/*- * SPDX-License-Identifier: BSD-2-Clause-FreeBSD * * Copyright (c) 2013 EMC Corp. * Copyright (c) 2011 Jeffrey Roberson * Copyright (c) 2008 Mayur Shardul * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. * */ /* * Path-compressed radix trie implementation. * * The implementation takes into account the following rationale: * - Size of the nodes should be as small as possible but still big enough * to avoid a large maximum depth for the trie. This is a balance * between the necessity to not wire too much physical memory for the nodes * and the necessity to avoid too much cache pollution during the trie * operations. * - There is not a huge bias toward the number of lookup operations over * the number of insert and remove operations. This basically implies * that optimizations supposedly helping one operation but hurting the * other might be carefully evaluated. * - On average not many nodes are expected to be fully populated, hence * level compression may just complicate things. */ #include __FBSDID("$FreeBSD$"); #include "opt_ddb.h" #include #include #include #include #include /* smr.h depends on struct thread. */ #include #include #ifdef DDB #include #endif #define PCTRIE_MASK (PCTRIE_COUNT - 1) #define PCTRIE_LIMIT (howmany(sizeof(uint64_t) * NBBY, PCTRIE_WIDTH) - 1) /* Flag bits stored in node pointers. */ #define PCTRIE_ISLEAF 0x1 #define PCTRIE_FLAGS 0x1 #define PCTRIE_PAD PCTRIE_FLAGS /* Returns one unit associated with specified level. */ #define PCTRIE_UNITLEVEL(lev) \ ((uint64_t)1 << ((lev) * PCTRIE_WIDTH)) struct pctrie_node; typedef SMR_POINTER(struct pctrie_node *) smr_pctnode_t; struct pctrie_node { uint64_t pn_owner; /* Owner of record. */ uint16_t pn_count; /* Valid children. */ uint8_t pn_clev; /* Current level. */ int8_t pn_last; /* Zero last ptr. */ smr_pctnode_t pn_child[PCTRIE_COUNT]; /* Child nodes. */ }; enum pctrie_access { PCTRIE_SMR, PCTRIE_LOCKED, PCTRIE_UNSERIALIZED }; static __inline void pctrie_node_store(smr_pctnode_t *p, void *val, enum pctrie_access access); /* * Allocate a node. Pre-allocation should ensure that the request * will always be satisfied. */ static struct pctrie_node * pctrie_node_get(struct pctrie *ptree, pctrie_alloc_t allocfn, uint64_t owner, uint16_t count, uint16_t clevel) { struct pctrie_node *node; node = allocfn(ptree); if (node == NULL) return (NULL); /* * We want to clear the last child pointer 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 (node->pn_last != 0) { pctrie_node_store(&node->pn_child[node->pn_last - 1], NULL, PCTRIE_UNSERIALIZED); node->pn_last = 0; } node->pn_owner = owner; node->pn_count = count; node->pn_clev = clevel; return (node); } /* * Free radix node. */ static __inline void pctrie_node_put(struct pctrie *ptree, struct pctrie_node *node, pctrie_free_t freefn, int8_t last) { #ifdef INVARIANTS int slot; KASSERT(node->pn_count == 0, ("pctrie_node_put: node %p has %d children", node, node->pn_count)); for (slot = 0; slot < PCTRIE_COUNT; slot++) { if (slot == last) continue; KASSERT(smr_unserialized_load(&node->pn_child[slot], true) == NULL, ("pctrie_node_put: node %p has a child", node)); } #endif node->pn_last = last + 1; freefn(ptree, node); } /* * Return the position in the array for a given level. */ static __inline int pctrie_slot(uint64_t index, uint16_t level) { return ((index >> (level * PCTRIE_WIDTH)) & PCTRIE_MASK); } /* Trims the key after the specified level. */ static __inline uint64_t pctrie_trimkey(uint64_t index, uint16_t level) { uint64_t ret; ret = index; if (level > 0) { ret >>= level * PCTRIE_WIDTH; ret <<= level * PCTRIE_WIDTH; } return (ret); } /* * Fetch a node pointer from a slot. */ static __inline struct pctrie_node * pctrie_node_load(smr_pctnode_t *p, smr_t smr, enum pctrie_access access) { switch (access) { case PCTRIE_UNSERIALIZED: return (smr_unserialized_load(p, true)); case PCTRIE_LOCKED: return (smr_serialized_load(p, true)); case PCTRIE_SMR: return (smr_entered_load(p, smr)); } __assert_unreachable(); } static __inline void pctrie_node_store(smr_pctnode_t *p, void *v, enum pctrie_access access) { switch (access) { case PCTRIE_UNSERIALIZED: smr_unserialized_store(p, v, true); break; case PCTRIE_LOCKED: smr_serialized_store(p, v, true); break; case PCTRIE_SMR: panic("%s: Not supported in SMR section.", __func__); break; default: __assert_unreachable(); break; } } /* * Get the root node for a tree. */ static __inline struct pctrie_node * pctrie_root_load(struct pctrie *ptree, smr_t smr, enum pctrie_access access) { return (pctrie_node_load((smr_pctnode_t *)&ptree->pt_root, smr, access)); } /* * Set the root node for a tree. */ static __inline void pctrie_root_store(struct pctrie *ptree, struct pctrie_node *node, enum pctrie_access access) { pctrie_node_store((smr_pctnode_t *)&ptree->pt_root, node, access); } /* * Returns TRUE if the specified node is a leaf and FALSE otherwise. */ static __inline bool pctrie_isleaf(struct pctrie_node *node) { return (((uintptr_t)node & PCTRIE_ISLEAF) != 0); } /* * Returns the associated val extracted from node. */ static __inline uint64_t * pctrie_toval(struct pctrie_node *node) { return ((uint64_t *)((uintptr_t)node & ~PCTRIE_FLAGS)); } /* * Adds the val as a child of the provided node. */ static __inline void pctrie_addval(struct pctrie_node *node, uint64_t index, uint16_t clev, uint64_t *val, enum pctrie_access access) { int slot; slot = pctrie_slot(index, clev); pctrie_node_store(&node->pn_child[slot], (void *)((uintptr_t)val | PCTRIE_ISLEAF), access); } /* * Returns the slot where two keys differ. * It cannot accept 2 equal keys. */ static __inline uint16_t pctrie_keydiff(uint64_t index1, uint64_t index2) { uint16_t clev; KASSERT(index1 != index2, ("%s: passing the same key value %jx", __func__, (uintmax_t)index1)); index1 ^= index2; for (clev = PCTRIE_LIMIT;; clev--) if (pctrie_slot(index1, clev) != 0) return (clev); } /* * Returns TRUE if it can be determined that key does not belong to the * specified node. Otherwise, returns FALSE. */ static __inline bool pctrie_keybarr(struct pctrie_node *node, uint64_t idx) { if (node->pn_clev < PCTRIE_LIMIT) { idx = pctrie_trimkey(idx, node->pn_clev + 1); return (idx != node->pn_owner); } return (false); } /* * Internal helper for pctrie_reclaim_allnodes(). * This function is recursive. */ static void pctrie_reclaim_allnodes_int(struct pctrie *ptree, struct pctrie_node *node, pctrie_free_t freefn) { struct pctrie_node *child; int slot; KASSERT(node->pn_count <= PCTRIE_COUNT, ("pctrie_reclaim_allnodes_int: bad count in node %p", node)); for (slot = 0; node->pn_count != 0; slot++) { child = pctrie_node_load(&node->pn_child[slot], NULL, PCTRIE_UNSERIALIZED); if (child == NULL) continue; if (!pctrie_isleaf(child)) pctrie_reclaim_allnodes_int(ptree, child, freefn); pctrie_node_store(&node->pn_child[slot], NULL, PCTRIE_UNSERIALIZED); node->pn_count--; } pctrie_node_put(ptree, node, freefn, -1); } /* * pctrie node zone initializer. */ int pctrie_zone_init(void *mem, int size __unused, int flags __unused) { struct pctrie_node *node; node = mem; node->pn_last = 0; memset(node->pn_child, 0, sizeof(node->pn_child)); return (0); } size_t pctrie_node_size(void) { return (sizeof(struct pctrie_node)); } /* * Inserts the key-value pair into the trie. * Panics if the key already exists. */ int pctrie_insert(struct pctrie *ptree, uint64_t *val, pctrie_alloc_t allocfn) { uint64_t index, newind; struct pctrie_node *node, *tmp; smr_pctnode_t *parentp; uint64_t *m; int slot; uint16_t clev; index = *val; /* * The owner of record for root is not really important because it * will never be used. */ node = pctrie_root_load(ptree, NULL, PCTRIE_LOCKED); if (node == NULL) { ptree->pt_root = (uintptr_t)val | PCTRIE_ISLEAF; return (0); } parentp = (smr_pctnode_t *)&ptree->pt_root; for (;;) { if (pctrie_isleaf(node)) { m = pctrie_toval(node); if (*m == index) panic("%s: key %jx is already present", __func__, (uintmax_t)index); clev = pctrie_keydiff(*m, index); tmp = pctrie_node_get(ptree, allocfn, pctrie_trimkey(index, clev + 1), 2, clev); if (tmp == NULL) return (ENOMEM); /* These writes are not yet visible due to ordering. */ pctrie_addval(tmp, index, clev, val, PCTRIE_UNSERIALIZED); pctrie_addval(tmp, *m, clev, m, PCTRIE_UNSERIALIZED); /* Synchronize to make leaf visible. */ pctrie_node_store(parentp, tmp, PCTRIE_LOCKED); return (0); } else if (pctrie_keybarr(node, index)) break; slot = pctrie_slot(index, node->pn_clev); parentp = &node->pn_child[slot]; tmp = pctrie_node_load(parentp, NULL, PCTRIE_LOCKED); if (tmp == NULL) { node->pn_count++; pctrie_addval(node, index, node->pn_clev, val, PCTRIE_LOCKED); return (0); } node = tmp; } /* * A new node is needed because the right insertion level is reached. * Setup the new intermediate node and add the 2 children: the * new object and the older edge. */ newind = node->pn_owner; clev = pctrie_keydiff(newind, index); tmp = pctrie_node_get(ptree, allocfn, pctrie_trimkey(index, clev + 1), 2, clev); if (tmp == NULL) return (ENOMEM); slot = pctrie_slot(newind, clev); /* These writes are not yet visible due to ordering. */ pctrie_addval(tmp, index, clev, val, PCTRIE_UNSERIALIZED); pctrie_node_store(&tmp->pn_child[slot], node, PCTRIE_UNSERIALIZED); /* Synchronize to make the above visible. */ pctrie_node_store(parentp, tmp, PCTRIE_LOCKED); return (0); } /* * Returns the value stored at the index. If the index is not present, * NULL is returned. */ static __always_inline uint64_t * _pctrie_lookup(struct pctrie *ptree, uint64_t index, smr_t smr, enum pctrie_access access) { struct pctrie_node *node; uint64_t *m; int slot; node = pctrie_root_load(ptree, smr, access); while (node != NULL) { if (pctrie_isleaf(node)) { m = pctrie_toval(node); if (*m == index) return (m); break; } if (pctrie_keybarr(node, index)) break; slot = pctrie_slot(index, node->pn_clev); node = pctrie_node_load(&node->pn_child[slot], smr, access); } return (NULL); } /* * Returns the value stored at the index, assuming access is externally * synchronized by a lock. * * If the index is not present, NULL is returned. */ uint64_t * pctrie_lookup(struct pctrie *ptree, uint64_t index) { return (_pctrie_lookup(ptree, index, NULL, PCTRIE_LOCKED)); } /* * Returns the value stored at the index without requiring an external lock. * * If the index is not present, NULL is returned. */ uint64_t * pctrie_lookup_unlocked(struct pctrie *ptree, uint64_t index, smr_t smr) { uint64_t *res; smr_enter(smr); res = _pctrie_lookup(ptree, index, smr, PCTRIE_SMR); smr_exit(smr); return (res); } /* * Look up the nearest entry at a position bigger than or equal to index, * assuming access is externally synchronized by a lock. */ uint64_t * pctrie_lookup_ge(struct pctrie *ptree, uint64_t index) { struct pctrie_node *stack[PCTRIE_LIMIT]; uint64_t inc; uint64_t *m; struct pctrie_node *child, *node; #ifdef INVARIANTS int loops = 0; #endif unsigned tos; int slot; node = pctrie_root_load(ptree, NULL, PCTRIE_LOCKED); if (node == NULL) return (NULL); else if (pctrie_isleaf(node)) { m = pctrie_toval(node); if (*m >= index) return (m); else return (NULL); } tos = 0; for (;;) { /* * If the keys differ before the current bisection node, * then the search key might rollback to the earliest * available bisection node or to the smallest key * in the current node (if the owner is greater than the * search key). */ if (pctrie_keybarr(node, index)) { if (index > node->pn_owner) { ascend: KASSERT(++loops < 1000, ("pctrie_lookup_ge: too many loops")); /* * Pop nodes from the stack until either the * stack is empty or a node that could have a * matching descendant is found. */ do { if (tos == 0) return (NULL); node = stack[--tos]; } while (pctrie_slot(index, node->pn_clev) == (PCTRIE_COUNT - 1)); /* * The following computation cannot overflow * because index's slot at the current level * is less than PCTRIE_COUNT - 1. */ index = pctrie_trimkey(index, node->pn_clev); index += PCTRIE_UNITLEVEL(node->pn_clev); } else index = node->pn_owner; KASSERT(!pctrie_keybarr(node, index), ("pctrie_lookup_ge: keybarr failed")); } slot = pctrie_slot(index, node->pn_clev); child = pctrie_node_load(&node->pn_child[slot], NULL, PCTRIE_LOCKED); if (pctrie_isleaf(child)) { m = pctrie_toval(child); if (*m >= index) return (m); } else if (child != NULL) goto descend; /* * Look for an available edge or val within the current * bisection node. */ if (slot < (PCTRIE_COUNT - 1)) { inc = PCTRIE_UNITLEVEL(node->pn_clev); index = pctrie_trimkey(index, node->pn_clev); do { index += inc; slot++; child = pctrie_node_load(&node->pn_child[slot], NULL, PCTRIE_LOCKED); if (pctrie_isleaf(child)) { m = pctrie_toval(child); if (*m >= index) return (m); } else if (child != NULL) goto descend; } while (slot < (PCTRIE_COUNT - 1)); } KASSERT(child == NULL || pctrie_isleaf(child), ("pctrie_lookup_ge: child is radix node")); /* * If a value or edge greater than the search slot is not found * in the current node, ascend to the next higher-level node. */ goto ascend; descend: KASSERT(node->pn_clev > 0, ("pctrie_lookup_ge: pushing leaf's parent")); KASSERT(tos < PCTRIE_LIMIT, ("pctrie_lookup_ge: stack overflow")); stack[tos++] = node; node = child; } } /* * Look up the nearest entry at a position less than or equal to index, * assuming access is externally synchronized by a lock. */ uint64_t * pctrie_lookup_le(struct pctrie *ptree, uint64_t index) { struct pctrie_node *stack[PCTRIE_LIMIT]; uint64_t inc; uint64_t *m; struct pctrie_node *child, *node; #ifdef INVARIANTS int loops = 0; #endif unsigned tos; int slot; node = pctrie_root_load(ptree, NULL, PCTRIE_LOCKED); if (node == NULL) return (NULL); else if (pctrie_isleaf(node)) { m = pctrie_toval(node); if (*m <= index) return (m); else return (NULL); } tos = 0; for (;;) { /* * If the keys differ before the current bisection node, * then the search key might rollback to the earliest * available bisection node or to the largest key * in the current node (if the owner is smaller than the * search key). */ if (pctrie_keybarr(node, index)) { if (index > node->pn_owner) { index = node->pn_owner + PCTRIE_COUNT * PCTRIE_UNITLEVEL(node->pn_clev); } else { ascend: KASSERT(++loops < 1000, ("pctrie_lookup_le: too many loops")); /* * Pop nodes from the stack until either the * stack is empty or a node that could have a * matching descendant is found. */ do { if (tos == 0) return (NULL); node = stack[--tos]; } while (pctrie_slot(index, node->pn_clev) == 0); /* * The following computation cannot overflow * because index's slot at the current level * is greater than 0. */ index = pctrie_trimkey(index, node->pn_clev); } index--; KASSERT(!pctrie_keybarr(node, index), ("pctrie_lookup_le: keybarr failed")); } slot = pctrie_slot(index, node->pn_clev); child = pctrie_node_load(&node->pn_child[slot], NULL, PCTRIE_LOCKED); if (pctrie_isleaf(child)) { m = pctrie_toval(child); if (*m <= index) return (m); } else if (child != NULL) goto descend; /* * Look for an available edge or value within the current * bisection node. */ if (slot > 0) { inc = PCTRIE_UNITLEVEL(node->pn_clev); index |= inc - 1; do { index -= inc; slot--; child = pctrie_node_load(&node->pn_child[slot], NULL, PCTRIE_LOCKED); if (pctrie_isleaf(child)) { m = pctrie_toval(child); if (*m <= index) return (m); } else if (child != NULL) goto descend; } while (slot > 0); } KASSERT(child == NULL || pctrie_isleaf(child), ("pctrie_lookup_le: child is radix node")); /* * If a value or edge smaller than the search slot is not found * in the current node, ascend to the next higher-level node. */ goto ascend; descend: KASSERT(node->pn_clev > 0, ("pctrie_lookup_le: pushing leaf's parent")); KASSERT(tos < PCTRIE_LIMIT, ("pctrie_lookup_le: stack overflow")); stack[tos++] = node; node = child; } } /* * Remove the specified index from the tree. * Panics if the key is not present. */ void pctrie_remove(struct pctrie *ptree, uint64_t index, pctrie_free_t freefn) { struct pctrie_node *node, *parent, *tmp; uint64_t *m; int i, slot; node = pctrie_root_load(ptree, NULL, PCTRIE_LOCKED); if (pctrie_isleaf(node)) { m = pctrie_toval(node); if (*m != index) panic("%s: invalid key found", __func__); pctrie_root_store(ptree, NULL, PCTRIE_LOCKED); return; } parent = NULL; for (;;) { if (node == NULL) panic("pctrie_remove: impossible to locate the key"); slot = pctrie_slot(index, node->pn_clev); tmp = pctrie_node_load(&node->pn_child[slot], NULL, PCTRIE_LOCKED); if (pctrie_isleaf(tmp)) { m = pctrie_toval(tmp); if (*m != index) panic("%s: invalid key found", __func__); pctrie_node_store(&node->pn_child[slot], NULL, PCTRIE_LOCKED); node->pn_count--; if (node->pn_count > 1) break; for (i = 0; i < PCTRIE_COUNT; i++) { tmp = pctrie_node_load(&node->pn_child[i], NULL, PCTRIE_LOCKED); if (tmp != NULL) break; } KASSERT(i != PCTRIE_COUNT, ("%s: invalid node configuration", __func__)); if (parent == NULL) pctrie_root_store(ptree, tmp, PCTRIE_LOCKED); else { slot = pctrie_slot(index, parent->pn_clev); KASSERT(pctrie_node_load( &parent->pn_child[slot], NULL, PCTRIE_LOCKED) == node, ("%s: invalid child value", __func__)); pctrie_node_store(&parent->pn_child[slot], tmp, PCTRIE_LOCKED); } /* * The child is still valid and we can not zero the * pointer until all SMR references are gone. */ node->pn_count--; pctrie_node_put(ptree, node, freefn, i); break; } parent = node; node = tmp; } } /* * Remove and free all the nodes from the tree. * This function is recursive but there is a tight control on it as the * maximum depth of the tree is fixed. */ void pctrie_reclaim_allnodes(struct pctrie *ptree, pctrie_free_t freefn) { struct pctrie_node *root; root = pctrie_root_load(ptree, NULL, PCTRIE_LOCKED); if (root == NULL) return; pctrie_root_store(ptree, NULL, PCTRIE_UNSERIALIZED); if (!pctrie_isleaf(root)) pctrie_reclaim_allnodes_int(ptree, root, freefn); } #ifdef DDB /* * Show details about the given node. */ DB_SHOW_COMMAND(pctrienode, db_show_pctrienode) { struct pctrie_node *node, *tmp; int i; if (!have_addr) return; node = (struct pctrie_node *)addr; db_printf("node %p, owner %jx, children count %u, level %u:\n", (void *)node, (uintmax_t)node->pn_owner, node->pn_count, node->pn_clev); for (i = 0; i < PCTRIE_COUNT; i++) { tmp = pctrie_node_load(&node->pn_child[i], NULL, PCTRIE_UNSERIALIZED); if (tmp != NULL) db_printf("slot: %d, val: %p, value: %p, clev: %d\n", i, (void *)tmp, pctrie_isleaf(tmp) ? pctrie_toval(tmp) : NULL, node->pn_clev); } } #endif /* DDB */