diff options
Diffstat (limited to 'lib')
| -rw-r--r-- | lib/Kconfig | 6 | ||||
| -rw-r--r-- | lib/Makefile | 1 | ||||
| -rw-r--r-- | lib/plist.c | 118 |
3 files changed, 125 insertions, 0 deletions
diff --git a/lib/Kconfig b/lib/Kconfig index 3de93357f5a..f6299342b88 100644 --- a/lib/Kconfig +++ b/lib/Kconfig @@ -86,4 +86,10 @@ config TEXTSEARCH_BM config TEXTSEARCH_FSM tristate +# +# plist support is select#ed if needed +# +config PLIST + boolean + endmenu diff --git a/lib/Makefile b/lib/Makefile index 79358ad1f11..10c13c9d782 100644 --- a/lib/Makefile +++ b/lib/Makefile @@ -25,6 +25,7 @@ lib-$(CONFIG_SEMAPHORE_SLEEPERS) += semaphore-sleepers.o lib-$(CONFIG_GENERIC_FIND_NEXT_BIT) += find_next_bit.o lib-$(CONFIG_GENERIC_HWEIGHT) += hweight.o obj-$(CONFIG_LOCK_KERNEL) += kernel_lock.o +obj-$(CONFIG_PLIST) += plist.o obj-$(CONFIG_DEBUG_PREEMPT) += smp_processor_id.o ifneq ($(CONFIG_HAVE_DEC_LOCK),y) diff --git a/lib/plist.c b/lib/plist.c new file mode 100644 index 00000000000..3074a02272f --- /dev/null +++ b/lib/plist.c @@ -0,0 +1,118 @@ +/* + * 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 Thomas Gleixner <tglx@linutronix.de> + * + * Simplifications of the original code by + * Oleg Nesterov <oleg@tv-sign.ru> + * + * Licensed under the FSF's GNU Public License v2 or later. + * + * 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/plist.h> +#include <linux/spinlock.h> + +#ifdef CONFIG_DEBUG_PI_LIST + +static void plist_check_prev_next(struct list_head *t, struct list_head *p, + struct list_head *n) +{ + if (n->prev != p || p->next != n) { + printk("top: %p, n: %p, p: %p\n", t, t->next, t->prev); + printk("prev: %p, n: %p, p: %p\n", p, p->next, p->prev); + printk("next: %p, n: %p, p: %p\n", n, n->next, n->prev); + WARN_ON(1); + } +} + +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) +{ + WARN_ON(!head->lock); + if (head->lock) + WARN_ON_SMP(!spin_is_locked(head->lock)); + plist_check_list(&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 *iter; + + plist_check_head(head); + WARN_ON(!plist_node_empty(node)); + + list_for_each_entry(iter, &head->prio_list, plist.prio_list) { + if (node->prio < iter->prio) + goto lt_prio; + else if (node->prio == iter->prio) { + iter = list_entry(iter->plist.prio_list.next, + struct plist_node, plist.prio_list); + goto eq_prio; + } + } + +lt_prio: + list_add_tail(&node->plist.prio_list, &iter->plist.prio_list); +eq_prio: + list_add_tail(&node->plist.node_list, &iter->plist.node_list); + + 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->plist.prio_list)) { + struct plist_node *next = plist_first(&node->plist); + + list_move_tail(&next->plist.prio_list, &node->plist.prio_list); + list_del_init(&node->plist.prio_list); + } + + list_del_init(&node->plist.node_list); + + plist_check_head(head); +} |