/*
* 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");
