Date: Mon, 10 Feb 2025 20:20:07 GMT From: Doug Moore <dougm@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-main@FreeBSD.org Subject: git: 90710f4a3473 - main - pctrie: add parent pointer to nodes Message-ID: <202502102020.51AKK7Ig036651@gitrepo.freebsd.org>
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The branch main has been updated by dougm: URL: https://cgit.FreeBSD.org/src/commit/?id=90710f4a3473f7cf0dd1cfa17a7c3176cc471c71 commit 90710f4a3473f7cf0dd1cfa17a7c3176cc471c71 Author: Doug Moore <dougm@FreeBSD.org> AuthorDate: 2025-02-10 20:17:28 +0000 Commit: Doug Moore <dougm@FreeBSD.org> CommitDate: 2025-02-10 20:17:28 +0000 pctrie: add parent pointer to nodes Add a parent pointer field to the pctrie_node struct, and maintain it as part of inserting and removing pctrie items. Much code is written to maintain one, or an array, of trailing pointers; that maintenance can be dropped with parent pointers available. Code affected includes remove, reclaim, lookup_le, and lookup_ge. In places, functions written once for iterator-free searching and again for iterator-maintaining searching can be replaced with a single function that serves both purposes. Fix an overflow error in lower-bound testing for lookup_le. Reviewed by: markj Tested by: pho Differential Revision: https://reviews.freebsd.org/D48588 --- sys/kern/subr_pctrie.c | 656 ++++++++++++++++--------------------------------- sys/sys/pctrie.h | 162 +++++------- 2 files changed, 268 insertions(+), 550 deletions(-) diff --git a/sys/kern/subr_pctrie.c b/sys/kern/subr_pctrie.c index a078f0587f37..16690c3521bf 100644 --- a/sys/kern/subr_pctrie.c +++ b/sys/kern/subr_pctrie.c @@ -81,6 +81,7 @@ struct pctrie_node { uint64_t pn_owner; /* Owner of record. */ pn_popmap_t pn_popmap; /* Valid children. */ uint8_t pn_clev; /* Level * WIDTH. */ + smr_pctnode_t pn_parent; /* Parent node. */ smr_pctnode_t pn_child[PCTRIE_COUNT]; /* Child nodes. */ }; @@ -107,28 +108,6 @@ pctrie_keybarr(struct pctrie_node *node, uint64_t index, int *slot) return (false); } -/* - * Check radix node. - */ -static __inline void -pctrie_node_put(struct pctrie_node *node) -{ -#ifdef INVARIANTS - int slot; - - KASSERT(powerof2(node->pn_popmap), - ("pctrie_node_put: node %p has too many children %04x", node, - node->pn_popmap)); - for (slot = 0; slot < PCTRIE_COUNT; slot++) { - if ((node->pn_popmap & (1 << slot)) != 0) - continue; - KASSERT(smr_unserialized_load(&node->pn_child[slot], true) == - PCTRIE_NULL, - ("pctrie_node_put: node %p has a child", node)); - } -#endif -} - enum pctrie_access { PCTRIE_SMR, PCTRIE_LOCKED, PCTRIE_UNSERIALIZED }; /* @@ -185,6 +164,16 @@ pctrie_root_load(struct pctrie *ptree, smr_t smr, enum pctrie_access access) return (pctrie_node_load(pctrie_root(ptree), smr, access)); } +/* + * Get the child of a node. + */ +static __inline smr_pctnode_t * +pctrie_child(struct pctrie *ptree, struct pctrie_node *node, uint64_t index) +{ + return (node == NULL ? pctrie_root(ptree) : + &node->pn_child[pctrie_slot(node, index)]); +} + /* * Returns TRUE if the specified node is a leaf and FALSE otherwise. */ @@ -221,6 +210,24 @@ pctrie_toptr(struct pctrie_node *node, int keyoff) return ((void *)(((uintptr_t)node & ~PCTRIE_FLAGS) - keyoff)); } +/* + * Make 'parent' a parent of 'child'. + */ +static __inline void +pctrie_setparent(struct pctrie_node *child, struct pctrie_node *parent) +{ + pctrie_node_store(&child->pn_parent, parent, PCTRIE_UNSERIALIZED); +} + +/* + * Return the parent of 'node'. + */ +static __inline struct pctrie_node * +pctrie_parent(struct pctrie_node *node) +{ + return (pctrie_node_load(&node->pn_parent, NULL, PCTRIE_UNSERIALIZED)); +} + /* * Make 'child' a child of 'node'. */ @@ -260,12 +267,6 @@ pctrie_node_size(void) return (sizeof(struct pctrie_node)); } -enum pctrie_insert_neighbor_mode { - PCTRIE_INSERT_NEIGHBOR_NONE, - PCTRIE_INSERT_NEIGHBOR_LT, - PCTRIE_INSERT_NEIGHBOR_GT, -}; - /* * Look for where to insert the key-value pair into the trie. Complete the * insertion if it replaces a null leaf. Return the insertion location if the @@ -273,19 +274,10 @@ enum pctrie_insert_neighbor_mode { * * If the key is already present in the trie, populate *found_out as if by * pctrie_lookup(). - * - * With mode PCTRIE_INSERT_NEIGHBOR_GT or PCTRIE_INSERT_NEIGHBOR_LT, set - * *neighbor_out to the lowest level node we encounter during the insert lookup - * that is a parent of the next greater or lesser entry. The value is not - * defined if the key was already present in the trie. - * - * Note that mode is expected to be a compile-time constant, and this procedure - * is expected to be inlined into callers with extraneous code optimized out. */ static __always_inline void * pctrie_insert_lookup_compound(struct pctrie *ptree, uint64_t *val, - uint64_t **found_out, struct pctrie_node **neighbor_out, - enum pctrie_insert_neighbor_mode mode) + struct pctrie_node **parent_out, uint64_t **found_out) { uint64_t index; struct pctrie_node *node, *parent; @@ -308,51 +300,29 @@ pctrie_insert_lookup_compound(struct pctrie *ptree, uint64_t *val, else pctrie_addnode(parent, index, pctrie_toleaf(val), PCTRIE_LOCKED); + *parent_out = parent; return (NULL); } if (*pctrie_toval(node) == index) { *found_out = pctrie_toval(node); + *parent_out = parent; return (NULL); } break; } if (pctrie_keybarr(node, index, &slot)) break; - /* - * Descend. If we're tracking the next neighbor and this node - * contains a neighboring entry in the right direction, record - * it. - */ - if (mode == PCTRIE_INSERT_NEIGHBOR_LT) { - if ((node->pn_popmap & ((1 << slot) - 1)) != 0) - *neighbor_out = node; - } else if (mode == PCTRIE_INSERT_NEIGHBOR_GT) { - if ((node->pn_popmap >> slot) > 1) - *neighbor_out = node; - } parent = node; node = pctrie_node_load(&node->pn_child[slot], NULL, PCTRIE_LOCKED); } - /* - * The caller will split this node. If we're tracking the next - * neighbor, record the old node if the old entry is in the right - * direction. - */ - if (mode == PCTRIE_INSERT_NEIGHBOR_LT) { - if (*pctrie_toval(node) < index) - *neighbor_out = node; - } else if (mode == PCTRIE_INSERT_NEIGHBOR_GT) { - if (*pctrie_toval(node) > index) - *neighbor_out = node; - } - /* * 'node' must be replaced in the tree with a new branch node, with * children 'node' and 'val'. Return the place that points to 'node' * now, and will point to to the new branching node later. */ + *parent_out = parent; return ((parent == NULL) ? pctrie_root(ptree): &parent->pn_child[slot]); } @@ -361,14 +331,15 @@ pctrie_insert_lookup_compound(struct pctrie *ptree, uint64_t *val, * if the key already exists, and do not look for neighboring entries. */ void * -pctrie_insert_lookup_strict(struct pctrie *ptree, uint64_t *val) +pctrie_insert_lookup_strict(struct pctrie *ptree, uint64_t *val, + struct pctrie_node **parent_out) { void *parentp; uint64_t *found; found = NULL; - parentp = pctrie_insert_lookup_compound(ptree, val, &found, NULL, - PCTRIE_INSERT_NEIGHBOR_NONE); + parentp = pctrie_insert_lookup_compound(ptree, val, parent_out, + &found); if (__predict_false(found != NULL)) panic("%s: key %jx is already present", __func__, (uintmax_t)*val); @@ -381,71 +352,47 @@ pctrie_insert_lookup_strict(struct pctrie *ptree, uint64_t *val) */ void * pctrie_insert_lookup(struct pctrie *ptree, uint64_t *val, - uint64_t **found_out) -{ - *found_out = NULL; - return (pctrie_insert_lookup_compound(ptree, val, found_out, NULL, - PCTRIE_INSERT_NEIGHBOR_NONE)); -} - -/* - * Wrap pctrie_insert_lookup_compound to implement find or insert and find next - * greater entry. Find a subtree that contains the next entry greater than the - * newly-inserted or to-be-inserted entry. - */ -void * -pctrie_insert_lookup_gt(struct pctrie *ptree, uint64_t *val, - uint64_t **found_out, struct pctrie_node **neighbor_out) + struct pctrie_node **parent_out, uint64_t **found_out) { *found_out = NULL; - *neighbor_out = NULL; - return (pctrie_insert_lookup_compound(ptree, val, found_out, - neighbor_out, PCTRIE_INSERT_NEIGHBOR_GT)); + return (pctrie_insert_lookup_compound(ptree, val, parent_out, + found_out)); } /* - * Wrap pctrie_insert_lookup_compound to implement find or insert and find next - * lesser entry. Find a subtree that contains the next entry less than the - * newly-inserted or to-be-inserted entry. - */ -void * -pctrie_insert_lookup_lt(struct pctrie *ptree, uint64_t *val, - uint64_t **found_out, struct pctrie_node **neighbor_out) -{ - *found_out = NULL; - *neighbor_out = NULL; - return (pctrie_insert_lookup_compound(ptree, val, found_out, - neighbor_out, PCTRIE_INSERT_NEIGHBOR_LT)); -} - -/* - * Uses new node to insert key-value pair into the trie at given location. + * Inserts newly allocated node 'child' into trie at location 'parentp', with + * parent 'parent' and two children, 'val' and whatever non-NULL node or leaf + * was at 'parentp' to begin with. */ void -pctrie_insert_node(void *parentp, struct pctrie_node *parent, uint64_t *val) +pctrie_insert_node(uint64_t *val, struct pctrie_node *parent, void *parentp, + struct pctrie_node *child) { struct pctrie_node *node; uint64_t index, newind; /* - * Clear the last child pointer of the newly allocated parent. We want + * Clear the last child pointer of the newly allocated child. We want * to clear it after the final section has exited so lookup can not * return false negatives. It is done here because it will be * cache-cold in the dtor callback. */ - if (parent->pn_popmap != 0) { - pctrie_node_store(&parent->pn_child[ffs(parent->pn_popmap) - 1], + if (child->pn_popmap != 0) { + pctrie_node_store(&child->pn_child[ffs(child->pn_popmap) - 1], PCTRIE_NULL, PCTRIE_UNSERIALIZED); - parent->pn_popmap = 0; + child->pn_popmap = 0; } /* - * Recover the values of the two children of the new parent node. If + * Recover the values of the two children of the new child node. If * 'node' is not a leaf, this stores into 'newind' the 'owner' field, * which must be first in the node. */ index = *val; node = pctrie_node_load(parentp, NULL, PCTRIE_UNSERIALIZED); + pctrie_setparent(child, parent); + if (!pctrie_isleaf(node)) + pctrie_setparent(node, child); newind = *pctrie_toval(node); /* @@ -456,17 +403,17 @@ pctrie_insert_node(void *parentp, struct pctrie_node *parent, uint64_t *val) _Static_assert(sizeof(long long) >= sizeof(uint64_t), "uint64 too wide"); _Static_assert(sizeof(uint64_t) * NBBY <= - (1 << (sizeof(parent->pn_clev) * NBBY)), "pn_clev too narrow"); - parent->pn_clev = rounddown(ilog2(index ^ newind), PCTRIE_WIDTH); - parent->pn_owner = PCTRIE_COUNT; - parent->pn_owner = index & -(parent->pn_owner << parent->pn_clev); + (1 << (sizeof(child->pn_clev) * NBBY)), "pn_clev too narrow"); + child->pn_clev = rounddown(ilog2(index ^ newind), PCTRIE_WIDTH); + child->pn_owner = PCTRIE_COUNT; + child->pn_owner = index & -(child->pn_owner << child->pn_clev); /* These writes are not yet visible due to ordering. */ - pctrie_addnode(parent, index, pctrie_toleaf(val), PCTRIE_UNSERIALIZED); - pctrie_addnode(parent, newind, node, PCTRIE_UNSERIALIZED); + pctrie_addnode(child, index, pctrie_toleaf(val), PCTRIE_UNSERIALIZED); + pctrie_addnode(child, newind, node, PCTRIE_UNSERIALIZED); /* Synchronize to make the above visible. */ - pctrie_node_store(parentp, parent, PCTRIE_LOCKED); + pctrie_node_store(parentp, child, PCTRIE_LOCKED); } /* @@ -531,41 +478,44 @@ pctrie_lookup_unlocked(struct pctrie *ptree, uint64_t index, smr_t smr) } /* - * Returns the last node examined in the search for the index, and updates the - * search path to that node. + * Returns the last node examined in the search for the index, and sets the + * parent of that node. */ static __always_inline struct pctrie_node * -_pctrie_iter_lookup_node(struct pctrie_iter *it, uint64_t index, smr_t smr, - enum pctrie_access access) +_pctrie_lookup_node(struct pctrie *ptree, struct pctrie_node *node, + uint64_t index, struct pctrie_node **parent_out, + smr_t smr, enum pctrie_access access) { - struct pctrie_node *node; + struct pctrie_node *parent; int slot; /* * Climb the search path to find the lowest node from which to start the * search for a value matching 'index'. */ - while (it->top != 0) { - node = it->path[it->top - 1]; + while (node != NULL) { KASSERT(!powerof2(node->pn_popmap), ("%s: freed node in iter path", __func__)); - if (!pctrie_keybarr(node, index, &slot)) { - node = pctrie_node_load( - &node->pn_child[slot], smr, access); + if (!pctrie_keybarr(node, index, &slot)) break; - } - --it->top; + node = pctrie_parent(node); + } + + if (node == NULL) { + parent = NULL; + node = pctrie_root_load(ptree, smr, access); + } else { + parent = node; + node = pctrie_node_load(&node->pn_child[slot], smr, access); } - if (it->top == 0) - node = pctrie_root_load(it->ptree, smr, access); /* Seek a node that matches index. */ while (!pctrie_isleaf(node) && !pctrie_keybarr(node, index, &slot)) { - KASSERT(it->top < nitems(it->path), - ("%s: path overflow in trie %p", __func__, it->ptree)); - it->path[it->top++] = node; + parent = node; node = pctrie_node_load(&node->pn_child[slot], smr, access); } + if (parent_out != NULL) + *parent_out = parent; return (node); } @@ -579,7 +529,8 @@ _pctrie_iter_lookup(struct pctrie_iter *it, uint64_t index, smr_t smr, struct pctrie_node *node; it->index = index; - node = _pctrie_iter_lookup_node(it, index, smr, access); + node = _pctrie_lookup_node(it->ptree, it->node, index, &it->node, + smr, access); return (pctrie_match_value(node, index)); } @@ -603,13 +554,14 @@ pctrie_iter_insert_lookup(struct pctrie_iter *it, uint64_t *val) struct pctrie_node *node; it->index = *val; - node = _pctrie_iter_lookup_node(it, *val, NULL, PCTRIE_LOCKED); + node = _pctrie_lookup_node(it->ptree, it->node, *val, &it->node, + NULL, PCTRIE_LOCKED); if (node == PCTRIE_NULL) { - if (it->top == 0) + if (it->node == NULL) pctrie_node_store(pctrie_root(it->ptree), pctrie_toleaf(val), PCTRIE_LOCKED); else - pctrie_addnode(it->path[it->top - 1], it->index, + pctrie_addnode(it->node, it->index, pctrie_toleaf(val), PCTRIE_LOCKED); return (NULL); } @@ -622,10 +574,7 @@ pctrie_iter_insert_lookup(struct pctrie_iter *it, uint64_t *val) * children 'node' and 'val'. Return the place that points to 'node' * now, and will point to to the new branching node later. */ - if (it->top == 0) - return (pctrie_root(it->ptree)); - node = it->path[it->top - 1]; - return (&node->pn_child[pctrie_slot(node, it->index)]); + return (pctrie_child(it->ptree, it->node, it->index)); } /* @@ -678,122 +627,21 @@ pctrie_iter_prev(struct pctrie_iter *it) return (_pctrie_iter_stride(it, -1, NULL, PCTRIE_LOCKED)); } -/* - * Returns the value with the least index that is greater than or equal to the - * specified index, or NULL if there are no such values. - * - * Requires that access be externally synchronized by a lock. - */ -static __inline uint64_t * -pctrie_lookup_ge_node(struct pctrie_node *node, uint64_t index) -{ - struct pctrie_node *succ; - uint64_t *m; - int slot; - - /* - * Descend the trie as if performing an ordinary lookup for the - * specified value. However, unlike an ordinary lookup, as we descend - * the trie, we use "succ" to remember the last branching-off point, - * that is, the interior node under which the least value that is both - * outside our current path down the trie and greater than the specified - * index resides. (The node's popmap makes it fast and easy to - * recognize a branching-off point.) If our ordinary lookup fails to - * yield a value that is greater than or equal to the specified index, - * then we will exit this loop and perform a lookup starting from - * "succ". If "succ" is not NULL, then that lookup is guaranteed to - * succeed. - */ - succ = NULL; - for (;;) { - if (pctrie_isleaf(node)) { - if ((m = pctrie_toval(node)) != NULL && *m >= index) - return (m); - break; - } - if (pctrie_keybarr(node, index, &slot)) { - /* - * If all values in this subtree are > index, then the - * least value in this subtree is the answer. - */ - if (node->pn_owner > index) - succ = node; - break; - } - - /* - * Just in case the next search step leads to a subtree of all - * values < index, check popmap to see if a next bigger step, to - * a subtree of all pages with values > index, is available. If - * so, remember to restart the search here. - */ - if ((node->pn_popmap >> slot) > 1) - succ = node; - node = pctrie_node_load(&node->pn_child[slot], NULL, - PCTRIE_LOCKED); - } - - /* - * Restart the search from the last place visited in the subtree that - * included some values > index, if there was such a place. - */ - if (succ == NULL) - return (NULL); - if (succ != node) { - /* - * Take a step to the next bigger sibling of the node chosen - * last time. In that subtree, all values > index. - */ - slot = pctrie_slot(succ, index) + 1; - KASSERT((succ->pn_popmap >> slot) != 0, - ("%s: no popmap siblings past slot %d in node %p", - __func__, slot, succ)); - slot += ffs(succ->pn_popmap >> slot) - 1; - succ = pctrie_node_load(&succ->pn_child[slot], NULL, - PCTRIE_LOCKED); - } - - /* - * Find the value in the subtree rooted at "succ" with the least index. - */ - while (!pctrie_isleaf(succ)) { - KASSERT(succ->pn_popmap != 0, - ("%s: no popmap children in node %p", __func__, succ)); - slot = ffs(succ->pn_popmap) - 1; - succ = pctrie_node_load(&succ->pn_child[slot], NULL, - PCTRIE_LOCKED); - } - return (pctrie_toval(succ)); -} - -uint64_t * -pctrie_lookup_ge(struct pctrie *ptree, uint64_t index) -{ - return (pctrie_lookup_ge_node( - pctrie_root_load(ptree, NULL, PCTRIE_LOCKED), index)); -} - -uint64_t * -pctrie_subtree_lookup_gt(struct pctrie_node *node, uint64_t index) -{ - if (node == NULL || index + 1 == 0) - return (NULL); - return (pctrie_lookup_ge_node(node, index + 1)); -} - /* * Find first leaf >= index, and fill iter with the path to the parent of that * leaf. Return NULL if there is no such leaf less than limit. */ -uint64_t * -pctrie_iter_lookup_ge(struct pctrie_iter *it, uint64_t index) +static __inline uint64_t * +_pctrie_lookup_ge(struct pctrie *ptree, struct pctrie_node *node, + uint64_t index, struct pctrie_node **parent_out, uint64_t limit) { - struct pctrie_node *node; + struct pctrie_node *parent; uint64_t *m; int slot; /* Seek a node that matches index. */ - node = _pctrie_iter_lookup_node(it, index, NULL, PCTRIE_LOCKED); + node = _pctrie_lookup_node(ptree, node, index, &parent, + NULL, PCTRIE_LOCKED); /* * If no such node was found, and instead this path leads only to nodes @@ -801,36 +649,58 @@ pctrie_iter_lookup_ge(struct pctrie_iter *it, uint64_t index) */ if (node == PCTRIE_NULL || *pctrie_toval(node) < index) { /* Climb the path to find a node with a descendant > index. */ - while (it->top != 0) { - node = it->path[it->top - 1]; + for (node = parent; node != NULL; node = pctrie_parent(node)) { slot = pctrie_slot(node, index) + 1; if ((node->pn_popmap >> slot) != 0) break; - --it->top; } - if (it->top == 0) + if (node == NULL) { + if (parent_out != NULL) + *parent_out = NULL; return (NULL); + } /* Step to the least child with a descendant > index. */ slot += ffs(node->pn_popmap >> slot) - 1; + parent = node; node = pctrie_node_load(&node->pn_child[slot], NULL, PCTRIE_LOCKED); } /* Descend to the least leaf of the subtrie. */ while (!pctrie_isleaf(node)) { - if (it->limit != 0 && node->pn_owner >= it->limit) + if (limit != 0 && node->pn_owner >= limit) return (NULL); slot = ffs(node->pn_popmap) - 1; - KASSERT(it->top < nitems(it->path), - ("%s: path overflow in trie %p", __func__, it->ptree)); - it->path[it->top++] = node; + parent = node; node = pctrie_node_load(&node->pn_child[slot], NULL, PCTRIE_LOCKED); } + if (parent_out != NULL) + *parent_out = parent; m = pctrie_toval(node); - if (it->limit != 0 && *m >= it->limit) + if (limit != 0 && *m >= limit) return (NULL); - it->index = *m; + return (m); +} + +uint64_t * +pctrie_lookup_ge(struct pctrie *ptree, uint64_t index) +{ + return (_pctrie_lookup_ge(ptree, NULL, index, NULL, 0)); +} + +/* + * Find first leaf >= index, and fill iter with the path to the parent of that + * leaf. Return NULL if there is no such leaf less than limit. + */ +uint64_t * +pctrie_iter_lookup_ge(struct pctrie_iter *it, uint64_t index) +{ + uint64_t *m; + + m = _pctrie_lookup_ge(it->ptree, it->node, index, &it->node, it->limit); + if (m != NULL) + it->index = *m; return (m); } @@ -851,91 +721,76 @@ pctrie_iter_jump_ge(struct pctrie_iter *it, int64_t jump) return (pctrie_iter_lookup_ge(it, index)); } -#ifdef INVARIANTS -void -pctrie_subtree_lookup_gt_assert(struct pctrie_node *node, uint64_t index, - struct pctrie *ptree, uint64_t *res) -{ - uint64_t *expected; - - if (index + 1 == 0) - expected = NULL; - else - expected = pctrie_lookup_ge(ptree, index + 1); - KASSERT(res == expected, - ("pctrie subtree lookup gt result different from root lookup: " - "ptree %p, index %ju, subtree %p, found %p, expected %p", ptree, - (uintmax_t)index, node, res, expected)); -} -#endif - /* - * Returns the value with the greatest index that is less than or equal to the - * specified index, or NULL if there are no such values. - * - * Requires that access be externally synchronized by a lock. + * Find first leaf <= index, and fill iter with the path to the parent of that + * leaf. Return NULL if there is no such leaf greater than limit. */ static __inline uint64_t * -pctrie_lookup_le_node(struct pctrie_node *node, uint64_t index) +_pctrie_lookup_le(struct pctrie *ptree, struct pctrie_node *node, + uint64_t index, struct pctrie_node **parent_out, uint64_t limit) { - struct pctrie_node *pred; + struct pctrie_node *parent; uint64_t *m; int slot; + /* Seek a node that matches index. */ + node = _pctrie_lookup_node(ptree, node, index, &parent, NULL, + PCTRIE_LOCKED); + /* - * Mirror the implementation of pctrie_lookup_ge_node, described above. + * If no such node was found, and instead this path leads only to nodes + * > index, back up to find a subtrie with the greatest value < index. */ - pred = NULL; - for (;;) { - if (pctrie_isleaf(node)) { - if ((m = pctrie_toval(node)) != NULL && *m <= index) - return (m); - break; + if (node == PCTRIE_NULL || *pctrie_toval(node) > index) { + /* Climb the path to find a node with a descendant < index. */ + for (node = parent; node != NULL; node = pctrie_parent(node)) { + slot = pctrie_slot(node, index); + if ((node->pn_popmap & ((1 << slot) - 1)) != 0) + break; } - if (pctrie_keybarr(node, index, &slot)) { - if (node->pn_owner < index) - pred = node; - break; + if (node == NULL) { + if (parent_out != NULL) + *parent_out = NULL; + return (NULL); } - if ((node->pn_popmap & ((1 << slot) - 1)) != 0) - pred = node; + + /* Step to the greatest child with a descendant < index. */ + slot = ilog2(node->pn_popmap & ((1 << slot) - 1)); + parent = node; node = pctrie_node_load(&node->pn_child[slot], NULL, PCTRIE_LOCKED); } - if (pred == NULL) - return (NULL); - if (pred != node) { - slot = pctrie_slot(pred, index); - KASSERT((pred->pn_popmap & ((1 << slot) - 1)) != 0, - ("%s: no popmap siblings before slot %d in node %p", - __func__, slot, pred)); - slot = ilog2(pred->pn_popmap & ((1 << slot) - 1)); - pred = pctrie_node_load(&pred->pn_child[slot], NULL, - PCTRIE_LOCKED); - } - while (!pctrie_isleaf(pred)) { - KASSERT(pred->pn_popmap != 0, - ("%s: no popmap children in node %p", __func__, pred)); - slot = ilog2(pred->pn_popmap); - pred = pctrie_node_load(&pred->pn_child[slot], NULL, + /* Descend to the greatest leaf of the subtrie. */ + while (!pctrie_isleaf(node)) { + if (limit != 0 && limit >= node->pn_owner + + ((uint64_t)PCTRIE_COUNT << node->pn_clev) - 1) + return (NULL); + slot = ilog2(node->pn_popmap); + parent = node; + node = pctrie_node_load(&node->pn_child[slot], NULL, PCTRIE_LOCKED); } - return (pctrie_toval(pred)); + if (parent_out != NULL) + *parent_out = parent; + m = pctrie_toval(node); + if (limit != 0 && *m <= limit) + return (NULL); + return (m); } uint64_t * pctrie_lookup_le(struct pctrie *ptree, uint64_t index) { - return (pctrie_lookup_le_node( - pctrie_root_load(ptree, NULL, PCTRIE_LOCKED), index)); + return (_pctrie_lookup_le(ptree, NULL, index, NULL, 0)); } uint64_t * -pctrie_subtree_lookup_lt(struct pctrie_node *node, uint64_t index) +pctrie_subtree_lookup_lt(struct pctrie *ptree, struct pctrie_node *node, + uint64_t index) { - if (node == NULL || index == 0) + if (index == 0) return (NULL); - return (pctrie_lookup_le_node(node, index - 1)); + return (_pctrie_lookup_le(ptree, node, index - 1, NULL, 0)); } /* @@ -945,50 +800,11 @@ pctrie_subtree_lookup_lt(struct pctrie_node *node, uint64_t index) uint64_t * pctrie_iter_lookup_le(struct pctrie_iter *it, uint64_t index) { - struct pctrie_node *node; uint64_t *m; - int slot; - - /* Seek a node that matches index. */ - node = _pctrie_iter_lookup_node(it, index, NULL, PCTRIE_LOCKED); - /* - * If no such node was found, and instead this path leads only to nodes - * > index, back up to find a subtrie with the greatest value < index. - */ - if (node == PCTRIE_NULL || *pctrie_toval(node) > index) { - /* Climb the path to find a node with a descendant < index. */ - while (it->top != 0) { - node = it->path[it->top - 1]; - slot = pctrie_slot(node, index); - if ((node->pn_popmap & ((1 << slot) - 1)) != 0) - break; - --it->top; - } - if (it->top == 0) - return (NULL); - - /* Step to the greatest child with a descendant < index. */ - slot = ilog2(node->pn_popmap & ((1 << slot) - 1)); - node = pctrie_node_load(&node->pn_child[slot], NULL, - PCTRIE_LOCKED); - } - /* Descend to the greatest leaf of the subtrie. */ - while (!pctrie_isleaf(node)) { - if (it->limit != 0 && it->limit >= - node->pn_owner + (PCTRIE_COUNT << node->pn_clev) - 1) - return (NULL); - slot = ilog2(node->pn_popmap); - KASSERT(it->top < nitems(it->path), - ("%s: path overflow in trie %p", __func__, it->ptree)); - it->path[it->top++] = node; - node = pctrie_node_load(&node->pn_child[slot], NULL, - PCTRIE_LOCKED); - } - m = pctrie_toval(node); - if (it->limit != 0 && *m <= it->limit) - return (NULL); - it->index = *m; + m = _pctrie_lookup_le(it->ptree, it->node, index, &it->node, it->limit); + if (m != NULL) + it->index = *m; return (m); } @@ -1009,35 +825,27 @@ pctrie_iter_jump_le(struct pctrie_iter *it, int64_t jump) return (pctrie_iter_lookup_le(it, index)); } -#ifdef INVARIANTS -void -pctrie_subtree_lookup_lt_assert(struct pctrie_node *node, uint64_t index, - struct pctrie *ptree, uint64_t *res) -{ - uint64_t *expected; - - if (index == 0) - expected = NULL; - else - expected = pctrie_lookup_le(ptree, index - 1); - KASSERT(res == expected, - ("pctrie subtree lookup lt result different from root lookup: " - "ptree %p, index %ju, subtree %p, found %p, expected %p", ptree, - (uintmax_t)index, node, res, expected)); -} -#endif - -static void -pctrie_remove(struct pctrie *ptree, uint64_t index, struct pctrie_node *parent, - struct pctrie_node *node, struct pctrie_node **freenode) +/* + * If 'child', a leaf and a child of 'parent', is not NULL and has key 'index', + * then remove it from the pctrie and return its value. If doing so produces an + * internal node with only one child, purge it from the pctrie and save it in + * *freenode for later disposal. + */ +static uint64_t * +pctrie_remove(struct pctrie *ptree, struct pctrie_node *node, uint64_t index, + struct pctrie_node *child, struct pctrie_node **freenode) { - struct pctrie_node *child; + uint64_t *m; int slot; + *freenode = NULL; + m = pctrie_match_value(child, index); + if (m == NULL) + return (m); if (node == NULL) { pctrie_node_store(pctrie_root(ptree), PCTRIE_NULL, PCTRIE_LOCKED); - return; + return (m); } slot = pctrie_slot(node, index); KASSERT((node->pn_popmap & (1 << slot)) != 0, @@ -1046,28 +854,19 @@ pctrie_remove(struct pctrie *ptree, uint64_t index, struct pctrie_node *parent, node->pn_popmap ^= 1 << slot; pctrie_node_store(&node->pn_child[slot], PCTRIE_NULL, PCTRIE_LOCKED); if (!powerof2(node->pn_popmap)) - return; + return (m); KASSERT(node->pn_popmap != 0, ("%s: bad popmap all zeroes", __func__)); slot = ffs(node->pn_popmap) - 1; child = pctrie_node_load(&node->pn_child[slot], NULL, PCTRIE_LOCKED); KASSERT(child != PCTRIE_NULL, ("%s: bad popmap slot %d in node %p", __func__, slot, node)); - if (parent == NULL) - pctrie_node_store(pctrie_root(ptree), child, PCTRIE_LOCKED); - else { - slot = pctrie_slot(parent, index); - KASSERT(node == - pctrie_node_load(&parent->pn_child[slot], NULL, - PCTRIE_LOCKED), ("%s: invalid child value", __func__)); - pctrie_node_store(&parent->pn_child[slot], child, - PCTRIE_LOCKED); - } - /* - * The child is still valid and we can not zero the - * pointer until all SMR references are gone. - */ - pctrie_node_put(node); *freenode = node; + node = pctrie_parent(node); + if (!pctrie_isleaf(child)) + pctrie_setparent(child, node); + pctrie_node_store(pctrie_child(ptree, node, index), child, + PCTRIE_LOCKED); + return (m); } /* @@ -1078,24 +877,18 @@ uint64_t * pctrie_remove_lookup(struct pctrie *ptree, uint64_t index, struct pctrie_node **freenode) { - struct pctrie_node *child, *node, *parent; - uint64_t *m; + struct pctrie_node *child, *node; int slot; - DEBUG_POISON_POINTER(parent); - *freenode = node = NULL; + node = NULL; child = pctrie_root_load(ptree, NULL, PCTRIE_LOCKED); while (!pctrie_isleaf(child)) { - parent = node; node = child; slot = pctrie_slot(node, index); child = pctrie_node_load(&node->pn_child[slot], NULL, PCTRIE_LOCKED); } - m = pctrie_match_value(child, index); - if (m != NULL) - pctrie_remove(ptree, index, parent, node, freenode); - return (m); + return (pctrie_remove(ptree, node, index, child, freenode)); } /* @@ -1105,27 +898,14 @@ pctrie_remove_lookup(struct pctrie *ptree, uint64_t index, uint64_t * pctrie_iter_remove(struct pctrie_iter *it, struct pctrie_node **freenode) { - struct pctrie_node *child, *node, *parent; + struct pctrie_node *child; uint64_t *m; - int slot; - DEBUG_POISON_POINTER(parent); - *freenode = NULL; - if (it->top >= 1) { - parent = (it->top >= 2) ? it->path[it->top - 2] : NULL; - node = it->path[it->top - 1]; - slot = pctrie_slot(node, it->index); - child = pctrie_node_load(&node->pn_child[slot], NULL, - PCTRIE_LOCKED); - } else { - node = NULL; - child = pctrie_root_load(it->ptree, NULL, PCTRIE_LOCKED); - } - m = pctrie_match_value(child, it->index); - if (m != NULL) - pctrie_remove(it->ptree, it->index, parent, node, freenode); + child = pctrie_node_load(pctrie_child(it->ptree, it->node, it->index), + NULL, PCTRIE_LOCKED); + m = pctrie_remove(it->ptree, it->node, it->index, child, freenode); if (*freenode != NULL) - --it->top; + it->node = pctrie_parent(it->node); return (m); } @@ -1137,25 +917,16 @@ uint64_t * pctrie_iter_value(struct pctrie_iter *it) { struct pctrie_node *node; - int slot; - if (it->top == 0) - node = pctrie_root_load(it->ptree, NULL, - PCTRIE_LOCKED); - else { - node = it->path[it->top - 1]; - slot = pctrie_slot(node, it->index); *** 319 LINES SKIPPED ***
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