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1 /* |
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2 * Descending-priority-sorted double-linked list |
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3 * |
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4 * (C) 2002-2003 Intel Corp |
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5 * Inaky Perez-Gonzalez <inaky.perez-gonzalez@intel.com>. |
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6 * |
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7 * 2001-2005 (c) MontaVista Software, Inc. |
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8 * Daniel Walker <dwalker@mvista.com> |
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9 * |
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10 * (C) 2005 Thomas Gleixner <tglx@linutronix.de> |
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11 * |
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12 * Simplifications of the original code by |
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13 * Oleg Nesterov <oleg@tv-sign.ru> |
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14 * |
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15 * Licensed under the FSF's GNU Public License v2 or later. |
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16 * |
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17 * Based on simple lists (include/linux/list.h). |
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18 * |
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19 * This is a priority-sorted list of nodes; each node has a |
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20 * priority from INT_MIN (highest) to INT_MAX (lowest). |
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21 * |
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22 * Addition is O(K), removal is O(1), change of priority of a node is |
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23 * O(K) and K is the number of RT priority levels used in the system. |
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24 * (1 <= K <= 99) |
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25 * |
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26 * This list is really a list of lists: |
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27 * |
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28 * - The tier 1 list is the prio_list, different priority nodes. |
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29 * |
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30 * - The tier 2 list is the node_list, serialized nodes. |
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31 * |
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32 * Simple ASCII art explanation: |
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33 * |
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34 * |HEAD | |
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35 * | | |
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36 * |prio_list.prev|<------------------------------------| |
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37 * |prio_list.next|<->|pl|<->|pl|<--------------->|pl|<-| |
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38 * |10 | |10| |21| |21| |21| |40| (prio) |
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39 * | | | | | | | | | | | | |
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40 * | | | | | | | | | | | | |
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41 * |node_list.next|<->|nl|<->|nl|<->|nl|<->|nl|<->|nl|<-| |
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42 * |node_list.prev|<------------------------------------| |
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43 * |
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44 * The nodes on the prio_list list are sorted by priority to simplify |
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45 * the insertion of new nodes. There are no nodes with duplicate |
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46 * priorites on the list. |
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47 * |
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48 * The nodes on the node_list is ordered by priority and can contain |
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49 * entries which have the same priority. Those entries are ordered |
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50 * FIFO |
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51 * |
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52 * Addition means: look for the prio_list node in the prio_list |
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53 * for the priority of the node and insert it before the node_list |
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54 * entry of the next prio_list node. If it is the first node of |
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55 * that priority, add it to the prio_list in the right position and |
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56 * insert it into the serialized node_list list |
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57 * |
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58 * Removal means remove it from the node_list and remove it from |
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59 * the prio_list if the node_list list_head is non empty. In case |
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60 * of removal from the prio_list it must be checked whether other |
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61 * entries of the same priority are on the list or not. If there |
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62 * is another entry of the same priority then this entry has to |
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63 * replace the removed entry on the prio_list. If the entry which |
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64 * is removed is the only entry of this priority then a simple |
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65 * remove from both list is sufficient. |
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66 * |
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67 * INT_MIN is the highest priority, 0 is the medium highest, INT_MAX |
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68 * is lowest priority. |
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69 * |
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70 * No locking is done, up to the caller. |
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71 * |
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72 */ |
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73 #ifndef _LINUX_PLIST_H_ |
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74 #define _LINUX_PLIST_H_ |
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75 |
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76 #include <linux/kernel.h> |
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77 #include <linux/list.h> |
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78 #include <linux/spinlock_types.h> |
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79 |
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80 struct plist_head { |
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81 struct list_head prio_list; |
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82 struct list_head node_list; |
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83 #ifdef CONFIG_DEBUG_PI_LIST |
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84 spinlock_t *lock; |
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85 #endif |
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86 }; |
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87 |
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88 struct plist_node { |
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89 int prio; |
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90 struct plist_head plist; |
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91 }; |
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92 |
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93 #ifdef CONFIG_DEBUG_PI_LIST |
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94 # define PLIST_HEAD_LOCK_INIT(_lock) .lock = _lock |
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95 #else |
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96 # define PLIST_HEAD_LOCK_INIT(_lock) |
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97 #endif |
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98 |
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99 /** |
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100 * PLIST_HEAD_INIT - static struct plist_head initializer |
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101 * @head: struct plist_head variable name |
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102 * @_lock: lock to initialize for this list |
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103 */ |
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104 #define PLIST_HEAD_INIT(head, _lock) \ |
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105 { \ |
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106 .prio_list = LIST_HEAD_INIT((head).prio_list), \ |
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107 .node_list = LIST_HEAD_INIT((head).node_list), \ |
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108 PLIST_HEAD_LOCK_INIT(&(_lock)) \ |
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109 } |
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110 |
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111 /** |
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112 * PLIST_NODE_INIT - static struct plist_node initializer |
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113 * @node: struct plist_node variable name |
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114 * @__prio: initial node priority |
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115 */ |
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116 #define PLIST_NODE_INIT(node, __prio) \ |
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117 { \ |
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118 .prio = (__prio), \ |
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119 .plist = PLIST_HEAD_INIT((node).plist, NULL), \ |
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120 } |
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121 |
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122 /** |
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123 * plist_head_init - dynamic struct plist_head initializer |
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124 * @head: &struct plist_head pointer |
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125 * @lock: list spinlock, remembered for debugging |
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126 */ |
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127 static inline void |
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128 plist_head_init(struct plist_head *head, spinlock_t *lock) |
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129 { |
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130 INIT_LIST_HEAD(&head->prio_list); |
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131 INIT_LIST_HEAD(&head->node_list); |
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132 #ifdef CONFIG_DEBUG_PI_LIST |
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133 head->lock = lock; |
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134 #endif |
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135 } |
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136 |
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137 /** |
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138 * plist_node_init - Dynamic struct plist_node initializer |
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139 * @node: &struct plist_node pointer |
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140 * @prio: initial node priority |
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141 */ |
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142 static inline void plist_node_init(struct plist_node *node, int prio) |
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143 { |
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144 node->prio = prio; |
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145 plist_head_init(&node->plist, NULL); |
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146 } |
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147 |
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148 extern void plist_add(struct plist_node *node, struct plist_head *head); |
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149 extern void plist_del(struct plist_node *node, struct plist_head *head); |
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150 |
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151 /** |
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152 * plist_for_each - iterate over the plist |
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153 * @pos: the type * to use as a loop counter |
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154 * @head: the head for your list |
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155 */ |
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156 #define plist_for_each(pos, head) \ |
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157 list_for_each_entry(pos, &(head)->node_list, plist.node_list) |
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158 |
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159 /** |
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160 * plist_for_each_safe - iterate safely over a plist of given type |
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161 * @pos: the type * to use as a loop counter |
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162 * @n: another type * to use as temporary storage |
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163 * @head: the head for your list |
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164 * |
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165 * Iterate over a plist of given type, safe against removal of list entry. |
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166 */ |
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167 #define plist_for_each_safe(pos, n, head) \ |
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168 list_for_each_entry_safe(pos, n, &(head)->node_list, plist.node_list) |
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169 |
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170 /** |
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171 * plist_for_each_entry - iterate over list of given type |
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172 * @pos: the type * to use as a loop counter |
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173 * @head: the head for your list |
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174 * @mem: the name of the list_struct within the struct |
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175 */ |
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176 #define plist_for_each_entry(pos, head, mem) \ |
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177 list_for_each_entry(pos, &(head)->node_list, mem.plist.node_list) |
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178 |
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179 /** |
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180 * plist_for_each_entry_safe - iterate safely over list of given type |
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181 * @pos: the type * to use as a loop counter |
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182 * @n: another type * to use as temporary storage |
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183 * @head: the head for your list |
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184 * @m: the name of the list_struct within the struct |
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185 * |
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186 * Iterate over list of given type, safe against removal of list entry. |
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187 */ |
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188 #define plist_for_each_entry_safe(pos, n, head, m) \ |
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189 list_for_each_entry_safe(pos, n, &(head)->node_list, m.plist.node_list) |
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190 |
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191 /** |
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192 * plist_head_empty - return !0 if a plist_head is empty |
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193 * @head: &struct plist_head pointer |
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194 */ |
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195 static inline int plist_head_empty(const struct plist_head *head) |
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196 { |
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197 return list_empty(&head->node_list); |
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198 } |
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199 |
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200 /** |
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201 * plist_node_empty - return !0 if plist_node is not on a list |
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202 * @node: &struct plist_node pointer |
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203 */ |
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204 static inline int plist_node_empty(const struct plist_node *node) |
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205 { |
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206 return plist_head_empty(&node->plist); |
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207 } |
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208 |
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209 /* All functions below assume the plist_head is not empty. */ |
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210 |
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211 /** |
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212 * plist_first_entry - get the struct for the first entry |
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213 * @head: the &struct plist_head pointer |
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214 * @type: the type of the struct this is embedded in |
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215 * @member: the name of the list_struct within the struct |
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216 */ |
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217 #ifdef CONFIG_DEBUG_PI_LIST |
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218 # define plist_first_entry(head, type, member) \ |
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219 ({ \ |
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220 WARN_ON(plist_head_empty(head)); \ |
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221 container_of(plist_first(head), type, member); \ |
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222 }) |
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223 #else |
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224 # define plist_first_entry(head, type, member) \ |
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225 container_of(plist_first(head), type, member) |
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226 #endif |
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227 |
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228 /** |
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229 * plist_first - return the first node (and thus, highest priority) |
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230 * @head: the &struct plist_head pointer |
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231 * |
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232 * Assumes the plist is _not_ empty. |
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233 */ |
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234 static inline struct plist_node* plist_first(const struct plist_head *head) |
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235 { |
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236 return list_entry(head->node_list.next, |
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237 struct plist_node, plist.node_list); |
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238 } |
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239 |
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240 #endif |