subr_lock.c

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    1 /*-
    2  * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
    3  *
    4  * Copyright (c) 2006 John Baldwin <jhb@FreeBSD.org>
    5  *
    6  * Redistribution and use in source and binary forms, with or without
    7  * modification, are permitted provided that the following conditions
    8  * are met:
    9  * 1. Redistributions of source code must retain the above copyright
   10  *    notice, this list of conditions and the following disclaimer.
   11  * 2. Redistributions in binary form must reproduce the above copyright
   12  *    notice, this list of conditions and the following disclaimer in the
   13  *    documentation and/or other materials provided with the distribution.
   14  *
   15  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
   16  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   17  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   18  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
   19  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   20  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   21  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   22  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   23  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   24  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   25  * SUCH DAMAGE.
   26  */
   27 
   28 /*
   29  * This module holds the global variables and functions used to maintain
   30  * lock_object structures.
   31  */
   32 
   33 #include <sys/cdefs.h>
   34 __FBSDID("$FreeBSD$");
   35 
   36 #include "opt_ddb.h"
   37 #include "opt_mprof.h"
   38 
   39 #include <sys/param.h>
   40 #include <sys/systm.h>
   41 #include <sys/kernel.h>
   42 #include <sys/ktr.h>
   43 #include <sys/lock.h>
   44 #include <sys/lock_profile.h>
   45 #include <sys/malloc.h>
   46 #include <sys/mutex.h>
   47 #include <sys/pcpu.h>
   48 #include <sys/proc.h>
   49 #include <sys/sbuf.h>
   50 #include <sys/sched.h>
   51 #include <sys/smp.h>
   52 #include <sys/sysctl.h>
   53 
   54 #ifdef DDB
   55 #include <ddb/ddb.h>
   56 #endif
   57 
   58 #include <machine/cpufunc.h>
   59 
   60 SDT_PROVIDER_DEFINE(lock);
   61 SDT_PROBE_DEFINE1(lock, , , starvation, "u_int");
   62 
   63 CTASSERT(LOCK_CLASS_MAX == 15);
   64 
   65 struct lock_class *lock_classes[LOCK_CLASS_MAX + 1] = {
   66         &lock_class_mtx_spin,
   67         &lock_class_mtx_sleep,
   68         &lock_class_sx,
   69         &lock_class_rm,
   70         &lock_class_rm_sleepable,
   71         &lock_class_rw,
   72         &lock_class_lockmgr,
   73 };
   74 
   75 void
   76 lock_init(struct lock_object *lock, struct lock_class *class, const char *name,
   77     const char *type, int flags)
   78 {
   79         int i;
   80 
   81         /* Check for double-init and zero object. */
   82         KASSERT(flags & LO_NEW || !lock_initialized(lock),
   83             ("lock \"%s\" %p already initialized", name, lock));
   84 
   85         /* Look up lock class to find its index. */
   86         for (i = 0; i < LOCK_CLASS_MAX; i++)
   87                 if (lock_classes[i] == class) {
   88                         lock->lo_flags = i << LO_CLASSSHIFT;
   89                         break;
   90                 }
   91         KASSERT(i < LOCK_CLASS_MAX, ("unknown lock class %p", class));
   92 
   93         /* Initialize the lock object. */
   94         lock->lo_name = name;
   95         lock->lo_flags |= flags | LO_INITIALIZED;
   96         LOCK_LOG_INIT(lock, 0);
   97         WITNESS_INIT(lock, (type != NULL) ? type : name);
   98 }
   99 
  100 void
  101 lock_destroy(struct lock_object *lock)
  102 {
  103 
  104         KASSERT(lock_initialized(lock), ("lock %p is not initialized", lock));
  105         WITNESS_DESTROY(lock);
  106         LOCK_LOG_DESTROY(lock, 0);
  107         lock->lo_flags &= ~LO_INITIALIZED;
  108 }
  109 
  110 static SYSCTL_NODE(_debug, OID_AUTO, lock, CTLFLAG_RD, NULL, "lock debugging");
  111 static SYSCTL_NODE(_debug_lock, OID_AUTO, delay, CTLFLAG_RD, NULL,
  112     "lock delay");
  113 
  114 static u_int __read_mostly starvation_limit = 131072;
  115 SYSCTL_INT(_debug_lock_delay, OID_AUTO, starvation_limit, CTLFLAG_RW,
  116     &starvation_limit, 0, "");
  117 
  118 static u_int __read_mostly restrict_starvation = 0;
  119 SYSCTL_INT(_debug_lock_delay, OID_AUTO, restrict_starvation, CTLFLAG_RW,
  120     &restrict_starvation, 0, "");
  121 
  122 void
  123 lock_delay(struct lock_delay_arg *la)
  124 {
  125         struct lock_delay_config *lc = la->config;
  126         u_int i;
  127 
  128         la->delay <<= 1;
  129         if (__predict_false(la->delay > lc->max))
  130                 la->delay = lc->max;
  131 
  132         for (i = la->delay; i > 0; i--)
  133                 cpu_spinwait();
  134 
  135         la->spin_cnt += la->delay;
  136         if (__predict_false(la->spin_cnt > starvation_limit)) {
  137                 SDT_PROBE1(lock, , , starvation, la->delay);
  138                 if (restrict_starvation)
  139                         la->delay = lc->base;
  140         }
  141 }
  142 
  143 static u_int
  144 lock_roundup_2(u_int val)
  145 {
  146         u_int res;
  147 
  148         for (res = 1; res <= val; res <<= 1)
  149                 continue;
  150 
  151         return (res);
  152 }
  153 
  154 void
  155 lock_delay_default_init(struct lock_delay_config *lc)
  156 {
  157 
  158         lc->base = 1;
  159         lc->max = lock_roundup_2(mp_ncpus) * 256;
  160         if (lc->max > 32678)
  161                 lc->max = 32678;
  162 }
  163 
  164 #ifdef DDB
  165 DB_SHOW_COMMAND(lock, db_show_lock)
  166 {
  167         struct lock_object *lock;
  168         struct lock_class *class;
  169 
  170         if (!have_addr)
  171                 return;
  172         lock = (struct lock_object *)addr;
  173         if (LO_CLASSINDEX(lock) > LOCK_CLASS_MAX) {
  174                 db_printf("Unknown lock class: %d\n", LO_CLASSINDEX(lock));
  175                 return;
  176         }
  177         class = LOCK_CLASS(lock);
  178         db_printf(" class: %s\n", class->lc_name);
  179         db_printf(" name: %s\n", lock->lo_name);
  180         class->lc_ddb_show(lock);
  181 }
  182 #endif
  183 
  184 #ifdef LOCK_PROFILING
  185 
  186 /*
  187  * One object per-thread for each lock the thread owns.  Tracks individual
  188  * lock instances.
  189  */
  190 struct lock_profile_object {
  191         LIST_ENTRY(lock_profile_object) lpo_link;
  192         struct lock_object *lpo_obj;
  193         const char      *lpo_file;
  194         int             lpo_line;
  195         uint16_t        lpo_ref;
  196         uint16_t        lpo_cnt;
  197         uint64_t        lpo_acqtime;
  198         uint64_t        lpo_waittime;
  199         u_int           lpo_contest_locking;
  200 };
  201 
  202 /*
  203  * One lock_prof for each (file, line, lock object) triple.
  204  */
  205 struct lock_prof {
  206         SLIST_ENTRY(lock_prof) link;
  207         struct lock_class *class;
  208         const char      *file;
  209         const char      *name;
  210         int             line;
  211         int             ticks;
  212         uintmax_t       cnt_wait_max;
  213         uintmax_t       cnt_max;
  214         uintmax_t       cnt_tot;
  215         uintmax_t       cnt_wait;
  216         uintmax_t       cnt_cur;
  217         uintmax_t       cnt_contest_locking;
  218 };
  219 
  220 SLIST_HEAD(lphead, lock_prof);
  221 
  222 #define LPROF_HASH_SIZE         4096
  223 #define LPROF_HASH_MASK         (LPROF_HASH_SIZE - 1)
  224 #define LPROF_CACHE_SIZE        4096
  225 
  226 /*
  227  * Array of objects and profs for each type of object for each cpu.  Spinlocks
  228  * are handled separately because a thread may be preempted and acquire a
  229  * spinlock while in the lock profiling code of a non-spinlock.  In this way
  230  * we only need a critical section to protect the per-cpu lists.
  231  */
  232 struct lock_prof_type {
  233         struct lphead           lpt_lpalloc;
  234         struct lpohead          lpt_lpoalloc;
  235         struct lphead           lpt_hash[LPROF_HASH_SIZE];
  236         struct lock_prof        lpt_prof[LPROF_CACHE_SIZE];
  237         struct lock_profile_object lpt_objs[LPROF_CACHE_SIZE];
  238 };
  239 
  240 struct lock_prof_cpu {
  241         struct lock_prof_type   lpc_types[2]; /* One for spin one for other. */
  242 };
  243 
  244 struct lock_prof_cpu *lp_cpu[MAXCPU];
  245 
  246 volatile int __read_mostly lock_prof_enable;
  247 static volatile int lock_prof_resetting;
  248 
  249 #define LPROF_SBUF_SIZE         256
  250 
  251 static int lock_prof_rejected;
  252 static int lock_prof_skipspin;
  253 static int lock_prof_skipcount;
  254 
  255 #ifndef USE_CPU_NANOSECONDS
  256 uint64_t
  257 nanoseconds(void)
  258 {
  259         struct bintime bt;
  260         uint64_t ns;
  261 
  262         binuptime(&bt);
  263         /* From bintime2timespec */
  264         ns = bt.sec * (uint64_t)1000000000;
  265         ns += ((uint64_t)1000000000 * (uint32_t)(bt.frac >> 32)) >> 32;
  266         return (ns);
  267 }
  268 #endif
  269 
  270 static void
  271 lock_prof_init_type(struct lock_prof_type *type)
  272 {
  273         int i;
  274 
  275         SLIST_INIT(&type->lpt_lpalloc);
  276         LIST_INIT(&type->lpt_lpoalloc);
  277         for (i = 0; i < LPROF_CACHE_SIZE; i++) {
  278                 SLIST_INSERT_HEAD(&type->lpt_lpalloc, &type->lpt_prof[i],
  279                     link);
  280                 LIST_INSERT_HEAD(&type->lpt_lpoalloc, &type->lpt_objs[i],
  281                     lpo_link);
  282         }
  283 }
  284 
  285 static void
  286 lock_prof_init(void *arg)
  287 {
  288         int cpu;
  289 
  290         for (cpu = 0; cpu <= mp_maxid; cpu++) {
  291                 lp_cpu[cpu] = malloc(sizeof(*lp_cpu[cpu]), M_DEVBUF,
  292                     M_WAITOK | M_ZERO);
  293                 lock_prof_init_type(&lp_cpu[cpu]->lpc_types[0]);
  294                 lock_prof_init_type(&lp_cpu[cpu]->lpc_types[1]);
  295         }
  296 }
  297 SYSINIT(lockprof, SI_SUB_SMP, SI_ORDER_ANY, lock_prof_init, NULL);
  298 
  299 static void
  300 lock_prof_reset_wait(void)
  301 {
  302 
  303         /*
  304          * Spin relinquishing our cpu so that quiesce_all_cpus may
  305          * complete.
  306          */
  307         while (lock_prof_resetting)
  308                 sched_relinquish(curthread);
  309 }
  310 
  311 static void
  312 lock_prof_reset(void)
  313 {
  314         struct lock_prof_cpu *lpc;
  315         int enabled, i, cpu;
  316 
  317         /*
  318          * We not only race with acquiring and releasing locks but also
  319          * thread exit.  To be certain that threads exit without valid head
  320          * pointers they must see resetting set before enabled is cleared.
  321          * Otherwise a lock may not be removed from a per-thread list due
  322          * to disabled being set but not wait for reset() to remove it below.
  323          */
  324         atomic_store_rel_int(&lock_prof_resetting, 1);
  325         enabled = lock_prof_enable;
  326         lock_prof_enable = 0;
  327         quiesce_all_cpus("profreset", 0);
  328         /*
  329          * Some objects may have migrated between CPUs.  Clear all links
  330          * before we zero the structures.  Some items may still be linked
  331          * into per-thread lists as well.
  332          */
  333         for (cpu = 0; cpu <= mp_maxid; cpu++) {
  334                 lpc = lp_cpu[cpu];
  335                 for (i = 0; i < LPROF_CACHE_SIZE; i++) {
  336                         LIST_REMOVE(&lpc->lpc_types[0].lpt_objs[i], lpo_link);
  337                         LIST_REMOVE(&lpc->lpc_types[1].lpt_objs[i], lpo_link);
  338                 }
  339         }
  340         for (cpu = 0; cpu <= mp_maxid; cpu++) {
  341                 lpc = lp_cpu[cpu];
  342                 bzero(lpc, sizeof(*lpc));
  343                 lock_prof_init_type(&lpc->lpc_types[0]);
  344                 lock_prof_init_type(&lpc->lpc_types[1]);
  345         }
  346         atomic_store_rel_int(&lock_prof_resetting, 0);
  347         lock_prof_enable = enabled;
  348 }
  349 
  350 static void
  351 lock_prof_output(struct lock_prof *lp, struct sbuf *sb)
  352 {
  353         const char *p;
  354 
  355         for (p = lp->file; p != NULL && strncmp(p, "../", 3) == 0; p += 3);
  356         sbuf_printf(sb,
  357             "%8ju %9ju %11ju %11ju %11ju %6ju %6ju %2ju %6ju %s:%d (%s:%s)\n",
  358             lp->cnt_max / 1000, lp->cnt_wait_max / 1000, lp->cnt_tot / 1000,
  359             lp->cnt_wait / 1000, lp->cnt_cur,
  360             lp->cnt_cur == 0 ? (uintmax_t)0 :
  361             lp->cnt_tot / (lp->cnt_cur * 1000),
  362             lp->cnt_cur == 0 ? (uintmax_t)0 :
  363             lp->cnt_wait / (lp->cnt_cur * 1000),
  364             (uintmax_t)0, lp->cnt_contest_locking,
  365             p, lp->line, lp->class->lc_name, lp->name);
  366 }
  367 
  368 static void
  369 lock_prof_sum(struct lock_prof *match, struct lock_prof *dst, int hash,
  370     int spin, int t)
  371 {
  372         struct lock_prof_type *type;
  373         struct lock_prof *l;
  374         int cpu;
  375 
  376         dst->file = match->file;
  377         dst->line = match->line;
  378         dst->class = match->class;
  379         dst->name = match->name;
  380 
  381         for (cpu = 0; cpu <= mp_maxid; cpu++) {
  382                 if (lp_cpu[cpu] == NULL)
  383                         continue;
  384                 type = &lp_cpu[cpu]->lpc_types[spin];
  385                 SLIST_FOREACH(l, &type->lpt_hash[hash], link) {
  386                         if (l->ticks == t)
  387                                 continue;
  388                         if (l->file != match->file || l->line != match->line ||
  389                             l->name != match->name)
  390                                 continue;
  391                         l->ticks = t;
  392                         if (l->cnt_max > dst->cnt_max)
  393                                 dst->cnt_max = l->cnt_max;
  394                         if (l->cnt_wait_max > dst->cnt_wait_max)
  395                                 dst->cnt_wait_max = l->cnt_wait_max;
  396                         dst->cnt_tot += l->cnt_tot;
  397                         dst->cnt_wait += l->cnt_wait;
  398                         dst->cnt_cur += l->cnt_cur;
  399                         dst->cnt_contest_locking += l->cnt_contest_locking;
  400                 }
  401         }
  402         
  403 }
  404 
  405 static void
  406 lock_prof_type_stats(struct lock_prof_type *type, struct sbuf *sb, int spin,
  407     int t)
  408 {
  409         struct lock_prof *l;
  410         int i;
  411 
  412         for (i = 0; i < LPROF_HASH_SIZE; ++i) {
  413                 SLIST_FOREACH(l, &type->lpt_hash[i], link) {
  414                         struct lock_prof lp = {};
  415 
  416                         if (l->ticks == t)
  417                                 continue;
  418                         lock_prof_sum(l, &lp, i, spin, t);
  419                         lock_prof_output(&lp, sb);
  420                 }
  421         }
  422 }
  423 
  424 static int
  425 dump_lock_prof_stats(SYSCTL_HANDLER_ARGS)
  426 {
  427         struct sbuf *sb;
  428         int error, cpu, t;
  429         int enabled;
  430 
  431         error = sysctl_wire_old_buffer(req, 0);
  432         if (error != 0)
  433                 return (error);
  434         sb = sbuf_new_for_sysctl(NULL, NULL, LPROF_SBUF_SIZE, req);
  435         sbuf_printf(sb, "\n%8s %9s %11s %11s %11s %6s %6s %2s %6s %s\n",
  436             "max", "wait_max", "total", "wait_total", "count", "avg", "wait_avg", "cnt_hold", "cnt_lock", "name");
  437         enabled = lock_prof_enable;
  438         lock_prof_enable = 0;
  439         quiesce_all_cpus("profstat", 0);
  440         t = ticks;
  441         for (cpu = 0; cpu <= mp_maxid; cpu++) {
  442                 if (lp_cpu[cpu] == NULL)
  443                         continue;
  444                 lock_prof_type_stats(&lp_cpu[cpu]->lpc_types[0], sb, 0, t);
  445                 lock_prof_type_stats(&lp_cpu[cpu]->lpc_types[1], sb, 1, t);
  446         }
  447         lock_prof_enable = enabled;
  448 
  449         error = sbuf_finish(sb);
  450         /* Output a trailing NUL. */
  451         if (error == 0)
  452                 error = SYSCTL_OUT(req, "", 1);
  453         sbuf_delete(sb);
  454         return (error);
  455 }
  456 
  457 static int
  458 enable_lock_prof(SYSCTL_HANDLER_ARGS)
  459 {
  460         int error, v;
  461 
  462         v = lock_prof_enable;
  463         error = sysctl_handle_int(oidp, &v, v, req);
  464         if (error)
  465                 return (error);
  466         if (req->newptr == NULL)
  467                 return (error);
  468         if (v == lock_prof_enable)
  469                 return (0);
  470         if (v == 1)
  471                 lock_prof_reset();
  472         lock_prof_enable = !!v;
  473 
  474         return (0);
  475 }
  476 
  477 static int
  478 reset_lock_prof_stats(SYSCTL_HANDLER_ARGS)
  479 {
  480         int error, v;
  481 
  482         v = 0;
  483         error = sysctl_handle_int(oidp, &v, 0, req);
  484         if (error)
  485                 return (error);
  486         if (req->newptr == NULL)
  487                 return (error);
  488         if (v == 0)
  489                 return (0);
  490         lock_prof_reset();
  491 
  492         return (0);
  493 }
  494 
  495 static struct lock_prof *
  496 lock_profile_lookup(struct lock_object *lo, int spin, const char *file,
  497     int line)
  498 {
  499         const char *unknown = "(unknown)";
  500         struct lock_prof_type *type;
  501         struct lock_prof *lp;
  502         struct lphead *head;
  503         const char *p;
  504         u_int hash;
  505 
  506         p = file;
  507         if (p == NULL || *p == '\0')
  508                 p = unknown;
  509         hash = (uintptr_t)lo->lo_name * 31 + (uintptr_t)p * 31 + line;
  510         hash &= LPROF_HASH_MASK;
  511         type = &lp_cpu[PCPU_GET(cpuid)]->lpc_types[spin];
  512         head = &type->lpt_hash[hash];
  513         SLIST_FOREACH(lp, head, link) {
  514                 if (lp->line == line && lp->file == p &&
  515                     lp->name == lo->lo_name)
  516                         return (lp);
  517 
  518         }
  519         lp = SLIST_FIRST(&type->lpt_lpalloc);
  520         if (lp == NULL) {
  521                 lock_prof_rejected++;
  522                 return (lp);
  523         }
  524         SLIST_REMOVE_HEAD(&type->lpt_lpalloc, link);
  525         lp->file = p;
  526         lp->line = line;
  527         lp->class = LOCK_CLASS(lo);
  528         lp->name = lo->lo_name;
  529         SLIST_INSERT_HEAD(&type->lpt_hash[hash], lp, link);
  530         return (lp);
  531 }
  532 
  533 static struct lock_profile_object *
  534 lock_profile_object_lookup(struct lock_object *lo, int spin, const char *file,
  535     int line)
  536 {
  537         struct lock_profile_object *l;
  538         struct lock_prof_type *type;
  539         struct lpohead *head;
  540 
  541         head = &curthread->td_lprof[spin];
  542         LIST_FOREACH(l, head, lpo_link)
  543                 if (l->lpo_obj == lo && l->lpo_file == file &&
  544                     l->lpo_line == line)
  545                         return (l);
  546         type = &lp_cpu[PCPU_GET(cpuid)]->lpc_types[spin];
  547         l = LIST_FIRST(&type->lpt_lpoalloc);
  548         if (l == NULL) {
  549                 lock_prof_rejected++;
  550                 return (NULL);
  551         }
  552         LIST_REMOVE(l, lpo_link);
  553         l->lpo_obj = lo;
  554         l->lpo_file = file;
  555         l->lpo_line = line;
  556         l->lpo_cnt = 0;
  557         LIST_INSERT_HEAD(head, l, lpo_link);
  558 
  559         return (l);
  560 }
  561 
  562 void
  563 lock_profile_obtain_lock_success(struct lock_object *lo, int contested,
  564     uint64_t waittime, const char *file, int line)
  565 {
  566         static int lock_prof_count;
  567         struct lock_profile_object *l;
  568         int spin;
  569 
  570         if (SCHEDULER_STOPPED())
  571                 return;
  572 
  573         /* don't reset the timer when/if recursing */
  574         if (!lock_prof_enable || (lo->lo_flags & LO_NOPROFILE))
  575                 return;
  576         if (lock_prof_skipcount &&
  577             (++lock_prof_count % lock_prof_skipcount) != 0)
  578                 return;
  579         spin = (LOCK_CLASS(lo)->lc_flags & LC_SPINLOCK) ? 1 : 0;
  580         if (spin && lock_prof_skipspin == 1)
  581                 return;
  582         critical_enter();
  583         /* Recheck enabled now that we're in a critical section. */
  584         if (lock_prof_enable == 0)
  585                 goto out;
  586         l = lock_profile_object_lookup(lo, spin, file, line);
  587         if (l == NULL)
  588                 goto out;
  589         l->lpo_cnt++;
  590         if (++l->lpo_ref > 1)
  591                 goto out;
  592         l->lpo_contest_locking = contested;
  593         l->lpo_acqtime = nanoseconds(); 
  594         if (waittime && (l->lpo_acqtime > waittime))
  595                 l->lpo_waittime = l->lpo_acqtime - waittime;
  596         else
  597                 l->lpo_waittime = 0;
  598 out:
  599         critical_exit();
  600 }
  601 
  602 void
  603 lock_profile_thread_exit(struct thread *td)
  604 {
  605 #ifdef INVARIANTS
  606         struct lock_profile_object *l;
  607 
  608         MPASS(curthread->td_critnest == 0);
  609 #endif
  610         /*
  611          * If lock profiling was disabled we have to wait for reset to
  612          * clear our pointers before we can exit safely.
  613          */
  614         lock_prof_reset_wait();
  615 #ifdef INVARIANTS
  616         LIST_FOREACH(l, &td->td_lprof[0], lpo_link)
  617                 printf("thread still holds lock acquired at %s:%d\n",
  618                     l->lpo_file, l->lpo_line);
  619         LIST_FOREACH(l, &td->td_lprof[1], lpo_link)
  620                 printf("thread still holds lock acquired at %s:%d\n",
  621                     l->lpo_file, l->lpo_line);
  622 #endif
  623         MPASS(LIST_FIRST(&td->td_lprof[0]) == NULL);
  624         MPASS(LIST_FIRST(&td->td_lprof[1]) == NULL);
  625 }
  626 
  627 void
  628 lock_profile_release_lock(struct lock_object *lo)
  629 {
  630         struct lock_profile_object *l;
  631         struct lock_prof_type *type;
  632         struct lock_prof *lp;
  633         uint64_t curtime, holdtime;
  634         struct lpohead *head;
  635         int spin;
  636 
  637         if (SCHEDULER_STOPPED())
  638                 return;
  639         if (lo->lo_flags & LO_NOPROFILE)
  640                 return;
  641         spin = (LOCK_CLASS(lo)->lc_flags & LC_SPINLOCK) ? 1 : 0;
  642         head = &curthread->td_lprof[spin];
  643         if (LIST_FIRST(head) == NULL)
  644                 return;
  645         critical_enter();
  646         /* Recheck enabled now that we're in a critical section. */
  647         if (lock_prof_enable == 0 && lock_prof_resetting == 1)
  648                 goto out;
  649         /*
  650          * If lock profiling is not enabled we still want to remove the
  651          * lpo from our queue.
  652          */
  653         LIST_FOREACH(l, head, lpo_link)
  654                 if (l->lpo_obj == lo)
  655                         break;
  656         if (l == NULL)
  657                 goto out;
  658         if (--l->lpo_ref > 0)
  659                 goto out;
  660         lp = lock_profile_lookup(lo, spin, l->lpo_file, l->lpo_line);
  661         if (lp == NULL)
  662                 goto release;
  663         curtime = nanoseconds();
  664         if (curtime < l->lpo_acqtime)
  665                 goto release;
  666         holdtime = curtime - l->lpo_acqtime;
  667 
  668         /*
  669          * Record if the lock has been held longer now than ever
  670          * before.
  671          */
  672         if (holdtime > lp->cnt_max)
  673                 lp->cnt_max = holdtime;
  674         if (l->lpo_waittime > lp->cnt_wait_max)
  675                 lp->cnt_wait_max = l->lpo_waittime;
  676         lp->cnt_tot += holdtime;
  677         lp->cnt_wait += l->lpo_waittime;
  678         lp->cnt_contest_locking += l->lpo_contest_locking;
  679         lp->cnt_cur += l->lpo_cnt;
  680 release:
  681         LIST_REMOVE(l, lpo_link);
  682         type = &lp_cpu[PCPU_GET(cpuid)]->lpc_types[spin];
  683         LIST_INSERT_HEAD(&type->lpt_lpoalloc, l, lpo_link);
  684 out:
  685         critical_exit();
  686 }
  687 
  688 static SYSCTL_NODE(_debug_lock, OID_AUTO, prof, CTLFLAG_RD, NULL,
  689     "lock profiling");
  690 SYSCTL_INT(_debug_lock_prof, OID_AUTO, skipspin, CTLFLAG_RW,
  691     &lock_prof_skipspin, 0, "Skip profiling on spinlocks.");
  692 SYSCTL_INT(_debug_lock_prof, OID_AUTO, skipcount, CTLFLAG_RW,
  693     &lock_prof_skipcount, 0, "Sample approximately every N lock acquisitions.");
  694 SYSCTL_INT(_debug_lock_prof, OID_AUTO, rejected, CTLFLAG_RD,
  695     &lock_prof_rejected, 0, "Number of rejected profiling records");
  696 SYSCTL_PROC(_debug_lock_prof, OID_AUTO, stats, CTLTYPE_STRING | CTLFLAG_RD,
  697     NULL, 0, dump_lock_prof_stats, "A", "Lock profiling statistics");
  698 SYSCTL_PROC(_debug_lock_prof, OID_AUTO, reset, CTLTYPE_INT | CTLFLAG_RW,
  699     NULL, 0, reset_lock_prof_stats, "I", "Reset lock profiling statistics");
  700 SYSCTL_PROC(_debug_lock_prof, OID_AUTO, enable, CTLTYPE_INT | CTLFLAG_RW,
  701     NULL, 0, enable_lock_prof, "I", "Enable lock profiling");
  702 
  703 #endif
Cache object: 1fde3f8a2c9b4abd4f51a91bf779116e
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FreeBSD/Linux Kernel Cross Reference sys/kern/subr_lock.c

FreeBSD/Linux Kernel Cross Reference
sys/kern/subr_lock.c
