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