Commit 11d43e62 authored by Wei Yang's avatar Wei Yang Committed by Linus Torvalds

lib/rbtree: set successor's parent unconditionally

Both in Case 2 and 3, we exchange n and s.  This mean no matter whether
child2 is NULL or not, successor's parent should be assigned to node's.

This patch takes this step out to make it explicit and reduce the
ambiguity.

Besides, this step reduces some symbol size like rb_erase().

   KERN_CONFIG       upstream       patched
   OPT_FOR_PERF      877            870
   OPT_FOR_SIZE      635            621

Link: http://lkml.kernel.org/r/20191028021442.5450-1-richardw.yang@linux.intel.comSigned-off-by: default avatarWei Yang <richardw.yang@linux.intel.com>
Acked-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: default avatarMichel Lespinasse <walken@google.com>
Reviewed-by: default avatarDavidlohr Bueso <dbueso@suse.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent ae81217e
......@@ -283,14 +283,13 @@ __rb_erase_augmented(struct rb_node *node, struct rb_root *root,
__rb_change_child(node, successor, tmp, root);
if (child2) {
successor->__rb_parent_color = pc;
rb_set_parent_color(child2, parent, RB_BLACK);
rebalance = NULL;
} else {
unsigned long pc2 = successor->__rb_parent_color;
successor->__rb_parent_color = pc;
rebalance = __rb_is_black(pc2) ? parent : NULL;
}
successor->__rb_parent_color = pc;
tmp = successor;
}
......
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