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375 lines
11 KiB
375 lines
11 KiB
/* |
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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 <[email protected]> |
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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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* @priority: 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_remove - 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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{ |
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parman->algo->item_remove(parman, prio, item); |
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} |
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EXPORT_SYMBOL(parman_item_remove); |
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MODULE_LICENSE("Dual BSD/GPL"); |
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MODULE_AUTHOR("Jiri Pirko <[email protected]>"); |
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MODULE_DESCRIPTION("Priority-based array manager");
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