153 lines
4.1 KiB
C
153 lines
4.1 KiB
C
/*
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* Copyright 2006, Red Hat, Inc., Dave Jones
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* Released under the General Public License (GPL).
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*
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* This file contains the linked list implementations for
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* DEBUG_LIST.
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*/
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#include <linux/export.h>
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#include <linux/list.h>
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#include <linux/bug.h>
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#include <linux/kernel.h>
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#include <linux/rculist.h>
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#ifdef CONFIG_X86_64
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static unsigned long count_bits(unsigned long value)
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{
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value = value - ((value >> 1) & 0x5555555555555555);
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value = (value & 0x3333333333333333) + ((value >> 2) & 0x3333333333333333);
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return (((value + (value >> 4)) & 0xF0F0F0F0F0F0F0F) * 0x101010101010101) >> 56;
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}
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#else
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static unsigned long count_bits(unsigned long value)
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{
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value = value - ((value >> 1) & 0x55555555);
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value = (value & 0x33333333) + ((value >> 2) & 0x33333333);
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return (((value + (value >> 4)) & 0x0F0F0F0F) * 0x01010101) >> 24;
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}
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#endif
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inline int check_list_corruption(void *ptr1, void *ptr2, void *ptr3, const char *func_name,
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const char *ptr1_name, const char *ptr2_name, const char *ptr3_name) {
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unsigned long delta_bits = (unsigned long)ptr1 ^ (unsigned long)ptr2;
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if (!delta_bits)
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return 0;
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if (count_bits(delta_bits) < 3) {
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/* less than 3 bits differ; probably a bit flip...*/
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panic("Bit flip in %s: value %p should be %p\n", func_name, ptr2, ptr1);
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}
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return WARN(1,
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"%s corruption. %s should be "
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"%s (%p), but was %p. (%s=%p).\n",
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func_name, ptr1_name, ptr2_name, ptr2, ptr1, ptr3_name, ptr3);
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}
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/*
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* Insert a new entry between two known consecutive entries.
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*
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* This is only for internal list manipulation where we know
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* the prev/next entries already!
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*/
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int panic_on_list_corruption;
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EXPORT_SYMBOL_GPL(panic_on_list_corruption);
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static int __init panic_on_list_corruption_setup(char *str)
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{
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unsigned long enabled;
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int ret;
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ret = kstrtoul(str, 10, &enabled);
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if (ret)
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return ret;
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if (enabled == 1)
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panic_on_list_corruption = 1;
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return 0;
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}
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early_param("panic_on_list_corruption", panic_on_list_corruption_setup);
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void __list_add(struct list_head *new,
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struct list_head *prev,
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struct list_head *next)
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{
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int warn = 0;
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warn |= check_list_corruption(next->prev, prev, next, __func__, "next->prev", "prev", "next");
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warn |= check_list_corruption(prev->next, next, prev, __func__, "prev->next", "next", "prev");
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warn |= WARN(new == prev || new == next,
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"list_add double add: new=%p, prev=%p, next=%p.\n",
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new, prev, next);
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if ((warn) && (panic_on_list_corruption))
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panic("List corruption");
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next->prev = new;
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new->next = next;
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new->prev = prev;
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prev->next = new;
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}
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EXPORT_SYMBOL(__list_add);
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void __list_del_entry(struct list_head *entry)
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{
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struct list_head *prev, *next;
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prev = entry->prev;
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next = entry->next;
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if (WARN(next == LIST_POISON1,
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"list_del corruption, %p->next is LIST_POISON1 (%p)\n",
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entry, LIST_POISON1) ||
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WARN(prev == LIST_POISON2,
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"list_del corruption, %p->prev is LIST_POISON2 (%p)\n",
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entry, LIST_POISON2) ||
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check_list_corruption(next->prev, entry, next,
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__func__, "next->prev", "entry", "next") ||
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check_list_corruption(prev->next, entry, prev,
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__func__, "prev->next", "entry", "prev")) {
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if (panic_on_list_corruption)
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panic("List corruption");
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return;
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}
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__list_del(prev, next);
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}
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EXPORT_SYMBOL(__list_del_entry);
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/**
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* list_del - deletes entry from list.
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* @entry: the element to delete from the list.
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* Note: list_empty on entry does not return true after this, the entry is
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* in an undefined state.
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*/
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void list_del(struct list_head *entry)
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{
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__list_del_entry(entry);
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entry->next = LIST_POISON1;
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entry->prev = LIST_POISON2;
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}
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EXPORT_SYMBOL(list_del);
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/*
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* RCU variants.
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*/
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void __list_add_rcu(struct list_head *new,
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struct list_head *prev, struct list_head *next)
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{
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int warn = 0;
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warn |= check_list_corruption(next->prev, prev, next, __func__, "next->prev", "prev", "next");
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warn |= check_list_corruption(prev->next, next, prev, __func__, "prev->next", "next", "prev");
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if ((warn) && (panic_on_list_corruption))
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panic("List corruption");
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new->next = next;
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new->prev = prev;
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rcu_assign_pointer(list_next_rcu(prev), new);
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next->prev = new;
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}
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EXPORT_SYMBOL(__list_add_rcu);
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