/* * lib/parman.c - Manager for linear priority array areas * Copyright (c) 2017 Mellanox Technologies. All rights reserved. * Copyright (c) 2017 Jiri Pirko <jiri@mellanox.com> * * 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. * 3. Neither the names of the copyright holders nor the names of its * contributors may be used to endorse or promote products derived from * this software without specific prior written permission. * * Alternatively, this software may be distributed under the terms of the * GNU General Public License ("GPL") version 2 as published by the Free * Software Foundation. * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS 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 COPYRIGHT OWNER 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. */ #include <linux/kernel.h> #include <linux/module.h> #include <linux/slab.h> #include <linux/export.h> #include <linux/list.h> #include <linux/err.h> #include <linux/parman.h> struct parman_algo { int (*item_add)(struct parman *parman, struct parman_prio *prio, struct parman_item *item); void (*item_remove)(struct parman *parman, struct parman_prio *prio, struct parman_item *item); }; struct parman { const struct parman_ops *ops; void *priv; const struct parman_algo *algo; unsigned long count; unsigned long limit_count; struct list_head prio_list; }; static int parman_enlarge(struct parman *parman) { unsigned long new_count = parman->limit_count + parman->ops->resize_step; int err; err = parman->ops->resize(parman->priv, new_count); if (err) return err; parman->limit_count = new_count; return 0; } static int parman_shrink(struct parman *parman) { unsigned long new_count = parman->limit_count - parman->ops->resize_step; int err; if (new_count < parman->ops->base_count) return 0; err = parman->ops->resize(parman->priv, new_count); if (err) return err; parman->limit_count = new_count; return 0; } static bool parman_prio_used(struct parman_prio *prio) { return !list_empty(&prio->item_list); } static struct parman_item *parman_prio_first_item(struct parman_prio *prio) { return list_first_entry(&prio->item_list, typeof(struct parman_item), list); } static unsigned long parman_prio_first_index(struct parman_prio *prio) { return parman_prio_first_item(prio)->index; } static struct parman_item *parman_prio_last_item(struct parman_prio *prio) { return list_last_entry(&prio->item_list, typeof(struct parman_item), list); } static unsigned long parman_prio_last_index(struct parman_prio *prio) { return parman_prio_last_item(prio)->index; } static unsigned long parman_lsort_new_index_find(struct parman *parman, struct parman_prio *prio) { list_for_each_entry_from_reverse(prio, &parman->prio_list, list) { if (!parman_prio_used(prio)) continue; return parman_prio_last_index(prio) + 1; } return 0; } static void __parman_prio_move(struct parman *parman, struct parman_prio *prio, struct parman_item *item, unsigned long to_index, unsigned long count) { parman->ops->move(parman->priv, item->index, to_index, count); } static void parman_prio_shift_down(struct parman *parman, struct parman_prio *prio) { struct parman_item *item; unsigned long to_index; if (!parman_prio_used(prio)) return; item = parman_prio_first_item(prio); to_index = parman_prio_last_index(prio) + 1; __parman_prio_move(parman, prio, item, to_index, 1); list_move_tail(&item->list, &prio->item_list); item->index = to_index; } static void parman_prio_shift_up(struct parman *parman, struct parman_prio *prio) { struct parman_item *item; unsigned long to_index; if (!parman_prio_used(prio)) return; item = parman_prio_last_item(prio); to_index = parman_prio_first_index(prio) - 1; __parman_prio_move(parman, prio, item, to_index, 1); list_move(&item->list, &prio->item_list); item->index = to_index; } static void parman_prio_item_remove(struct parman *parman, struct parman_prio *prio, struct parman_item *item) { struct parman_item *last_item; unsigned long to_index; last_item = parman_prio_last_item(prio); if (last_item == item) { list_del(&item->list); return; } to_index = item->index; __parman_prio_move(parman, prio, last_item, to_index, 1); list_del(&last_item->list); list_replace(&item->list, &last_item->list); last_item->index = to_index; } static int parman_lsort_item_add(struct parman *parman, struct parman_prio *prio, struct parman_item *item) { struct parman_prio *prio2; unsigned long new_index; int err; if (parman->count + 1 > parman->limit_count) { err = parman_enlarge(parman); if (err) return err; } new_index = parman_lsort_new_index_find(parman, prio); list_for_each_entry_reverse(prio2, &parman->prio_list, list) { if (prio2 == prio) break; parman_prio_shift_down(parman, prio2); } item->index = new_index; list_add_tail(&item->list, &prio->item_list); parman->count++; return 0; } static void parman_lsort_item_remove(struct parman *parman, struct parman_prio *prio, struct parman_item *item) { parman_prio_item_remove(parman, prio, item); list_for_each_entry_continue(prio, &parman->prio_list, list) parman_prio_shift_up(parman, prio); parman->count--; if (parman->limit_count - parman->count >= parman->ops->resize_step) parman_shrink(parman); } static const struct parman_algo parman_lsort = { .item_add = parman_lsort_item_add, .item_remove = parman_lsort_item_remove, }; static const struct parman_algo *parman_algos[] = { &parman_lsort, }; /** * parman_create - creates a new parman instance * @ops: caller-specific callbacks * @priv: pointer to a private data passed to the ops * * Note: all locking must be provided by the caller. * * Each parman instance manages an array area with chunks of entries * with the same priority. Consider following example: * * item 1 with prio 10 * item 2 with prio 10 * item 3 with prio 10 * item 4 with prio 20 * item 5 with prio 20 * item 6 with prio 30 * item 7 with prio 30 * item 8 with prio 30 * * In this example, there are 3 priority chunks. The order of the priorities * matters, however the order of items within a single priority chunk does not * matter. So the same array could be ordered as follows: * * item 2 with prio 10 * item 3 with prio 10 * item 1 with prio 10 * item 5 with prio 20 * item 4 with prio 20 * item 7 with prio 30 * item 8 with prio 30 * item 6 with prio 30 * * The goal of parman is to maintain the priority ordering. The caller * provides @ops with callbacks parman uses to move the items * and resize the array area. * * Returns a pointer to newly created parman instance in case of success, * otherwise it returns NULL. */ struct parman *parman_create(const struct parman_ops *ops, void *priv) { struct parman *parman; parman = kzalloc(sizeof(*parman), GFP_KERNEL); if (!parman) return NULL; INIT_LIST_HEAD(&parman->prio_list); parman->ops = ops; parman->priv = priv; parman->limit_count = ops->base_count; parman->algo = parman_algos[ops->algo]; return parman; } EXPORT_SYMBOL(parman_create); /** * parman_destroy - destroys existing parman instance * @parman: parman instance * * Note: all locking must be provided by the caller. */ void parman_destroy(struct parman *parman) { WARN_ON(!list_empty(&parman->prio_list)); kfree(parman); } EXPORT_SYMBOL(parman_destroy); /** * parman_prio_init - initializes a parman priority chunk * @parman: parman instance * @prio: parman prio structure to be initialized * @prority: desired priority of the chunk * * Note: all locking must be provided by the caller. * * Before caller could add an item with certain priority, he has to * initialize a priority chunk for it using this function. */ void parman_prio_init(struct parman *parman, struct parman_prio *prio, unsigned long priority) { struct parman_prio *prio2; struct list_head *pos; INIT_LIST_HEAD(&prio->item_list); prio->priority = priority; /* Position inside the list according to priority */ list_for_each(pos, &parman->prio_list) { prio2 = list_entry(pos, typeof(*prio2), list); if (prio2->priority > prio->priority) break; } list_add_tail(&prio->list, pos); } EXPORT_SYMBOL(parman_prio_init); /** * parman_prio_fini - finalizes use of parman priority chunk * @prio: parman prio structure * * Note: all locking must be provided by the caller. */ void parman_prio_fini(struct parman_prio *prio) { WARN_ON(parman_prio_used(prio)); list_del(&prio->list); } EXPORT_SYMBOL(parman_prio_fini); /** * parman_item_add - adds a parman item under defined priority * @parman: parman instance * @prio: parman prio instance to add the item to * @item: parman item instance * * Note: all locking must be provided by the caller. * * Adds item to a array managed by parman instance under the specified priority. * * Returns 0 in case of success, negative number to indicate an error. */ int parman_item_add(struct parman *parman, struct parman_prio *prio, struct parman_item *item) { return parman->algo->item_add(parman, prio, item); } EXPORT_SYMBOL(parman_item_add); /** * parman_item_del - deletes parman item * @parman: parman instance * @prio: parman prio instance to delete the item from * @item: parman item instance * * Note: all locking must be provided by the caller. */ void parman_item_remove(struct parman *parman, struct parman_prio *prio, struct parman_item *item) { parman->algo->item_remove(parman, prio, item); } EXPORT_SYMBOL(parman_item_remove); MODULE_LICENSE("Dual BSD/GPL"); MODULE_AUTHOR("Jiri Pirko <jiri@mellanox.com>"); MODULE_DESCRIPTION("Priority-based array manager");