1 /* 2 * CDDL HEADER START 3 * 4 * The contents of this file are subject to the terms of the 5 * Common Development and Distribution License, Version 1.0 only 6 * (the "License"). You may not use this file except in compliance 7 * with the License. 8 * 9 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE 10 * or http://www.opensolaris.org/os/licensing. 11 * See the License for the specific language governing permissions 12 * and limitations under the License. 13 * 14 * When distributing Covered Code, include this CDDL HEADER in each 15 * file and include the License file at usr/src/OPENSOLARIS.LICENSE. 16 * If applicable, add the following below this CDDL HEADER, with the 17 * fields enclosed by brackets "[]" replaced with your own identifying 18 * information: Portions Copyright [yyyy] [name of copyright owner] 19 * 20 * CDDL HEADER END 21 */ 22 /* 23 * Copyright 2004 Sun Microsystems, Inc. All rights reserved. 24 * Use is subject to license terms. 25 */ 26 27 #pragma ident "%Z%%M% %I% %E% SMI" 28 29 /* 30 * Standard module for handling DLPI Style 2 attach/detach 31 */ 32 33 #include <sys/types.h> 34 #include <sys/conf.h> 35 #include <sys/modctl.h> 36 #include <sys/cmn_err.h> 37 #include <sys/sunddi.h> 38 #include <sys/esunddi.h> 39 #include <sys/strsubr.h> 40 #include <sys/ddi.h> 41 #include <sys/dlpi.h> 42 #include <sys/strsun.h> 43 #include <sys/policy.h> 44 45 static struct streamtab drstab; 46 47 static struct fmodsw fsw = { 48 DRMODNAME, 49 &drstab, 50 D_MP 51 }; 52 53 54 /* 55 * Module linkage information for the kernel. 56 */ 57 58 static struct modlstrmod modlstrmod = { 59 &mod_strmodops, "dr compatibility for DLPI style 2 drivers %I%", &fsw 60 }; 61 62 63 static struct modlinkage modlinkage = { 64 MODREV_1, &modlstrmod, NULL 65 }; 66 67 68 int 69 _init(void) 70 { 71 return (mod_install(&modlinkage)); 72 } 73 74 int 75 _fini(void) 76 { 77 return (mod_remove(&modlinkage)); 78 } 79 80 int 81 _info(struct modinfo *modinfop) 82 { 83 return (mod_info(&modlinkage, modinfop)); 84 } 85 86 87 static int dropen(queue_t *, dev_t *, int, int, cred_t *); 88 static int drclose(queue_t *, int, cred_t *); 89 static int drrput(queue_t *, mblk_t *); 90 static int drwput(queue_t *, mblk_t *); 91 92 static struct module_info drinfo = { 93 0, 94 DRMODNAME, 95 0, 96 INFPSZ, 97 1, 98 0 99 }; 100 101 static struct qinit drrinit = { 102 (int (*)())drrput, 103 NULL, 104 dropen, 105 drclose, 106 NULL, 107 &drinfo 108 }; 109 110 static struct qinit drwinit = { 111 (int (*)())drwput, 112 NULL, 113 NULL, 114 NULL, 115 NULL, 116 &drinfo 117 }; 118 119 static struct streamtab drstab = { 120 &drrinit, 121 &drwinit, 122 NULL, 123 NULL 124 }; 125 126 /* 127 * This module is pushed directly on top of the bottom driver 128 * in a DLPI style-2 stream by stropen(). It intercepts 129 * DL_ATTACH_REQ/DL_DETACH_REQ messages on the write side 130 * and acks on the read side, calls qassociate where needed. 131 * The primary purpose is to workaround a DR race condition 132 * affecting non-DDI compliant DLPI style 2 drivers, which may 133 * cause the system to panic. 134 * 135 * The following action is taken: 136 * Write side (drwput): 137 * attach request: hold driver instance assuming ppa == instance. 138 * This way, the instance cannot be detached while the 139 * driver is processing DL_ATTACH_REQ. 140 * 141 * On a successful hold, store the dip in a ring buffer 142 * to be processed lated by the read side. 143 * If hold fails (most likely ppa != instance), we store 144 * NULL in the ring buffer and read side won't take 145 * any action on ack. 146 * 147 * Read side (drrput): 148 * attach success: if (dip held on write side) associate queue with dip 149 * attach failure: if (dip held on write side) release hold on dip 150 * detach success: associate queue with NULL 151 * detach failure: do nothing 152 * 153 * The module assumes that incoming DL_ATTACH_REQ/DL_DETACH_REQ 154 * messages are ordered (non-concurrent) and the bottom 155 * driver processes them and sends acknowledgements in the same 156 * order. This assumption is reasonable because concurrent 157 * association results in non-deterministic queue behavior. 158 * The module is coded carefully such that unordered messages 159 * do not result in a system panic. 160 * 161 * The module handles multiple outstanding messages queued 162 * in the bottom driver. Messages processed on the write side 163 * but not yet arrived at read side are placed in the ring buffer 164 * dr_dip[], between dr_nfirst and dr_nlast. The write side is 165 * producer and the read side is the consumer. The buffer is full 166 * when dr_nfirst == dr_nlast. 167 * 168 * The current size of the ring buffer is 64 (MAX_DLREQS) per stream. 169 * During normal testing, we have not seen outstanding messages 170 * above 10. 171 */ 172 173 #define MAX_DLREQS 64 174 #define INCR(x) {(x)++; if ((x) >= MAX_DLREQS) (x) = 0; } 175 176 struct drstate { 177 kmutex_t dr_lock; 178 major_t dr_major; 179 int dr_nfirst; 180 int dr_nlast; 181 dev_info_t *dr_dip[MAX_DLREQS]; 182 }; 183 184 /* ARGSUSED1 */ 185 static int 186 dropen(queue_t *q, dev_t *devp, int oflag, int sflag, cred_t *crp) 187 { 188 struct drstate *dsp; 189 190 if (sflag != MODOPEN) { /* must be a pushed module */ 191 return (EINVAL); 192 } 193 194 if (secpolicy_net_rawaccess(crp) != 0) { 195 return (EPERM); 196 } 197 198 if (q->q_ptr != NULL) { 199 return (0); /* already open */ 200 } 201 202 dsp = kmem_zalloc(sizeof (*dsp), KM_SLEEP); 203 dsp->dr_major = getmajor(*devp); 204 mutex_init(&dsp->dr_lock, NULL, MUTEX_DEFAULT, NULL); 205 q->q_ptr = OTHERQ(q)->q_ptr = dsp; 206 qprocson(q); 207 ddi_assoc_queue_with_devi(q, NULL); 208 return (0); 209 } 210 211 /* ARGSUSED1 */ 212 static int 213 drclose(queue_t *q, int cflag, cred_t *crp) 214 { 215 struct drstate *dsp = q->q_ptr; 216 217 ASSERT(dsp); 218 ddi_assoc_queue_with_devi(q, NULL); 219 qprocsoff(q); 220 221 mutex_destroy(&dsp->dr_lock); 222 kmem_free(dsp, sizeof (*dsp)); 223 q->q_ptr = NULL; 224 225 return (0); 226 } 227 228 static int 229 drrput(queue_t *q, mblk_t *mp) 230 { 231 struct drstate *dsp; 232 union DL_primitives *dlp; 233 dev_info_t *dip; 234 235 switch (DB_TYPE(mp)) { 236 case M_PROTO: 237 case M_PCPROTO: 238 break; 239 default: 240 putnext(q, mp); 241 return (0); 242 } 243 244 /* make sure size is sufficient for dl_primitive */ 245 if (MBLKL(mp) < sizeof (t_uscalar_t)) { 246 putnext(q, mp); 247 return (0); 248 } 249 250 dlp = (union DL_primitives *)mp->b_rptr; 251 switch (dlp->dl_primitive) { 252 case DL_OK_ACK: { 253 /* check for proper size, let upper layer deal with error */ 254 if (MBLKL(mp) < DL_OK_ACK_SIZE) { 255 putnext(q, mp); 256 return (0); 257 } 258 259 dsp = q->q_ptr; 260 switch (dlp->ok_ack.dl_correct_primitive) { 261 case DL_ATTACH_REQ: 262 /* 263 * ddi_assoc_queue_with_devi() will hold dip, 264 * so release after association. 265 * 266 * dip is NULL means we didn't hold dip on read side. 267 * (unlikely, but possible), so we do nothing. 268 */ 269 mutex_enter(&dsp->dr_lock); 270 dip = dsp->dr_dip[dsp->dr_nlast]; 271 dsp->dr_dip[dsp->dr_nlast] = NULL; 272 INCR(dsp->dr_nlast); 273 mutex_exit(&dsp->dr_lock); 274 if (dip) { 275 ddi_assoc_queue_with_devi(q, dip); 276 ddi_release_devi(dip); 277 } 278 break; 279 280 case DL_DETACH_REQ: 281 ddi_assoc_queue_with_devi(q, NULL); 282 break; 283 default: 284 break; 285 } 286 break; 287 } 288 case DL_ERROR_ACK: 289 if (dlp->error_ack.dl_error_primitive != DL_ATTACH_REQ) 290 break; 291 292 dsp = q->q_ptr; 293 mutex_enter(&dsp->dr_lock); 294 dip = dsp->dr_dip[dsp->dr_nlast]; 295 dsp->dr_dip[dsp->dr_nlast] = NULL; 296 INCR(dsp->dr_nlast); 297 mutex_exit(&dsp->dr_lock); 298 /* 299 * Release dip on attach failure 300 */ 301 if (dip) { 302 ddi_release_devi(dip); 303 } 304 break; 305 default: 306 break; 307 } 308 309 putnext(q, mp); 310 return (0); 311 } 312 313 /* 314 * Detect dl attach, hold the dip to prevent it from detaching 315 */ 316 static int 317 drwput(queue_t *q, mblk_t *mp) 318 { 319 struct drstate *dsp; 320 union DL_primitives *dlp; 321 dev_info_t *dip; 322 323 switch (DB_TYPE(mp)) { 324 case M_PROTO: 325 case M_PCPROTO: 326 break; 327 default: 328 putnext(q, mp); 329 return (0); 330 } 331 332 /* make sure size is sufficient for dl_primitive */ 333 if (MBLKL(mp) < sizeof (t_uscalar_t)) { 334 putnext(q, mp); 335 return (0); 336 } 337 338 dlp = (union DL_primitives *)mp->b_rptr; 339 switch (dlp->dl_primitive) { 340 case DL_ATTACH_REQ: 341 /* 342 * Check for proper size of the message. 343 * 344 * If size is correct, get the ppa and attempt to 345 * hold the device assuming ppa is instance. 346 * 347 * If size is wrong, we can't get the ppa, but 348 * still increment dr_nfirst because the read side 349 * will get a error ack on DL_ATTACH_REQ. 350 */ 351 dip = NULL; 352 dsp = q->q_ptr; 353 if (MBLKL(mp) >= DL_OK_ACK_SIZE) { 354 dip = ddi_hold_devi_by_instance(dsp->dr_major, 355 dlp->attach_req.dl_ppa, E_DDI_HOLD_DEVI_NOATTACH); 356 } 357 358 mutex_enter(&dsp->dr_lock); 359 dsp->dr_dip[dsp->dr_nfirst] = dip; 360 INCR(dsp->dr_nfirst); 361 /* 362 * Check if ring buffer is full. If so, assert in debug 363 * kernel and produce a warning in non-debug kernel. 364 */ 365 ASSERT(dsp->dr_nfirst != dsp->dr_nlast); 366 if (dsp->dr_nfirst == dsp->dr_nlast) { 367 cmn_err(CE_WARN, "drcompat: internal buffer full"); 368 } 369 mutex_exit(&dsp->dr_lock); 370 break; 371 default: 372 break; 373 } 374 375 putnext(q, mp); 376 return (0); 377 } 378