1 | /** |
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2 | * @file |
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3 | * |
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4 | * @ingroup rtems_disk |
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5 | * |
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6 | * @brief Block device disk management implementation. |
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7 | */ |
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8 | |
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9 | /* |
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10 | * Copyright (C) 2001 OKTET Ltd., St.-Petersburg, Russia |
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11 | * Author: Victor V. Vengerov <vvv@oktet.ru> |
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12 | * |
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13 | * Copyright (c) 2009, 2017 embedded brains GmbH. |
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14 | */ |
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15 | |
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16 | #if HAVE_CONFIG_H |
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17 | #include "config.h" |
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18 | #endif |
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19 | |
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20 | #include <stdlib.h> |
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21 | #include <unistd.h> |
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22 | #include <string.h> |
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23 | |
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24 | #include <rtems.h> |
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25 | #include <rtems/libio.h> |
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26 | #include <rtems/diskdevs.h> |
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27 | #include <rtems/blkdev.h> |
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28 | #include <rtems/bdbuf.h> |
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29 | #include <rtems/thread.h> |
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30 | |
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31 | #define DISKTAB_INITIAL_SIZE 8 |
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32 | |
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33 | /* Table of disk devices having the same major number */ |
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34 | typedef struct rtems_disk_device_table { |
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35 | rtems_disk_device **minor; /* minor-indexed disk device table */ |
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36 | rtems_device_minor_number size; /* Number of entries in the table */ |
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37 | } rtems_disk_device_table; |
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38 | |
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39 | /* Pointer to [major].minor[minor] indexed array of disk devices */ |
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40 | static rtems_disk_device_table *disktab; |
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41 | |
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42 | /* Number of allocated entries in disktab table */ |
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43 | static rtems_device_major_number disktab_size; |
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44 | |
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45 | /* Mutual exclusion semaphore for disk devices table */ |
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46 | static rtems_mutex diskdevs_mutex = RTEMS_MUTEX_INITIALIZER("diskdevs"); |
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47 | |
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48 | /* diskdevs data structures protection flag. |
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49 | * Normally, only table lookup operations performed. It is quite fast, so |
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50 | * it is possible to done lookups when interrupts are disabled, avoiding |
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51 | * obtaining the semaphore. This flags sets immediately after entering in |
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52 | * mutex-protected section and cleared before leaving this section in |
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53 | * "big" primitives like add/delete new device etc. Lookup function first |
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54 | * disable interrupts and check this flag. If it is set, lookup function |
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55 | * will be blocked on semaphore and lookup operation will be performed in |
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56 | * semaphore-protected code. If it is not set (very-very frequent case), |
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57 | * we can do lookup safely, enable interrupts and return result. |
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58 | */ |
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59 | static volatile bool diskdevs_protected; |
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60 | |
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61 | RTEMS_INTERRUPT_LOCK_DEFINE(static, diskdevs_lock, "diskdevs") |
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62 | |
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63 | static rtems_status_code disk_delete_locked(dev_t dev); |
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64 | |
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65 | static void |
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66 | disk_lock(void) |
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67 | { |
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68 | rtems_mutex_lock(&diskdevs_mutex); |
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69 | diskdevs_protected = true; |
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70 | } |
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71 | |
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72 | static void |
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73 | disk_unlock(void) |
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74 | { |
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75 | diskdevs_protected = false; |
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76 | rtems_mutex_unlock(&diskdevs_mutex); |
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77 | } |
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78 | |
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79 | static rtems_disk_device * |
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80 | get_disk_entry(dev_t dev, bool lookup_only) |
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81 | { |
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82 | rtems_device_major_number major = 0; |
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83 | rtems_device_minor_number minor = 0; |
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84 | |
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85 | rtems_filesystem_split_dev_t(dev, major, minor); |
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86 | |
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87 | if (major < disktab_size && disktab != NULL) { |
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88 | rtems_disk_device_table *dtab = disktab + major; |
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89 | |
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90 | if (minor < dtab->size && dtab->minor != NULL) { |
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91 | rtems_disk_device *dd = dtab->minor [minor]; |
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92 | |
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93 | if (dd != NULL && !lookup_only) { |
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94 | if (!dd->deleted) { |
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95 | ++dd->uses; |
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96 | } else { |
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97 | dd = NULL; |
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98 | } |
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99 | } |
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100 | |
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101 | return dd; |
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102 | } |
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103 | } |
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104 | |
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105 | return NULL; |
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106 | } |
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107 | |
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108 | static rtems_disk_device ** |
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109 | create_disk_table_entry(dev_t dev) |
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110 | { |
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111 | rtems_device_major_number major = 0; |
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112 | rtems_device_minor_number minor = 0; |
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113 | |
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114 | rtems_filesystem_split_dev_t(dev, major, minor); |
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115 | |
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116 | if (major >= disktab_size) { |
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117 | rtems_disk_device_table *table = disktab; |
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118 | rtems_device_major_number old_size = disktab_size; |
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119 | rtems_device_major_number new_size = 2 * old_size; |
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120 | |
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121 | if (major >= new_size) { |
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122 | new_size = major + 1; |
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123 | } |
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124 | |
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125 | table = realloc(table, new_size * sizeof(*table)); |
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126 | if (table == NULL) { |
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127 | return NULL; |
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128 | } |
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129 | |
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130 | memset(table + old_size, 0, (new_size - old_size) * sizeof(*table)); |
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131 | disktab = table; |
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132 | disktab_size = new_size; |
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133 | } |
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134 | |
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135 | if (disktab [major].minor == NULL || minor >= disktab[major].size) { |
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136 | rtems_disk_device **table = disktab [major].minor; |
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137 | rtems_device_minor_number old_size = disktab [major].size; |
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138 | rtems_device_minor_number new_size = 0; |
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139 | |
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140 | if (old_size == 0) { |
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141 | new_size = DISKTAB_INITIAL_SIZE; |
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142 | } else { |
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143 | new_size = 2 * old_size; |
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144 | } |
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145 | if (minor >= new_size) { |
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146 | new_size = minor + 1; |
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147 | } |
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148 | |
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149 | table = realloc(table, new_size * sizeof(*table)); |
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150 | if (table == NULL) { |
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151 | return NULL; |
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152 | } |
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153 | |
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154 | memset(table + old_size, 0, (new_size - old_size) * sizeof(*table)); |
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155 | disktab [major].minor = table; |
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156 | disktab [major].size = new_size; |
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157 | } |
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158 | |
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159 | return disktab [major].minor + minor; |
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160 | } |
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161 | |
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162 | static rtems_status_code |
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163 | create_disk( |
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164 | dev_t dev, |
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165 | const char *name, |
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166 | rtems_disk_device **dd_ptr, |
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167 | char **alloc_name_ptr |
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168 | ) |
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169 | { |
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170 | rtems_disk_device **dd_entry = create_disk_table_entry(dev); |
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171 | rtems_disk_device *dd = NULL; |
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172 | char *alloc_name = NULL; |
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173 | |
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174 | if (dd_entry == NULL) { |
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175 | return RTEMS_NO_MEMORY; |
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176 | } |
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177 | |
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178 | if (*dd_entry != NULL) { |
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179 | return RTEMS_RESOURCE_IN_USE; |
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180 | } |
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181 | |
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182 | dd = malloc(sizeof(*dd)); |
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183 | if (dd == NULL) { |
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184 | return RTEMS_NO_MEMORY; |
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185 | } |
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186 | |
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187 | if (name != NULL) { |
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188 | alloc_name = strdup(name); |
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189 | |
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190 | if (alloc_name == NULL) { |
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191 | free(dd); |
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192 | |
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193 | return RTEMS_NO_MEMORY; |
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194 | } |
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195 | } |
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196 | |
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197 | if (name != NULL) { |
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198 | if (mknod(alloc_name, 0777 | S_IFBLK, dev) < 0) { |
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199 | free(alloc_name); |
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200 | free(dd); |
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201 | return RTEMS_UNSATISFIED; |
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202 | } |
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203 | } |
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204 | |
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205 | *dd_entry = dd; |
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206 | *dd_ptr = dd; |
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207 | *alloc_name_ptr = alloc_name; |
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208 | |
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209 | return RTEMS_SUCCESSFUL; |
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210 | } |
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211 | |
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212 | static int null_handler( |
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213 | rtems_disk_device *dd, |
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214 | uint32_t req, |
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215 | void *argp |
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216 | ) |
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217 | { |
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218 | return -1; |
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219 | } |
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220 | |
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221 | rtems_status_code rtems_disk_create_phys( |
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222 | dev_t dev, |
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223 | uint32_t block_size, |
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224 | rtems_blkdev_bnum block_count, |
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225 | rtems_block_device_ioctl handler, |
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226 | void *driver_data, |
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227 | const char *name |
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228 | ) |
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229 | { |
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230 | rtems_disk_device *dd = NULL; |
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231 | rtems_status_code sc = RTEMS_SUCCESSFUL; |
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232 | char *alloc_name = NULL; |
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233 | |
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234 | if (handler == NULL) { |
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235 | return RTEMS_INVALID_ADDRESS; |
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236 | } |
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237 | |
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238 | disk_lock(); |
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239 | |
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240 | sc = create_disk(dev, name, &dd, &alloc_name); |
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241 | if (sc != RTEMS_SUCCESSFUL) { |
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242 | disk_unlock(); |
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243 | |
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244 | return sc; |
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245 | } |
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246 | |
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247 | sc = rtems_disk_init_phys( |
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248 | dd, |
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249 | block_size, |
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250 | block_count, |
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251 | handler, |
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252 | driver_data |
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253 | ); |
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254 | |
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255 | dd->dev = dev; |
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256 | dd->name = alloc_name; |
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257 | |
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258 | if (sc != RTEMS_SUCCESSFUL) { |
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259 | dd->ioctl = null_handler; |
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260 | disk_delete_locked(dev); |
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261 | disk_unlock(); |
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262 | |
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263 | return sc; |
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264 | } |
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265 | |
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266 | disk_unlock(); |
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267 | |
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268 | return RTEMS_SUCCESSFUL; |
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269 | } |
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270 | |
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271 | static bool |
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272 | is_physical_disk(const rtems_disk_device *dd) |
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273 | { |
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274 | return dd->phys_dev == dd; |
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275 | } |
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276 | |
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277 | rtems_status_code rtems_disk_create_log( |
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278 | dev_t dev, |
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279 | dev_t phys, |
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280 | rtems_blkdev_bnum block_begin, |
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281 | rtems_blkdev_bnum block_count, |
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282 | const char *name |
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283 | ) |
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284 | { |
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285 | rtems_status_code sc = RTEMS_SUCCESSFUL; |
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286 | rtems_disk_device *phys_dd = NULL; |
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287 | rtems_disk_device *dd = NULL; |
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288 | char *alloc_name = NULL; |
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289 | |
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290 | disk_lock(); |
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291 | |
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292 | phys_dd = get_disk_entry(phys, true); |
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293 | if (phys_dd == NULL) { |
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294 | disk_unlock(); |
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295 | |
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296 | return RTEMS_INVALID_ID; |
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297 | } |
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298 | |
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299 | sc = create_disk(dev, name, &dd, &alloc_name); |
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300 | if (sc != RTEMS_SUCCESSFUL) { |
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301 | disk_unlock(); |
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302 | |
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303 | return sc; |
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304 | } |
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305 | |
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306 | sc = rtems_disk_init_log( |
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307 | dd, |
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308 | phys_dd, |
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309 | block_begin, |
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310 | block_count |
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311 | ); |
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312 | |
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313 | dd->dev = dev; |
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314 | dd->name = alloc_name; |
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315 | |
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316 | ++phys_dd->uses; |
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317 | |
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318 | if (sc != RTEMS_SUCCESSFUL) { |
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319 | dd->ioctl = null_handler; |
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320 | disk_delete_locked(dev); |
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321 | disk_unlock(); |
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322 | |
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323 | return sc; |
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324 | } |
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325 | |
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326 | disk_unlock(); |
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327 | |
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328 | return RTEMS_SUCCESSFUL; |
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329 | } |
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330 | |
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331 | static void |
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332 | free_disk_device(rtems_disk_device *dd) |
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333 | { |
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334 | if (is_physical_disk(dd)) { |
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335 | (*dd->ioctl)(dd, RTEMS_BLKIO_DELETED, NULL); |
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336 | } |
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337 | if (dd->name != NULL) { |
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338 | unlink(dd->name); |
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339 | free(dd->name); |
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340 | } |
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341 | free(dd); |
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342 | } |
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343 | |
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344 | static void |
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345 | rtems_disk_cleanup(rtems_disk_device *disk_to_remove) |
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346 | { |
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347 | rtems_disk_device *const physical_disk = disk_to_remove->phys_dev; |
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348 | rtems_device_major_number major = 0; |
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349 | rtems_device_minor_number minor = 0; |
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350 | |
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351 | if (physical_disk->deleted) { |
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352 | dev_t dev = physical_disk->dev; |
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353 | unsigned deleted_count = 0; |
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354 | |
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355 | for (major = 0; major < disktab_size; ++major) { |
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356 | rtems_disk_device_table *dtab = disktab + major; |
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357 | |
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358 | for (minor = 0; minor < dtab->size; ++minor) { |
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359 | rtems_disk_device *dd = dtab->minor [minor]; |
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360 | |
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361 | if (dd != NULL && dd->phys_dev->dev == dev && dd != physical_disk) { |
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362 | if (dd->uses == 0) { |
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363 | ++deleted_count; |
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364 | dtab->minor [minor] = NULL; |
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365 | free_disk_device(dd); |
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366 | } else { |
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367 | dd->deleted = true; |
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368 | } |
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369 | } |
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370 | } |
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371 | } |
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372 | |
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373 | physical_disk->uses -= deleted_count; |
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374 | if (physical_disk->uses == 0) { |
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375 | rtems_filesystem_split_dev_t(physical_disk->dev, major, minor); |
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376 | disktab [major].minor [minor] = NULL; |
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377 | free_disk_device(physical_disk); |
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378 | } |
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379 | } else { |
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380 | if (disk_to_remove->uses == 0) { |
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381 | --physical_disk->uses; |
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382 | rtems_filesystem_split_dev_t(disk_to_remove->dev, major, minor); |
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383 | disktab [major].minor [minor] = NULL; |
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384 | free_disk_device(disk_to_remove); |
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385 | } |
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386 | } |
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387 | } |
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388 | |
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389 | static rtems_status_code |
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390 | disk_delete_locked(dev_t dev) |
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391 | { |
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392 | rtems_disk_device *dd = NULL; |
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393 | |
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394 | dd = get_disk_entry(dev, true); |
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395 | if (dd == NULL) { |
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396 | return RTEMS_INVALID_ID; |
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397 | } |
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398 | |
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399 | dd->deleted = true; |
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400 | rtems_disk_cleanup(dd); |
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401 | |
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402 | return RTEMS_SUCCESSFUL; |
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403 | } |
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404 | |
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405 | rtems_status_code |
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406 | rtems_disk_delete(dev_t dev) |
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407 | { |
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408 | rtems_status_code sc; |
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409 | |
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410 | disk_lock(); |
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411 | sc = disk_delete_locked(dev); |
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412 | disk_unlock(); |
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413 | |
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414 | return sc; |
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415 | } |
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416 | |
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417 | rtems_disk_device * |
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418 | rtems_disk_obtain(dev_t dev) |
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419 | { |
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420 | rtems_disk_device *dd = NULL; |
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421 | rtems_interrupt_lock_context lock_context; |
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422 | |
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423 | rtems_interrupt_lock_acquire(&diskdevs_lock, &lock_context); |
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424 | if (!diskdevs_protected) { |
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425 | /* Frequent and quickest case */ |
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426 | dd = get_disk_entry(dev, false); |
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427 | rtems_interrupt_lock_release(&diskdevs_lock, &lock_context); |
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428 | } else { |
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429 | rtems_interrupt_lock_release(&diskdevs_lock, &lock_context); |
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430 | |
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431 | disk_lock(); |
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432 | dd = get_disk_entry(dev, false); |
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433 | disk_unlock(); |
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434 | } |
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435 | |
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436 | return dd; |
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437 | } |
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438 | |
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439 | rtems_status_code |
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440 | rtems_disk_release(rtems_disk_device *dd) |
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441 | { |
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442 | rtems_interrupt_lock_context lock_context; |
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443 | dev_t dev = dd->dev; |
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444 | unsigned uses = 0; |
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445 | bool deleted = false; |
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446 | |
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447 | rtems_interrupt_lock_acquire(&diskdevs_lock, &lock_context); |
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448 | uses = --dd->uses; |
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449 | deleted = dd->deleted; |
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450 | rtems_interrupt_lock_release(&diskdevs_lock, &lock_context); |
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451 | |
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452 | if (uses == 0 && deleted) { |
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453 | rtems_disk_delete(dev); |
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454 | } |
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455 | |
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456 | return RTEMS_SUCCESSFUL; |
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457 | } |
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458 | |
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459 | rtems_disk_device * |
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460 | rtems_disk_next(dev_t dev) |
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461 | { |
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462 | rtems_disk_device_table *dtab = NULL; |
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463 | rtems_device_major_number major = 0; |
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464 | rtems_device_minor_number minor = 0; |
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465 | |
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466 | if (dev != (dev_t) -1) { |
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467 | rtems_filesystem_split_dev_t(dev, major, minor); |
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468 | |
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469 | /* If minor wraps around */ |
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470 | if ((minor + 1) < minor) { |
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471 | /* If major wraps around */ |
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472 | if ((major + 1) < major) { |
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473 | return NULL; |
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474 | } |
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475 | ++major; |
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476 | minor = 0; |
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477 | } else { |
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478 | ++minor; |
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479 | } |
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480 | } |
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481 | |
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482 | disk_lock(); |
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483 | |
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484 | if (major >= disktab_size) { |
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485 | disk_unlock(); |
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486 | |
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487 | return NULL; |
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488 | } |
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489 | |
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490 | dtab = disktab + major; |
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491 | while (true) { |
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492 | if (dtab->minor == NULL || minor >= dtab->size) { |
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493 | minor = 0; |
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494 | ++major; |
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495 | if (major >= disktab_size) { |
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496 | disk_unlock(); |
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497 | |
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498 | return NULL; |
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499 | } |
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500 | dtab = disktab + major; |
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501 | } else if (dtab->minor [minor] == NULL) { |
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502 | ++minor; |
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503 | } else { |
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504 | ++dtab->minor [minor]->uses; |
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505 | disk_unlock(); |
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506 | |
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507 | return dtab->minor [minor]; |
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508 | } |
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509 | } |
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510 | } |
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511 | |
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512 | rtems_status_code |
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513 | rtems_disk_io_initialize(void) |
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514 | { |
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515 | rtems_status_code sc = RTEMS_SUCCESSFUL; |
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516 | rtems_device_major_number size = DISKTAB_INITIAL_SIZE; |
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517 | |
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518 | if (disktab_size > 0) { |
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519 | return RTEMS_SUCCESSFUL; |
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520 | } |
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521 | |
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522 | disktab = calloc(size, sizeof(rtems_disk_device_table)); |
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523 | if (disktab == NULL) { |
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524 | return RTEMS_NO_MEMORY; |
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525 | } |
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526 | |
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527 | sc = rtems_bdbuf_init(); |
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528 | if (sc != RTEMS_SUCCESSFUL) { |
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529 | free(disktab); |
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530 | |
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531 | return RTEMS_UNSATISFIED; |
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532 | } |
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533 | |
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534 | disktab_size = size; |
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535 | |
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536 | return RTEMS_SUCCESSFUL; |
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537 | } |
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538 | |
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539 | rtems_status_code |
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540 | rtems_disk_io_done(void) |
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541 | { |
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542 | rtems_device_major_number major = 0; |
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543 | rtems_device_minor_number minor = 0; |
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544 | |
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545 | for (major = 0; major < disktab_size; ++major) { |
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546 | rtems_disk_device_table *dtab = disktab + major; |
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547 | |
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548 | for (minor = 0; minor < dtab->size; ++minor) { |
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549 | rtems_disk_device *dd = dtab->minor [minor]; |
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550 | |
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551 | if (dd != NULL) { |
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552 | free_disk_device(dd); |
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553 | } |
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554 | } |
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555 | free(dtab->minor); |
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556 | } |
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557 | free(disktab); |
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558 | |
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559 | disktab = NULL; |
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560 | disktab_size = 0; |
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561 | |
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562 | return RTEMS_SUCCESSFUL; |
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563 | } |
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