From: zijun_hu <[email protected]> for LP64 ABI, struct rb_node aligns at 8 bytes boundary due to sizeof(long) == 8 normally, so 0x07 should be used to extract node's parent rather than 0x03
the mask is corrected based on normal alignment of struct rb_node macros are introduced to replace hard coding numbers too Signed-off-by: zijun_hu <[email protected]> --- an alternative to macro RB_PARENT_MASK is shown below via __alignof__ #define RB_PARENT_MASK \ (~((unsigned long)__alignof__(struct rb_node) - 1)) include/linux/rbtree.h | 4 +++- include/linux/rbtree_augmented.h | 5 +++-- 2 files changed, 6 insertions(+), 3 deletions(-) diff --git a/include/linux/rbtree.h b/include/linux/rbtree.h index e585018..f3a8596 100644 --- a/include/linux/rbtree.h +++ b/include/linux/rbtree.h @@ -44,8 +44,10 @@ struct rb_root { struct rb_node *rb_node; }; +#define RB_PARENT_MASK (~((unsigned long)sizeof(long) - 1)) -#define rb_parent(r) ((struct rb_node *)((r)->__rb_parent_color & ~3)) +#define rb_parent(r) \ + ((struct rb_node *)((r)->__rb_parent_color & RB_PARENT_MASK)) #define RB_ROOT (struct rb_root) { NULL, } #define rb_entry(ptr, type, member) container_of(ptr, type, member) diff --git a/include/linux/rbtree_augmented.h b/include/linux/rbtree_augmented.h index d076183..0a839ea 100644 --- a/include/linux/rbtree_augmented.h +++ b/include/linux/rbtree_augmented.h @@ -96,10 +96,11 @@ rbstatic const struct rb_augment_callbacks rbname = { \ #define RB_RED 0 #define RB_BLACK 1 +#define RB_COLOR_MASK 1UL -#define __rb_parent(pc) ((struct rb_node *)(pc & ~3)) +#define __rb_parent(pc) ((struct rb_node *)(pc & RB_PARENT_MASK)) -#define __rb_color(pc) ((pc) & 1) +#define __rb_color(pc) ((pc) & RB_COLOR_MASK) #define __rb_is_black(pc) __rb_color(pc) #define __rb_is_red(pc) (!__rb_color(pc)) #define rb_color(rb) __rb_color((rb)->__rb_parent_color) -- 1.9.1
