linux-kernel - [PATCH 2/2] mm/vmalloc: use generated callback to populate subtree_max

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Message-Id: <20190811184613.20463-3-urezki@gmail.com>
Date:   Sun, 11 Aug 2019 20:46:13 +0200
From:   "Uladzislau Rezki (Sony)" <urezki@...il.com>
To:     Andrew Morton <akpm@...ux-foundation.org>,
        Michel Lespinasse <walken@...gle.com>
Cc:     linux-mm@...ck.org, LKML <linux-kernel@...r.kernel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Roman Gushchin <guro@...com>,
        Uladzislau Rezki <urezki@...il.com>,
        Hillf Danton <hdanton@...a.com>,
        Michal Hocko <mhocko@...e.com>,
        Matthew Wilcox <willy@...radead.org>,
        Oleksiy Avramchenko <oleksiy.avramchenko@...ymobile.com>,
        Steven Rostedt <rostedt@...dmis.org>
Subject: [PATCH 2/2] mm/vmalloc: use generated callback to populate subtree_max_size

RB_DECLARE_CALLBACKS_MAX defines its own callback to update the
augmented subtree information after a node is modified. It makes
sense to use it instead of our own propagate implementation.

Apart of that, in case of using generated callback we can eliminate
compute_subtree_max_size() function and get rid of duplication.

Signed-off-by: Uladzislau Rezki (Sony) <urezki@...il.com>
---
 mm/vmalloc.c | 31 +------------------------------
 1 file changed, 1 insertion(+), 30 deletions(-)

diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index b8101030f79e..e03444598ae1 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -385,17 +385,6 @@ get_subtree_max_size(struct rb_node *node)
 	return va ? va->subtree_max_size : 0;
 }
 
-/*
- * Gets called when remove the node and rotate.
- */
-static __always_inline unsigned long
-compute_subtree_max_size(struct vmap_area *va)
-{
-	return max3(va_size(va),
-		get_subtree_max_size(va->rb_node.rb_left),
-		get_subtree_max_size(va->rb_node.rb_right));
-}
-
 RB_DECLARE_CALLBACKS_MAX(static, free_vmap_area_rb_augment_cb,
 	struct vmap_area, rb_node, unsigned long, subtree_max_size, va_size)
 
@@ -623,25 +612,7 @@ augment_tree_propagate_check(struct rb_node *n)
 static __always_inline void
 augment_tree_propagate_from(struct vmap_area *va)
 {
-	struct rb_node *node = &va->rb_node;
-	unsigned long new_va_sub_max_size;
-
-	while (node) {
-		va = rb_entry(node, struct vmap_area, rb_node);
-		new_va_sub_max_size = compute_subtree_max_size(va);
-
-		/*
-		 * If the newly calculated maximum available size of the
-		 * subtree is equal to the current one, then it means that
-		 * the tree is propagated correctly. So we have to stop at
-		 * this point to save cycles.
-		 */
-		if (va->subtree_max_size == new_va_sub_max_size)
-			break;
-
-		va->subtree_max_size = new_va_sub_max_size;
-		node = rb_parent(&va->rb_node);
-	}
+	free_vmap_area_rb_augment_cb_propagate(&va->rb_node, NULL);
 
 #if DEBUG_AUGMENT_PROPAGATE_CHECK
 	augment_tree_propagate_check(free_vmap_area_root.rb_node);
-- 
2.11.0