1 /* 2 * Copyright (c) 2007 The DragonFly Project. All rights reserved. 3 * 4 * This code is derived from software contributed to The DragonFly Project 5 * by Matthew Dillon <dillon@backplane.com> 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in 15 * the documentation and/or other materials provided with the 16 * distribution. 17 * 3. Neither the name of The DragonFly Project nor the names of its 18 * contributors may be used to endorse or promote products derived 19 * from this software without specific, prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 22 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 23 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 24 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 25 * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, 26 * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING, 27 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 28 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED 29 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, 30 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT 31 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32 * SUCH DAMAGE. 33 */ 34 /* 35 * System resource control module for all cluster-addressable system resource 36 * structures. 37 * 38 * This module implements the core ref counting, sysid registration, and 39 * objcache-backed allocation mechanism for all major system resource 40 * structures. 41 * 42 * sysid registrations operate via the objcache ctor/dtor mechanism and 43 * sysids will be reused if the resource is not explicitly accessed via 44 * its sysid. This removes all RB tree handling overhead from the critical 45 * path for locally used resources. 46 */ 47 48 #include <sys/param.h> 49 #include <sys/systm.h> 50 #include <sys/kernel.h> 51 #include <sys/malloc.h> 52 #include <sys/tree.h> 53 #include <sys/spinlock.h> 54 #include <machine/atomic.h> 55 #include <machine/cpufunc.h> 56 57 #include <sys/spinlock2.h> 58 #include <sys/sysref2.h> 59 60 static boolean_t sysref_ctor(void *data, void *privdata, int ocflags); 61 static void sysref_dtor(void *data, void *privdata); 62 63 /* 64 * Red-Black tree support 65 */ 66 static int rb_sysref_compare(struct sysref *sr1, struct sysref *sr2); 67 RB_GENERATE2(sysref_rb_tree, sysref, rbnode, rb_sysref_compare, sysid_t, sysid); 68 69 static struct srpercpu { 70 struct sysref_rb_tree rbtree; 71 struct spinlock spin; 72 } sysref_array[MAXCPU]; 73 74 static void 75 sysrefbootinit(void *dummy __unused) 76 { 77 struct srpercpu *sa; 78 int i; 79 80 for (i = 0; i < ncpus; ++i) { 81 sa = &sysref_array[i]; 82 spin_init(&sa->spin, "sysrefbootinit"); 83 RB_INIT(&sa->rbtree); 84 } 85 } 86 87 SYSINIT(sysref, SI_BOOT2_MACHDEP, SI_ORDER_ANY, sysrefbootinit, NULL); 88 89 static 90 int 91 rb_sysref_compare(struct sysref *sr1, struct sysref *sr2) 92 { 93 if (sr1->sysid < sr2->sysid) 94 return(-1); 95 if (sr1->sysid > sr2->sysid) 96 return(1); 97 return(0); 98 } 99 100 /* 101 * Manual initialization of a resource structure's sysref, only used during 102 * booting to set up certain statically declared resources which cannot 103 * be deallocated. 104 */ 105 void 106 sysref_init(struct sysref *sr, struct sysref_class *srclass) 107 { 108 struct srpercpu *sa; 109 globaldata_t gd; 110 111 gd = mycpu; 112 crit_enter_gd(gd); 113 gd->gd_sysid_alloc += ncpus_fit; /* next unique sysid */ 114 sr->sysid = gd->gd_sysid_alloc; 115 KKASSERT(((int)sr->sysid & ncpus_fit_mask) == gd->gd_cpuid); 116 sr->refcnt = -0x40000000; 117 sr->flags = 0; 118 sr->srclass = srclass; 119 120 sa = &sysref_array[gd->gd_cpuid]; 121 spin_lock(&sa->spin); 122 sysref_rb_tree_RB_INSERT(&sa->rbtree, sr); 123 spin_unlock(&sa->spin); 124 crit_exit_gd(gd); 125 } 126 127 /* 128 * Allocate a resource structure of the specified class, initialize a 129 * sysid and add the resource to the RB tree. The caller must complete 130 * initialization of the resource and call sysref_activate() to activate it. 131 */ 132 void * 133 sysref_alloc(struct sysref_class *srclass) 134 { 135 struct sysref *sr; 136 char *data; 137 int n; 138 139 /* 140 * Create the object cache backing store. 141 */ 142 if (srclass->oc == NULL) { 143 KKASSERT(srclass->mtype != NULL); 144 srclass->oc = objcache_create_mbacked( 145 srclass->mtype, srclass->objsize, 146 0, srclass->nom_cache, 147 sysref_ctor, sysref_dtor, srclass); 148 } 149 150 /* 151 * Allocate the resource. 152 */ 153 data = objcache_get(srclass->oc, M_WAITOK); 154 sr = (struct sysref *)(data + srclass->offset); 155 KKASSERT(sr->flags & SRF_PUTAWAY); 156 sr->flags &= ~SRF_PUTAWAY; 157 158 /* 159 * Refcnt isn't touched while it is zero. The objcache ctor 160 * function has already allocated a sysid and emplaced the 161 * structure in the RB tree. 162 */ 163 KKASSERT(sr->refcnt == 0); 164 sr->refcnt = -0x40000000; 165 166 /* 167 * Clean out the structure unless the caller wants to deal with 168 * it (e.g. like the vmspace code). 169 */ 170 if ((srclass->flags & SRC_MANAGEDINIT) == 0) { 171 if (srclass->offset != 0) 172 bzero(data, srclass->offset); 173 n = srclass->offset + sizeof(struct sysref); 174 KKASSERT(n <= srclass->objsize); 175 if (n != srclass->objsize) 176 bzero(data + n, srclass->objsize - n); 177 } 178 return(data); 179 } 180 181 /* 182 * Object cache backing store ctor function. 183 * 184 * This allocates the sysid and associates the structure with the 185 * red-black tree, allowing it to be looked up. The actual resource 186 * structure has NOT yet been allocated so it is marked free. 187 * 188 * If the sysid is not used to access the resource, we will just 189 * allow the sysid to be reused when the resource structure is reused, 190 * allowing the RB tree operation to be 'cached'. This results in 191 * virtually no performance penalty for using the sysref facility. 192 */ 193 static 194 boolean_t 195 sysref_ctor(void *data, void *privdata, int ocflags) 196 { 197 globaldata_t gd; 198 struct srpercpu *sa; 199 struct sysref_class *srclass = privdata; 200 struct sysref *sr = (void *)((char *)data + srclass->offset); 201 202 /* 203 * Resource structures need to be cleared when allocating from 204 * malloc backing store. This is different from the zeroing 205 * that we do in sysref_alloc(). 206 */ 207 bzero(data, srclass->objsize); 208 209 /* 210 * Resources managed by our objcache do the sysid and RB tree 211 * handling in the objcache ctor/dtor, so we can reuse the 212 * structure without re-treeing it over and over again. 213 */ 214 gd = mycpu; 215 crit_enter_gd(gd); 216 gd->gd_sysid_alloc += ncpus_fit; /* next unique sysid */ 217 sr->sysid = gd->gd_sysid_alloc; 218 KKASSERT(((int)sr->sysid & ncpus_fit_mask) == gd->gd_cpuid); 219 /* sr->refcnt= 0; already zero */ 220 sr->flags = SRF_ALLOCATED | SRF_PUTAWAY; 221 sr->srclass = srclass; 222 223 sa = &sysref_array[gd->gd_cpuid]; 224 spin_lock(&sa->spin); 225 sysref_rb_tree_RB_INSERT(&sa->rbtree, sr); 226 spin_unlock(&sa->spin); 227 crit_exit_gd(gd); 228 229 /* 230 * Execute the class's ctor function, if any. NOTE: The class 231 * should not try to zero out the structure, we've already handled 232 * that and preinitialized the sysref. 233 * 234 * XXX ignores return value for now 235 */ 236 if (srclass->ctor) 237 srclass->ctor(data, privdata, ocflags); 238 return TRUE; 239 } 240 241 /* 242 * Object cache destructor, allowing the structure to be returned 243 * to the system memory pool. The resource structure must be 244 * removed from the RB tree. All other references have already 245 * been destroyed and the RB tree will not create any new references 246 * to the structure in its current state. 247 */ 248 static 249 void 250 sysref_dtor(void *data, void *privdata) 251 { 252 struct srpercpu *sa; 253 struct sysref_class *srclass = privdata; 254 struct sysref *sr = (void *)((char *)data + srclass->offset); 255 256 KKASSERT(sr->refcnt == 0); 257 sa = &sysref_array[(int)sr->sysid & ncpus_fit_mask]; 258 spin_lock(&sa->spin); 259 sysref_rb_tree_RB_REMOVE(&sa->rbtree, sr); 260 spin_unlock(&sa->spin); 261 if (srclass->dtor) 262 srclass->dtor(data, privdata); 263 } 264 265 /* 266 * Activate or reactivate a resource. 0x40000001 is added to the ref count 267 * so -0x40000000 (during initialization) will translate to a ref count of 1. 268 * Any references made during initialization will translate to additional 269 * positive ref counts. 270 * 271 * MPSAFE 272 */ 273 void 274 sysref_activate(struct sysref *sr) 275 { 276 int count; 277 278 for (;;) { 279 count = sr->refcnt; 280 KASSERT(count < 0 && count + 0x40000001 > 0, 281 ("sysref_activate: bad count %08x", count)); 282 if (atomic_cmpset_int(&sr->refcnt, count, count + 0x40000001)) 283 break; 284 cpu_pause(); 285 } 286 } 287 288 /* 289 * Release a reference under special circumstances. This call is made 290 * from the sysref_put() inline from sys/sysref2.h for any 1->0 transitions, 291 * negative->negative 'termination in progress' transitions, and when the 292 * cmpset instruction fails during a normal transition. 293 * 294 * This function is called from the sysref_put() inline in sys/sysref2.h, 295 * but handles all cases regardless. 296 */ 297 void 298 _sysref_put(struct sysref *sr) 299 { 300 int count; 301 void *data; 302 303 KKASSERT((sr->flags & SRF_PUTAWAY) == 0); 304 305 for (;;) { 306 count = sr->refcnt; 307 if (count > 1) { 308 /* 309 * release 1 count, nominal case, active resource 310 * structure, no other action required. 311 */ 312 if (atomic_cmpset_int(&sr->refcnt, count, count - 1)) 313 break; 314 } else if (count == 1) { 315 /* 316 * 1->0 transitions transition to -0x40000000 instead, 317 * placing the resource structure into a termination- 318 * in-progress state. The termination function is 319 * then called. 320 */ 321 data = (char *)sr - sr->srclass->offset; 322 sr->srclass->ops.lock(data); 323 if (atomic_cmpset_int(&sr->refcnt, count, -0x40000000)) { 324 sr->srclass->ops.terminate(data); 325 /* callback unlocks */ 326 break; 327 } 328 sr->srclass->ops.unlock(data); 329 } else if (count > -0x40000000) { 330 /* 331 * release 1 count, nominal case, resource undergoing 332 * termination. The Resource can be ref'd and 333 * deref'd while undergoing termination. 334 */ 335 if (atomic_cmpset_int(&sr->refcnt, count, count - 1)) 336 break; 337 } else { 338 /* 339 * Final release, set refcnt to 0. 340 * Resource must have been allocated. 341 * 342 * If SRF_SYSIDUSED is not set just objcache_put() the 343 * resource, otherwise objcache_dtor() the resource. 344 */ 345 KKASSERT(count == -0x40000000); 346 if (atomic_cmpset_int(&sr->refcnt, count, 0)) { 347 KKASSERT(sr->flags & SRF_ALLOCATED); 348 sr->flags |= SRF_PUTAWAY; 349 data = (char *)sr - sr->srclass->offset; 350 if (sr->flags & SRF_SYSIDUSED) 351 objcache_dtor(sr->srclass->oc, data); 352 else 353 objcache_put(sr->srclass->oc, data); 354 break; 355 } 356 } 357 /* loop until the cmpset succeeds */ 358 cpu_pause(); 359 } 360 } 361 362 sysid_t 363 allocsysid(void) 364 { 365 globaldata_t gd = mycpu; 366 sysid_t sysid; 367 368 crit_enter_gd(gd); 369 gd->gd_sysid_alloc += ncpus_fit; 370 sysid = gd->gd_sysid_alloc; 371 crit_exit_gd(gd); 372 return(sysid); 373 } 374 375