// SPDX-License-Identifier: GPL-2.0 /* * Copyright (C) 2011 STRATO AG * written by Arne Jansen <sensille@gmx.net> */ #include <linux/slab.h> #include "ulist.h" #include "ctree.h" /* * ulist is a generic data structure to hold a collection of unique u64 * values. The only operations it supports is adding to the list and * enumerating it. * It is possible to store an auxiliary value along with the key. * * A sample usage for ulists is the enumeration of directed graphs without * visiting a node twice. The pseudo-code could look like this: * * ulist = ulist_alloc(); * ulist_add(ulist, root); * ULIST_ITER_INIT(&uiter); * * while ((elem = ulist_next(ulist, &uiter)) { * for (all child nodes n in elem) * ulist_add(ulist, n); * do something useful with the node; * } * ulist_free(ulist); * * This assumes the graph nodes are addressable by u64. This stems from the * usage for tree enumeration in btrfs, where the logical addresses are * 64 bit. * * It is also useful for tree enumeration which could be done elegantly * recursively, but is not possible due to kernel stack limitations. The * loop would be similar to the above. */ /** * ulist_init - freshly initialize a ulist * @ulist: the ulist to initialize * * Note: don't use this function to init an already used ulist, use * ulist_reinit instead. */ void ulist_init(struct ulist *ulist) { INIT_LIST_HEAD(&ulist->nodes); ulist->root = RB_ROOT; ulist->nnodes = 0; } /** * ulist_release - free up additionally allocated memory for the ulist * @ulist: the ulist from which to free the additional memory * * This is useful in cases where the base 'struct ulist' has been statically * allocated. */ void ulist_release(struct ulist *ulist) { struct ulist_node *node; struct ulist_node *next; list_for_each_entry_safe(node, next, &ulist->nodes, list) { kfree(node); } ulist->root = RB_ROOT; INIT_LIST_HEAD(&ulist->nodes); } /** * ulist_reinit - prepare a ulist for reuse * @ulist: ulist to be reused * * Free up all additional memory allocated for the list elements and reinit * the ulist. */ void ulist_reinit(struct ulist *ulist) { ulist_release(ulist); ulist_init(ulist); } /** * ulist_alloc - dynamically allocate a ulist * @gfp_mask: allocation flags to for base allocation * * The allocated ulist will be returned in an initialized state. */ struct ulist *ulist_alloc(gfp_t gfp_mask) { struct ulist *ulist = kmalloc(sizeof(*ulist), gfp_mask); if (!ulist) return NULL; ulist_init(ulist); return ulist; } /** * ulist_free - free dynamically allocated ulist * @ulist: ulist to free * * It is not necessary to call ulist_release before. */ void ulist_free(struct ulist *ulist) { if (!ulist) return; ulist_release(ulist); kfree(ulist); } static struct ulist_node *ulist_rbtree_search(struct ulist *ulist, u64 val) { struct rb_node *n = ulist->root.rb_node; struct ulist_node *u = NULL; while (n) { u = rb_entry(n, struct ulist_node, rb_node); if (u->val < val) n = n->rb_right; else if (u->val > val) n = n->rb_left; else return u; } return NULL; } static void ulist_rbtree_erase(struct ulist *ulist, struct ulist_node *node) { rb_erase(&node->rb_node, &ulist->root); list_del(&node->list); kfree(node); BUG_ON(ulist->nnodes == 0); ulist->nnodes--; } static int ulist_rbtree_insert(struct ulist *ulist, struct ulist_node *ins) { struct rb_node **p = &ulist->root.rb_node; struct rb_node *parent = NULL; struct ulist_node *cur = NULL; while (*p) { parent = *p; cur = rb_entry(parent, struct ulist_node, rb_node); if (cur->val < ins->val) p = &(*p)->rb_right; else if (cur->val > ins->val) p = &(*p)->rb_left; else return -EEXIST; } rb_link_node(&ins->rb_node, parent, p); rb_insert_color(&ins->rb_node, &ulist->root); return 0; } /** * ulist_add - add an element to the ulist * @ulist: ulist to add the element to * @val: value to add to ulist * @aux: auxiliary value to store along with val * @gfp_mask: flags to use for allocation * * Note: locking must be provided by the caller. In case of rwlocks write * locking is needed * * Add an element to a ulist. The @val will only be added if it doesn't * already exist. If it is added, the auxiliary value @aux is stored along with * it. In case @val already exists in the ulist, @aux is ignored, even if * it differs from the already stored value. * * ulist_add returns 0 if @val already exists in ulist and 1 if @val has been * inserted. * In case of allocation failure -ENOMEM is returned and the ulist stays * unaltered. */ int ulist_add(struct ulist *ulist, u64 val, u64 aux, gfp_t gfp_mask) { return ulist_add_merge(ulist, val, aux, NULL, gfp_mask); } int ulist_add_merge(struct ulist *ulist, u64 val, u64 aux, u64 *old_aux, gfp_t gfp_mask) { int ret; struct ulist_node *node; node = ulist_rbtree_search(ulist, val); if (node) { if (old_aux) *old_aux = node->aux; return 0; } node = kmalloc(sizeof(*node), gfp_mask); if (!node) return -ENOMEM; node->val = val; node->aux = aux; ret = ulist_rbtree_insert(ulist, node); ASSERT(!ret); list_add_tail(&node->list, &ulist->nodes); ulist->nnodes++; return 1; } /* * ulist_del - delete one node from ulist * @ulist: ulist to remove node from * @val: value to delete * @aux: aux to delete * * The deletion will only be done when *BOTH* val and aux matches. * Return 0 for successful delete. * Return > 0 for not found. */ int ulist_del(struct ulist *ulist, u64 val, u64 aux) { struct ulist_node *node; node = ulist_rbtree_search(ulist, val); /* Not found */ if (!node) return 1; if (node->aux != aux) return 1; /* Found and delete */ ulist_rbtree_erase(ulist, node); return 0; } /** * ulist_next - iterate ulist * @ulist: ulist to iterate * @uiter: iterator variable, initialized with ULIST_ITER_INIT(&iterator) * * Note: locking must be provided by the caller. In case of rwlocks only read * locking is needed * * This function is used to iterate an ulist. * It returns the next element from the ulist or %NULL when the * end is reached. No guarantee is made with respect to the order in which * the elements are returned. They might neither be returned in order of * addition nor in ascending order. * It is allowed to call ulist_add during an enumeration. Newly added items * are guaranteed to show up in the running enumeration. */ struct ulist_node *ulist_next(struct ulist *ulist, struct ulist_iterator *uiter) { struct ulist_node *node; if (list_empty(&ulist->nodes)) return NULL; if (uiter->cur_list && uiter->cur_list->next == &ulist->nodes) return NULL; if (uiter->cur_list) { uiter->cur_list = uiter->cur_list->next; } else { uiter->cur_list = ulist->nodes.next; } node = list_entry(uiter->cur_list, struct ulist_node, list); return node; }