * @RB_VERIFY_USAGE: Perform checks upon node insertion for a small run-time
+ * overhead. This has other usage restrictions, so read
+ * the Description section before using. Available only
+ * when CONFIG_DEBUG_GRBTREE is enabled.
+ * @RB_VERIFY_INTEGRITY:Perform exauhstive integrity checks on most operations
+ * (large run-time overhead). Available only when
+ * CONFIG_DEBUG_GRBTREE is enabled.
* @RB_ALL_FLAGS: (internal use)
+ *
+ *
+ * When RB_VERIFY_USAGE is set in the relationship flags and
+ * CONFIG_DEBUG_GRBTREE is enabled, you will be required to initialize nodes
+ * with rb_debug_clear_node() prior to inserting them (which is normally not
+ * necessary). Upon insertion (rb_insert and rb_insert_near), additional
+ * checks will be performed to verify that the node is properly initialized and
+ * does not belong to another tree. Upon removal (rb_remove) the node is
+ * re-initialized, so calling rb_debug_clear_node() is only required when you
+ * originally create the node. If you remove it and re-add it multiple times
+ * (or to multiple trees) you do not have to manually re-initialize it. This
+ * causes a small run-time overhead.
+ *
+ * When RB_VERIFY_INTEGRITY is set and CONFIG_DEBUG_GRBTREE is enabled,
+ * validation of tree integrity will occur in most functions. As the tree is
+ * traversed downward, each child's parent link will be verified. When the
+ * tree is traversed upwards (__rb_find_subtree) each parent's left or right
+ * link (respective to the traversal) will be verified. Finally, when
+ * iterating over a tree, the compare function will be called to verify the
+ * order of elements. This has a high run-time overhead.
*/
-
enum rb_flags {
RB_HAS_LEFTMOST = 0x00000001,
RB_HAS_RIGHTMOST = 0x00000002,
RB_HAS_COUNT = 0x00000004,
RB_UNIQUE_KEYS = 0x00000008,
RB_INSERT_REPLACES = 0x00000010,
+ RB_VERIFY_USAGE = 0x00000080 & __RB_DEBUG_ENABLE_MASK,
+ RB_VERIFY_INTEGRITY = 0x00000100 & __RB_DEBUG_ENABLE_MASK,
RB_ALL_FLAGS = RB_HAS_LEFTMOST | RB_HAS_RIGHTMOST
| RB_HAS_COUNT | RB_UNIQUE_KEYS
- | RB_INSERT_REPLACES,
+ | RB_INSERT_REPLACES
+ | RB_VERIFY_USAGE | RB_VERIFY_INTEGRITY,
};
/**
@@ -257,7 +297,6 @@ const void *rb_to_key(const void *ptr, const struct rb_relationship *rel)
return __RB_PTR(const void, ptr, rel->key_offset);
}
-
/* checked conversion functions that will error on run-time values */
static __always_inline
struct rb_root *__rb_to_root(const void *ptr,
@@ -367,6 +406,87 @@ void __rb_assert_good_rel(const struct rb_relationship *rel)
}
+
+#if GRBTREE_DEBUG
+/* debug functions */
+
+/*
+ * __rb_verify_parent - validate a child's parent link
+ */
+static inline
+void __rb_verify_parent(const rb_node *child, const rb_node *parent,
+ const struct rb_relationship *rel)
+{
+ if ((rel->flags & RB_VERIFY_INTEGRITY) || GRBTREE_VALIDATE) {
+ BUG_ON(rb_parent(child) != parent);
+ }
+}
+
+/*
+ * __rb_verify_child - validate a parent's right or left link
+ */
+static inline
+void __rb_verify_child(const rb_node *parent, const rb_node *child,
+ const int is_left, const struct rb_relationship *rel)
+{
+ BUILD_BUG_ON_NON_CONST(is_left);
+ if ((rel->flags & RB_VERIFY_INTEGRITY) || GRBTREE_VALIDATE) {
+ const rb_node *ptr = is_left ? parent->rb_left : parent->right;
+ BUG_ON(ptr != child);
+ }
+}
+
+/*
+ * __rb_verify_less - call compare function and verify node order
+ */
+static inline
+void __rb_verify_less(const rb_node *a, const rb_node *b,
+ const struct rb_relationship *rel)
+{
+ if ((rel->flags & RB_VERIFY_INTEGRITY) || GRBTREE_VALIDATE) {
+ /* if we're using non-unique keys, diff can be zero */
+ const long max_diff = (rel->flags & RB_UNIQUE_KEYS) ? -1 : 0;
+ long diff = rel->compare(__rb_node_to_key(a, rel),
+ __rb_node_to_key(a, rel))
+ BUG_ON(diff > max_diff);
+ }
+}
+
+/*
+ * __rb_verify_node_cleared - verify a node has been initialized/cleared
+ */
+static inline
+void __rb_verify_node_cleared(const rb_node *node,
+ const struct rb_relationship *rel)
+{
+ if ((rel->flags & RB_VERIFY_USAGE) || GRBTREE_VALIDATE) {
+ BUG_ON(node->rb_parent_color != (unsigned long)node);
+ BUG_ON(node->rb_left != NULL);
+ BUG_ON(node->rb_right != NULL);
+ }
+}
+
+/**
+ * rb_debug_clear_node - clear a node (enabled when GRBTREE_DEBUG is set)
+ */
+static inline
+void rb_debug_clear_node(rb_node *node)
+{
+ node->__rb_parent_color = (unsigned long)node;
+ node->rb_left = NULL;
+ node->rb_right = NULL;
+}
+
+
+#else /* GRBTREE_DEBUG */
+# define __rb_verify_parent(child, parent, rel) ((void) 0)
+# define __rb_verify_child(parent, child, is_left, rel) ((void) 0)
+# define __rb_verify_less(a, b, rel) ((void) 0)
+# define __rb_verify_node_cleared(node, rel) ((void) 0)
+# define rb_debug_clear_node(node) ((void) 0)
+#endif /* GRBTREE_DEBUG */
+
+
/**
* __rb_find() - Perform a (normal) search on a Red-Black Tree, starting at the
* specified node, traversing downward.
@@ -384,11 +504,13 @@ struct rb_node *__rb_find(
while (node) {
long diff = rel->compare(key, __rb_node_to_key(node, rel));
- if (diff > 0)
+ if (diff > 0) {
+ __rb_verify_parent(node->rb_right, node, rel);
node = node->rb_right;
- else if (diff < 0)
+ } else if (diff < 0) {
+ __rb_verify_parent(node->rb_left, node, rel);
node = node->rb_left;
- else
+ } else
return node;
}
@@ -426,11 +548,13 @@ struct rb_node *__rb_find_first_last(
while (node) {
long diff = rel->compare(key, __rb_node_to_key(node, rel));
- if (diff > 0)
+ if (diff > 0) {
+ __rb_verify_parent(node->rb_right, node, rel);
node = node->rb_right;
- else if (diff < 0)
+ } else if (diff < 0) {
+ __rb_verify_parent(node->rb_left, node, rel);
node = node->rb_left;
- else {
+ } else {
if (find_first && node->rb_left)
node = node->rb_left;
else if (!find_first && node->rb_right)
@@ -767,6 +891,7 @@ struct rb_node *rb_insert(
#endif
__rb_assert_good_rel(rel);
+ __rb_verify_node_cleared(node, rel);
while (*p) {
@@ -845,6 +970,7 @@ struct rb_node *rb_insert_near(
long diff;
BUILD_BUG_ON_NON_CONST42(rel->flags);
+ __rb_verify_node_cleared(node, rel);
ret = __rb_find_subtree(root, start, key, &matched, &p, &parent, rel,
1);
@@ -917,6 +1043,11 @@ void rb_remove(
if ((rel->flags & RB_HAS_COUNT))
--*__rb_root_to_count(root, rel);
+
+ /* When RB_VERIFY_USAGE enabled, we re-init node upon removal */
+ if (GRBTREE_DEBUG && (rel->flags & RB_VERIFY_USAGE)) {
+ rb_debug_clear_node(node);
+ }
}
@@ -1182,12 +1313,14 @@ obj_type *prefix ## _find_prev(const obj_type *obj) \
static __always_inline obj_type *prefix ## _next(const obj_type *obj) \
{ \
struct rb_node *ret = rb_next(&obj->node); \
+ __rb_verify_less(&obj->node, ret, &prefix ## _rel); \
return ret ? rb_entry(ret, obj_type, node) : 0; \
} \
\
static __always_inline obj_type *prefix ## _prev(const obj_type *obj) \
{ \
struct rb_node *ret = rb_prev(&obj->node); \
+ __rb_verify_less(ret, &obj->node, &prefix ## _rel); \
return ret ? rb_entry(ret, obj_type, node) : 0; \
} \
\
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 42cd4d8..0f42fd5 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -747,7 +747,7 @@ config DEBUG_KOBJECT
depends on DEBUG_KERNEL
help
If you say Y here, some extra kobject debugging messages will be sent
- to the syslog.
+ to the syslog.
config DEBUG_HIGHMEM
bool "Highmem debugging"
@@ -868,6 +868,26 @@ config TEST_LIST_SORT
If unsure, say N.
+config DEBUG_GRBTREE
+ bool "Debug generic red-black trees"
+ depends on DEBUG_KERNEL
+ help
+ Enables debug checks to red-black trees. Enabling this parameter
+ causes flags RB_VERIFY_USAGE and RB_VERIFY_INTEGRITY to become
+ useable (see rbtree.h for more details).
+
+ If unsure, say N.
+
+config DEBUG_GRBTREE_VALIDATE
+ bool "Generic Red-black tree validation"
+ depends on DEBUG_GRBTREE
+ help
+ Perform exahustive checks on all generic red-black tree operations.
+ This is the same as enabling the RB_VERIFY_INTEGRITY flag for all
+ generic red-black trees.
+
+ If unsure, say N.
+
config DEBUG_SG
bool "Debug SG table operations"
depends on DEBUG_KERNEL
--
1.7.3.4
--
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