From 44091d29f2075972aede47ef17e1e70db3d51190 Mon Sep 17 00:00:00 2001 From: Jiri Pirko Date: Fri, 3 Feb 2017 10:29:06 +0100 Subject: lib: Introduce priority array area manager This introduces a infrastructure for management of linear priority areas. Priority order in an array matters, however order of items inside a priority group does not matter. As an initial implementation, L-sort algorithm is used. It is quite trivial. More advanced algorithm called P-sort will be introduced as a follow-up. The infrastructure is prepared for other algos. Alongside this, a testing module is introduced as well. Signed-off-by: Jiri Pirko Signed-off-by: David S. Miller --- lib/parman.c | 376 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 376 insertions(+) create mode 100644 lib/parman.c (limited to 'lib/parman.c') diff --git a/lib/parman.c b/lib/parman.c new file mode 100644 index 000000000000..c6e42a8db824 --- /dev/null +++ b/lib/parman.c @@ -0,0 +1,376 @@ +/* + * lib/parman.c - Manager for linear priority array areas + * Copyright (c) 2017 Mellanox Technologies. All rights reserved. + * Copyright (c) 2017 Jiri Pirko + * + * 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 +#include +#include +#include +#include +#include +#include + +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 "); +MODULE_DESCRIPTION("Priority-based array manager"); -- cgit v1.2.3