cf904cfa7c
The main advantage of circular lists (the fact that the head node has the same memory layout as any other node) is completely negated by the implementation in qemu-queue.h. Not surprisingly, nobody uses QCIRCLEQ. While this might change if RCU is ever adopted by QEMU, the QLIST is also RCU-friendly and in fact it is used in a RCU-like manner by 9pfs already. So, just kill QCIRCLEQ. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
415 lines
20 KiB
C
415 lines
20 KiB
C
/* $NetBSD: queue.h,v 1.52 2009/04/20 09:56:08 mschuett Exp $ */
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/*
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* Qemu version: Copy from netbsd, removed debug code, removed some of
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* the implementations. Left in singly-linked lists, lists, simple
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* queues, and tail queues.
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*/
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/*
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* Copyright (c) 1991, 1993
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* The Regents of the University of California. All rights reserved.
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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
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* are met:
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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 name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* 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 REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* @(#)queue.h 8.5 (Berkeley) 8/20/94
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*/
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#ifndef QEMU_SYS_QUEUE_H_
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#define QEMU_SYS_QUEUE_H_
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/*
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* This file defines four types of data structures: singly-linked lists,
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* lists, simple queues, and tail queues.
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*
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* A singly-linked list is headed by a single forward pointer. The
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* elements are singly linked for minimum space and pointer manipulation
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* overhead at the expense of O(n) removal for arbitrary elements. New
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* elements can be added to the list after an existing element or at the
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* head of the list. Elements being removed from the head of the list
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* should use the explicit macro for this purpose for optimum
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* efficiency. A singly-linked list may only be traversed in the forward
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* direction. Singly-linked lists are ideal for applications with large
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* datasets and few or no removals or for implementing a LIFO queue.
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*
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* A list is headed by a single forward pointer (or an array of forward
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* pointers for a hash table header). The elements are doubly linked
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* so that an arbitrary element can be removed without a need to
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* traverse the list. New elements can be added to the list before
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* or after an existing element or at the head of the list. A list
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* may only be traversed in the forward direction.
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*
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* A simple queue is headed by a pair of pointers, one the head of the
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* list and the other to the tail of the list. The elements are singly
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* linked to save space, so elements can only be removed from the
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* head of the list. New elements can be added to the list after
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* an existing element, at the head of the list, or at the end of the
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* list. A simple queue may only be traversed in the forward direction.
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*
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* A tail queue is headed by a pair of pointers, one to the head of the
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* list and the other to the tail of the list. The elements are doubly
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* linked so that an arbitrary element can be removed without a need to
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* traverse the list. New elements can be added to the list before or
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* after an existing element, at the head of the list, or at the end of
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* the list. A tail queue may be traversed in either direction.
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*
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* For details on the use of these macros, see the queue(3) manual page.
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*/
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#include "qemu-barrier.h" /* for smp_wmb() */
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/*
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* List definitions.
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*/
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#define QLIST_HEAD(name, type) \
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struct name { \
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struct type *lh_first; /* first element */ \
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}
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#define QLIST_HEAD_INITIALIZER(head) \
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{ NULL }
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#define QLIST_ENTRY(type) \
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struct { \
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struct type *le_next; /* next element */ \
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struct type **le_prev; /* address of previous next element */ \
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}
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/*
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* List functions.
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*/
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#define QLIST_INIT(head) do { \
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(head)->lh_first = NULL; \
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} while (/*CONSTCOND*/0)
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#define QLIST_INSERT_AFTER(listelm, elm, field) do { \
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if (((elm)->field.le_next = (listelm)->field.le_next) != NULL) \
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(listelm)->field.le_next->field.le_prev = \
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&(elm)->field.le_next; \
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(listelm)->field.le_next = (elm); \
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(elm)->field.le_prev = &(listelm)->field.le_next; \
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} while (/*CONSTCOND*/0)
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#define QLIST_INSERT_BEFORE(listelm, elm, field) do { \
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(elm)->field.le_prev = (listelm)->field.le_prev; \
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(elm)->field.le_next = (listelm); \
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*(listelm)->field.le_prev = (elm); \
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(listelm)->field.le_prev = &(elm)->field.le_next; \
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} while (/*CONSTCOND*/0)
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#define QLIST_INSERT_HEAD(head, elm, field) do { \
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if (((elm)->field.le_next = (head)->lh_first) != NULL) \
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(head)->lh_first->field.le_prev = &(elm)->field.le_next;\
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(head)->lh_first = (elm); \
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(elm)->field.le_prev = &(head)->lh_first; \
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} while (/*CONSTCOND*/0)
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#define QLIST_INSERT_HEAD_RCU(head, elm, field) do { \
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(elm)->field.le_prev = &(head)->lh_first; \
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(elm)->field.le_next = (head)->lh_first; \
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smp_wmb(); /* fill elm before linking it */ \
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if ((head)->lh_first != NULL) { \
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(head)->lh_first->field.le_prev = &(elm)->field.le_next; \
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} \
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(head)->lh_first = (elm); \
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smp_wmb(); \
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} while (/* CONSTCOND*/0)
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#define QLIST_REMOVE(elm, field) do { \
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if ((elm)->field.le_next != NULL) \
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(elm)->field.le_next->field.le_prev = \
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(elm)->field.le_prev; \
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*(elm)->field.le_prev = (elm)->field.le_next; \
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} while (/*CONSTCOND*/0)
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#define QLIST_FOREACH(var, head, field) \
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for ((var) = ((head)->lh_first); \
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(var); \
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(var) = ((var)->field.le_next))
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#define QLIST_FOREACH_SAFE(var, head, field, next_var) \
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for ((var) = ((head)->lh_first); \
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(var) && ((next_var) = ((var)->field.le_next), 1); \
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(var) = (next_var))
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/*
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* List access methods.
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*/
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#define QLIST_EMPTY(head) ((head)->lh_first == NULL)
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#define QLIST_FIRST(head) ((head)->lh_first)
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#define QLIST_NEXT(elm, field) ((elm)->field.le_next)
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/*
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* Singly-linked List definitions.
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*/
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#define QSLIST_HEAD(name, type) \
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struct name { \
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struct type *slh_first; /* first element */ \
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}
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#define QSLIST_HEAD_INITIALIZER(head) \
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{ NULL }
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#define QSLIST_ENTRY(type) \
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struct { \
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struct type *sle_next; /* next element */ \
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}
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/*
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* Singly-linked List functions.
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*/
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#define QSLIST_INIT(head) do { \
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(head)->slh_first = NULL; \
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} while (/*CONSTCOND*/0)
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#define QSLIST_INSERT_AFTER(slistelm, elm, field) do { \
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(elm)->field.sle_next = (slistelm)->field.sle_next; \
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(slistelm)->field.sle_next = (elm); \
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} while (/*CONSTCOND*/0)
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#define QSLIST_INSERT_HEAD(head, elm, field) do { \
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(elm)->field.sle_next = (head)->slh_first; \
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(head)->slh_first = (elm); \
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} while (/*CONSTCOND*/0)
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#define QSLIST_REMOVE_HEAD(head, field) do { \
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(head)->slh_first = (head)->slh_first->field.sle_next; \
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} while (/*CONSTCOND*/0)
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#define QSLIST_REMOVE_AFTER(slistelm, field) do { \
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(slistelm)->field.sle_next = \
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QSLIST_NEXT(QSLIST_NEXT((slistelm), field), field); \
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} while (/*CONSTCOND*/0)
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#define QSLIST_FOREACH(var, head, field) \
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for((var) = (head)->slh_first; (var); (var) = (var)->field.sle_next)
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#define QSLIST_FOREACH_SAFE(var, head, field, tvar) \
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for ((var) = QSLIST_FIRST((head)); \
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(var) && ((tvar) = QSLIST_NEXT((var), field), 1); \
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(var) = (tvar))
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/*
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* Singly-linked List access methods.
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*/
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#define QSLIST_EMPTY(head) ((head)->slh_first == NULL)
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#define QSLIST_FIRST(head) ((head)->slh_first)
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#define QSLIST_NEXT(elm, field) ((elm)->field.sle_next)
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/*
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* Simple queue definitions.
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*/
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#define QSIMPLEQ_HEAD(name, type) \
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struct name { \
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struct type *sqh_first; /* first element */ \
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struct type **sqh_last; /* addr of last next element */ \
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}
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#define QSIMPLEQ_HEAD_INITIALIZER(head) \
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{ NULL, &(head).sqh_first }
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#define QSIMPLEQ_ENTRY(type) \
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struct { \
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struct type *sqe_next; /* next element */ \
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}
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/*
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* Simple queue functions.
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*/
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#define QSIMPLEQ_INIT(head) do { \
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(head)->sqh_first = NULL; \
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(head)->sqh_last = &(head)->sqh_first; \
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} while (/*CONSTCOND*/0)
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#define QSIMPLEQ_INSERT_HEAD(head, elm, field) do { \
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if (((elm)->field.sqe_next = (head)->sqh_first) == NULL) \
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(head)->sqh_last = &(elm)->field.sqe_next; \
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(head)->sqh_first = (elm); \
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} while (/*CONSTCOND*/0)
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#define QSIMPLEQ_INSERT_TAIL(head, elm, field) do { \
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(elm)->field.sqe_next = NULL; \
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*(head)->sqh_last = (elm); \
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(head)->sqh_last = &(elm)->field.sqe_next; \
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} while (/*CONSTCOND*/0)
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#define QSIMPLEQ_INSERT_AFTER(head, listelm, elm, field) do { \
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if (((elm)->field.sqe_next = (listelm)->field.sqe_next) == NULL) \
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(head)->sqh_last = &(elm)->field.sqe_next; \
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(listelm)->field.sqe_next = (elm); \
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} while (/*CONSTCOND*/0)
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#define QSIMPLEQ_REMOVE_HEAD(head, field) do { \
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if (((head)->sqh_first = (head)->sqh_first->field.sqe_next) == NULL)\
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(head)->sqh_last = &(head)->sqh_first; \
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} while (/*CONSTCOND*/0)
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#define QSIMPLEQ_REMOVE(head, elm, type, field) do { \
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if ((head)->sqh_first == (elm)) { \
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QSIMPLEQ_REMOVE_HEAD((head), field); \
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} else { \
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struct type *curelm = (head)->sqh_first; \
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while (curelm->field.sqe_next != (elm)) \
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curelm = curelm->field.sqe_next; \
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if ((curelm->field.sqe_next = \
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curelm->field.sqe_next->field.sqe_next) == NULL) \
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(head)->sqh_last = &(curelm)->field.sqe_next; \
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} \
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} while (/*CONSTCOND*/0)
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#define QSIMPLEQ_FOREACH(var, head, field) \
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for ((var) = ((head)->sqh_first); \
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(var); \
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(var) = ((var)->field.sqe_next))
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#define QSIMPLEQ_FOREACH_SAFE(var, head, field, next) \
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for ((var) = ((head)->sqh_first); \
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(var) && ((next = ((var)->field.sqe_next)), 1); \
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(var) = (next))
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#define QSIMPLEQ_CONCAT(head1, head2) do { \
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if (!QSIMPLEQ_EMPTY((head2))) { \
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*(head1)->sqh_last = (head2)->sqh_first; \
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(head1)->sqh_last = (head2)->sqh_last; \
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QSIMPLEQ_INIT((head2)); \
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} \
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} while (/*CONSTCOND*/0)
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#define QSIMPLEQ_LAST(head, type, field) \
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(QSIMPLEQ_EMPTY((head)) ? \
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NULL : \
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((struct type *)(void *) \
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((char *)((head)->sqh_last) - offsetof(struct type, field))))
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/*
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* Simple queue access methods.
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*/
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#define QSIMPLEQ_EMPTY(head) ((head)->sqh_first == NULL)
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#define QSIMPLEQ_FIRST(head) ((head)->sqh_first)
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#define QSIMPLEQ_NEXT(elm, field) ((elm)->field.sqe_next)
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/*
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* Tail queue definitions.
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*/
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#define Q_TAILQ_HEAD(name, type, qual) \
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struct name { \
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qual type *tqh_first; /* first element */ \
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qual type *qual *tqh_last; /* addr of last next element */ \
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}
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#define QTAILQ_HEAD(name, type) Q_TAILQ_HEAD(name, struct type,)
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#define QTAILQ_HEAD_INITIALIZER(head) \
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{ NULL, &(head).tqh_first }
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#define Q_TAILQ_ENTRY(type, qual) \
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struct { \
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qual type *tqe_next; /* next element */ \
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qual type *qual *tqe_prev; /* address of previous next element */\
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}
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#define QTAILQ_ENTRY(type) Q_TAILQ_ENTRY(struct type,)
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/*
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* Tail queue functions.
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*/
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#define QTAILQ_INIT(head) do { \
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(head)->tqh_first = NULL; \
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(head)->tqh_last = &(head)->tqh_first; \
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} while (/*CONSTCOND*/0)
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#define QTAILQ_INSERT_HEAD(head, elm, field) do { \
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if (((elm)->field.tqe_next = (head)->tqh_first) != NULL) \
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(head)->tqh_first->field.tqe_prev = \
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&(elm)->field.tqe_next; \
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else \
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(head)->tqh_last = &(elm)->field.tqe_next; \
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(head)->tqh_first = (elm); \
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(elm)->field.tqe_prev = &(head)->tqh_first; \
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} while (/*CONSTCOND*/0)
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#define QTAILQ_INSERT_TAIL(head, elm, field) do { \
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(elm)->field.tqe_next = NULL; \
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(elm)->field.tqe_prev = (head)->tqh_last; \
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*(head)->tqh_last = (elm); \
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(head)->tqh_last = &(elm)->field.tqe_next; \
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} while (/*CONSTCOND*/0)
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#define QTAILQ_INSERT_AFTER(head, listelm, elm, field) do { \
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if (((elm)->field.tqe_next = (listelm)->field.tqe_next) != NULL)\
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(elm)->field.tqe_next->field.tqe_prev = \
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&(elm)->field.tqe_next; \
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else \
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(head)->tqh_last = &(elm)->field.tqe_next; \
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(listelm)->field.tqe_next = (elm); \
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(elm)->field.tqe_prev = &(listelm)->field.tqe_next; \
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} while (/*CONSTCOND*/0)
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#define QTAILQ_INSERT_BEFORE(listelm, elm, field) do { \
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(elm)->field.tqe_prev = (listelm)->field.tqe_prev; \
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(elm)->field.tqe_next = (listelm); \
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*(listelm)->field.tqe_prev = (elm); \
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(listelm)->field.tqe_prev = &(elm)->field.tqe_next; \
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} while (/*CONSTCOND*/0)
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#define QTAILQ_REMOVE(head, elm, field) do { \
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if (((elm)->field.tqe_next) != NULL) \
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(elm)->field.tqe_next->field.tqe_prev = \
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(elm)->field.tqe_prev; \
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else \
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(head)->tqh_last = (elm)->field.tqe_prev; \
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*(elm)->field.tqe_prev = (elm)->field.tqe_next; \
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} while (/*CONSTCOND*/0)
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#define QTAILQ_FOREACH(var, head, field) \
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for ((var) = ((head)->tqh_first); \
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(var); \
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(var) = ((var)->field.tqe_next))
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#define QTAILQ_FOREACH_SAFE(var, head, field, next_var) \
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for ((var) = ((head)->tqh_first); \
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(var) && ((next_var) = ((var)->field.tqe_next), 1); \
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(var) = (next_var))
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#define QTAILQ_FOREACH_REVERSE(var, head, headname, field) \
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for ((var) = (*(((struct headname *)((head)->tqh_last))->tqh_last)); \
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(var); \
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(var) = (*(((struct headname *)((var)->field.tqe_prev))->tqh_last)))
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/*
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* Tail queue access methods.
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*/
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#define QTAILQ_EMPTY(head) ((head)->tqh_first == NULL)
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#define QTAILQ_FIRST(head) ((head)->tqh_first)
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#define QTAILQ_NEXT(elm, field) ((elm)->field.tqe_next)
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#define QTAILQ_LAST(head, headname) \
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(*(((struct headname *)((head)->tqh_last))->tqh_last))
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#define QTAILQ_PREV(elm, headname, field) \
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(*(((struct headname *)((elm)->field.tqe_prev))->tqh_last))
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#endif /* !QEMU_SYS_QUEUE_H_ */
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