1 | #include <machine/rtems-bsd-kernel-space.h> |
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2 | |
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3 | /*- |
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4 | * Copyright (c) 2008 Ed Schouten <ed@FreeBSD.org> |
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5 | * All rights reserved. |
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6 | * |
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7 | * Portions of this software were developed under sponsorship from Snow |
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8 | * B.V., the Netherlands. |
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9 | * |
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10 | * Redistribution and use in source and binary forms, with or without |
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11 | * modification, are permitted provided that the following conditions |
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12 | * are met: |
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13 | * 1. Redistributions of source code must retain the above copyright |
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14 | * notice, this list of conditions and the following disclaimer. |
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15 | * 2. Redistributions in binary form must reproduce the above copyright |
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16 | * notice, this list of conditions and the following disclaimer in the |
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17 | * documentation and/or other materials provided with the distribution. |
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18 | * |
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19 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND |
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20 | * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
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21 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
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22 | * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE |
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23 | * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL |
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24 | * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS |
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25 | * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
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26 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
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27 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY |
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28 | * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
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29 | * SUCH DAMAGE. |
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30 | */ |
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31 | |
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32 | #include <sys/cdefs.h> |
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33 | __FBSDID("$FreeBSD$"); |
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34 | |
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35 | #include <rtems/bsd/sys/param.h> |
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36 | #include <sys/kernel.h> |
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37 | #include <rtems/bsd/sys/lock.h> |
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38 | #include <sys/queue.h> |
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39 | #include <sys/systm.h> |
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40 | #include <sys/tty.h> |
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41 | #include <sys/uio.h> |
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42 | |
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43 | #include <vm/uma.h> |
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44 | |
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45 | /* |
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46 | * TTY output queue buffering. |
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47 | * |
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48 | * The previous design of the TTY layer offered the so-called clists. |
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49 | * These clists were used for both the input queues and the output |
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50 | * queue. We don't use certain features on the output side, like quoting |
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51 | * bits for parity marking and such. This mechanism is similar to the |
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52 | * old clists, but only contains the features we need to buffer the |
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53 | * output. |
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54 | */ |
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55 | |
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56 | struct ttyoutq_block { |
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57 | struct ttyoutq_block *tob_next; |
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58 | char tob_data[TTYOUTQ_DATASIZE]; |
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59 | }; |
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60 | |
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61 | static uma_zone_t ttyoutq_zone; |
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62 | |
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63 | #define TTYOUTQ_INSERT_TAIL(to, tob) do { \ |
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64 | if (to->to_end == 0) { \ |
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65 | tob->tob_next = to->to_firstblock; \ |
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66 | to->to_firstblock = tob; \ |
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67 | } else { \ |
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68 | tob->tob_next = to->to_lastblock->tob_next; \ |
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69 | to->to_lastblock->tob_next = tob; \ |
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70 | } \ |
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71 | to->to_nblocks++; \ |
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72 | } while (0) |
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73 | |
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74 | #define TTYOUTQ_REMOVE_HEAD(to) do { \ |
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75 | to->to_firstblock = to->to_firstblock->tob_next; \ |
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76 | to->to_nblocks--; \ |
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77 | } while (0) |
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78 | |
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79 | #define TTYOUTQ_RECYCLE(to, tob) do { \ |
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80 | if (to->to_quota <= to->to_nblocks) \ |
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81 | uma_zfree(ttyoutq_zone, tob); \ |
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82 | else \ |
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83 | TTYOUTQ_INSERT_TAIL(to, tob); \ |
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84 | } while(0) |
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85 | |
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86 | void |
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87 | ttyoutq_flush(struct ttyoutq *to) |
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88 | { |
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89 | |
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90 | to->to_begin = 0; |
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91 | to->to_end = 0; |
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92 | } |
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93 | |
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94 | int |
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95 | ttyoutq_setsize(struct ttyoutq *to, struct tty *tp, size_t size) |
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96 | { |
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97 | struct ttyoutq_block *tob; |
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98 | |
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99 | to->to_quota = howmany(size, TTYOUTQ_DATASIZE); |
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100 | |
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101 | while (to->to_quota > to->to_nblocks) { |
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102 | /* |
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103 | * List is getting bigger. |
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104 | * Add new blocks to the tail of the list. |
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105 | * |
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106 | * We must unlock the TTY temporarily, because we need |
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107 | * to allocate memory. This won't be a problem, because |
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108 | * in the worst case, another thread ends up here, which |
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109 | * may cause us to allocate too many blocks, but this |
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110 | * will be caught by the loop below. |
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111 | */ |
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112 | tty_unlock(tp); |
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113 | tob = uma_zalloc(ttyoutq_zone, M_WAITOK); |
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114 | tty_lock(tp); |
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115 | |
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116 | if (tty_gone(tp)) { |
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117 | uma_zfree(ttyoutq_zone, tob); |
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118 | return (ENXIO); |
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119 | } |
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120 | |
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121 | TTYOUTQ_INSERT_TAIL(to, tob); |
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122 | } |
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123 | return (0); |
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124 | } |
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125 | |
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126 | void |
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127 | ttyoutq_free(struct ttyoutq *to) |
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128 | { |
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129 | struct ttyoutq_block *tob; |
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130 | |
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131 | ttyoutq_flush(to); |
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132 | to->to_quota = 0; |
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133 | |
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134 | while ((tob = to->to_firstblock) != NULL) { |
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135 | TTYOUTQ_REMOVE_HEAD(to); |
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136 | uma_zfree(ttyoutq_zone, tob); |
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137 | } |
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138 | |
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139 | MPASS(to->to_nblocks == 0); |
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140 | } |
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141 | |
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142 | size_t |
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143 | ttyoutq_read(struct ttyoutq *to, void *buf, size_t len) |
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144 | { |
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145 | char *cbuf = buf; |
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146 | |
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147 | while (len > 0) { |
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148 | struct ttyoutq_block *tob; |
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149 | size_t cbegin, cend, clen; |
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150 | |
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151 | /* See if there still is data. */ |
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152 | if (to->to_begin == to->to_end) |
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153 | break; |
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154 | tob = to->to_firstblock; |
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155 | if (tob == NULL) |
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156 | break; |
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157 | |
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158 | /* |
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159 | * The end address should be the lowest of these three: |
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160 | * - The write pointer |
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161 | * - The blocksize - we can't read beyond the block |
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162 | * - The end address if we could perform the full read |
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163 | */ |
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164 | cbegin = to->to_begin; |
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165 | cend = MIN(MIN(to->to_end, to->to_begin + len), |
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166 | TTYOUTQ_DATASIZE); |
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167 | clen = cend - cbegin; |
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168 | |
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169 | /* Copy the data out of the buffers. */ |
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170 | memcpy(cbuf, tob->tob_data + cbegin, clen); |
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171 | cbuf += clen; |
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172 | len -= clen; |
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173 | |
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174 | if (cend == to->to_end) { |
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175 | /* Read the complete queue. */ |
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176 | to->to_begin = 0; |
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177 | to->to_end = 0; |
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178 | } else if (cend == TTYOUTQ_DATASIZE) { |
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179 | /* Read the block until the end. */ |
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180 | TTYOUTQ_REMOVE_HEAD(to); |
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181 | to->to_begin = 0; |
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182 | to->to_end -= TTYOUTQ_DATASIZE; |
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183 | TTYOUTQ_RECYCLE(to, tob); |
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184 | } else { |
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185 | /* Read the block partially. */ |
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186 | to->to_begin += clen; |
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187 | } |
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188 | } |
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189 | |
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190 | return (cbuf - (char *)buf); |
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191 | } |
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192 | |
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193 | /* |
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194 | * An optimized version of ttyoutq_read() which can be used in pseudo |
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195 | * TTY drivers to directly copy data from the outq to userspace, instead |
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196 | * of buffering it. |
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197 | * |
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198 | * We can only copy data directly if we need to read the entire block |
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199 | * back to the user, because we temporarily remove the block from the |
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200 | * queue. Otherwise we need to copy it to a temporary buffer first, to |
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201 | * make sure data remains in the correct order. |
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202 | */ |
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203 | int |
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204 | ttyoutq_read_uio(struct ttyoutq *to, struct tty *tp, struct uio *uio) |
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205 | { |
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206 | |
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207 | while (uio->uio_resid > 0) { |
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208 | int error; |
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209 | struct ttyoutq_block *tob; |
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210 | size_t cbegin, cend, clen; |
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211 | |
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212 | /* See if there still is data. */ |
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213 | if (to->to_begin == to->to_end) |
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214 | return (0); |
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215 | tob = to->to_firstblock; |
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216 | if (tob == NULL) |
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217 | return (0); |
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218 | |
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219 | /* |
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220 | * The end address should be the lowest of these three: |
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221 | * - The write pointer |
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222 | * - The blocksize - we can't read beyond the block |
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223 | * - The end address if we could perform the full read |
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224 | */ |
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225 | cbegin = to->to_begin; |
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226 | cend = MIN(MIN(to->to_end, to->to_begin + uio->uio_resid), |
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227 | TTYOUTQ_DATASIZE); |
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228 | clen = cend - cbegin; |
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229 | |
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230 | /* |
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231 | * We can prevent buffering in some cases: |
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232 | * - We need to read the block until the end. |
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233 | * - We don't need to read the block until the end, but |
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234 | * there is no data beyond it, which allows us to move |
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235 | * the write pointer to a new block. |
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236 | */ |
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237 | if (cend == TTYOUTQ_DATASIZE || cend == to->to_end) { |
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238 | /* |
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239 | * Fast path: zero copy. Remove the first block, |
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240 | * so we can unlock the TTY temporarily. |
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241 | */ |
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242 | TTYOUTQ_REMOVE_HEAD(to); |
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243 | to->to_begin = 0; |
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244 | if (to->to_end <= TTYOUTQ_DATASIZE) |
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245 | to->to_end = 0; |
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246 | else |
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247 | to->to_end -= TTYOUTQ_DATASIZE; |
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248 | |
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249 | /* Temporary unlock and copy the data to userspace. */ |
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250 | tty_unlock(tp); |
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251 | error = uiomove(tob->tob_data + cbegin, clen, uio); |
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252 | tty_lock(tp); |
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253 | |
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254 | /* Block can now be readded to the list. */ |
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255 | TTYOUTQ_RECYCLE(to, tob); |
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256 | } else { |
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257 | char ob[TTYOUTQ_DATASIZE - 1]; |
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258 | |
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259 | /* |
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260 | * Slow path: store data in a temporary buffer. |
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261 | */ |
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262 | memcpy(ob, tob->tob_data + cbegin, clen); |
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263 | to->to_begin += clen; |
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264 | MPASS(to->to_begin < TTYOUTQ_DATASIZE); |
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265 | |
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266 | /* Temporary unlock and copy the data to userspace. */ |
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267 | tty_unlock(tp); |
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268 | error = uiomove(ob, clen, uio); |
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269 | tty_lock(tp); |
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270 | } |
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271 | |
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272 | if (error != 0) |
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273 | return (error); |
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274 | } |
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275 | |
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276 | return (0); |
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277 | } |
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278 | |
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279 | size_t |
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280 | ttyoutq_write(struct ttyoutq *to, const void *buf, size_t nbytes) |
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281 | { |
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282 | const char *cbuf = buf; |
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283 | struct ttyoutq_block *tob; |
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284 | unsigned int boff; |
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285 | size_t l; |
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286 | |
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287 | while (nbytes > 0) { |
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288 | boff = to->to_end % TTYOUTQ_DATASIZE; |
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289 | |
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290 | if (to->to_end == 0) { |
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291 | /* First time we're being used or drained. */ |
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292 | MPASS(to->to_begin == 0); |
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293 | tob = to->to_firstblock; |
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294 | if (tob == NULL) { |
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295 | /* Queue has no blocks. */ |
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296 | break; |
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297 | } |
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298 | to->to_lastblock = tob; |
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299 | } else if (boff == 0) { |
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300 | /* We reached the end of this block on last write. */ |
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301 | tob = to->to_lastblock->tob_next; |
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302 | if (tob == NULL) { |
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303 | /* We've reached the watermark. */ |
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304 | break; |
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305 | } |
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306 | to->to_lastblock = tob; |
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307 | } else { |
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308 | tob = to->to_lastblock; |
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309 | } |
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310 | |
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311 | /* Don't copy more than was requested. */ |
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312 | l = MIN(nbytes, TTYOUTQ_DATASIZE - boff); |
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313 | MPASS(l > 0); |
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314 | memcpy(tob->tob_data + boff, cbuf, l); |
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315 | |
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316 | cbuf += l; |
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317 | nbytes -= l; |
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318 | to->to_end += l; |
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319 | } |
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320 | |
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321 | return (cbuf - (const char *)buf); |
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322 | } |
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323 | |
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324 | int |
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325 | ttyoutq_write_nofrag(struct ttyoutq *to, const void *buf, size_t nbytes) |
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326 | { |
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327 | size_t ret; |
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328 | |
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329 | if (ttyoutq_bytesleft(to) < nbytes) |
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330 | return (-1); |
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331 | |
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332 | /* We should always be able to write it back. */ |
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333 | ret = ttyoutq_write(to, buf, nbytes); |
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334 | MPASS(ret == nbytes); |
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335 | |
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336 | return (0); |
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337 | } |
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338 | |
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339 | static void |
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340 | ttyoutq_startup(void *dummy) |
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341 | { |
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342 | |
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343 | ttyoutq_zone = uma_zcreate("ttyoutq", sizeof(struct ttyoutq_block), |
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344 | NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0); |
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345 | } |
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346 | |
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347 | SYSINIT(ttyoutq, SI_SUB_DRIVERS, SI_ORDER_FIRST, ttyoutq_startup, NULL); |
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