sys/kern/lwkt_token.c

   1 /*
   2  * Copyright (c) 2003,2004 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  * $DragonFly: src/sys/kern/lwkt_token.c,v 1.29 2006/12/27 06:51:47 dillon Exp $
  35  */
  36
  37 #ifdef _KERNEL
  38
  39 #include <sys/param.h>
  40 #include <sys/systm.h>
  41 #include <sys/kernel.h>
  42 #include <sys/proc.h>
  43 #include <sys/rtprio.h>
  44 #include <sys/queue.h>
  45 #include <sys/sysctl.h>
  46 #include <sys/ktr.h>
  47 #include <sys/kthread.h>
  48 #include <machine/cpu.h>
  49 #include <sys/lock.h>
  50 #include <sys/caps.h>
  51 #include <sys/spinlock.h>
  52
  53 #include <sys/thread2.h>
  54 #include <sys/spinlock2.h>
  55
  56 #include <vm/vm.h>
  57 #include <vm/vm_param.h>
  58 #include <vm/vm_kern.h>
  59 #include <vm/vm_object.h>
  60 #include <vm/vm_page.h>
  61 #include <vm/vm_map.h>
  62 #include <vm/vm_pager.h>
  63 #include <vm/vm_extern.h>
  64 #include <vm/vm_zone.h>
  65
  66 #include <machine/stdarg.h>
  67 #include <machine/smp.h>
  68
  69 #else
  70
  71 #include <sys/stdint.h>
  72 #include <libcaps/thread.h>
  73 #include <sys/thread.h>
  74 #include <sys/msgport.h>
  75 #include <sys/errno.h>
  76 #include <libcaps/globaldata.h>
  77 #include <machine/cpufunc.h>
  78 #include <sys/thread2.h>
  79 #include <sys/msgport2.h>
  80 #include <stdio.h>
  81 #include <stdlib.h>
  82 #include <string.h>
  83 #include <machine/lock.h>
  84 #include <machine/cpu.h>
  85
  86 #endif
  87
  88 #ifndef LWKT_NUM_POOL_TOKENS
  89 #define LWKT_NUM_POOL_TOKENS    1024    /* power of 2 */
  90 #endif
  91 #define LWKT_MASK_POOL_TOKENS   (LWKT_NUM_POOL_TOKENS - 1)
  92
  93 #ifdef INVARIANTS
  94 static int token_debug = 0;
  95 #endif
  96
  97 static lwkt_token       pool_tokens[LWKT_NUM_POOL_TOKENS];
  98
  99 #define TOKEN_STRING    "REF=%p TOK=%p TD=%p"
 100 #define CONTENDED_STRING        "REF=%p TOK=%p TD=%p (contention started)"
 101 #define UNCONTENDED_STRING      "REF=%p TOK=%p TD=%p (contention stopped)"
 102 #if !defined(KTR_TOKENS)
 103 #define KTR_TOKENS      KTR_ALL
 104 #endif
 105
 106 KTR_INFO_MASTER(tokens);
 107 KTR_INFO(KTR_TOKENS, tokens, try, 0, TOKEN_STRING, sizeof(void *) * 3);
 108 KTR_INFO(KTR_TOKENS, tokens, get, 1, TOKEN_STRING, sizeof(void *) * 3);
 109 KTR_INFO(KTR_TOKENS, tokens, release, 2, TOKEN_STRING, sizeof(void *) * 3);
 110 #if 0
 111 KTR_INFO(KTR_TOKENS, tokens, remote, 3, TOKEN_STRING, sizeof(void *) * 3);
 112 KTR_INFO(KTR_TOKENS, tokens, reqremote, 4, TOKEN_STRING, sizeof(void *) * 3);
 113 KTR_INFO(KTR_TOKENS, tokens, reqfail, 5, TOKEN_STRING, sizeof(void *) * 3);
 114 KTR_INFO(KTR_TOKENS, tokens, drain, 6, TOKEN_STRING, sizeof(void *) * 3);
 115 KTR_INFO(KTR_TOKENS, tokens, contention_start, 7, CONTENDED_STRING, sizeof(void *) * 3);
 116 KTR_INFO(KTR_TOKENS, tokens, contention_stop, 7, UNCONTENDED_STRING, sizeof(void *) * 3);
 117 #endif
 118
 119 #define logtoken(name, ref)                                             \
 120         KTR_LOG(tokens_ ## name, ref, ref->tr_tok, curthread)
 121
 122 #ifdef _KERNEL
 123
 124 #ifdef INVARIANTS
 125 SYSCTL_INT(_lwkt, OID_AUTO, token_debug, CTLFLAG_RW, &token_debug, 0, "");
 126 #endif
 127
 128 #endif
 129
 130 #ifdef SMP
 131
 132 /*
 133  * Obtain all the tokens required by the specified thread on the current
 134  * cpu, return 0 on failure and non-zero on success.
 135  *
 136  * NOTE: This code does not work with UP 'degenerate' spinlocks.  SMP only.
 137  *
 138  * The preemption code will not allow a target thread holding spinlocks to
 139  * preempt the current thread so we do not have to implement this for UP.
 140  */
 141 int
 142 lwkt_getalltokens(thread_t td)
 143 {
 144     lwkt_tokref_t refs;
 145     lwkt_tokref_t undo;
 146     lwkt_token_t tok;
 147
 148     for (refs = td->td_toks; refs; refs = refs->tr_next) {
 149         KKASSERT(refs->tr_state == 0);
 150         tok = refs->tr_tok;
 151         if (tok->t_owner != td) {
 152             if (spin_trylock_wr(&tok->t_spinlock) == 0) {
 153                 /*
 154                  * Release the partial list of tokens obtained and return
 155                  * failure.
 156                  */
 157                 for (undo = td->td_toks; undo != refs; undo = undo->tr_next) {
 158                     tok = undo->tr_tok;
 159                     undo->tr_state = 0;
 160                     if (--tok->t_count == 0) {
 161                         tok->t_owner = NULL;
 162                         spin_unlock_wr(&tok->t_spinlock);
 163                     }
 164                 }
 165                 return (FALSE);
 166             }
 167             tok->t_owner = td;
 168             KKASSERT(tok->t_count == 0);
 169         }
 170         ++tok->t_count;
 171         refs->tr_state = 1;
 172     }
 173     return (TRUE);
 174 }
 175
 176 /*
 177  * Release all tokens owned by the specified thread on the current cpu.
 178  */
 179 void
 180 lwkt_relalltokens(thread_t td)
 181 {
 182     lwkt_tokref_t scan;
 183     lwkt_token_t tok;
 184
 185     for (scan = td->td_toks; scan; scan = scan->tr_next) {
 186         if (scan->tr_state) {
 187             scan->tr_state = 0;
 188             tok = scan->tr_tok;
 189             KKASSERT(tok->t_owner == td && tok->t_count > 0);
 190             if (--tok->t_count == 0) {
 191                 tok->t_owner = NULL;
 192                 spin_unlock_wr(&tok->t_spinlock);
 193             }
 194         }
 195     }
 196 }
 197
 198 #endif
 199
 200 /*
 201  * Acquire a serializing token.  This routine can block.
 202  *
 203  * On SMP systems we track ownership and a per-owner counter.  Tokens are
 204  * released when a thread switches out and reacquired when a thread
 205  * switches back in.  On UP systems we track a global counter for debugging
 206  * but otherwise the only issue we have is if a preempting thread wants a
 207  * token that is being held by the preempted thread.
 208  */
 209 static __inline
 210 void
 211 _lwkt_gettokref(lwkt_tokref_t ref)
 212 {
 213 #ifndef SMP
 214     lwkt_tokref_t scan;
 215 #endif
 216     lwkt_token_t tok;
 217     thread_t td;
 218
 219     KKASSERT(mycpu->gd_intr_nesting_level == 0);
 220     td = curthread;
 221     tok = ref->tr_tok;
 222
 223     /*
 224      * Link the tokref to the thread's list
 225      */
 226     ref->tr_next = td->td_toks;
 227     cpu_ccfence();
 228     td->td_toks = ref;
 229
 230 #ifdef SMP
 231     /*
 232      * Gain ownership of the token's spinlock, SMP version.
 233      */
 234     if (tok->t_owner != td) {
 235         if (spin_trylock_wr(&tok->t_spinlock) == 0) {
 236             lwkt_yield();
 237             return;
 238         }
 239         KKASSERT(tok->t_owner == NULL && tok->t_count == 0);
 240         tok->t_owner = td;
 241     }
 242     ++tok->t_count;
 243 #else
 244     /*
 245      * Gain ownership of the token, UP version.   All we have to do
 246      * is check the token if we are preempting someone owning the
 247      * same token.  If we are, we yield the cpu back to the originator
 248      * and we will get rescheduled as non-preemptive.
 249      */
 250     while ((td = td->td_preempted) != NULL) {
 251         for (scan = td->td_toks; scan; scan = scan->tr_next) {
 252             if (scan->tr_tok == tok) {
 253                 lwkt_yield();
 254                 return;
 255             }
 256         }
 257     }
 258     /* NOTE: 'td' invalid after loop */
 259     ++tok->t_globalcount;
 260 #endif
 261     ref->tr_state = 1;
 262 }
 263
 264 static __inline
 265 int
 266 _lwkt_trytokref(lwkt_tokref_t ref)
 267 {
 268 #ifndef SMP
 269     lwkt_tokref_t scan;
 270 #endif
 271     lwkt_token_t tok;
 272     thread_t td;
 273
 274     KKASSERT(mycpu->gd_intr_nesting_level == 0);
 275     td = curthread;
 276     tok = ref->tr_tok;
 277
 278     /*
 279      * Link the tokref to the thread's list
 280      */
 281     ref->tr_next = td->td_toks;
 282     cpu_ccfence();
 283     td->td_toks = ref;
 284
 285 #ifdef SMP
 286     /*
 287      * Gain ownership of the token's spinlock, SMP version.
 288      */
 289     if (tok->t_owner != td) {
 290         if (spin_trylock_wr(&tok->t_spinlock) == 0) {
 291             td->td_toks = ref->tr_next;
 292             return (FALSE);
 293         }
 294         KKASSERT(tok->t_owner == NULL && tok->t_count == 0);
 295         tok->t_owner = td;
 296     }
 297     ++tok->t_count;
 298 #else
 299     /*
 300      * Gain ownership of the token, UP version.   All we have to do
 301      * is check the token if we are preempting someone owning the
 302      * same token.  If we are, we yield the cpu back to the originator
 303      * and we will get rescheduled as non-preemptive.
 304      */
 305     while ((td = td->td_preempted) != NULL) {
 306         for (scan = td->td_toks; scan; scan = scan->tr_next) {
 307             if (scan->tr_tok == tok) {
 308                 td->td_toks = ref->tr_next;
 309                 return (FALSE);
 310             }
 311         }
 312     }
 313     /* NOTE: 'td' invalid after loop */
 314     ++tok->t_globalcount;
 315 #endif
 316     ref->tr_state = 1;
 317     return (TRUE);
 318 }
 319
 320 void
 321 lwkt_gettoken(lwkt_tokref_t ref, lwkt_token_t tok)
 322 {
 323     lwkt_tokref_init(ref, tok);
 324     logtoken(get, ref);
 325     _lwkt_gettokref(ref);
 326 }
 327
 328 void
 329 lwkt_gettokref(lwkt_tokref_t ref)
 330 {
 331     logtoken(get, ref);
 332     _lwkt_gettokref(ref);
 333 }
 334
 335 int
 336 lwkt_trytoken(lwkt_tokref_t ref, lwkt_token_t tok)
 337 {
 338     lwkt_tokref_init(ref, tok);
 339     logtoken(try, ref);
 340     return(_lwkt_trytokref(ref));
 341 }
 342
 343 int
 344 lwkt_trytokref(lwkt_tokref_t ref)
 345 {
 346     logtoken(try, ref);
 347     return(_lwkt_trytokref(ref));
 348 }
 349
 350 /*
 351  * Release a serializing token
 352  */
 353 void
 354 lwkt_reltoken(lwkt_tokref *ref)
 355 {
 356     struct lwkt_tokref **scanp;
 357     lwkt_token_t tok;
 358     thread_t td;
 359
 360     td = curthread;
 361     tok = ref->tr_tok;
 362
 363 #ifdef SMP
 364     KKASSERT(ref->tr_state == 1 && tok->t_owner == td && tok->t_count > 0);
 365 #else
 366     KKASSERT(ref->tr_state == 1 && tok->t_globalcount > 0);
 367 #endif
 368
 369     for (scanp = &td->td_toks; *scanp != ref; scanp = &((*scanp)->tr_next))
 370         ;
 371     *scanp = ref->tr_next;
 372     ref->tr_state = 0;
 373
 374 #ifdef SMP
 375     if (--tok->t_count == 0) {
 376         tok->t_owner = NULL;
 377         spin_unlock_wr(&tok->t_spinlock);
 378     }
 379 #else
 380     --tok->t_globalcount;
 381 #endif
 382     logtoken(release, ref);
 383 }
 384
 385 /*
 386  * Pool tokens are used to provide a type-stable serializing token
 387  * pointer that does not race against disappearing data structures.
 388  *
 389  * This routine is called in early boot just after we setup the BSP's
 390  * globaldata structure.
 391  */
 392 void
 393 lwkt_token_pool_init(void)
 394 {
 395     int i;
 396
 397     for (i = 0; i < LWKT_NUM_POOL_TOKENS; ++i)
 398         lwkt_token_init(&pool_tokens[i]);
 399 }
 400
 401 lwkt_token_t
 402 lwkt_token_pool_get(void *ptraddr)
 403 {
 404     int i;
 405
 406     i = ((int)(intptr_t)ptraddr >> 2) ^ ((int)(intptr_t)ptraddr >> 12);
 407     return(&pool_tokens[i & LWKT_MASK_POOL_TOKENS]);
 408 }
 409
 410 /*
 411  * Initialize the owner and release-to cpu to the current cpu
 412  * and reset the generation count.
 413  */
 414 void
 415 lwkt_token_init(lwkt_token_t tok)
 416 {
 417 #ifdef SMP
 418     spin_init(&tok->t_spinlock);
 419     tok->t_owner = NULL;
 420     tok->t_count = 0;
 421 #else
 422     tok->t_globalcount = 0;
 423 #endif
 424 }
 425
 426 void
 427 lwkt_token_uninit(lwkt_token_t tok)
 428 {
 429     /* empty */
 430 }