1 | // |
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2 | // Cforall Version 1.0.0 Copyright (C) 2020 University of Waterloo |
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3 | // |
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4 | // The contents of this file are covered under the licence agreement in the |
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5 | // file "LICENCE" distributed with Cforall. |
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6 | // |
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7 | // io.cfa -- |
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8 | // |
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9 | // Author : Thierry Delisle |
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10 | // Created On : Thu Apr 23 17:31:00 2020 |
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11 | // Last Modified By : |
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12 | // Last Modified On : |
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13 | // Update Count : |
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14 | // |
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15 | |
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16 | #define __cforall_thread__ |
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17 | #define _GNU_SOURCE |
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18 | |
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19 | #if defined(__CFA_DEBUG__) |
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20 | // #define __CFA_DEBUG_PRINT_IO__ |
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21 | // #define __CFA_DEBUG_PRINT_IO_CORE__ |
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22 | #endif |
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23 | |
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24 | |
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25 | #if defined(CFA_HAVE_LINUX_IO_URING_H) |
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26 | #include <errno.h> |
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27 | #include <signal.h> |
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28 | #include <stdint.h> |
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29 | #include <string.h> |
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30 | #include <unistd.h> |
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31 | |
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32 | extern "C" { |
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33 | #include <sys/syscall.h> |
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34 | #include <sys/eventfd.h> |
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35 | |
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36 | #include <linux/io_uring.h> |
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37 | } |
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38 | |
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39 | #include "stats.hfa" |
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40 | #include "kernel.hfa" |
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41 | #include "kernel/fwd.hfa" |
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42 | #include "kernel_private.hfa" |
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43 | #include "io/types.hfa" |
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44 | |
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45 | __attribute__((unused)) static const char * opcodes[] = { |
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46 | "OP_NOP", |
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47 | "OP_READV", |
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48 | "OP_WRITEV", |
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49 | "OP_FSYNC", |
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50 | "OP_READ_FIXED", |
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51 | "OP_WRITE_FIXED", |
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52 | "OP_POLL_ADD", |
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53 | "OP_POLL_REMOVE", |
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54 | "OP_SYNC_FILE_RANGE", |
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55 | "OP_SENDMSG", |
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56 | "OP_RECVMSG", |
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57 | "OP_TIMEOUT", |
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58 | "OP_TIMEOUT_REMOVE", |
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59 | "OP_ACCEPT", |
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60 | "OP_ASYNC_CANCEL", |
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61 | "OP_LINK_TIMEOUT", |
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62 | "OP_CONNECT", |
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63 | "OP_FALLOCATE", |
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64 | "OP_OPENAT", |
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65 | "OP_CLOSE", |
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66 | "OP_FILES_UPDATE", |
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67 | "OP_STATX", |
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68 | "OP_READ", |
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69 | "OP_WRITE", |
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70 | "OP_FADVISE", |
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71 | "OP_MADVISE", |
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72 | "OP_SEND", |
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73 | "OP_RECV", |
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74 | "OP_OPENAT2", |
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75 | "OP_EPOLL_CTL", |
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76 | "OP_SPLICE", |
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77 | "OP_PROVIDE_BUFFERS", |
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78 | "OP_REMOVE_BUFFERS", |
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79 | "OP_TEE", |
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80 | "INVALID_OP" |
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81 | }; |
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82 | |
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83 | static $io_context * __ioarbiter_allocate( $io_arbiter & this, __u32 idxs[], __u32 want ); |
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84 | static void __ioarbiter_submit( $io_context * , __u32 idxs[], __u32 have, bool lazy ); |
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85 | static void __ioarbiter_flush ( $io_context & ); |
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86 | static inline void __ioarbiter_notify( $io_context & ctx ); |
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87 | //============================================================================================= |
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88 | // I/O Polling |
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89 | //============================================================================================= |
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90 | static inline unsigned __flush( struct $io_context & ); |
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91 | static inline __u32 __release_sqes( struct $io_context & ); |
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92 | extern void __kernel_unpark( thread$ * thrd, unpark_hint ); |
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93 | |
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94 | bool __cfa_io_drain( processor * proc ) { |
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95 | /* paranoid */ verify( ! __preemption_enabled() ); |
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96 | /* paranoid */ verify( ready_schedule_islocked() ); |
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97 | /* paranoid */ verify( proc ); |
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98 | /* paranoid */ verify( proc->io.ctx ); |
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99 | |
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100 | // Drain the queue |
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101 | $io_context * ctx = proc->io.ctx; |
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102 | unsigned head = *ctx->cq.head; |
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103 | unsigned tail = *ctx->cq.tail; |
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104 | const __u32 mask = *ctx->cq.mask; |
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105 | |
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106 | __u32 count = tail - head; |
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107 | __STATS__( false, io.calls.drain++; io.calls.completed += count; ) |
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108 | |
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109 | if(count == 0) return false; |
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110 | |
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111 | for(i; count) { |
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112 | unsigned idx = (head + i) & mask; |
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113 | volatile struct io_uring_cqe & cqe = ctx->cq.cqes[idx]; |
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114 | |
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115 | /* paranoid */ verify(&cqe); |
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116 | |
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117 | struct io_future_t * future = (struct io_future_t *)(uintptr_t)cqe.user_data; |
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118 | __cfadbg_print_safe( io, "Kernel I/O : Syscall completed : cqe %p, result %d for %p\n", &cqe, cqe.res, future ); |
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119 | |
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120 | __kernel_unpark( fulfil( *future, cqe.res, false ), UNPARK_LOCAL ); |
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121 | } |
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122 | |
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123 | __cfadbg_print_safe(io, "Kernel I/O : %u completed\n", count); |
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124 | |
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125 | // Mark to the kernel that the cqe has been seen |
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126 | // Ensure that the kernel only sees the new value of the head index after the CQEs have been read. |
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127 | __atomic_store_n( ctx->cq.head, head + count, __ATOMIC_SEQ_CST ); |
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128 | |
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129 | /* paranoid */ verify( ready_schedule_islocked() ); |
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130 | /* paranoid */ verify( ! __preemption_enabled() ); |
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131 | |
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132 | return true; |
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133 | } |
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134 | |
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135 | bool __cfa_io_flush( processor * proc, int min_comp ) { |
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136 | /* paranoid */ verify( ! __preemption_enabled() ); |
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137 | /* paranoid */ verify( proc ); |
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138 | /* paranoid */ verify( proc->io.ctx ); |
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139 | |
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140 | __attribute__((unused)) cluster * cltr = proc->cltr; |
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141 | $io_context & ctx = *proc->io.ctx; |
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142 | |
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143 | __ioarbiter_flush( ctx ); |
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144 | |
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145 | __STATS__( true, io.calls.flush++; ) |
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146 | int ret = syscall( __NR_io_uring_enter, ctx.fd, ctx.sq.to_submit, min_comp, min_comp > 0 ? IORING_ENTER_GETEVENTS : 0, (sigset_t *)0p, _NSIG / 8); |
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147 | if( ret < 0 ) { |
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148 | switch((int)errno) { |
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149 | case EAGAIN: |
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150 | case EINTR: |
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151 | case EBUSY: |
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152 | // Update statistics |
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153 | __STATS__( false, io.calls.errors.busy ++; ) |
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154 | return false; |
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155 | default: |
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156 | abort( "KERNEL ERROR: IO_URING SYSCALL - (%d) %s\n", (int)errno, strerror(errno) ); |
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157 | } |
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158 | } |
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159 | |
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160 | __cfadbg_print_safe(io, "Kernel I/O : %u submitted to io_uring %d\n", ret, ctx.fd); |
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161 | __STATS__( true, io.calls.submitted += ret; ) |
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162 | /* paranoid */ verify( ctx.sq.to_submit <= *ctx.sq.num ); |
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163 | /* paranoid */ verify( ctx.sq.to_submit >= ret ); |
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164 | |
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165 | ctx.sq.to_submit -= ret; |
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166 | |
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167 | /* paranoid */ verify( ctx.sq.to_submit <= *ctx.sq.num ); |
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168 | |
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169 | // Release the consumed SQEs |
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170 | __release_sqes( ctx ); |
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171 | |
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172 | /* paranoid */ verify( ! __preemption_enabled() ); |
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173 | |
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174 | ctx.proc->io.pending = false; |
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175 | ready_schedule_lock(); |
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176 | bool ret = __cfa_io_drain( proc ); |
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177 | ready_schedule_unlock(); |
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178 | return ret; |
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179 | } |
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180 | |
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181 | //============================================================================================= |
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182 | // I/O Submissions |
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183 | //============================================================================================= |
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184 | |
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185 | // Submition steps : |
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186 | // 1 - Allocate a queue entry. The ring already has memory for all entries but only the ones |
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187 | // listed in sq.array are visible by the kernel. For those not listed, the kernel does not |
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188 | // offer any assurance that an entry is not being filled by multiple flags. Therefore, we |
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189 | // need to write an allocator that allows allocating concurrently. |
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190 | // |
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191 | // 2 - Actually fill the submit entry, this is the only simple and straightforward step. |
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192 | // |
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193 | // 3 - Append the entry index to the array and adjust the tail accordingly. This operation |
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194 | // needs to arrive to two concensus at the same time: |
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195 | // A - The order in which entries are listed in the array: no two threads must pick the |
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196 | // same index for their entries |
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197 | // B - When can the tail be update for the kernel. EVERY entries in the array between |
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198 | // head and tail must be fully filled and shouldn't ever be touched again. |
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199 | // |
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200 | //============================================================================================= |
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201 | // Allocation |
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202 | // for user's convenience fill the sqes from the indexes |
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203 | static inline void __fill(struct io_uring_sqe * out_sqes[], __u32 want, __u32 idxs[], struct $io_context * ctx) { |
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204 | struct io_uring_sqe * sqes = ctx->sq.sqes; |
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205 | for(i; want) { |
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206 | __cfadbg_print_safe(io, "Kernel I/O : filling loop\n"); |
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207 | out_sqes[i] = &sqes[idxs[i]]; |
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208 | } |
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209 | } |
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210 | |
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211 | // Try to directly allocate from the a given context |
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212 | // Not thread-safe |
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213 | static inline bool __alloc(struct $io_context * ctx, __u32 idxs[], __u32 want) { |
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214 | __sub_ring_t & sq = ctx->sq; |
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215 | const __u32 mask = *sq.mask; |
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216 | __u32 fhead = sq.free_ring.head; // get the current head of the queue |
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217 | __u32 ftail = sq.free_ring.tail; // get the current tail of the queue |
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218 | |
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219 | // If we don't have enough sqes, fail |
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220 | if((ftail - fhead) < want) { return false; } |
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221 | |
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222 | // copy all the indexes we want from the available list |
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223 | for(i; want) { |
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224 | __cfadbg_print_safe(io, "Kernel I/O : allocating loop\n"); |
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225 | idxs[i] = sq.free_ring.array[(fhead + i) & mask]; |
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226 | } |
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227 | |
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228 | // Advance the head to mark the indexes as consumed |
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229 | __atomic_store_n(&sq.free_ring.head, fhead + want, __ATOMIC_RELEASE); |
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230 | |
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231 | // return success |
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232 | return true; |
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233 | } |
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234 | |
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235 | // Allocate an submit queue entry. |
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236 | // The kernel cannot see these entries until they are submitted, but other threads must be |
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237 | // able to see which entries can be used and which are already un used by an other thread |
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238 | // for convenience, return both the index and the pointer to the sqe |
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239 | // sqe == &sqes[idx] |
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240 | struct $io_context * cfa_io_allocate(struct io_uring_sqe * sqes[], __u32 idxs[], __u32 want) { |
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241 | __cfadbg_print_safe(io, "Kernel I/O : attempting to allocate %u\n", want); |
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242 | |
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243 | disable_interrupts(); |
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244 | processor * proc = __cfaabi_tls.this_processor; |
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245 | $io_context * ctx = proc->io.ctx; |
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246 | /* paranoid */ verify( __cfaabi_tls.this_processor ); |
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247 | /* paranoid */ verify( ctx ); |
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248 | |
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249 | __cfadbg_print_safe(io, "Kernel I/O : attempting to fast allocation\n"); |
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250 | |
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251 | // We can proceed to the fast path |
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252 | if( __alloc(ctx, idxs, want) ) { |
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253 | // Allocation was successful |
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254 | __STATS__( true, io.alloc.fast += 1; ) |
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255 | enable_interrupts(); |
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256 | |
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257 | __cfadbg_print_safe(io, "Kernel I/O : fast allocation successful from ring %d\n", ctx->fd); |
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258 | |
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259 | __fill( sqes, want, idxs, ctx ); |
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260 | return ctx; |
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261 | } |
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262 | // The fast path failed, fallback |
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263 | __STATS__( true, io.alloc.fail += 1; ) |
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264 | |
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265 | // Fast path failed, fallback on arbitration |
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266 | __STATS__( true, io.alloc.slow += 1; ) |
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267 | enable_interrupts(); |
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268 | |
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269 | $io_arbiter * ioarb = proc->cltr->io.arbiter; |
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270 | /* paranoid */ verify( ioarb ); |
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271 | |
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272 | __cfadbg_print_safe(io, "Kernel I/O : falling back on arbiter for allocation\n"); |
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273 | |
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274 | struct $io_context * ret = __ioarbiter_allocate(*ioarb, idxs, want); |
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275 | |
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276 | __cfadbg_print_safe(io, "Kernel I/O : slow allocation completed from ring %d\n", ret->fd); |
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277 | |
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278 | __fill( sqes, want, idxs,ret ); |
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279 | return ret; |
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280 | } |
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281 | |
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282 | //============================================================================================= |
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283 | // submission |
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284 | static inline void __submit( struct $io_context * ctx, __u32 idxs[], __u32 have, bool lazy) { |
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285 | // We can proceed to the fast path |
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286 | // Get the right objects |
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287 | __sub_ring_t & sq = ctx->sq; |
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288 | const __u32 mask = *sq.mask; |
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289 | __u32 tail = *sq.kring.tail; |
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290 | |
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291 | // Add the sqes to the array |
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292 | for( i; have ) { |
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293 | __cfadbg_print_safe(io, "Kernel I/O : __submit loop\n"); |
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294 | sq.kring.array[ (tail + i) & mask ] = idxs[i]; |
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295 | } |
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296 | |
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297 | // Make the sqes visible to the submitter |
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298 | __atomic_store_n(sq.kring.tail, tail + have, __ATOMIC_RELEASE); |
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299 | sq.to_submit += have; |
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300 | |
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301 | ctx->proc->io.pending = true; |
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302 | ctx->proc->io.dirty = true; |
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303 | if(sq.to_submit > 30 || !lazy) { |
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304 | __cfa_io_flush( ctx->proc, 0 ); |
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305 | } |
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306 | } |
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307 | |
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308 | void cfa_io_submit( struct $io_context * inctx, __u32 idxs[], __u32 have, bool lazy ) __attribute__((nonnull (1))) { |
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309 | __cfadbg_print_safe(io, "Kernel I/O : attempting to submit %u (%s)\n", have, lazy ? "lazy" : "eager"); |
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310 | |
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311 | disable_interrupts(); |
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312 | processor * proc = __cfaabi_tls.this_processor; |
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313 | $io_context * ctx = proc->io.ctx; |
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314 | /* paranoid */ verify( __cfaabi_tls.this_processor ); |
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315 | /* paranoid */ verify( ctx ); |
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316 | |
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317 | // Can we proceed to the fast path |
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318 | if( ctx == inctx ) // We have the right instance? |
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319 | { |
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320 | __submit(ctx, idxs, have, lazy); |
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321 | |
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322 | // Mark the instance as no longer in-use, re-enable interrupts and return |
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323 | __STATS__( true, io.submit.fast += 1; ) |
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324 | enable_interrupts(); |
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325 | |
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326 | __cfadbg_print_safe(io, "Kernel I/O : submitted on fast path\n"); |
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327 | return; |
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328 | } |
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329 | |
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330 | // Fast path failed, fallback on arbitration |
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331 | __STATS__( true, io.submit.slow += 1; ) |
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332 | enable_interrupts(); |
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333 | |
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334 | __cfadbg_print_safe(io, "Kernel I/O : falling back on arbiter for submission\n"); |
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335 | |
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336 | __ioarbiter_submit(inctx, idxs, have, lazy); |
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337 | } |
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338 | |
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339 | //============================================================================================= |
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340 | // Flushing |
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341 | // Go through the ring's submit queue and release everything that has already been consumed |
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342 | // by io_uring |
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343 | // This cannot be done by multiple threads |
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344 | static __u32 __release_sqes( struct $io_context & ctx ) { |
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345 | const __u32 mask = *ctx.sq.mask; |
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346 | |
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347 | __attribute__((unused)) |
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348 | __u32 ctail = *ctx.sq.kring.tail; // get the current tail of the queue |
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349 | __u32 chead = *ctx.sq.kring.head; // get the current head of the queue |
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350 | __u32 phead = ctx.sq.kring.released; // get the head the last time we were here |
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351 | |
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352 | __u32 ftail = ctx.sq.free_ring.tail; // get the current tail of the queue |
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353 | |
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354 | // the 3 fields are organized like this diagram |
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355 | // except it's are ring |
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356 | // ---+--------+--------+---- |
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357 | // ---+--------+--------+---- |
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358 | // ^ ^ ^ |
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359 | // phead chead ctail |
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360 | |
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361 | // make sure ctail doesn't wrap around and reach phead |
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362 | /* paranoid */ verify( |
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363 | (ctail >= chead && chead >= phead) |
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364 | || (chead >= phead && phead >= ctail) |
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365 | || (phead >= ctail && ctail >= chead) |
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366 | ); |
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367 | |
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368 | // find the range we need to clear |
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369 | __u32 count = chead - phead; |
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370 | |
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371 | if(count == 0) { |
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372 | return 0; |
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373 | } |
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374 | |
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375 | // We acquired an previous-head/current-head range |
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376 | // go through the range and release the sqes |
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377 | for( i; count ) { |
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378 | __cfadbg_print_safe(io, "Kernel I/O : release loop\n"); |
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379 | __u32 idx = ctx.sq.kring.array[ (phead + i) & mask ]; |
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380 | ctx.sq.free_ring.array[ (ftail + i) & mask ] = idx; |
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381 | } |
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382 | |
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383 | ctx.sq.kring.released = chead; // note up to were we processed |
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384 | __atomic_store_n(&ctx.sq.free_ring.tail, ftail + count, __ATOMIC_SEQ_CST); |
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385 | |
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386 | __ioarbiter_notify(ctx); |
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387 | |
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388 | return count; |
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389 | } |
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390 | |
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391 | //============================================================================================= |
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392 | // I/O Arbiter |
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393 | //============================================================================================= |
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394 | static inline void block(__outstanding_io_queue & queue, __outstanding_io & item) { |
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395 | // Lock the list, it's not thread safe |
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396 | lock( queue.lock __cfaabi_dbg_ctx2 ); |
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397 | { |
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398 | // Add our request to the list |
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399 | add( queue.queue, item ); |
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400 | |
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401 | // Mark as pending |
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402 | __atomic_store_n( &queue.empty, false, __ATOMIC_SEQ_CST ); |
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403 | } |
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404 | unlock( queue.lock ); |
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405 | |
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406 | wait( item.sem ); |
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407 | } |
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408 | |
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409 | static inline bool empty(__outstanding_io_queue & queue ) { |
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410 | return __atomic_load_n( &queue.empty, __ATOMIC_SEQ_CST); |
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411 | } |
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412 | |
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413 | static $io_context * __ioarbiter_allocate( $io_arbiter & this, __u32 idxs[], __u32 want ) { |
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414 | __cfadbg_print_safe(io, "Kernel I/O : arbiter allocating\n"); |
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415 | |
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416 | __STATS__( false, io.alloc.block += 1; ) |
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417 | |
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418 | // No one has any resources left, wait for something to finish |
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419 | // We need to add ourself to a list of pending allocs and wait for an answer |
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420 | __pending_alloc pa; |
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421 | pa.idxs = idxs; |
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422 | pa.want = want; |
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423 | |
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424 | block(this.pending, (__outstanding_io&)pa); |
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425 | |
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426 | return pa.ctx; |
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427 | |
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428 | } |
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429 | |
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430 | static void __ioarbiter_notify( $io_arbiter & this, $io_context * ctx ) { |
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431 | /* paranoid */ verify( !empty(this.pending.queue) ); |
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432 | |
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433 | lock( this.pending.lock __cfaabi_dbg_ctx2 ); |
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434 | { |
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435 | while( !empty(this.pending.queue) ) { |
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436 | __cfadbg_print_safe(io, "Kernel I/O : notifying\n"); |
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437 | __u32 have = ctx->sq.free_ring.tail - ctx->sq.free_ring.head; |
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438 | __pending_alloc & pa = (__pending_alloc&)head( this.pending.queue ); |
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439 | |
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440 | if( have > pa.want ) goto DONE; |
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441 | drop( this.pending.queue ); |
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442 | |
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443 | /* paranoid */__attribute__((unused)) bool ret = |
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444 | |
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445 | __alloc(ctx, pa.idxs, pa.want); |
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446 | |
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447 | /* paranoid */ verify( ret ); |
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448 | |
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449 | pa.ctx = ctx; |
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450 | |
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451 | post( pa.sem ); |
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452 | } |
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453 | |
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454 | this.pending.empty = true; |
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455 | DONE:; |
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456 | } |
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457 | unlock( this.pending.lock ); |
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458 | } |
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459 | |
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460 | static void __ioarbiter_notify( $io_context & ctx ) { |
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461 | if(!empty( ctx.arbiter->pending )) { |
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462 | __ioarbiter_notify( *ctx.arbiter, &ctx ); |
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463 | } |
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464 | } |
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465 | |
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466 | // Simply append to the pending |
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467 | static void __ioarbiter_submit( $io_context * ctx, __u32 idxs[], __u32 have, bool lazy ) { |
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468 | __cfadbg_print_safe(io, "Kernel I/O : submitting %u from the arbiter to context %u\n", have, ctx->fd); |
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469 | |
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470 | __cfadbg_print_safe(io, "Kernel I/O : waiting to submit %u\n", have); |
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471 | |
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472 | __external_io ei; |
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473 | ei.idxs = idxs; |
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474 | ei.have = have; |
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475 | ei.lazy = lazy; |
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476 | |
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477 | block(ctx->ext_sq, (__outstanding_io&)ei); |
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478 | |
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479 | __cfadbg_print_safe(io, "Kernel I/O : %u submitted from arbiter\n", have); |
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480 | } |
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481 | |
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482 | static void __ioarbiter_flush( $io_context & ctx ) { |
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483 | if(!empty( ctx.ext_sq )) { |
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484 | __STATS__( false, io.flush.external += 1; ) |
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485 | |
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486 | __cfadbg_print_safe(io, "Kernel I/O : arbiter flushing\n"); |
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487 | |
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488 | lock( ctx.ext_sq.lock __cfaabi_dbg_ctx2 ); |
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489 | { |
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490 | while( !empty(ctx.ext_sq.queue) ) { |
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491 | __external_io & ei = (__external_io&)drop( ctx.ext_sq.queue ); |
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492 | |
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493 | __submit(&ctx, ei.idxs, ei.have, ei.lazy); |
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494 | |
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495 | post( ei.sem ); |
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496 | } |
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497 | |
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498 | ctx.ext_sq.empty = true; |
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499 | } |
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500 | unlock(ctx.ext_sq.lock ); |
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501 | } |
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502 | } |
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503 | |
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504 | bool __kernel_read(processor * proc, io_future_t & future, char buf[], int fd) { |
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505 | $io_context * ctx = proc->io.ctx; |
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506 | /* paranoid */ verify( ! __preemption_enabled() ); |
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507 | /* paranoid */ verify( proc == __cfaabi_tls.this_processor ); |
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508 | /* paranoid */ verify( ctx ); |
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509 | |
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510 | __u32 idx; |
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511 | struct io_uring_sqe * sqe; |
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512 | |
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513 | // We can proceed to the fast path |
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514 | if( !__alloc(ctx, &idx, 1) ) return false; |
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515 | |
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516 | // Allocation was successful |
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517 | __fill( &sqe, 1, &idx, ctx ); |
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518 | |
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519 | sqe->opcode = IORING_OP_READ; |
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520 | sqe->user_data = (uintptr_t)&future; |
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521 | sqe->flags = 0; |
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522 | sqe->ioprio = 0; |
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523 | sqe->fd = fd; |
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524 | sqe->off = 0; |
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525 | sqe->fsync_flags = 0; |
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526 | sqe->__pad2[0] = 0; |
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527 | sqe->__pad2[1] = 0; |
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528 | sqe->__pad2[2] = 0; |
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529 | sqe->addr = (uintptr_t)buf; |
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530 | sqe->len = sizeof(uint64_t); |
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531 | |
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532 | asm volatile("": : :"memory"); |
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533 | |
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534 | /* paranoid */ verify( sqe->user_data == (uintptr_t)&future ); |
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535 | __submit( ctx, &idx, 1, true ); |
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536 | |
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537 | /* paranoid */ verify( proc == __cfaabi_tls.this_processor ); |
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538 | /* paranoid */ verify( ! __preemption_enabled() ); |
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539 | } |
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540 | #endif |
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