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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [resend PATCH] xen: common: rbtree: ported updates from linux tree
The patch contains the updated version of rbtree implementation from linux kernel tree containing the fixes so far handled. Signed-off-by: Praveen Kumar <kpraveen.lkml@xxxxxxxxx> --- xen/common/rbtree.c | 748 +++++++++++++++++++++++++------------ xen/include/xen/compiler.h | 60 +++ xen/include/xen/rbtree.h | 120 ++++-- xen/include/xen/rbtree_augmented.h | 283 ++++++++++++++ 4 files changed, 931 insertions(+), 280 deletions(-) create mode 100644 xen/include/xen/rbtree_augmented.h diff --git a/xen/common/rbtree.c b/xen/common/rbtree.c index 3328960d56..ae152c5bf2 100644 --- a/xen/common/rbtree.c +++ b/xen/common/rbtree.c @@ -2,7 +2,8 @@ Red Black Trees (C) 1999 Andrea Arcangeli <andrea@xxxxxxx> (C) 2002 David Woodhouse <dwmw2@xxxxxxxxxxxxx> - + (C) 2012 Michel Lespinasse <walken@xxxxxxxxxx> + 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 @@ -14,286 +15,479 @@ 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, see <http://www.gnu.org/licenses/>. + along with this program; if not, write to the Free Software + Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA linux/lib/rbtree.c */ +#include <xen/rbtree_augmented.h> #include <xen/types.h> -#include <xen/rbtree.h> - -static void __rb_rotate_left(struct rb_node *node, struct rb_root *root) -{ - struct rb_node *right = node->rb_right; - struct rb_node *parent = rb_parent(node); - if ((node->rb_right = right->rb_left)) - rb_set_parent(right->rb_left, node); - right->rb_left = node; +/* + * red-black trees properties: http://en.wikipedia.org/wiki/Rbtree + * + * 1) A node is either red or black + * 2) The root is black + * 3) All leaves (NULL) are black + * 4) Both children of every red node are black + * 5) Every simple path from root to leaves contains the same number + * of black nodes. + * + * 4 and 5 give the O(log n) guarantee, since 4 implies you cannot have two + * consecutive red nodes in a path and every red node is therefore followed by + * a black. So if B is the number of black nodes on every simple path (as per + * 5), then the longest possible path due to 4 is 2B. + * + * We shall indicate color with case, where black nodes are uppercase and red + * nodes will be lowercase. Unknown color nodes shall be drawn as red within + * parentheses and have some accompanying text comment. + */ - rb_set_parent(right, parent); +/* + * Notes on lockless lookups: + * + * All stores to the tree structure (rb_left and rb_right) must be done using + * WRITE_ONCE(). And we must not inadvertently cause (temporary) loops in the + * tree structure as seen in program order. + * + * These two requirements will allow lockless iteration of the tree -- not + * correct iteration mind you, tree rotations are not atomic so a lookup might + * miss entire subtrees. + * + * But they do guarantee that any such traversal will only see valid elements + * and that it will indeed complete -- does not get stuck in a loop. + * + * It also guarantees that if the lookup returns an element it is the 'correct' + * one. But not returning an element does _NOT_ mean it's not present. + * + * NOTE: + * + * Stores to __rb_parent_color are not important for simple lookups so those + * are left undone as of now. Nor did I check for loops involving parent + * pointers. + */ - if (parent) - { - if (node == parent->rb_left) - parent->rb_left = right; - else - parent->rb_right = right; - } - else - root->rb_node = right; - rb_set_parent(node, right); +static inline void rb_set_black(struct rb_node *rb) +{ + rb->__rb_parent_color |= RB_BLACK; } -static void __rb_rotate_right(struct rb_node *node, struct rb_root *root) +static inline struct rb_node *rb_red_parent(struct rb_node *red) { - struct rb_node *left = node->rb_left; - struct rb_node *parent = rb_parent(node); - - if ((node->rb_left = left->rb_right)) - rb_set_parent(left->rb_right, node); - left->rb_right = node; - - rb_set_parent(left, parent); + return (struct rb_node *)red->__rb_parent_color; +} - if (parent) - { - if (node == parent->rb_right) - parent->rb_right = left; - else - parent->rb_left = left; - } - else - root->rb_node = left; - rb_set_parent(node, left); +/* + * Helper function for rotations: + * - old's parent and color get assigned to new + * - old gets assigned new as a parent and 'color' as a color. + */ +static inline void +__rb_rotate_set_parents(struct rb_node *old, struct rb_node *new, + struct rb_root *root, int color) +{ + struct rb_node *parent = rb_parent(old); + new->__rb_parent_color = old->__rb_parent_color; + rb_set_parent_color(old, new, color); + __rb_change_child(old, new, parent, root); } -void rb_insert_color(struct rb_node *node, struct rb_root *root) +static __always_inline void +__rb_insert(struct rb_node *node, struct rb_root *root, + void (*augment_rotate)(struct rb_node *old, struct rb_node *new)) { - struct rb_node *parent, *gparent; + struct rb_node *parent = rb_red_parent(node), *gparent, *tmp; - while ((parent = rb_parent(node)) && rb_is_red(parent)) + while (true) { - gparent = rb_parent(parent); - - if (parent == gparent->rb_left) + /* + * Loop invariant: node is red + * + * If there is a black parent, we are done. + * Otherwise, take some corrective action as we don't + * want a red root or two consecutive red nodes. + */ + if (!parent) { + rb_set_parent_color(node, NULL, RB_BLACK); + break; + } else if (rb_is_black(parent)) + break; + + gparent = rb_red_parent(parent); + + tmp = gparent->rb_right; + if (parent != tmp) + { /* parent == gparent->rb_left */ + if (tmp && rb_is_red(tmp)) { - register struct rb_node *uncle = gparent->rb_right; - if (uncle && rb_is_red(uncle)) - { - rb_set_black(uncle); - rb_set_black(parent); - rb_set_red(gparent); - node = gparent; - continue; - } + /* + * Case 1 - color flips + * + * G g + * / \ / \ + * p u --> P U + * / / + * n n + * + * However, since g's parent might be red, and + * 4) does not allow this, we need to recurse + * at g. + */ + rb_set_parent_color(tmp, gparent, RB_BLACK); + rb_set_parent_color(parent, gparent, RB_BLACK); + node = gparent; + parent = rb_parent(node); + rb_set_parent_color(node, parent, RB_RED); + continue; } - if (parent->rb_right == node) + tmp = parent->rb_right; + if (node == tmp) { - register struct rb_node *tmp; - __rb_rotate_left(parent, root); - tmp = parent; + /* + * Case 2 - left rotate at parent + * + * G G + * / \ / \ + * p U --> n U + * \ / + * n p + * + * This still leaves us in violation of 4), the + * continuation into Case 3 will fix that. + */ + tmp = node->rb_left; + WRITE_ONCE(parent->rb_right, tmp); + WRITE_ONCE(node->rb_left, parent); + if (tmp) + rb_set_parent_color(tmp, parent, + RB_BLACK); + rb_set_parent_color(parent, node, RB_RED); + augment_rotate(parent, node); parent = node; - node = tmp; + tmp = node->rb_right; } - rb_set_black(parent); - rb_set_red(gparent); - __rb_rotate_right(gparent, root); - } else { + /* + * Case 3 - right rotate at gparent + * + * G P + * / \ / \ + * p U --> n g + * / \ + * n U + */ + WRITE_ONCE(gparent->rb_left, tmp); /* == parent->rb_right */ + WRITE_ONCE(parent->rb_right, gparent); + if (tmp) + rb_set_parent_color(tmp, gparent, RB_BLACK); + __rb_rotate_set_parents(gparent, parent, root, RB_RED); + augment_rotate(gparent, parent); + break; + } + else + { + tmp = gparent->rb_left; + if (tmp && rb_is_red(tmp)) { - register struct rb_node *uncle = gparent->rb_left; - if (uncle && rb_is_red(uncle)) - { - rb_set_black(uncle); - rb_set_black(parent); - rb_set_red(gparent); - node = gparent; - continue; - } + /* Case 1 - color flips */ + rb_set_parent_color(tmp, gparent, RB_BLACK); + rb_set_parent_color(parent, gparent, RB_BLACK); + node = gparent; + parent = rb_parent(node); + rb_set_parent_color(node, parent, RB_RED); + continue; } - if (parent->rb_left == node) + tmp = parent->rb_left; + if (node == tmp) { - register struct rb_node *tmp; - __rb_rotate_right(parent, root); - tmp = parent; + /* Case 2 - right rotate at parent */ + tmp = node->rb_right; + WRITE_ONCE(parent->rb_left, tmp); + WRITE_ONCE(node->rb_right, parent); + if (tmp) + rb_set_parent_color(tmp, parent, + RB_BLACK); + rb_set_parent_color(parent, node, RB_RED); + augment_rotate(parent, node); parent = node; - node = tmp; + tmp = node->rb_left; } - rb_set_black(parent); - rb_set_red(gparent); - __rb_rotate_left(gparent, root); + /* Case 3 - left rotate at gparent */ + WRITE_ONCE(gparent->rb_right, tmp); /* == parent->rb_left */ + WRITE_ONCE(parent->rb_left, gparent); + if (tmp) + rb_set_parent_color(tmp, gparent, RB_BLACK); + __rb_rotate_set_parents(gparent, parent, root, RB_RED); + augment_rotate(gparent, parent); + break; } } - - rb_set_black(root->rb_node); } -EXPORT_SYMBOL(rb_insert_color); -static void __rb_erase_color(struct rb_node *node, struct rb_node *parent, - struct rb_root *root) +/* + * Inline version for rb_erase() use - we want to be able to inline + * and eliminate the dummy_rotate callback there + */ +static __always_inline void +____rb_erase_color(struct rb_node *parent, struct rb_root *root, + void (*augment_rotate)(struct rb_node *old, struct rb_node *new)) { - struct rb_node *other; + struct rb_node *node = NULL, *sibling, *tmp1, *tmp2; - while ((!node || rb_is_black(node)) && node != root->rb_node) + while (true) { - if (parent->rb_left == node) - { - other = parent->rb_right; - if (rb_is_red(other)) + /* + * Loop invariants: + * - node is black (or NULL on first iteration) + * - node is not the root (parent is not NULL) + * - All leaf paths going through parent and node have a + * black node count that is 1 lower than other leaf paths. + */ + sibling = parent->rb_right; + if (node != sibling) + { /* node == parent->rb_left */ + if (rb_is_red(sibling)) { - rb_set_black(other); - rb_set_red(parent); - __rb_rotate_left(parent, root); - other = parent->rb_right; - } - if ((!other->rb_left || rb_is_black(other->rb_left)) && - (!other->rb_right || rb_is_black(other->rb_right))) - { - rb_set_red(other); - node = parent; - parent = rb_parent(node); + /* + * Case 1 - left rotate at parent + * + * P S + * / \ / \ + * N s --> p Sr + * / \ / \ + * Sl Sr N Sl + */ + tmp1 = sibling->rb_left; + WRITE_ONCE(parent->rb_right, tmp1); + WRITE_ONCE(sibling->rb_left, parent); + rb_set_parent_color(tmp1, parent, RB_BLACK); + __rb_rotate_set_parents(parent, sibling, root, + RB_RED); + augment_rotate(parent, sibling); + sibling = tmp1; } - else + tmp1 = sibling->rb_right; + if (!tmp1 || rb_is_black(tmp1)) { - if (!other->rb_right || rb_is_black(other->rb_right)) + tmp2 = sibling->rb_left; + if (!tmp2 || rb_is_black(tmp2)) { - struct rb_node *o_left; - if ((o_left = other->rb_left)) - rb_set_black(o_left); - rb_set_red(other); - __rb_rotate_right(other, root); - other = parent->rb_right; + /* + * Case 2 - sibling color flip + * (p could be either color here) + * + * (p) (p) + * / \ / \ + * N S --> N s + * / \ / \ + * Sl Sr Sl Sr + * + * This leaves us violating 5) which + * can be fixed by flipping p to black + * if it was red, or by recursing at p. + * p is red when coming from Case 1. + */ + rb_set_parent_color(sibling, parent, + RB_RED); + if (rb_is_red(parent)) + rb_set_black(parent); + else + { + node = parent; + parent = rb_parent(node); + if (parent) + continue; + } + break; } - rb_set_color(other, rb_color(parent)); - rb_set_black(parent); - if (other->rb_right) - rb_set_black(other->rb_right); - __rb_rotate_left(parent, root); - node = root->rb_node; - break; + /* + * Case 3 - right rotate at sibling + * (p could be either color here) + * + * (p) (p) + * / \ / \ + * N S --> N sl + * / \ \ + * sl Sr S + * \ + * Sr + * + * Note: p might be red, and then both + * p and sl are red after rotation(which + * breaks property 4). This is fixed in + * Case 4 (in __rb_rotate_set_parents() + * which set sl the color of p + * and set p RB_BLACK) + * + * (p) (sl) + * / \ / \ + * N sl --> P S + * \ / \ + * S N Sr + * \ + * Sr + */ + tmp1 = tmp2->rb_right; + WRITE_ONCE(sibling->rb_left, tmp1); + WRITE_ONCE(tmp2->rb_right, sibling); + WRITE_ONCE(parent->rb_right, tmp2); + if (tmp1) + rb_set_parent_color(tmp1, sibling, + RB_BLACK); + augment_rotate(sibling, tmp2); + tmp1 = sibling; + sibling = tmp2; } + /* + * Case 4 - left rotate at parent + color flips + * (p and sl could be either color here. + * After rotation, p becomes black, s acquires + * p's color, and sl keeps its color) + * + * (p) (s) + * / \ / \ + * N S --> P Sr + * / \ / \ + * (sl) sr N (sl) + */ + tmp2 = sibling->rb_left; + WRITE_ONCE(parent->rb_right, tmp2); + WRITE_ONCE(sibling->rb_left, parent); + rb_set_parent_color(tmp1, sibling, RB_BLACK); + if (tmp2) + rb_set_parent(tmp2, parent); + __rb_rotate_set_parents(parent, sibling, root, + RB_BLACK); + augment_rotate(parent, sibling); + break; } else { - other = parent->rb_left; - if (rb_is_red(other)) + sibling = parent->rb_left; + if (rb_is_red(sibling)) { - rb_set_black(other); - rb_set_red(parent); - __rb_rotate_right(parent, root); - other = parent->rb_left; + /* Case 1 - right rotate at parent */ + tmp1 = sibling->rb_right; + WRITE_ONCE(parent->rb_left, tmp1); + WRITE_ONCE(sibling->rb_right, parent); + rb_set_parent_color(tmp1, parent, RB_BLACK); + __rb_rotate_set_parents(parent, sibling, root, + RB_RED); + augment_rotate(parent, sibling); + sibling = tmp1; } - if ((!other->rb_left || rb_is_black(other->rb_left)) && - (!other->rb_right || rb_is_black(other->rb_right))) + tmp1 = sibling->rb_left; + if (!tmp1 || rb_is_black(tmp1)) { - rb_set_red(other); - node = parent; - parent = rb_parent(node); - } - else - { - if (!other->rb_left || rb_is_black(other->rb_left)) + tmp2 = sibling->rb_right; + if (!tmp2 || rb_is_black(tmp2)) { - register struct rb_node *o_right; - if ((o_right = other->rb_right)) - rb_set_black(o_right); - rb_set_red(other); - __rb_rotate_left(other, root); - other = parent->rb_left; + /* Case 2 - sibling color flip */ + rb_set_parent_color(sibling, parent, + RB_RED); + if (rb_is_red(parent)) + rb_set_black(parent); + else + { + node = parent; + parent = rb_parent(node); + if (parent) + continue; + } + break; } - rb_set_color(other, rb_color(parent)); - rb_set_black(parent); - if (other->rb_left) - rb_set_black(other->rb_left); - __rb_rotate_right(parent, root); - node = root->rb_node; - break; + /* Case 3 - left rotate at sibling */ + tmp1 = tmp2->rb_left; + WRITE_ONCE(sibling->rb_right, tmp1); + WRITE_ONCE(tmp2->rb_left, sibling); + WRITE_ONCE(parent->rb_left, tmp2); + if (tmp1) + rb_set_parent_color(tmp1, sibling, + RB_BLACK); + augment_rotate(sibling, tmp2); + tmp1 = sibling; + sibling = tmp2; } + /* Case 4 - right rotate at parent + color flips */ + tmp2 = sibling->rb_right; + WRITE_ONCE(parent->rb_left, tmp2); + WRITE_ONCE(sibling->rb_right, parent); + rb_set_parent_color(tmp1, sibling, RB_BLACK); + if (tmp2) + rb_set_parent(tmp2, parent); + __rb_rotate_set_parents(parent, sibling, root, + RB_BLACK); + augment_rotate(parent, sibling); + break; } } - if (node) - rb_set_black(node); } -void rb_erase(struct rb_node *node, struct rb_root *root) +/* Non-inline version for rb_erase_augmented() use */ +void __rb_erase_color(struct rb_node *parent, struct rb_root *root, + void (*augment_rotate)(struct rb_node *old, struct rb_node *new)) { - struct rb_node *child, *parent; - int color; - - if (!node->rb_left) - child = node->rb_right; - else if (!node->rb_right) - child = node->rb_left; - else - { - struct rb_node *old = node, *left; - - node = node->rb_right; - while ((left = node->rb_left) != NULL) - node = left; - child = node->rb_right; - parent = rb_parent(node); - color = rb_color(node); - - if (child) - rb_set_parent(child, parent); - if (parent == old) { - parent->rb_right = child; - parent = node; - } else - parent->rb_left = child; - - node->rb_parent_color = old->rb_parent_color; - node->rb_right = old->rb_right; - node->rb_left = old->rb_left; - - if (rb_parent(old)) - { - if (rb_parent(old)->rb_left == old) - rb_parent(old)->rb_left = node; - else - rb_parent(old)->rb_right = node; - } else - root->rb_node = node; - - rb_set_parent(old->rb_left, node); - if (old->rb_right) - rb_set_parent(old->rb_right, node); - goto color; - } + ____rb_erase_color(parent, root, augment_rotate); +} +EXPORT_SYMBOL(__rb_erase_color); - parent = rb_parent(node); - color = rb_color(node); +/* + * Non-augmented rbtree manipulation functions. + * + * We use dummy augmented callbacks here, and have the compiler optimize them + * out of the rb_insert_color() and rb_erase() function definitions. + */ - if (child) - rb_set_parent(child, parent); - if (parent) - { - if (parent->rb_left == node) - parent->rb_left = child; - else - parent->rb_right = child; - } - else - root->rb_node = child; +static inline void dummy_propagate(struct rb_node *node, struct rb_node *stop) {} +static inline void dummy_copy(struct rb_node *old, struct rb_node *new) {} +static inline void dummy_rotate(struct rb_node *old, struct rb_node *new) {} + +static const struct rb_augment_callbacks dummy_callbacks = { + .propagate = dummy_propagate, + .copy = dummy_copy, + .rotate = dummy_rotate +}; + +void rb_insert_color(struct rb_node *node, struct rb_root *root) +{ + __rb_insert(node, root, dummy_rotate); +} +EXPORT_SYMBOL(rb_insert_color); - color: - if (color == RB_BLACK) - __rb_erase_color(child, parent, root); +void rb_erase(struct rb_node *node, struct rb_root *root) +{ + struct rb_node *rebalance; + rebalance = __rb_erase_augmented(node, root, &dummy_callbacks); + if (rebalance) + ____rb_erase_color(rebalance, root, dummy_rotate); } EXPORT_SYMBOL(rb_erase); /* + * Augmented rbtree manipulation functions. + * + * This instantiates the same __always_inline functions as in the non-augmented + * case, but this time with user-defined callbacks. + */ + +void __rb_insert_augmented(struct rb_node *node, struct rb_root *root, + void (*augment_rotate)(struct rb_node *old, struct rb_node *new)) +{ + __rb_insert(node, root, augment_rotate); +} +EXPORT_SYMBOL(__rb_insert_augmented); + +/* * This function returns the first node (in sort order) of the tree. */ -struct rb_node *rb_first(struct rb_root *root) +struct rb_node *rb_first(const struct rb_root *root) { - struct rb_node *n; + struct rb_node *n; n = root->rb_node; if (!n) @@ -304,9 +498,9 @@ struct rb_node *rb_first(struct rb_root *root) } EXPORT_SYMBOL(rb_first); -struct rb_node *rb_last(struct rb_root *root) +struct rb_node *rb_last(const struct rb_root *root) { - struct rb_node *n; + struct rb_node *n; n = root->rb_node; if (!n) @@ -317,28 +511,32 @@ struct rb_node *rb_last(struct rb_root *root) } EXPORT_SYMBOL(rb_last); -struct rb_node *rb_next(struct rb_node *node) +struct rb_node *rb_next(const struct rb_node *node) { struct rb_node *parent; - if (rb_parent(node) == node) + if (RB_EMPTY_NODE(node)) return NULL; - /* If we have a right-hand child, go down and then left as far - as we can. */ - if (node->rb_right) { + /* + * If we have a right-hand child, go down and then left as far + * as we can. + */ + if (node->rb_right) + { node = node->rb_right; while (node->rb_left) node=node->rb_left; - return node; + return (struct rb_node *)node; } - /* No right-hand children. Everything down and left is - smaller than us, so any 'next' node must be in the general - direction of our parent. Go up the tree; any time the - ancestor is a right-hand child of its parent, keep going - up. First time it's a left-hand child of its parent, said - parent is our 'next' node. */ + /* + * No right-hand children. Everything down and left is smaller than us, + * so any 'next' node must be in the general direction of our parent. + * Go up the tree; any time the ancestor is a right-hand child of its + * parent, keep going up. First time it's a left-hand child of its + * parent, said parent is our 'next' node. + */ while ((parent = rb_parent(node)) && node == parent->rb_right) node = parent; @@ -346,24 +544,29 @@ struct rb_node *rb_next(struct rb_node *node) } EXPORT_SYMBOL(rb_next); -struct rb_node *rb_prev(struct rb_node *node) +struct rb_node *rb_prev(const struct rb_node *node) { struct rb_node *parent; - if (rb_parent(node) == node) + if (RB_EMPTY_NODE(node)) return NULL; - /* If we have a left-hand child, go down and then right as far - as we can. */ - if (node->rb_left) { + /* + * If we have a left-hand child, go down and then right as far + * as we can. + */ + if (node->rb_left) + { node = node->rb_left; while (node->rb_right) node=node->rb_right; - return node; + return (struct rb_node *)node; } - /* No left-hand children. Go up till we find an ancestor which - is a right-hand child of its parent */ + /* + * No left-hand children. Go up till we find an ancestor which + * is a right-hand child of its parent. + */ while ((parent = rb_parent(node)) && node == parent->rb_left) node = parent; @@ -372,25 +575,82 @@ struct rb_node *rb_prev(struct rb_node *node) EXPORT_SYMBOL(rb_prev); void rb_replace_node(struct rb_node *victim, struct rb_node *new, - struct rb_root *root) + struct rb_root *root) { struct rb_node *parent = rb_parent(victim); + /* Copy the pointers/colour from the victim to the replacement */ + *new = *victim; + /* Set the surrounding nodes to point to the replacement */ - if (parent) { - if (victim == parent->rb_left) - parent->rb_left = new; - else - parent->rb_right = new; - } else { - root->rb_node = new; - } if (victim->rb_left) rb_set_parent(victim->rb_left, new); if (victim->rb_right) rb_set_parent(victim->rb_right, new); + __rb_change_child(victim, new, parent, root); +} +EXPORT_SYMBOL(rb_replace_node); + +void rb_replace_node_rcu(struct rb_node *victim, struct rb_node *new, + struct rb_root *root) +{ + struct rb_node *parent = rb_parent(victim); /* Copy the pointers/colour from the victim to the replacement */ *new = *victim; + + /* Set the surrounding nodes to point to the replacement */ + if (victim->rb_left) + rb_set_parent(victim->rb_left, new); + if (victim->rb_right) + rb_set_parent(victim->rb_right, new); + + /* Set the parent's pointer to the new node last after an RCU barrier + * so that the pointers onwards are seen to be set correctly when doing + * an RCU walk over the tree. + */ + __rb_change_child_rcu(victim, new, parent, root); } -EXPORT_SYMBOL(rb_replace_node); +EXPORT_SYMBOL(rb_replace_node_rcu); + +static struct rb_node *rb_left_deepest_node(const struct rb_node *node) +{ + for (;;) + { + if (node->rb_left) + node = node->rb_left; + else if (node->rb_right) + node = node->rb_right; + else + return (struct rb_node *)node; + } +} + +struct rb_node *rb_next_postorder(const struct rb_node *node) +{ + const struct rb_node *parent; + if (!node) + return NULL; + parent = rb_parent(node); + + /* If we're sitting on node, we've already seen our children */ + if (parent && node == parent->rb_left && parent->rb_right) + { + /* If we are the parent's left node, go to the parent's right + * node then all the way down to the left */ + return rb_left_deepest_node(parent->rb_right); + } else + /* Otherwise we are the parent's right node, and the parent + * should be next */ + return (struct rb_node *)parent; +} +EXPORT_SYMBOL(rb_next_postorder); + +struct rb_node *rb_first_postorder(const struct rb_root *root) +{ + if (!root->rb_node) + return NULL; + + return rb_left_deepest_node(root->rb_node); +} +EXPORT_SYMBOL(rb_first_postorder); diff --git a/xen/include/xen/compiler.h b/xen/include/xen/compiler.h index 533a8ea0f3..8cea29a26b 100644 --- a/xen/include/xen/compiler.h +++ b/xen/include/xen/compiler.h @@ -127,4 +127,64 @@ # define CLANG_DISABLE_WARN_GCC_COMPAT_END #endif +#include <xen/types.h> + +#ifndef __always_inline +#define __always_inline inline +#endif + +#define __READ_ONCE_SIZE \ +({ \ + switch(size) { \ + case 1: *(__u8 *)res = *(volatile __u8 *)p; break; \ + case 2: *(__u16 *)res = *(volatile __u16 *)p; break; \ + case 4: *(__u32 *)res = *(volatile __u32 *)p; break; \ + case 8: *(__u64 *)res = *(volatile __u64 *)p; break; \ + default: \ + barrier(); \ + __builtin_memcpy((void *)res, (const void *)p, size); \ + barrier(); \ + } \ +}) + +static __always_inline +void __read_once_size(const volatile void *p, void *res, int size) +{ + __READ_ONCE_SIZE; +} + +static __always_inline +void __write_once_size(volatile void *p, void *res, int size) +{ + switch (size) { + case 1: *(volatile __u8 *)p = *(__u8 *)res; break; + case 2: *(volatile __u16 *)p = *(__u16 *)res; break; + case 4: *(volatile __u32 *)p = *(__u32 *)res; break; + case 8: *(volatile __u64 *)p = *(__u64 *)res; break; + default: + barrier(); + __builtin_memcpy((void *)p, (const void *)res, size); + barrier(); + } +} + +#define __READ_ONCE(x, check) \ +({ \ + union { typeof(x) __val; char __c[1]; } __u; \ + __read_once_size(&(x), __u.__c, sizeof(x)); \ +}) + +#define READ_ONCE(x) __READ_ONCE(x, 1) + +#define WRITE_ONCE(x, val) \ +({ \ + union { typeof(x) __val; char __c[1]; } __u = \ + { .__val = (__force typeof(x)) (val) }; \ + __write_once_size(&(x), __u.__c, sizeof(x)); \ + __u.__val; \ +}) + + + + #endif /* __LINUX_COMPILER_H */ diff --git a/xen/include/xen/rbtree.h b/xen/include/xen/rbtree.h index f93c4d5823..6c51d0c918 100644 --- a/xen/include/xen/rbtree.h +++ b/xen/include/xen/rbtree.h @@ -13,69 +13,117 @@ 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, see <http://www.gnu.org/licenses/>. + along with this program; if not, write to the Free Software + Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA + + linux/include/linux/rbtree.h + + To use rbtrees you'll have to implement your own insert and search cores. + This will avoid us to use callbacks and to drop drammatically performances. + I know it's not the cleaner way, but in C (not in C++) to get + performances and genericity... + + See Documentation/rbtree.txt for documentation and samples. */ -#ifndef __RBTREE_H__ -#define __RBTREE_H__ +#ifndef _LINUX_RBTREE_H +#define _LINUX_RBTREE_H + +#include <xen/kernel.h> +#include <xen/rcupdate.h> struct rb_node { - unsigned long rb_parent_color; -#define RB_RED 0 -#define RB_BLACK 1 + unsigned long __rb_parent_color; struct rb_node *rb_right; struct rb_node *rb_left; -}; +} __attribute__((aligned(sizeof(long)))); + /* The alignment might seem pointless, but allegedly CRIS needs it */ struct rb_root { struct rb_node *rb_node; }; -#define rb_parent(r) ((struct rb_node *)((r)->rb_parent_color & ~3)) -#define rb_color(r) ((r)->rb_parent_color & 1) -#define rb_is_red(r) (!rb_color(r)) -#define rb_is_black(r) rb_color(r) -#define rb_set_red(r) do { (r)->rb_parent_color &= ~1; } while (0) -#define rb_set_black(r) do { (r)->rb_parent_color |= 1; } while (0) -static inline void rb_set_parent(struct rb_node *rb, struct rb_node *p) -{ - rb->rb_parent_color = (rb->rb_parent_color & 3) | (unsigned long)p; -} -static inline void rb_set_color(struct rb_node *rb, int color) -{ - rb->rb_parent_color = (rb->rb_parent_color & ~1) | color; -} +#define rb_parent(r) ((struct rb_node *)((r)->__rb_parent_color & ~3)) + +#define RB_ROOT (struct rb_root) { NULL, } +#define rb_entry(ptr, type, member) container_of(ptr, type, member) -#define RB_ROOT (struct rb_root) { NULL, } -#define rb_entry(ptr, type, member) container_of(ptr, type, member) +#define RB_EMPTY_ROOT(root) (READ_ONCE((root)->rb_node) == NULL) + +/* 'empty' nodes are nodes that are known not to be inserted in an rbtree */ +#define RB_EMPTY_NODE(node) \ + ((node)->__rb_parent_color == (unsigned long)(node)) +#define RB_CLEAR_NODE(node) \ + ((node)->__rb_parent_color = (unsigned long)(node)) -#define RB_EMPTY_ROOT(root) ((root)->rb_node == NULL) -#define RB_EMPTY_NODE(node) (rb_parent(node) == node) -#define RB_CLEAR_NODE(node) (rb_set_parent(node, node)) extern void rb_insert_color(struct rb_node *, struct rb_root *); extern void rb_erase(struct rb_node *, struct rb_root *); + /* Find logical next and previous nodes in a tree */ -extern struct rb_node *rb_next(struct rb_node *); -extern struct rb_node *rb_prev(struct rb_node *); -extern struct rb_node *rb_first(struct rb_root *); -extern struct rb_node *rb_last(struct rb_root *); +extern struct rb_node *rb_next(const struct rb_node *); +extern struct rb_node *rb_prev(const struct rb_node *); +extern struct rb_node *rb_first(const struct rb_root *); +extern struct rb_node *rb_last(const struct rb_root *); + +/* Postorder iteration - always visit the parent after its children */ +extern struct rb_node *rb_first_postorder(const struct rb_root *); +extern struct rb_node *rb_next_postorder(const struct rb_node *); /* Fast replacement of a single node without remove/rebalance/add/rebalance */ -extern void rb_replace_node(struct rb_node *victim, struct rb_node *new, - struct rb_root *root); +extern void rb_replace_node(struct rb_node *victim, struct rb_node *new, + struct rb_root *root); +extern void rb_replace_node_rcu(struct rb_node *victim, struct rb_node *new, + struct rb_root *root); -static inline void rb_link_node(struct rb_node * node, struct rb_node * parent, - struct rb_node ** rb_link) +static inline void rb_link_node(struct rb_node *node, struct rb_node *parent, + struct rb_node **rb_link) { - node->rb_parent_color = (unsigned long )parent; + node->__rb_parent_color = (unsigned long)parent; node->rb_left = node->rb_right = NULL; *rb_link = node; } -#endif /* __RBTREE_H__ */ +static inline void rb_link_node_rcu(struct rb_node *node, struct rb_node *parent, + struct rb_node **rb_link) +{ + node->__rb_parent_color = (unsigned long)parent; + node->rb_left = node->rb_right = NULL; + + rcu_assign_pointer(*rb_link, node); +} + +#define rb_entry_safe(ptr, type, member) \ + ({ typeof(ptr) ____ptr = (ptr); \ + ____ptr ? rb_entry(____ptr, type, member) : NULL; \ + }) + +/** + * rbtree_postorder_for_each_entry_safe - iterate in post-order over rb_root of + * given type allowing the backing memory of @pos to be invalidated + * + * @pos: the 'type *' to use as a loop cursor. + * @n: another 'type *' to use as temporary storage + * @root: 'rb_root *' of the rbtree. + * @field: the name of the rb_node field within 'type'. + * + * rbtree_postorder_for_each_entry_safe() provides a similar guarantee as + * list_for_each_entry_safe() and allows the iteration to continue independent + * of changes to @pos by the body of the loop. + * + * Note, however, that it cannot handle other modifications that re-order the + * rbtree it is iterating over. This includes calling rb_erase() on @pos, as + * rb_erase() may rebalance the tree, causing us to miss some nodes. + */ +#define rbtree_postorder_for_each_entry_safe(pos, n, root, field) \ + for (pos = rb_entry_safe(rb_first_postorder(root), typeof(*pos), field); \ + pos && ({ n = rb_entry_safe(rb_next_postorder(&pos->field), \ + typeof(*pos), field); 1; }); \ + pos = n) + +#endif /* _LINUX_RBTREE_H */ diff --git a/xen/include/xen/rbtree_augmented.h b/xen/include/xen/rbtree_augmented.h new file mode 100644 index 0000000000..2d355501dc --- /dev/null +++ b/xen/include/xen/rbtree_augmented.h @@ -0,0 +1,283 @@ +/* + Red Black Trees + (C) 1999 Andrea Arcangeli <andrea@xxxxxxx> + (C) 2002 David Woodhouse <dwmw2@xxxxxxxxxxxxx> + (C) 2012 Michel Lespinasse <walken@xxxxxxxxxx> + + 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 + + linux/include/linux/rbtree_augmented.h +*/ + +#ifndef _LINUX_RBTREE_AUGMENTED_H +#define _LINUX_RBTREE_AUGMENTED_H + +#include <xen/compiler.h> +#include <xen/rbtree.h> + +/* + * Please note - only struct rb_augment_callbacks and the prototypes for + * rb_insert_augmented() and rb_erase_augmented() are intended to be public. + * The rest are implementation details you are not expected to depend on. + * + * See Documentation/rbtree.txt for documentation and samples. + */ + +struct rb_augment_callbacks +{ + void (*propagate)(struct rb_node *node, struct rb_node *stop); + void (*copy)(struct rb_node *old, struct rb_node *new); + void (*rotate)(struct rb_node *old, struct rb_node *new); +}; + +extern void __rb_insert_augmented(struct rb_node *node, struct rb_root *root, + void (*augment_rotate)(struct rb_node *old, struct rb_node *new)); +/* + * Fixup the rbtree and update the augmented information when rebalancing. + * + * On insertion, the user must update the augmented information on the path + * leading to the inserted node, then call rb_link_node() as usual and + * rb_augment_inserted() instead of the usual rb_insert_color() call. + * If rb_augment_inserted() rebalances the rbtree, it will callback into + * a user provided function to update the augmented information on the + * affected subtrees. + */ +static inline void +rb_insert_augmented(struct rb_node *node, struct rb_root *root, + const struct rb_augment_callbacks *augment) +{ + __rb_insert_augmented(node, root, augment->rotate); +} + +#define RB_DECLARE_CALLBACKS(rbstatic, rbname, rbstruct, rbfield, \ + rbtype, rbaugmented, rbcompute) \ +static inline void \ +rbname ## _propagate(struct rb_node *rb, struct rb_node *stop) \ +{ \ + while (rb != stop) \ + { \ + rbstruct *node = rb_entry(rb, rbstruct, rbfield); \ + rbtype augmented = rbcompute(node); \ + if (node->rbaugmented == augmented) \ + break; \ + node->rbaugmented = augmented; \ + rb = rb_parent(&node->rbfield); \ + } \ +} \ +static inline void \ +rbname ## _copy(struct rb_node *rb_old, struct rb_node *rb_new) \ +{ \ + rbstruct *old = rb_entry(rb_old, rbstruct, rbfield); \ + rbstruct *new = rb_entry(rb_new, rbstruct, rbfield); \ + new->rbaugmented = old->rbaugmented; \ +} \ +static void \ +rbname ## _rotate(struct rb_node *rb_old, struct rb_node *rb_new) \ +{ \ + rbstruct *old = rb_entry(rb_old, rbstruct, rbfield); \ + rbstruct *new = rb_entry(rb_new, rbstruct, rbfield); \ + new->rbaugmented = old->rbaugmented; \ + old->rbaugmented = rbcompute(old); \ +} \ +rbstatic const struct rb_augment_callbacks rbname = { \ + .propagate = rbname ## _propagate, \ + .copy = rbname ## _copy, \ + .rotate = rbname ## _rotate \ +}; + + +#define RB_RED 0 +#define RB_BLACK 1 + +#define __rb_parent(pc) ((struct rb_node *)(pc & ~3)) + +#define __rb_color(pc) ((pc) & 1) +#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) +#define rb_is_red(rb) __rb_is_red((rb)->__rb_parent_color) +#define rb_is_black(rb) __rb_is_black((rb)->__rb_parent_color) + +static inline void rb_set_parent(struct rb_node *rb, struct rb_node *p) +{ + rb->__rb_parent_color = rb_color(rb) | (unsigned long)p; +} + +static inline void rb_set_parent_color(struct rb_node *rb, + struct rb_node *p, int color) +{ + rb->__rb_parent_color = (unsigned long)p | color; +} + +static inline void +__rb_change_child(struct rb_node *old, struct rb_node *new, + struct rb_node *parent, struct rb_root *root) +{ + if (parent) + { + if (parent->rb_left == old) + WRITE_ONCE(parent->rb_left, new); + else + WRITE_ONCE(parent->rb_right, new); + } else + WRITE_ONCE(root->rb_node, new); +} + +static inline void +__rb_change_child_rcu(struct rb_node *old, struct rb_node *new, + struct rb_node *parent, struct rb_root *root) +{ + if (parent) + { + if (parent->rb_left == old) + rcu_assign_pointer(parent->rb_left, new); + else + rcu_assign_pointer(parent->rb_right, new); + } + else + rcu_assign_pointer(root->rb_node, new); +} + +extern void __rb_erase_color(struct rb_node *parent, struct rb_root *root, + void (*augment_rotate)(struct rb_node *old, struct rb_node *new)); + +static __always_inline struct rb_node * +__rb_erase_augmented(struct rb_node *node, struct rb_root *root, + const struct rb_augment_callbacks *augment) +{ + struct rb_node *child = node->rb_right; + struct rb_node *tmp = node->rb_left; + struct rb_node *parent, *rebalance; + unsigned long pc; + + if (!tmp) + { + /* + * Case 1: node to erase has no more than 1 child (easy!) + * + * Note that if there is one child it must be red due to 5) + * and node must be black due to 4). We adjust colors locally + * so as to bypass __rb_erase_color() later on. + */ + pc = node->__rb_parent_color; + parent = __rb_parent(pc); + __rb_change_child(node, child, parent, root); + if (child) + { + child->__rb_parent_color = pc; + rebalance = NULL; + } + else + rebalance = __rb_is_black(pc) ? parent : NULL; + tmp = parent; + } + else if (!child) + { + /* Still case 1, but this time the child is node->rb_left */ + tmp->__rb_parent_color = pc = node->__rb_parent_color; + parent = __rb_parent(pc); + __rb_change_child(node, tmp, parent, root); + rebalance = NULL; + tmp = parent; + } + else + { + struct rb_node *successor = child, *child2; + + tmp = child->rb_left; + if (!tmp) + { + /* + * Case 2: node's successor is its right child + * + * (n) (s) + * / \ / \ + * (x) (s) -> (x) (c) + * \ + * (c) + */ + parent = successor; + child2 = successor->rb_right; + + augment->copy(node, successor); + } + else + { + /* + * Case 3: node's successor is leftmost under + * node's right child subtree + * + * (n) (s) + * / \ / \ + * (x) (y) -> (x) (y) + * / / + * (p) (p) + * / / + * (s) (c) + * \ + * (c) + */ + do + { + parent = successor; + successor = tmp; + tmp = tmp->rb_left; + } while (tmp); + child2 = successor->rb_right; + WRITE_ONCE(parent->rb_left, child2); + WRITE_ONCE(successor->rb_right, child); + rb_set_parent(child, successor); + + augment->copy(node, successor); + augment->propagate(parent, successor); + } + + tmp = node->rb_left; + WRITE_ONCE(successor->rb_left, tmp); + rb_set_parent(tmp, successor); + + pc = node->__rb_parent_color; + tmp = __rb_parent(pc); + __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; + } + tmp = successor; + } + + augment->propagate(tmp, NULL); + return rebalance; +} + +static __always_inline void +rb_erase_augmented(struct rb_node *node, struct rb_root *root, + const struct rb_augment_callbacks *augment) +{ + struct rb_node *rebalance = __rb_erase_augmented(node, root, augment); + if (rebalance) + __rb_erase_color(rebalance, root, augment->rotate); +} + +#endif /* _LINUX_RBTREE_AUGMENTED_H */ -- 2.12.0 _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx https://lists.xen.org/xen-devel
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