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mm: interval tree updates
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Update the generic interval tree code that was introduced in "mm: replace
vma prio_tree with an interval tree".

Changes:

- fixed 'endpoing' typo noticed by Andrew Morton

- replaced include/linux/interval_tree_tmpl.h, which was used as a
  template (including it automatically defined the interval tree
  functions) with include/linux/interval_tree_generic.h, which only
  defines a preprocessor macro INTERVAL_TREE_DEFINE(), which itself
  defines the interval tree functions when invoked. Now that is a very
  long macro which is unfortunate, but it does make the usage sites
  (lib/interval_tree.c and mm/interval_tree.c) a bit nicer than previously.

- make use of RB_DECLARE_CALLBACKS() in the INTERVAL_TREE_DEFINE() macro,
  instead of duplicating that code in the interval tree template.

- replaced vma_interval_tree_add(), which was actually handling the
  nonlinear and interval tree cases, with vma_interval_tree_insert_after()
  which handles only the interval tree case and has an API that is more
  consistent with the other interval tree handling functions.
  The nonlinear case is now handled explicitly in kernel/fork.c dup_mmap().

Signed-off-by: Michel Lespinasse <[email protected]>
Cc: Andrea Arcangeli <[email protected]>
Cc: Rik van Riel <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Daniel Santos <[email protected]>
Cc: Hugh Dickins <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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walken-google authored and torvalds committed Oct 9, 2012
1 parent 9c079ad commit 9826a51
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191 changes: 191 additions & 0 deletions include/linux/interval_tree_generic.h
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/*
Interval Trees
(C) 2012 Michel Lespinasse <[email protected]>
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
include/linux/interval_tree_generic.h
*/

#include <linux/rbtree_augmented.h>

/*
* Template for implementing interval trees
*
* ITSTRUCT: struct type of the interval tree nodes
* ITRB: name of struct rb_node field within ITSTRUCT
* ITTYPE: type of the interval endpoints
* ITSUBTREE: name of ITTYPE field within ITSTRUCT holding last-in-subtree
* ITSTART(n): start endpoint of ITSTRUCT node n
* ITLAST(n): last endpoint of ITSTRUCT node n
* ITSTATIC: 'static' or empty
* ITPREFIX: prefix to use for the inline tree definitions
*
* Note - before using this, please consider if non-generic version
* (interval_tree.h) would work for you...
*/

#define INTERVAL_TREE_DEFINE(ITSTRUCT, ITRB, ITTYPE, ITSUBTREE, \
ITSTART, ITLAST, ITSTATIC, ITPREFIX) \
\
/* Callbacks for augmented rbtree insert and remove */ \
\
static inline ITTYPE ITPREFIX ## _compute_subtree_last(ITSTRUCT *node) \
{ \
ITTYPE max = ITLAST(node), subtree_last; \
if (node->ITRB.rb_left) { \
subtree_last = rb_entry(node->ITRB.rb_left, \
ITSTRUCT, ITRB)->ITSUBTREE; \
if (max < subtree_last) \
max = subtree_last; \
} \
if (node->ITRB.rb_right) { \
subtree_last = rb_entry(node->ITRB.rb_right, \
ITSTRUCT, ITRB)->ITSUBTREE; \
if (max < subtree_last) \
max = subtree_last; \
} \
return max; \
} \
\
RB_DECLARE_CALLBACKS(static, ITPREFIX ## _augment, ITSTRUCT, ITRB, \
ITTYPE, ITSUBTREE, ITPREFIX ## _compute_subtree_last) \
\
/* Insert / remove interval nodes from the tree */ \
\
ITSTATIC void ITPREFIX ## _insert(ITSTRUCT *node, struct rb_root *root) \
{ \
struct rb_node **link = &root->rb_node, *rb_parent = NULL; \
ITTYPE start = ITSTART(node), last = ITLAST(node); \
ITSTRUCT *parent; \
\
while (*link) { \
rb_parent = *link; \
parent = rb_entry(rb_parent, ITSTRUCT, ITRB); \
if (parent->ITSUBTREE < last) \
parent->ITSUBTREE = last; \
if (start < ITSTART(parent)) \
link = &parent->ITRB.rb_left; \
else \
link = &parent->ITRB.rb_right; \
} \
\
node->ITSUBTREE = last; \
rb_link_node(&node->ITRB, rb_parent, link); \
rb_insert_augmented(&node->ITRB, root, &ITPREFIX ## _augment); \
} \
\
ITSTATIC void ITPREFIX ## _remove(ITSTRUCT *node, struct rb_root *root) \
{ \
rb_erase_augmented(&node->ITRB, root, &ITPREFIX ## _augment); \
} \
\
/* \
* Iterate over intervals intersecting [start;last] \
* \
* Note that a node's interval intersects [start;last] iff: \
* Cond1: ITSTART(node) <= last \
* and \
* Cond2: start <= ITLAST(node) \
*/ \
\
static ITSTRUCT * \
ITPREFIX ## _subtree_search(ITSTRUCT *node, ITTYPE start, ITTYPE last) \
{ \
while (true) { \
/* \
* Loop invariant: start <= node->ITSUBTREE \
* (Cond2 is satisfied by one of the subtree nodes) \
*/ \
if (node->ITRB.rb_left) { \
ITSTRUCT *left = rb_entry(node->ITRB.rb_left, \
ITSTRUCT, ITRB); \
if (start <= left->ITSUBTREE) { \
/* \
* Some nodes in left subtree satisfy Cond2. \
* Iterate to find the leftmost such node N. \
* If it also satisfies Cond1, that's the \
* match we are looking for. Otherwise, there \
* is no matching interval as nodes to the \
* right of N can't satisfy Cond1 either. \
*/ \
node = left; \
continue; \
} \
} \
if (ITSTART(node) <= last) { /* Cond1 */ \
if (start <= ITLAST(node)) /* Cond2 */ \
return node; /* node is leftmost match */ \
if (node->ITRB.rb_right) { \
node = rb_entry(node->ITRB.rb_right, \
ITSTRUCT, ITRB); \
if (start <= node->ITSUBTREE) \
continue; \
} \
} \
return NULL; /* No match */ \
} \
} \
\
ITSTATIC ITSTRUCT * \
ITPREFIX ## _iter_first(struct rb_root *root, ITTYPE start, ITTYPE last) \
{ \
ITSTRUCT *node; \
\
if (!root->rb_node) \
return NULL; \
node = rb_entry(root->rb_node, ITSTRUCT, ITRB); \
if (node->ITSUBTREE < start) \
return NULL; \
return ITPREFIX ## _subtree_search(node, start, last); \
} \
\
ITSTATIC ITSTRUCT * \
ITPREFIX ## _iter_next(ITSTRUCT *node, ITTYPE start, ITTYPE last) \
{ \
struct rb_node *rb = node->ITRB.rb_right, *prev; \
\
while (true) { \
/* \
* Loop invariants: \
* Cond1: ITSTART(node) <= last \
* rb == node->ITRB.rb_right \
* \
* First, search right subtree if suitable \
*/ \
if (rb) { \
ITSTRUCT *right = rb_entry(rb, ITSTRUCT, ITRB); \
if (start <= right->ITSUBTREE) \
return ITPREFIX ## _subtree_search(right, \
start, last); \
} \
\
/* Move up the tree until we come from a node's left child */ \
do { \
rb = rb_parent(&node->ITRB); \
if (!rb) \
return NULL; \
prev = &node->ITRB; \
node = rb_entry(rb, ITSTRUCT, ITRB); \
rb = node->ITRB.rb_right; \
} while (prev == rb); \
\
/* Check if the node intersects [start;last] */ \
if (last < ITSTART(node)) /* !Cond1 */ \
return NULL; \
else if (start <= ITLAST(node)) /* Cond2 */ \
return node; \
} \
}
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