Author: Vegard Nossum <vegard.nossum@xxxxxxxxx>
AuthorDate: Sat, 30 Aug 2008 12:16:05 +0200
Commit: Vegard Nossum <vegard.nossum@xxxxxxxxx>
CommitDate: Sun, 22 Feb 2009 11:39:36 +0100
kmemcheck: bitfield API
Add the bitfield API which can be used to annotate bitfields in structs
and get rid of false positive reports.
Signed-off-by: Vegard Nossum <vegard.nossum@xxxxxxxxx>
---
include/linux/kmemcheck.h | 39 +++++++++++++++++++++++++++++++++++++++
1 files changed, 39 insertions(+), 0 deletions(-)
diff --git a/include/linux/kmemcheck.h b/include/linux/kmemcheck.h
index 57bb125..7073121 100644
--- a/include/linux/kmemcheck.h
+++ b/include/linux/kmemcheck.h
@@ -4,6 +4,38 @@
#include <linux/mm_types.h>
#include <linux/types.h>
+/*
+ * How to use: If you have a struct using bitfields, for example
+ *
+ * struct a {
+ * int x:8, y:8;
+ * };
+ *
+ * then this should be rewritten as
+ *
+ * struct a {
+ * kmemcheck_define_bitfield(flags, {
+ * int x:8, y:8;
+ * });
+ * };
+ *
+ * Now the "flags" member may be used to refer to the bitfield (and things
+ * like &x.flags is allowed). As soon as the struct is allocated, the bit-
+ * fields should be annotated:
+ *
+ * struct a *a = kmalloc(sizeof(struct a), GFP_KERNEL);
+ * if (a)
+ * kmemcheck_annotate_bitfield(a->flags);
+ *
+ * Note: We provide the same definitions for both kmemcheck and non-
+ * kmemcheck kernels. This makes it harder to introduce accidental errors.
+ */
+#define kmemcheck_define_bitfield(name, fields...) \
+ union { \
+ struct fields name; \
+ struct fields; \
+ };
+
#ifdef CONFIG_KMEMCHECK
extern int kmemcheck_enabled;
@@ -32,6 +64,11 @@ void kmemcheck_mark_uninitialized_pages(struct page *p, unsigned int n);
int kmemcheck_show_addr(unsigned long address);
int kmemcheck_hide_addr(unsigned long address);
+
+#define kmemcheck_annotate_bitfield(field) \
+ do { \
+ memset(&(field), 0, sizeof(field)); \
+ } while (0)
#else
#define kmemcheck_enabled 0
@@ -81,6 +118,8 @@ static inline void kmemcheck_mark_initialized(void *address, unsigned int n)
static inline void kmemcheck_mark_freed(void *address, unsigned int n)
{
}
+
+#define kmemcheck_annotate_bitfield(field) do { } while (0)
#endif /* CONFIG_KMEMCHECK */
#endif /* LINUX_KMEMCHECK_H */
--
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