377 lines
11 KiB
C
377 lines
11 KiB
C
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/*
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* lib/parman.c - Manager for linear priority array areas
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* Copyright (c) 2017 Mellanox Technologies. All rights reserved.
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* Copyright (c) 2017 Jiri Pirko <jiri@mellanox.com>
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the names of the copyright holders nor the names of its
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* contributors may be used to endorse or promote products derived from
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* this software without specific prior written permission.
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*
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* Alternatively, this software may be distributed under the terms of the
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* GNU General Public License ("GPL") version 2 as published by the Free
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* Software Foundation.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
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* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*/
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/slab.h>
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#include <linux/export.h>
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#include <linux/list.h>
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#include <linux/err.h>
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#include <linux/parman.h>
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struct parman_algo {
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int (*item_add)(struct parman *parman, struct parman_prio *prio,
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struct parman_item *item);
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void (*item_remove)(struct parman *parman, struct parman_prio *prio,
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struct parman_item *item);
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};
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struct parman {
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const struct parman_ops *ops;
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void *priv;
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const struct parman_algo *algo;
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unsigned long count;
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unsigned long limit_count;
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struct list_head prio_list;
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};
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static int parman_enlarge(struct parman *parman)
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{
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unsigned long new_count = parman->limit_count +
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parman->ops->resize_step;
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int err;
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err = parman->ops->resize(parman->priv, new_count);
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if (err)
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return err;
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parman->limit_count = new_count;
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return 0;
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}
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static int parman_shrink(struct parman *parman)
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{
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unsigned long new_count = parman->limit_count -
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parman->ops->resize_step;
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int err;
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if (new_count < parman->ops->base_count)
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return 0;
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err = parman->ops->resize(parman->priv, new_count);
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if (err)
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return err;
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parman->limit_count = new_count;
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return 0;
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}
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static bool parman_prio_used(struct parman_prio *prio)
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{
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return !list_empty(&prio->item_list);
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}
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static struct parman_item *parman_prio_first_item(struct parman_prio *prio)
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{
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return list_first_entry(&prio->item_list,
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typeof(struct parman_item), list);
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}
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static unsigned long parman_prio_first_index(struct parman_prio *prio)
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{
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return parman_prio_first_item(prio)->index;
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}
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static struct parman_item *parman_prio_last_item(struct parman_prio *prio)
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{
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return list_last_entry(&prio->item_list,
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typeof(struct parman_item), list);
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}
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static unsigned long parman_prio_last_index(struct parman_prio *prio)
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{
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return parman_prio_last_item(prio)->index;
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}
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static unsigned long parman_lsort_new_index_find(struct parman *parman,
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struct parman_prio *prio)
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{
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list_for_each_entry_from_reverse(prio, &parman->prio_list, list) {
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if (!parman_prio_used(prio))
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continue;
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return parman_prio_last_index(prio) + 1;
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}
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return 0;
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}
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static void __parman_prio_move(struct parman *parman, struct parman_prio *prio,
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struct parman_item *item, unsigned long to_index,
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unsigned long count)
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{
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parman->ops->move(parman->priv, item->index, to_index, count);
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}
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static void parman_prio_shift_down(struct parman *parman,
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struct parman_prio *prio)
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{
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struct parman_item *item;
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unsigned long to_index;
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if (!parman_prio_used(prio))
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return;
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item = parman_prio_first_item(prio);
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to_index = parman_prio_last_index(prio) + 1;
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__parman_prio_move(parman, prio, item, to_index, 1);
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list_move_tail(&item->list, &prio->item_list);
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item->index = to_index;
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}
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static void parman_prio_shift_up(struct parman *parman,
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struct parman_prio *prio)
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{
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struct parman_item *item;
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unsigned long to_index;
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if (!parman_prio_used(prio))
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return;
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item = parman_prio_last_item(prio);
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to_index = parman_prio_first_index(prio) - 1;
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__parman_prio_move(parman, prio, item, to_index, 1);
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list_move(&item->list, &prio->item_list);
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item->index = to_index;
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}
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static void parman_prio_item_remove(struct parman *parman,
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struct parman_prio *prio,
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struct parman_item *item)
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{
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struct parman_item *last_item;
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unsigned long to_index;
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last_item = parman_prio_last_item(prio);
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if (last_item == item) {
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list_del(&item->list);
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return;
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}
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to_index = item->index;
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__parman_prio_move(parman, prio, last_item, to_index, 1);
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list_del(&last_item->list);
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list_replace(&item->list, &last_item->list);
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last_item->index = to_index;
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}
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static int parman_lsort_item_add(struct parman *parman,
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struct parman_prio *prio,
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struct parman_item *item)
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{
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struct parman_prio *prio2;
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unsigned long new_index;
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int err;
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if (parman->count + 1 > parman->limit_count) {
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err = parman_enlarge(parman);
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if (err)
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return err;
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}
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new_index = parman_lsort_new_index_find(parman, prio);
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list_for_each_entry_reverse(prio2, &parman->prio_list, list) {
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if (prio2 == prio)
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break;
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parman_prio_shift_down(parman, prio2);
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}
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item->index = new_index;
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list_add_tail(&item->list, &prio->item_list);
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parman->count++;
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return 0;
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}
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static void parman_lsort_item_remove(struct parman *parman,
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struct parman_prio *prio,
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struct parman_item *item)
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{
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parman_prio_item_remove(parman, prio, item);
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list_for_each_entry_continue(prio, &parman->prio_list, list)
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parman_prio_shift_up(parman, prio);
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parman->count--;
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if (parman->limit_count - parman->count >= parman->ops->resize_step)
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parman_shrink(parman);
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}
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static const struct parman_algo parman_lsort = {
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.item_add = parman_lsort_item_add,
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.item_remove = parman_lsort_item_remove,
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};
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static const struct parman_algo *parman_algos[] = {
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&parman_lsort,
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};
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/**
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* parman_create - creates a new parman instance
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* @ops: caller-specific callbacks
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* @priv: pointer to a private data passed to the ops
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*
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* Note: all locking must be provided by the caller.
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*
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* Each parman instance manages an array area with chunks of entries
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* with the same priority. Consider following example:
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*
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* item 1 with prio 10
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* item 2 with prio 10
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* item 3 with prio 10
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* item 4 with prio 20
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* item 5 with prio 20
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* item 6 with prio 30
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* item 7 with prio 30
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* item 8 with prio 30
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*
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* In this example, there are 3 priority chunks. The order of the priorities
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* matters, however the order of items within a single priority chunk does not
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* matter. So the same array could be ordered as follows:
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*
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* item 2 with prio 10
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* item 3 with prio 10
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* item 1 with prio 10
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* item 5 with prio 20
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* item 4 with prio 20
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* item 7 with prio 30
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* item 8 with prio 30
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* item 6 with prio 30
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*
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* The goal of parman is to maintain the priority ordering. The caller
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* provides @ops with callbacks parman uses to move the items
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* and resize the array area.
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*
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* Returns a pointer to newly created parman instance in case of success,
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* otherwise it returns NULL.
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*/
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struct parman *parman_create(const struct parman_ops *ops, void *priv)
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{
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struct parman *parman;
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parman = kzalloc(sizeof(*parman), GFP_KERNEL);
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if (!parman)
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return NULL;
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INIT_LIST_HEAD(&parman->prio_list);
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parman->ops = ops;
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parman->priv = priv;
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parman->limit_count = ops->base_count;
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parman->algo = parman_algos[ops->algo];
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return parman;
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}
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EXPORT_SYMBOL(parman_create);
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/**
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* parman_destroy - destroys existing parman instance
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* @parman: parman instance
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*
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* Note: all locking must be provided by the caller.
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*/
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void parman_destroy(struct parman *parman)
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{
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WARN_ON(!list_empty(&parman->prio_list));
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kfree(parman);
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}
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EXPORT_SYMBOL(parman_destroy);
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/**
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* parman_prio_init - initializes a parman priority chunk
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* @parman: parman instance
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* @prio: parman prio structure to be initialized
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* @prority: desired priority of the chunk
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*
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* Note: all locking must be provided by the caller.
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*
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* Before caller could add an item with certain priority, he has to
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* initialize a priority chunk for it using this function.
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*/
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void parman_prio_init(struct parman *parman, struct parman_prio *prio,
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unsigned long priority)
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{
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struct parman_prio *prio2;
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struct list_head *pos;
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INIT_LIST_HEAD(&prio->item_list);
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prio->priority = priority;
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/* Position inside the list according to priority */
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list_for_each(pos, &parman->prio_list) {
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prio2 = list_entry(pos, typeof(*prio2), list);
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if (prio2->priority > prio->priority)
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break;
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}
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list_add_tail(&prio->list, pos);
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}
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EXPORT_SYMBOL(parman_prio_init);
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/**
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* parman_prio_fini - finalizes use of parman priority chunk
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* @prio: parman prio structure
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*
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* Note: all locking must be provided by the caller.
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*/
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void parman_prio_fini(struct parman_prio *prio)
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{
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WARN_ON(parman_prio_used(prio));
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list_del(&prio->list);
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}
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EXPORT_SYMBOL(parman_prio_fini);
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/**
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* parman_item_add - adds a parman item under defined priority
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* @parman: parman instance
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* @prio: parman prio instance to add the item to
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* @item: parman item instance
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*
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* Note: all locking must be provided by the caller.
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*
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* Adds item to a array managed by parman instance under the specified priority.
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*
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* Returns 0 in case of success, negative number to indicate an error.
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*/
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int parman_item_add(struct parman *parman, struct parman_prio *prio,
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struct parman_item *item)
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{
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return parman->algo->item_add(parman, prio, item);
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}
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EXPORT_SYMBOL(parman_item_add);
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/**
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* parman_item_del - deletes parman item
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* @parman: parman instance
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* @prio: parman prio instance to delete the item from
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* @item: parman item instance
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*
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* Note: all locking must be provided by the caller.
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*/
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void parman_item_remove(struct parman *parman, struct parman_prio *prio,
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struct parman_item *item)
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|
{
|
||
|
|
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");
|