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Rev | Author | Line No. | Line |
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4104 | Serge | 1 | /* |
2 | * Copyright (c) 2006-2009 VMware, Inc., Palo Alto, CA., USA |
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3 | * Copyright (c) 2012 David Airlie |
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4 | * Copyright (c) 2013 David Herrmann |
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5 | * |
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6 | * Permission is hereby granted, free of charge, to any person obtaining a |
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7 | * copy of this software and associated documentation files (the "Software"), |
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8 | * to deal in the Software without restriction, including without limitation |
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9 | * the rights to use, copy, modify, merge, publish, distribute, sublicense, |
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10 | * and/or sell copies of the Software, and to permit persons to whom the |
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11 | * Software is furnished to do so, subject to the following conditions: |
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12 | * |
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13 | * The above copyright notice and this permission notice shall be included in |
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14 | * all copies or substantial portions of the Software. |
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15 | * |
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16 | * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR |
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17 | * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, |
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18 | * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL |
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19 | * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR |
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20 | * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, |
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21 | * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR |
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22 | * OTHER DEALINGS IN THE SOFTWARE. |
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23 | */ |
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24 | |||
25 | #include |
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26 | #include |
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27 | #include |
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4560 | Serge | 28 | #include |
4104 | Serge | 29 | #include |
30 | #include |
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31 | #include |
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32 | #include |
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33 | #include |
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34 | #include |
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35 | |||
36 | /** |
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37 | * DOC: vma offset manager |
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38 | * |
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39 | * The vma-manager is responsible to map arbitrary driver-dependent memory |
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40 | * regions into the linear user address-space. It provides offsets to the |
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41 | * caller which can then be used on the address_space of the drm-device. It |
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42 | * takes care to not overlap regions, size them appropriately and to not |
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43 | * confuse mm-core by inconsistent fake vm_pgoff fields. |
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44 | * Drivers shouldn't use this for object placement in VMEM. This manager should |
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45 | * only be used to manage mappings into linear user-space VMs. |
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46 | * |
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47 | * We use drm_mm as backend to manage object allocations. But it is highly |
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48 | * optimized for alloc/free calls, not lookups. Hence, we use an rb-tree to |
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49 | * speed up offset lookups. |
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50 | * |
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51 | * You must not use multiple offset managers on a single address_space. |
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52 | * Otherwise, mm-core will be unable to tear down memory mappings as the VM will |
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6084 | serge | 53 | * no longer be linear. |
4104 | Serge | 54 | * |
55 | * This offset manager works on page-based addresses. That is, every argument |
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56 | * and return code (with the exception of drm_vma_node_offset_addr()) is given |
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57 | * in number of pages, not number of bytes. That means, object sizes and offsets |
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58 | * must always be page-aligned (as usual). |
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59 | * If you want to get a valid byte-based user-space address for a given offset, |
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60 | * please see drm_vma_node_offset_addr(). |
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61 | * |
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62 | * Additionally to offset management, the vma offset manager also handles access |
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63 | * management. For every open-file context that is allowed to access a given |
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64 | * node, you must call drm_vma_node_allow(). Otherwise, an mmap() call on this |
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65 | * open-file with the offset of the node will fail with -EACCES. To revoke |
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66 | * access again, use drm_vma_node_revoke(). However, the caller is responsible |
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67 | * for destroying already existing mappings, if required. |
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68 | */ |
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69 | |||
70 | /** |
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71 | * drm_vma_offset_manager_init - Initialize new offset-manager |
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72 | * @mgr: Manager object |
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73 | * @page_offset: Offset of available memory area (page-based) |
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74 | * @size: Size of available address space range (page-based) |
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75 | * |
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76 | * Initialize a new offset-manager. The offset and area size available for the |
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77 | * manager are given as @page_offset and @size. Both are interpreted as |
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78 | * page-numbers, not bytes. |
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79 | * |
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80 | * Adding/removing nodes from the manager is locked internally and protected |
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81 | * against concurrent access. However, node allocation and destruction is left |
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82 | * for the caller. While calling into the vma-manager, a given node must |
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83 | * always be guaranteed to be referenced. |
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84 | */ |
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85 | void drm_vma_offset_manager_init(struct drm_vma_offset_manager *mgr, |
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86 | unsigned long page_offset, unsigned long size) |
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87 | { |
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88 | rwlock_init(&mgr->vm_lock); |
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89 | mgr->vm_addr_space_rb = RB_ROOT; |
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90 | drm_mm_init(&mgr->vm_addr_space_mm, page_offset, size); |
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91 | } |
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92 | EXPORT_SYMBOL(drm_vma_offset_manager_init); |
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93 | |||
94 | /** |
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95 | * drm_vma_offset_manager_destroy() - Destroy offset manager |
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96 | * @mgr: Manager object |
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97 | * |
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98 | * Destroy an object manager which was previously created via |
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99 | * drm_vma_offset_manager_init(). The caller must remove all allocated nodes |
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100 | * before destroying the manager. Otherwise, drm_mm will refuse to free the |
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101 | * requested resources. |
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102 | * |
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103 | * The manager must not be accessed after this function is called. |
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104 | */ |
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105 | void drm_vma_offset_manager_destroy(struct drm_vma_offset_manager *mgr) |
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106 | { |
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107 | /* take the lock to protect against buggy drivers */ |
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108 | write_lock(&mgr->vm_lock); |
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109 | drm_mm_takedown(&mgr->vm_addr_space_mm); |
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110 | write_unlock(&mgr->vm_lock); |
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111 | } |
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112 | EXPORT_SYMBOL(drm_vma_offset_manager_destroy); |
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113 | |||
114 | /** |
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6084 | serge | 115 | * drm_vma_offset_lookup_locked() - Find node in offset space |
4104 | Serge | 116 | * @mgr: Manager object |
117 | * @start: Start address for object (page-based) |
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118 | * @pages: Size of object (page-based) |
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119 | * |
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120 | * Find a node given a start address and object size. This returns the _best_ |
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121 | * match for the given node. That is, @start may point somewhere into a valid |
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122 | * region and the given node will be returned, as long as the node spans the |
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123 | * whole requested area (given the size in number of pages as @pages). |
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124 | * |
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6084 | serge | 125 | * Note that before lookup the vma offset manager lookup lock must be acquired |
126 | * with drm_vma_offset_lock_lookup(). See there for an example. This can then be |
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127 | * used to implement weakly referenced lookups using kref_get_unless_zero(). |
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128 | * |
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129 | * Example: |
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130 | * drm_vma_offset_lock_lookup(mgr); |
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131 | * node = drm_vma_offset_lookup_locked(mgr); |
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132 | * if (node) |
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133 | * kref_get_unless_zero(container_of(node, sth, entr)); |
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134 | * drm_vma_offset_unlock_lookup(mgr); |
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135 | * |
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4104 | Serge | 136 | * RETURNS: |
137 | * Returns NULL if no suitable node can be found. Otherwise, the best match |
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138 | * is returned. It's the caller's responsibility to make sure the node doesn't |
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139 | * get destroyed before the caller can access it. |
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140 | */ |
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141 | struct drm_vma_offset_node *drm_vma_offset_lookup_locked(struct drm_vma_offset_manager *mgr, |
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142 | unsigned long start, |
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143 | unsigned long pages) |
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144 | { |
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145 | struct drm_vma_offset_node *node, *best; |
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146 | struct rb_node *iter; |
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147 | unsigned long offset; |
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148 | |||
149 | iter = mgr->vm_addr_space_rb.rb_node; |
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150 | best = NULL; |
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151 | |||
152 | while (likely(iter)) { |
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153 | node = rb_entry(iter, struct drm_vma_offset_node, vm_rb); |
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154 | offset = node->vm_node.start; |
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155 | if (start >= offset) { |
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156 | iter = iter->rb_right; |
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157 | best = node; |
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158 | if (start == offset) |
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159 | break; |
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160 | } else { |
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161 | iter = iter->rb_left; |
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162 | } |
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163 | } |
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164 | |||
165 | /* verify that the node spans the requested area */ |
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166 | if (best) { |
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167 | offset = best->vm_node.start + best->vm_node.size; |
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168 | if (offset < start + pages) |
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169 | best = NULL; |
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170 | } |
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171 | |||
172 | return best; |
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173 | } |
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174 | EXPORT_SYMBOL(drm_vma_offset_lookup_locked); |
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175 | |||
176 | /* internal helper to link @node into the rb-tree */ |
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177 | static void _drm_vma_offset_add_rb(struct drm_vma_offset_manager *mgr, |
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178 | struct drm_vma_offset_node *node) |
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179 | { |
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180 | struct rb_node **iter = &mgr->vm_addr_space_rb.rb_node; |
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181 | struct rb_node *parent = NULL; |
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182 | struct drm_vma_offset_node *iter_node; |
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183 | |||
184 | while (likely(*iter)) { |
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185 | parent = *iter; |
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186 | iter_node = rb_entry(*iter, struct drm_vma_offset_node, vm_rb); |
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187 | |||
188 | if (node->vm_node.start < iter_node->vm_node.start) |
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189 | iter = &(*iter)->rb_left; |
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190 | else if (node->vm_node.start > iter_node->vm_node.start) |
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191 | iter = &(*iter)->rb_right; |
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192 | else |
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193 | BUG(); |
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194 | } |
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195 | |||
196 | rb_link_node(&node->vm_rb, parent, iter); |
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197 | rb_insert_color(&node->vm_rb, &mgr->vm_addr_space_rb); |
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198 | } |
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199 | |||
200 | /** |
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201 | * drm_vma_offset_add() - Add offset node to manager |
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202 | * @mgr: Manager object |
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203 | * @node: Node to be added |
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204 | * @pages: Allocation size visible to user-space (in number of pages) |
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205 | * |
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206 | * Add a node to the offset-manager. If the node was already added, this does |
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207 | * nothing and return 0. @pages is the size of the object given in number of |
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208 | * pages. |
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209 | * After this call succeeds, you can access the offset of the node until it |
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210 | * is removed again. |
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211 | * |
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212 | * If this call fails, it is safe to retry the operation or call |
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213 | * drm_vma_offset_remove(), anyway. However, no cleanup is required in that |
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214 | * case. |
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215 | * |
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216 | * @pages is not required to be the same size as the underlying memory object |
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217 | * that you want to map. It only limits the size that user-space can map into |
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218 | * their address space. |
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219 | * |
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220 | * RETURNS: |
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221 | * 0 on success, negative error code on failure. |
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222 | */ |
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223 | int drm_vma_offset_add(struct drm_vma_offset_manager *mgr, |
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224 | struct drm_vma_offset_node *node, unsigned long pages) |
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225 | { |
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226 | int ret; |
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227 | |||
228 | write_lock(&mgr->vm_lock); |
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229 | |||
230 | if (drm_mm_node_allocated(&node->vm_node)) { |
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231 | ret = 0; |
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232 | goto out_unlock; |
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233 | } |
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234 | |||
235 | ret = drm_mm_insert_node(&mgr->vm_addr_space_mm, &node->vm_node, |
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236 | pages, 0, DRM_MM_SEARCH_DEFAULT); |
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237 | if (ret) |
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238 | goto out_unlock; |
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239 | |||
240 | _drm_vma_offset_add_rb(mgr, node); |
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241 | |||
242 | out_unlock: |
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243 | write_unlock(&mgr->vm_lock); |
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244 | return ret; |
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245 | } |
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246 | EXPORT_SYMBOL(drm_vma_offset_add); |
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247 | |||
248 | /** |
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249 | * drm_vma_offset_remove() - Remove offset node from manager |
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250 | * @mgr: Manager object |
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251 | * @node: Node to be removed |
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252 | * |
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253 | * Remove a node from the offset manager. If the node wasn't added before, this |
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254 | * does nothing. After this call returns, the offset and size will be 0 until a |
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255 | * new offset is allocated via drm_vma_offset_add() again. Helper functions like |
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256 | * drm_vma_node_start() and drm_vma_node_offset_addr() will return 0 if no |
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257 | * offset is allocated. |
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258 | */ |
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259 | void drm_vma_offset_remove(struct drm_vma_offset_manager *mgr, |
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260 | struct drm_vma_offset_node *node) |
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261 | { |
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262 | write_lock(&mgr->vm_lock); |
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263 | |||
264 | if (drm_mm_node_allocated(&node->vm_node)) { |
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265 | rb_erase(&node->vm_rb, &mgr->vm_addr_space_rb); |
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266 | drm_mm_remove_node(&node->vm_node); |
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267 | memset(&node->vm_node, 0, sizeof(node->vm_node)); |
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268 | } |
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269 | |||
270 | write_unlock(&mgr->vm_lock); |
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271 | } |
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272 | EXPORT_SYMBOL(drm_vma_offset_remove); |
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273 | |||
274 | /** |
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275 | * drm_vma_node_allow - Add open-file to list of allowed users |
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276 | * @node: Node to modify |
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277 | * @filp: Open file to add |
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278 | * |
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279 | * Add @filp to the list of allowed open-files for this node. If @filp is |
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280 | * already on this list, the ref-count is incremented. |
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281 | * |
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282 | * The list of allowed-users is preserved across drm_vma_offset_add() and |
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283 | * drm_vma_offset_remove() calls. You may even call it if the node is currently |
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284 | * not added to any offset-manager. |
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285 | * |
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286 | * You must remove all open-files the same number of times as you added them |
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287 | * before destroying the node. Otherwise, you will leak memory. |
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288 | * |
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289 | * This is locked against concurrent access internally. |
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290 | * |
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291 | * RETURNS: |
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292 | * 0 on success, negative error code on internal failure (out-of-mem) |
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293 | */ |
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294 | int drm_vma_node_allow(struct drm_vma_offset_node *node, struct file *filp) |
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295 | { |
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296 | struct rb_node **iter; |
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297 | struct rb_node *parent = NULL; |
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298 | struct drm_vma_offset_file *new, *entry; |
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299 | int ret = 0; |
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300 | |||
301 | /* Preallocate entry to avoid atomic allocations below. It is quite |
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302 | * unlikely that an open-file is added twice to a single node so we |
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303 | * don't optimize for this case. OOM is checked below only if the entry |
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304 | * is actually used. */ |
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305 | new = kmalloc(sizeof(*entry), GFP_KERNEL); |
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306 | |||
307 | write_lock(&node->vm_lock); |
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308 | |||
309 | iter = &node->vm_files.rb_node; |
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310 | |||
311 | while (likely(*iter)) { |
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312 | parent = *iter; |
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313 | entry = rb_entry(*iter, struct drm_vma_offset_file, vm_rb); |
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314 | |||
315 | if (filp == entry->vm_filp) { |
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316 | entry->vm_count++; |
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317 | goto unlock; |
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318 | } else if (filp > entry->vm_filp) { |
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319 | iter = &(*iter)->rb_right; |
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320 | } else { |
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321 | iter = &(*iter)->rb_left; |
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322 | } |
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323 | } |
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324 | |||
325 | if (!new) { |
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326 | ret = -ENOMEM; |
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327 | goto unlock; |
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328 | } |
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329 | |||
330 | new->vm_filp = filp; |
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331 | new->vm_count = 1; |
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332 | rb_link_node(&new->vm_rb, parent, iter); |
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333 | rb_insert_color(&new->vm_rb, &node->vm_files); |
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334 | new = NULL; |
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335 | |||
336 | unlock: |
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337 | write_unlock(&node->vm_lock); |
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338 | kfree(new); |
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339 | return ret; |
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340 | } |
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341 | EXPORT_SYMBOL(drm_vma_node_allow); |
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342 | |||
343 | /** |
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344 | * drm_vma_node_revoke - Remove open-file from list of allowed users |
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345 | * @node: Node to modify |
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346 | * @filp: Open file to remove |
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347 | * |
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348 | * Decrement the ref-count of @filp in the list of allowed open-files on @node. |
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349 | * If the ref-count drops to zero, remove @filp from the list. You must call |
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350 | * this once for every drm_vma_node_allow() on @filp. |
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351 | * |
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352 | * This is locked against concurrent access internally. |
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353 | * |
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354 | * If @filp is not on the list, nothing is done. |
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355 | */ |
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356 | void drm_vma_node_revoke(struct drm_vma_offset_node *node, struct file *filp) |
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357 | { |
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358 | struct drm_vma_offset_file *entry; |
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359 | struct rb_node *iter; |
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360 | |||
361 | write_lock(&node->vm_lock); |
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362 | |||
363 | iter = node->vm_files.rb_node; |
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364 | while (likely(iter)) { |
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365 | entry = rb_entry(iter, struct drm_vma_offset_file, vm_rb); |
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366 | if (filp == entry->vm_filp) { |
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367 | if (!--entry->vm_count) { |
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368 | rb_erase(&entry->vm_rb, &node->vm_files); |
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369 | kfree(entry); |
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370 | } |
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371 | break; |
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372 | } else if (filp > entry->vm_filp) { |
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373 | iter = iter->rb_right; |
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374 | } else { |
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375 | iter = iter->rb_left; |
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376 | } |
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377 | } |
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378 | |||
379 | write_unlock(&node->vm_lock); |
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380 | } |
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381 | EXPORT_SYMBOL(drm_vma_node_revoke); |
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382 | |||
383 | /** |
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384 | * drm_vma_node_is_allowed - Check whether an open-file is granted access |
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385 | * @node: Node to check |
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386 | * @filp: Open-file to check for |
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387 | * |
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388 | * Search the list in @node whether @filp is currently on the list of allowed |
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389 | * open-files (see drm_vma_node_allow()). |
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390 | * |
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391 | * This is locked against concurrent access internally. |
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392 | * |
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393 | * RETURNS: |
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394 | * true iff @filp is on the list |
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395 | */ |
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396 | bool drm_vma_node_is_allowed(struct drm_vma_offset_node *node, |
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397 | struct file *filp) |
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398 | { |
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399 | struct drm_vma_offset_file *entry; |
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400 | struct rb_node *iter; |
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401 | |||
402 | read_lock(&node->vm_lock); |
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403 | |||
404 | iter = node->vm_files.rb_node; |
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405 | while (likely(iter)) { |
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406 | entry = rb_entry(iter, struct drm_vma_offset_file, vm_rb); |
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407 | if (filp == entry->vm_filp) |
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408 | break; |
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409 | else if (filp > entry->vm_filp) |
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410 | iter = iter->rb_right; |
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411 | else |
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412 | iter = iter->rb_left; |
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413 | } |
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414 | |||
415 | read_unlock(&node->vm_lock); |
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416 | |||
417 | return iter; |
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418 | } |
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419 | EXPORT_SYMBOL(drm_vma_node_is_allowed);>> |