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Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176177178179180181182183184185186187188189190191192193194195196197198199200201202203204205206207208209210211212213214215216217218219220221222223224225226227228229230231232233234235236237238239240241242243244245246247248249250251252253254255256257258259260261262263264265266267268269270271272273274275276277278279280281282283284285286287288289290291292293294295296297298299300301302303304305306307308309310311312// SPDX-License-Identifier: GPL-2.0-or-later/* * lib/plist.c * * Descending-priority-sorted double-linked list * * (C) 2002-2003 Intel Corp * Inaky Perez-Gonzalez <inaky.perez-gonzalez@intel.com>. * * 2001-2005 (c) MontaVista Software, Inc. * Daniel Walker <dwalker@mvista.com> * * (C) 2005 Linutronix GmbH, Thomas Gleixner <tglx@kernel.org> * * Simplifications of the original code by * Oleg Nesterov <oleg@tv-sign.ru> * * Based on simple lists (include/linux/list.h). * * This file contains the add / del functions which are considered to * be too large to inline. See include/linux/plist.h for further * information. */
#include <linux/bug.h>#include <linux/plist.h>
#ifdef CONFIG_DEBUG_PLIST
static struct plist_head test_head;
static void plist_check_prev_next(struct list_head *t, struct list_head *p, struct list_head *n){ WARN(n->prev != p || p->next != n, "top: %p, n: %p, p: %p\n" "prev: %p, n: %p, p: %p\n" "next: %p, n: %p, p: %p\n", t, t->next, t->prev, p, p->next, p->prev, n, n->next, n->prev);}
static void plist_check_list(struct list_head *top){ struct list_head *prev = top, *next = top->next;
plist_check_prev_next(top, prev, next); while (next != top) { prev = next; next = prev->next; plist_check_prev_next(top, prev, next); }}
static void plist_check_head(struct plist_head *head){ if (!plist_head_empty(head)) plist_check_list(&plist_first(head)->prio_list); plist_check_list(&head->node_list);}
#else# define plist_check_head(h) do { } while (0)#endif
/** * plist_add - add @node to @head * * @node: &struct plist_node pointer * @head: &struct plist_head pointer */void plist_add(struct plist_node *node, struct plist_head *head){ struct plist_node *first, *iter, *prev = NULL, *last, *reverse_iter; struct list_head *node_next = &head->node_list;
plist_check_head(head); WARN_ON(!plist_node_empty(node)); WARN_ON(!list_empty(&node->prio_list));
if (plist_head_empty(head)) goto ins_node;
first = iter = plist_first(head); last = reverse_iter = list_entry(first->prio_list.prev, struct plist_node, prio_list);
do { if (node->prio < iter->prio) { node_next = &iter->node_list; break; } else if (node->prio >= reverse_iter->prio) { prev = reverse_iter; iter = list_entry(reverse_iter->prio_list.next, struct plist_node, prio_list); if (likely(reverse_iter != last)) node_next = &iter->node_list; break; }
prev = iter; iter = list_entry(iter->prio_list.next, struct plist_node, prio_list); reverse_iter = list_entry(reverse_iter->prio_list.prev, struct plist_node, prio_list); } while (iter != first);
if (!prev || prev->prio != node->prio) list_add_tail(&node->prio_list, &iter->prio_list);ins_node: list_add_tail(&node->node_list, node_next);
plist_check_head(head);}
/** * plist_del - Remove a @node from plist. * * @node: &struct plist_node pointer - entry to be removed * @head: &struct plist_head pointer - list head */void plist_del(struct plist_node *node, struct plist_head *head){ plist_check_head(head);
if (!list_empty(&node->prio_list)) { if (node->node_list.next != &head->node_list) { struct plist_node *next;
next = list_entry(node->node_list.next, struct plist_node, node_list);
/* add the next plist_node into prio_list */ if (list_empty(&next->prio_list)) list_add(&next->prio_list, &node->prio_list); } list_del_init(&node->prio_list); }
list_del_init(&node->node_list);
plist_check_head(head);}
/** * plist_requeue - Requeue @node at end of same-prio entries. * * This is essentially an optimized plist_del() followed by * plist_add(). It moves an entry already in the plist to * after any other same-priority entries. * * @node: &struct plist_node pointer - entry to be moved * @head: &struct plist_head pointer - list head */void plist_requeue(struct plist_node *node, struct plist_head *head){ struct plist_node *iter; struct list_head *node_next = &head->node_list;
plist_check_head(head); BUG_ON(plist_head_empty(head)); BUG_ON(plist_node_empty(node));
if (node == plist_last(head)) return;
iter = plist_next(node);
if (node->prio != iter->prio) return;
plist_del(node, head);
/* * After plist_del(), iter is the replacement of the node. If the node * was on prio_list, take shortcut to find node_next instead of looping. */ if (!list_empty(&iter->prio_list)) { iter = list_entry(iter->prio_list.next, struct plist_node, prio_list); node_next = &iter->node_list; goto queue; }
plist_for_each_continue(iter, head) { if (node->prio != iter->prio) { node_next = &iter->node_list; break; } }queue: list_add_tail(&node->node_list, node_next);
plist_check_head(head);}
#ifdef CONFIG_DEBUG_PLIST#include <linux/sched.h>#include <linux/sched/clock.h>#include <linux/module.h>#include <linux/init.h>
static struct plist_node __initdata test_node[241];
static void __init plist_test_check(int nr_expect){ struct plist_node *first, *prio_pos, *node_pos;
if (plist_head_empty(&test_head)) { BUG_ON(nr_expect != 0); return; }
prio_pos = first = plist_first(&test_head); plist_for_each(node_pos, &test_head) { if (nr_expect-- < 0) break; if (node_pos == first) continue; if (node_pos->prio == prio_pos->prio) { BUG_ON(!list_empty(&node_pos->prio_list)); continue; }
BUG_ON(prio_pos->prio > node_pos->prio); BUG_ON(prio_pos->prio_list.next != &node_pos->prio_list); prio_pos = node_pos; }
BUG_ON(nr_expect != 0); BUG_ON(prio_pos->prio_list.next != &first->prio_list);}
static void __init plist_test_requeue(struct plist_node *node){ plist_requeue(node, &test_head);
if (node != plist_last(&test_head)) BUG_ON(node->prio == plist_next(node)->prio);}
static int __init plist_test(void){ int nr_expect = 0, i, loop; unsigned int r = local_clock();
printk(KERN_DEBUG "start plist test\n"); plist_head_init(&test_head); for (i = 0; i < ARRAY_SIZE(test_node); i++) plist_node_init(test_node + i, 0);
for (loop = 0; loop < 1000; loop++) { r = r * 193939 % 47629; i = r % ARRAY_SIZE(test_node); if (plist_node_empty(test_node + i)) { r = r * 193939 % 47629; test_node[i].prio = r % 99; plist_add(test_node + i, &test_head); nr_expect++; } else { plist_del(test_node + i, &test_head); nr_expect--; } plist_test_check(nr_expect); if (!plist_node_empty(test_node + i)) { plist_test_requeue(test_node + i); plist_test_check(nr_expect); } }
for (i = 0; i < ARRAY_SIZE(test_node); i++) { if (plist_node_empty(test_node + i)) continue; plist_del(test_node + i, &test_head); nr_expect--; plist_test_check(nr_expect); }
printk(KERN_DEBUG "end plist test\n");
/* Worst case test for plist_add() */ unsigned int test_data[241];
for (i = 0; i < ARRAY_SIZE(test_data); i++) test_data[i] = i;
ktime_t start, end, time_elapsed = 0;
plist_head_init(&test_head);
for (i = 0; i < ARRAY_SIZE(test_node); i++) { plist_node_init(test_node + i, 0); test_node[i].prio = test_data[i]; }
for (i = 0; i < ARRAY_SIZE(test_node); i++) { if (plist_node_empty(test_node + i)) { start = ktime_get(); plist_add(test_node + i, &test_head); end = ktime_get(); time_elapsed += (end - start); } }
pr_debug("plist_add worst case test time elapsed %lld\n", time_elapsed); return 0;}
module_init(plist_test);
#endif