1 | /*
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2 | * CDDL HEADER START
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3 | *
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4 | * The contents of this file are subject to the terms of the
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5 | * Common Development and Distribution License (the "License").
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6 | * You may not use this file except in compliance with the License.
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7 | *
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8 | * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
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9 | * or http://www.opensolaris.org/os/licensing.
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10 | * See the License for the specific language governing permissions
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11 | * and limitations under the License.
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12 | *
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13 | * When distributing Covered Code, include this CDDL HEADER in each
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14 | * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
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15 | * If applicable, add the following below this CDDL HEADER, with the
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16 | * fields enclosed by brackets "[]" replaced with your own identifying
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17 | * information: Portions Copyright [yyyy] [name of copyright owner]
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18 | *
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19 | * CDDL HEADER END
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20 | */
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21 | /*
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22 | * Copyright 2009 Sun Microsystems, Inc. All rights reserved.
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23 | * Use is subject to license terms.
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24 | */
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25 |
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26 |
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27 | #include <sys/types.h>
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28 | #include <sys/param.h>
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29 | #include <sys/stat.h>
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30 | #include <sys/open.h>
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31 | #include <sys/file.h>
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32 | #include <sys/conf.h>
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33 | #include <sys/modctl.h>
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34 | #include <sys/cmn_err.h>
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35 | #include <sys/bitmap.h>
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36 | #include <sys/debug.h>
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37 | #include <sys/kmem.h>
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38 | #include <sys/errno.h>
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39 | #include <sys/sysmacros.h>
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40 | #include <sys/lockstat.h>
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41 | #include <sys/atomic.h>
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42 | #include <sys/dtrace.h>
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43 |
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44 | #include <sys/ddi.h>
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45 | #include <sys/sunddi.h>
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46 |
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47 | typedef struct lockstat_probe {
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48 | const char *lsp_func;
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49 | const char *lsp_name;
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50 | int lsp_probe;
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51 | dtrace_id_t lsp_id;
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52 | } lockstat_probe_t;
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53 |
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54 | lockstat_probe_t lockstat_probes[] =
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55 | {
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56 | { LS_MUTEX_ENTER, LSA_ACQUIRE, LS_MUTEX_ENTER_ACQUIRE },
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57 | { LS_MUTEX_ENTER, LSA_BLOCK, LS_MUTEX_ENTER_BLOCK },
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58 | { LS_MUTEX_ENTER, LSA_SPIN, LS_MUTEX_ENTER_SPIN },
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59 | { LS_MUTEX_EXIT, LSA_RELEASE, LS_MUTEX_EXIT_RELEASE },
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60 | { LS_MUTEX_DESTROY, LSA_RELEASE, LS_MUTEX_DESTROY_RELEASE },
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61 | { LS_MUTEX_TRYENTER, LSA_ACQUIRE, LS_MUTEX_TRYENTER_ACQUIRE },
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62 | { LS_LOCK_SET, LSS_ACQUIRE, LS_LOCK_SET_ACQUIRE },
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63 | { LS_LOCK_SET, LSS_SPIN, LS_LOCK_SET_SPIN },
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64 | { LS_LOCK_SET_SPL, LSS_ACQUIRE, LS_LOCK_SET_SPL_ACQUIRE },
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65 | { LS_LOCK_SET_SPL, LSS_SPIN, LS_LOCK_SET_SPL_SPIN },
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66 | { LS_LOCK_TRY, LSS_ACQUIRE, LS_LOCK_TRY_ACQUIRE },
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67 | { LS_LOCK_CLEAR, LSS_RELEASE, LS_LOCK_CLEAR_RELEASE },
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68 | { LS_LOCK_CLEAR_SPLX, LSS_RELEASE, LS_LOCK_CLEAR_SPLX_RELEASE },
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69 | { LS_CLOCK_UNLOCK, LSS_RELEASE, LS_CLOCK_UNLOCK_RELEASE },
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70 | { LS_RW_ENTER, LSR_ACQUIRE, LS_RW_ENTER_ACQUIRE },
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71 | { LS_RW_ENTER, LSR_BLOCK, LS_RW_ENTER_BLOCK },
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72 | { LS_RW_EXIT, LSR_RELEASE, LS_RW_EXIT_RELEASE },
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73 | { LS_RW_TRYENTER, LSR_ACQUIRE, LS_RW_TRYENTER_ACQUIRE },
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74 | { LS_RW_TRYUPGRADE, LSR_UPGRADE, LS_RW_TRYUPGRADE_UPGRADE },
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75 | { LS_RW_DOWNGRADE, LSR_DOWNGRADE, LS_RW_DOWNGRADE_DOWNGRADE },
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76 | { LS_THREAD_LOCK, LST_SPIN, LS_THREAD_LOCK_SPIN },
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77 | { LS_THREAD_LOCK_HIGH, LST_SPIN, LS_THREAD_LOCK_HIGH_SPIN },
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78 | { NULL }
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79 | };
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80 |
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81 | static dev_info_t *lockstat_devi; /* saved in xxattach() for xxinfo() */
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82 | static kmutex_t lockstat_test; /* for testing purposes only */
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83 | static dtrace_provider_id_t lockstat_id;
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84 |
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85 | /*ARGSUSED*/
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86 | static int
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87 | lockstat_enable(void *arg, dtrace_id_t id, void *parg)
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88 | {
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89 | lockstat_probe_t *probe = parg;
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90 |
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91 | ASSERT(!lockstat_probemap[probe->lsp_probe]);
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92 |
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93 | lockstat_probemap[probe->lsp_probe] = id;
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94 | membar_producer();
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95 |
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96 | lockstat_hot_patch();
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97 | membar_producer();
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98 |
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99 | /*
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100 | * Immediately generate a record for the lockstat_test mutex
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101 | * to verify that the mutex hot-patch code worked as expected.
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102 | */
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103 | mutex_enter(&lockstat_test);
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104 | mutex_exit(&lockstat_test);
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105 | return (0);
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106 | }
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107 |
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108 | /*ARGSUSED*/
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109 | static void
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110 | lockstat_disable(void *arg, dtrace_id_t id, void *parg)
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111 | {
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112 | lockstat_probe_t *probe = parg;
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113 | int i;
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114 |
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115 | ASSERT(lockstat_probemap[probe->lsp_probe]);
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116 |
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117 | lockstat_probemap[probe->lsp_probe] = 0;
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118 | lockstat_hot_patch();
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119 | membar_producer();
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120 |
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121 | /*
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122 | * See if we have any probes left enabled.
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123 | */
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124 | for (i = 0; i < LS_NPROBES; i++) {
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125 | if (lockstat_probemap[i]) {
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126 | /*
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127 | * This probe is still enabled. We don't need to deal
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128 | * with waiting for all threads to be out of the
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129 | * lockstat critical sections; just return.
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130 | */
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131 | return;
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132 | }
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133 | }
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134 |
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135 | /*
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136 | * The delay() here isn't as cheesy as you might think. We don't
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137 | * want to busy-loop in the kernel, so we have to give up the
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138 | * CPU between calls to lockstat_active_threads(); that much is
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139 | * obvious. But the reason it's a do..while loop rather than a
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140 | * while loop is subtle. The memory barrier above guarantees that
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141 | * no threads will enter the lockstat code from this point forward.
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142 | * However, another thread could already be executing lockstat code
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143 | * without our knowledge if the update to its t_lockstat field hasn't
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144 | * cleared its CPU's store buffer. Delaying for one clock tick
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145 | * guarantees that either (1) the thread will have *ample* time to
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146 | * complete its work, or (2) the thread will be preempted, in which
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147 | * case it will have to grab and release a dispatcher lock, which
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148 | * will flush that CPU's store buffer. Either way we're covered.
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149 | */
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150 | do {
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151 | delay(1);
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152 | } while (lockstat_active_threads());
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153 | }
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154 |
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155 | /*ARGSUSED*/
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156 | static int
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157 | lockstat_open(dev_t *devp, int flag, int otyp, cred_t *cred_p)
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158 | {
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159 | return (0);
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160 | }
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161 |
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162 | /* ARGSUSED */
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163 | static int
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164 | lockstat_info(dev_info_t *dip, ddi_info_cmd_t infocmd, void *arg, void **result)
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165 | {
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166 | int error;
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167 |
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168 | switch (infocmd) {
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169 | case DDI_INFO_DEVT2DEVINFO:
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170 | *result = (void *) lockstat_devi;
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171 | error = DDI_SUCCESS;
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172 | break;
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173 | case DDI_INFO_DEVT2INSTANCE:
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174 | *result = (void *)0;
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175 | error = DDI_SUCCESS;
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176 | break;
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177 | default:
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178 | error = DDI_FAILURE;
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179 | }
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180 | return (error);
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181 | }
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182 |
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183 | /*ARGSUSED*/
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184 | static void
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185 | lockstat_provide(void *arg, const dtrace_probedesc_t *desc)
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186 | {
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187 | int i = 0;
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188 |
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189 | for (i = 0; lockstat_probes[i].lsp_func != NULL; i++) {
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190 | lockstat_probe_t *probe = &lockstat_probes[i];
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191 |
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192 | if (dtrace_probe_lookup(lockstat_id, "genunix",
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193 | probe->lsp_func, probe->lsp_name) != 0)
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194 | continue;
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195 |
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196 | ASSERT(!probe->lsp_id);
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197 | probe->lsp_id = dtrace_probe_create(lockstat_id,
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198 | "genunix", probe->lsp_func, probe->lsp_name,
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199 | 1, probe);
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200 | }
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201 | }
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202 |
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203 | /*ARGSUSED*/
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204 | static void
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205 | lockstat_destroy(void *arg, dtrace_id_t id, void *parg)
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206 | {
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207 | lockstat_probe_t *probe = parg;
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208 |
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209 | ASSERT(!lockstat_probemap[probe->lsp_probe]);
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210 | probe->lsp_id = 0;
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211 | }
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212 |
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213 | static dtrace_pattr_t lockstat_attr = {
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214 | { DTRACE_STABILITY_EVOLVING, DTRACE_STABILITY_EVOLVING, DTRACE_CLASS_COMMON },
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215 | { DTRACE_STABILITY_PRIVATE, DTRACE_STABILITY_PRIVATE, DTRACE_CLASS_UNKNOWN },
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216 | { DTRACE_STABILITY_PRIVATE, DTRACE_STABILITY_PRIVATE, DTRACE_CLASS_UNKNOWN },
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217 | { DTRACE_STABILITY_EVOLVING, DTRACE_STABILITY_EVOLVING, DTRACE_CLASS_COMMON },
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218 | { DTRACE_STABILITY_EVOLVING, DTRACE_STABILITY_EVOLVING, DTRACE_CLASS_COMMON },
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219 | };
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220 |
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221 | static dtrace_pops_t lockstat_pops = {
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222 | lockstat_provide,
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223 | NULL,
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224 | lockstat_enable,
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225 | lockstat_disable,
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226 | NULL,
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227 | NULL,
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228 | NULL,
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229 | NULL,
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230 | NULL,
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231 | lockstat_destroy
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232 | };
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233 |
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234 | static int
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235 | lockstat_attach(dev_info_t *devi, ddi_attach_cmd_t cmd)
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236 | {
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237 | switch (cmd) {
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238 | case DDI_ATTACH:
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239 | break;
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240 | case DDI_RESUME:
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241 | return (DDI_SUCCESS);
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242 | default:
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243 | return (DDI_FAILURE);
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244 | }
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245 |
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246 | if (ddi_create_minor_node(devi, "lockstat", S_IFCHR, 0,
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247 | DDI_PSEUDO, 0) == DDI_FAILURE ||
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248 | dtrace_register("lockstat", &lockstat_attr, DTRACE_PRIV_KERNEL,
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249 | NULL, &lockstat_pops, NULL, &lockstat_id) != 0) {
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250 | ddi_remove_minor_node(devi, NULL);
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251 | return (DDI_FAILURE);
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252 | }
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253 |
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254 | lockstat_probe = dtrace_probe;
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255 | membar_producer();
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256 |
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257 | ddi_report_dev(devi);
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258 | lockstat_devi = devi;
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259 | return (DDI_SUCCESS);
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260 | }
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261 |
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262 | static int
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263 | lockstat_detach(dev_info_t *devi, ddi_detach_cmd_t cmd)
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264 | {
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265 | switch (cmd) {
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266 | case DDI_DETACH:
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267 | break;
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268 | case DDI_SUSPEND:
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269 | return (DDI_SUCCESS);
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270 | default:
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271 | return (DDI_FAILURE);
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272 | }
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273 |
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274 | if (dtrace_unregister(lockstat_id) != 0)
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275 | return (DDI_FAILURE);
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276 |
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277 | ddi_remove_minor_node(devi, NULL);
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278 | return (DDI_SUCCESS);
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279 | }
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280 |
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281 | /*
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282 | * Configuration data structures
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283 | */
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284 | static struct cb_ops lockstat_cb_ops = {
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285 | lockstat_open, /* open */
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286 | nodev, /* close */
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287 | nulldev, /* strategy */
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288 | nulldev, /* print */
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289 | nodev, /* dump */
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290 | nodev, /* read */
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291 | nodev, /* write */
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292 | nodev, /* ioctl */
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293 | nodev, /* devmap */
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294 | nodev, /* mmap */
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295 | nodev, /* segmap */
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296 | nochpoll, /* poll */
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297 | ddi_prop_op, /* cb_prop_op */
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298 | 0, /* streamtab */
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299 | D_MP | D_NEW /* Driver compatibility flag */
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300 | };
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301 |
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302 | static struct dev_ops lockstat_ops = {
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303 | DEVO_REV, /* devo_rev, */
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304 | 0, /* refcnt */
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305 | lockstat_info, /* getinfo */
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306 | nulldev, /* identify */
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307 | nulldev, /* probe */
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308 | lockstat_attach, /* attach */
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309 | lockstat_detach, /* detach */
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310 | nulldev, /* reset */
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311 | &lockstat_cb_ops, /* cb_ops */
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312 | NULL, /* bus_ops */
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313 | NULL, /* power */
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314 | ddi_quiesce_not_needed, /* quiesce */
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315 | };
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316 |
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317 | static struct modldrv modldrv = {
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318 | &mod_driverops, /* Type of module. This one is a driver */
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319 | "Lock Statistics", /* name of module */
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320 | &lockstat_ops, /* driver ops */
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321 | };
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322 |
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323 | static struct modlinkage modlinkage = {
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324 | MODREV_1, (void *)&modldrv, NULL
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325 | };
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326 |
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327 | int
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328 | _init(void)
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329 | {
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330 | return (mod_install(&modlinkage));
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331 | }
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332 |
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333 | int
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334 | _fini(void)
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335 | {
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336 | return (mod_remove(&modlinkage));
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337 | }
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338 |
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339 | int
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340 | _info(struct modinfo *modinfop)
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341 | {
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342 | return (mod_info(&modlinkage, modinfop));
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343 | }
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