subr_lock.c

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    1 /*-
    2  * Copyright (c) 2006 John Baldwin <jhb@FreeBSD.org>
    3  *
    4  * Redistribution and use in source and binary forms, with or without
    5  * modification, are permitted provided that the following conditions
    6  * are met:
    7  * 1. Redistributions of source code must retain the above copyright
    8  *    notice, this list of conditions and the following disclaimer.
    9  * 2. Redistributions in binary form must reproduce the above copyright
   10  *    notice, this list of conditions and the following disclaimer in the
   11  *    documentation and/or other materials provided with the distribution.
   12  *
   13  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
   14  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   15  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   16  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
   17  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   18  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   19  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   20  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   21  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   22  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   23  * SUCH DAMAGE.
   24  */
   25 
   26 /*
   27  * This module holds the global variables and functions used to maintain
   28  * lock_object structures.
   29  */
   30 
   31 #include <sys/cdefs.h>
   32 __FBSDID("$FreeBSD$");
   33 
   34 #include "opt_ddb.h"
   35 #include "opt_mprof.h"
   36 
   37 #include <sys/param.h>
   38 #include <sys/systm.h>
   39 #include <sys/kernel.h>
   40 #include <sys/ktr.h>
   41 #include <sys/lock.h>
   42 #include <sys/lock_profile.h>
   43 #include <sys/malloc.h>
   44 #include <sys/mutex.h>
   45 #include <sys/pcpu.h>
   46 #include <sys/proc.h>
   47 #include <sys/sbuf.h>
   48 #include <sys/sched.h>
   49 #include <sys/smp.h>
   50 #include <sys/sysctl.h>
   51 
   52 #ifdef DDB
   53 #include <ddb/ddb.h>
   54 #endif
   55 
   56 #include <machine/cpufunc.h>
   57 
   58 SDT_PROVIDER_DEFINE(lock);
   59 SDT_PROBE_DEFINE1(lock, , , starvation, "u_int");
   60 
   61 CTASSERT(LOCK_CLASS_MAX == 15);
   62 
   63 struct lock_class *lock_classes[LOCK_CLASS_MAX + 1] = {
   64         &lock_class_mtx_spin,
   65         &lock_class_mtx_sleep,
   66         &lock_class_sx,
   67         &lock_class_rm,
   68         &lock_class_rm_sleepable,
   69         &lock_class_rw,
   70         &lock_class_lockmgr,
   71 };
   72 
   73 void
   74 lock_init(struct lock_object *lock, struct lock_class *class, const char *name,
   75     const char *type, int flags)
   76 {
   77         int i;
   78 
   79         /* Check for double-init and zero object. */
   80         KASSERT(flags & LO_NEW || !lock_initialized(lock),
   81             ("lock \"%s\" %p already initialized", name, lock));
   82 
   83         /* Look up lock class to find its index. */
   84         for (i = 0; i < LOCK_CLASS_MAX; i++)
   85                 if (lock_classes[i] == class) {
   86                         lock->lo_flags = i << LO_CLASSSHIFT;
   87                         break;
   88                 }
   89         KASSERT(i < LOCK_CLASS_MAX, ("unknown lock class %p", class));
   90 
   91         /* Initialize the lock object. */
   92         lock->lo_name = name;
   93         lock->lo_flags |= flags | LO_INITIALIZED;
   94         LOCK_LOG_INIT(lock, 0);
   95         WITNESS_INIT(lock, (type != NULL) ? type : name);
   96 }
   97 
   98 void
   99 lock_destroy(struct lock_object *lock)
  100 {
  101 
  102         KASSERT(lock_initialized(lock), ("lock %p is not initialized", lock));
  103         WITNESS_DESTROY(lock);
  104         LOCK_LOG_DESTROY(lock, 0);
  105         lock->lo_flags &= ~LO_INITIALIZED;
  106 }
  107 
  108 static SYSCTL_NODE(_debug, OID_AUTO, lock, CTLFLAG_RD, NULL, "lock debugging");
  109 static SYSCTL_NODE(_debug_lock, OID_AUTO, delay, CTLFLAG_RD, NULL,
  110     "lock delay");
  111 
  112 static u_int __read_mostly starvation_limit = 131072;
  113 SYSCTL_INT(_debug_lock_delay, OID_AUTO, starvation_limit, CTLFLAG_RW,
  114     &starvation_limit, 0, "");
  115 
  116 static u_int __read_mostly restrict_starvation = 0;
  117 SYSCTL_INT(_debug_lock_delay, OID_AUTO, restrict_starvation, CTLFLAG_RW,
  118     &restrict_starvation, 0, "");
  119 
  120 void
  121 lock_delay(struct lock_delay_arg *la)
  122 {
  123         struct lock_delay_config *lc = la->config;
  124         u_int i;
  125 
  126         la->delay <<= 1;
  127         if (__predict_false(la->delay > lc->max))
  128                 la->delay = lc->max;
  129 
  130         for (i = la->delay; i > 0; i--)
  131                 cpu_spinwait();
  132 
  133         la->spin_cnt += la->delay;
  134         if (__predict_false(la->spin_cnt > starvation_limit)) {
  135                 SDT_PROBE1(lock, , , starvation, la->delay);
  136                 if (restrict_starvation)
  137                         la->delay = lc->base;
  138         }
  139 }
  140 
  141 static u_int
  142 lock_roundup_2(u_int val)
  143 {
  144         u_int res;
  145 
  146         for (res = 1; res <= val; res <<= 1)
  147                 continue;
  148 
  149         return (res);
  150 }
  151 
  152 void
  153 lock_delay_default_init(struct lock_delay_config *lc)
  154 {
  155 
  156         lc->base = lock_roundup_2(mp_ncpus) / 4;
  157         lc->max = lc->base * 1024;
  158 }
  159 
  160 #ifdef DDB
  161 DB_SHOW_COMMAND(lock, db_show_lock)
  162 {
  163         struct lock_object *lock;
  164         struct lock_class *class;
  165 
  166         if (!have_addr)
  167                 return;
  168         lock = (struct lock_object *)addr;
  169         if (LO_CLASSINDEX(lock) > LOCK_CLASS_MAX) {
  170                 db_printf("Unknown lock class: %d\n", LO_CLASSINDEX(lock));
  171                 return;
  172         }
  173         class = LOCK_CLASS(lock);
  174         db_printf(" class: %s\n", class->lc_name);
  175         db_printf(" name: %s\n", lock->lo_name);
  176         class->lc_ddb_show(lock);
  177 }
  178 #endif
  179 
  180 #ifdef LOCK_PROFILING
  181 
  182 /*
  183  * One object per-thread for each lock the thread owns.  Tracks individual
  184  * lock instances.
  185  */
  186 struct lock_profile_object {
  187         LIST_ENTRY(lock_profile_object) lpo_link;
  188         struct lock_object *lpo_obj;
  189         const char      *lpo_file;
  190         int             lpo_line;
  191         uint16_t        lpo_ref;
  192         uint16_t        lpo_cnt;
  193         uint64_t        lpo_acqtime;
  194         uint64_t        lpo_waittime;
  195         u_int           lpo_contest_locking;
  196 };
  197 
  198 /*
  199  * One lock_prof for each (file, line, lock object) triple.
  200  */
  201 struct lock_prof {
  202         SLIST_ENTRY(lock_prof) link;
  203         struct lock_class *class;
  204         const char      *file;
  205         const char      *name;
  206         int             line;
  207         int             ticks;
  208         uintmax_t       cnt_wait_max;
  209         uintmax_t       cnt_max;
  210         uintmax_t       cnt_tot;
  211         uintmax_t       cnt_wait;
  212         uintmax_t       cnt_cur;
  213         uintmax_t       cnt_contest_locking;
  214 };
  215 
  216 SLIST_HEAD(lphead, lock_prof);
  217 
  218 #define LPROF_HASH_SIZE         4096
  219 #define LPROF_HASH_MASK         (LPROF_HASH_SIZE - 1)
  220 #define LPROF_CACHE_SIZE        4096
  221 
  222 /*
  223  * Array of objects and profs for each type of object for each cpu.  Spinlocks
  224  * are handled separately because a thread may be preempted and acquire a
  225  * spinlock while in the lock profiling code of a non-spinlock.  In this way
  226  * we only need a critical section to protect the per-cpu lists.
  227  */
  228 struct lock_prof_type {
  229         struct lphead           lpt_lpalloc;
  230         struct lpohead          lpt_lpoalloc;
  231         struct lphead           lpt_hash[LPROF_HASH_SIZE];
  232         struct lock_prof        lpt_prof[LPROF_CACHE_SIZE];
  233         struct lock_profile_object lpt_objs[LPROF_CACHE_SIZE];
  234 };
  235 
  236 struct lock_prof_cpu {
  237         struct lock_prof_type   lpc_types[2]; /* One for spin one for other. */
  238 };
  239 
  240 struct lock_prof_cpu *lp_cpu[MAXCPU];
  241 
  242 volatile int __read_mostly lock_prof_enable;
  243 static volatile int lock_prof_resetting;
  244 
  245 #define LPROF_SBUF_SIZE         256
  246 
  247 static int lock_prof_rejected;
  248 static int lock_prof_skipspin;
  249 static int lock_prof_skipcount;
  250 
  251 #ifndef USE_CPU_NANOSECONDS
  252 uint64_t
  253 nanoseconds(void)
  254 {
  255         struct bintime bt;
  256         uint64_t ns;
  257 
  258         binuptime(&bt);
  259         /* From bintime2timespec */
  260         ns = bt.sec * (uint64_t)1000000000;
  261         ns += ((uint64_t)1000000000 * (uint32_t)(bt.frac >> 32)) >> 32;
  262         return (ns);
  263 }
  264 #endif
  265 
  266 static void
  267 lock_prof_init_type(struct lock_prof_type *type)
  268 {
  269         int i;
  270 
  271         SLIST_INIT(&type->lpt_lpalloc);
  272         LIST_INIT(&type->lpt_lpoalloc);
  273         for (i = 0; i < LPROF_CACHE_SIZE; i++) {
  274                 SLIST_INSERT_HEAD(&type->lpt_lpalloc, &type->lpt_prof[i],
  275                     link);
  276                 LIST_INSERT_HEAD(&type->lpt_lpoalloc, &type->lpt_objs[i],
  277                     lpo_link);
  278         }
  279 }
  280 
  281 static void
  282 lock_prof_init(void *arg)
  283 {
  284         int cpu;
  285 
  286         for (cpu = 0; cpu <= mp_maxid; cpu++) {
  287                 lp_cpu[cpu] = malloc(sizeof(*lp_cpu[cpu]), M_DEVBUF,
  288                     M_WAITOK | M_ZERO);
  289                 lock_prof_init_type(&lp_cpu[cpu]->lpc_types[0]);
  290                 lock_prof_init_type(&lp_cpu[cpu]->lpc_types[1]);
  291         }
  292 }
  293 SYSINIT(lockprof, SI_SUB_SMP, SI_ORDER_ANY, lock_prof_init, NULL);
  294 
  295 static void
  296 lock_prof_reset_wait(void)
  297 {
  298 
  299         /*
  300          * Spin relinquishing our cpu so that quiesce_all_cpus may
  301          * complete.
  302          */
  303         while (lock_prof_resetting)
  304                 sched_relinquish(curthread);
  305 }
  306 
  307 static void
  308 lock_prof_reset(void)
  309 {
  310         struct lock_prof_cpu *lpc;
  311         int enabled, i, cpu;
  312 
  313         /*
  314          * We not only race with acquiring and releasing locks but also
  315          * thread exit.  To be certain that threads exit without valid head
  316          * pointers they must see resetting set before enabled is cleared.
  317          * Otherwise a lock may not be removed from a per-thread list due
  318          * to disabled being set but not wait for reset() to remove it below.
  319          */
  320         atomic_store_rel_int(&lock_prof_resetting, 1);
  321         enabled = lock_prof_enable;
  322         lock_prof_enable = 0;
  323         quiesce_all_cpus("profreset", 0);
  324         /*
  325          * Some objects may have migrated between CPUs.  Clear all links
  326          * before we zero the structures.  Some items may still be linked
  327          * into per-thread lists as well.
  328          */
  329         for (cpu = 0; cpu <= mp_maxid; cpu++) {
  330                 lpc = lp_cpu[cpu];
  331                 for (i = 0; i < LPROF_CACHE_SIZE; i++) {
  332                         LIST_REMOVE(&lpc->lpc_types[0].lpt_objs[i], lpo_link);
  333                         LIST_REMOVE(&lpc->lpc_types[1].lpt_objs[i], lpo_link);
  334                 }
  335         }
  336         for (cpu = 0; cpu <= mp_maxid; cpu++) {
  337                 lpc = lp_cpu[cpu];
  338                 bzero(lpc, sizeof(*lpc));
  339                 lock_prof_init_type(&lpc->lpc_types[0]);
  340                 lock_prof_init_type(&lpc->lpc_types[1]);
  341         }
  342         atomic_store_rel_int(&lock_prof_resetting, 0);
  343         lock_prof_enable = enabled;
  344 }
  345 
  346 static void
  347 lock_prof_output(struct lock_prof *lp, struct sbuf *sb)
  348 {
  349         const char *p;
  350 
  351         for (p = lp->file; p != NULL && strncmp(p, "../", 3) == 0; p += 3);
  352         sbuf_printf(sb,
  353             "%8ju %9ju %11ju %11ju %11ju %6ju %6ju %2ju %6ju %s:%d (%s:%s)\n",
  354             lp->cnt_max / 1000, lp->cnt_wait_max / 1000, lp->cnt_tot / 1000,
  355             lp->cnt_wait / 1000, lp->cnt_cur,
  356             lp->cnt_cur == 0 ? (uintmax_t)0 :
  357             lp->cnt_tot / (lp->cnt_cur * 1000),
  358             lp->cnt_cur == 0 ? (uintmax_t)0 :
  359             lp->cnt_wait / (lp->cnt_cur * 1000),
  360             (uintmax_t)0, lp->cnt_contest_locking,
  361             p, lp->line, lp->class->lc_name, lp->name);
  362 }
  363 
  364 static void
  365 lock_prof_sum(struct lock_prof *match, struct lock_prof *dst, int hash,
  366     int spin, int t)
  367 {
  368         struct lock_prof_type *type;
  369         struct lock_prof *l;
  370         int cpu;
  371 
  372         dst->file = match->file;
  373         dst->line = match->line;
  374         dst->class = match->class;
  375         dst->name = match->name;
  376 
  377         for (cpu = 0; cpu <= mp_maxid; cpu++) {
  378                 if (lp_cpu[cpu] == NULL)
  379                         continue;
  380                 type = &lp_cpu[cpu]->lpc_types[spin];
  381                 SLIST_FOREACH(l, &type->lpt_hash[hash], link) {
  382                         if (l->ticks == t)
  383                                 continue;
  384                         if (l->file != match->file || l->line != match->line ||
  385                             l->name != match->name)
  386                                 continue;
  387                         l->ticks = t;
  388                         if (l->cnt_max > dst->cnt_max)
  389                                 dst->cnt_max = l->cnt_max;
  390                         if (l->cnt_wait_max > dst->cnt_wait_max)
  391                                 dst->cnt_wait_max = l->cnt_wait_max;
  392                         dst->cnt_tot += l->cnt_tot;
  393                         dst->cnt_wait += l->cnt_wait;
  394                         dst->cnt_cur += l->cnt_cur;
  395                         dst->cnt_contest_locking += l->cnt_contest_locking;
  396                 }
  397         }
  398         
  399 }
  400 
  401 static void
  402 lock_prof_type_stats(struct lock_prof_type *type, struct sbuf *sb, int spin,
  403     int t)
  404 {
  405         struct lock_prof *l;
  406         int i;
  407 
  408         for (i = 0; i < LPROF_HASH_SIZE; ++i) {
  409                 SLIST_FOREACH(l, &type->lpt_hash[i], link) {
  410                         struct lock_prof lp = {};
  411 
  412                         if (l->ticks == t)
  413                                 continue;
  414                         lock_prof_sum(l, &lp, i, spin, t);
  415                         lock_prof_output(&lp, sb);
  416                 }
  417         }
  418 }
  419 
  420 static int
  421 dump_lock_prof_stats(SYSCTL_HANDLER_ARGS)
  422 {
  423         struct sbuf *sb;
  424         int error, cpu, t;
  425         int enabled;
  426 
  427         error = sysctl_wire_old_buffer(req, 0);
  428         if (error != 0)
  429                 return (error);
  430         sb = sbuf_new_for_sysctl(NULL, NULL, LPROF_SBUF_SIZE, req);
  431         sbuf_printf(sb, "\n%8s %9s %11s %11s %11s %6s %6s %2s %6s %s\n",
  432             "max", "wait_max", "total", "wait_total", "count", "avg", "wait_avg", "cnt_hold", "cnt_lock", "name");
  433         enabled = lock_prof_enable;
  434         lock_prof_enable = 0;
  435         quiesce_all_cpus("profstat", 0);
  436         t = ticks;
  437         for (cpu = 0; cpu <= mp_maxid; cpu++) {
  438                 if (lp_cpu[cpu] == NULL)
  439                         continue;
  440                 lock_prof_type_stats(&lp_cpu[cpu]->lpc_types[0], sb, 0, t);
  441                 lock_prof_type_stats(&lp_cpu[cpu]->lpc_types[1], sb, 1, t);
  442         }
  443         lock_prof_enable = enabled;
  444 
  445         error = sbuf_finish(sb);
  446         /* Output a trailing NUL. */
  447         if (error == 0)
  448                 error = SYSCTL_OUT(req, "", 1);
  449         sbuf_delete(sb);
  450         return (error);
  451 }
  452 
  453 static int
  454 enable_lock_prof(SYSCTL_HANDLER_ARGS)
  455 {
  456         int error, v;
  457 
  458         v = lock_prof_enable;
  459         error = sysctl_handle_int(oidp, &v, v, req);
  460         if (error)
  461                 return (error);
  462         if (req->newptr == NULL)
  463                 return (error);
  464         if (v == lock_prof_enable)
  465                 return (0);
  466         if (v == 1)
  467                 lock_prof_reset();
  468         lock_prof_enable = !!v;
  469 
  470         return (0);
  471 }
  472 
  473 static int
  474 reset_lock_prof_stats(SYSCTL_HANDLER_ARGS)
  475 {
  476         int error, v;
  477 
  478         v = 0;
  479         error = sysctl_handle_int(oidp, &v, 0, req);
  480         if (error)
  481                 return (error);
  482         if (req->newptr == NULL)
  483                 return (error);
  484         if (v == 0)
  485                 return (0);
  486         lock_prof_reset();
  487 
  488         return (0);
  489 }
  490 
  491 static struct lock_prof *
  492 lock_profile_lookup(struct lock_object *lo, int spin, const char *file,
  493     int line)
  494 {
  495         const char *unknown = "(unknown)";
  496         struct lock_prof_type *type;
  497         struct lock_prof *lp;
  498         struct lphead *head;
  499         const char *p;
  500         u_int hash;
  501 
  502         p = file;
  503         if (p == NULL || *p == '\0')
  504                 p = unknown;
  505         hash = (uintptr_t)lo->lo_name * 31 + (uintptr_t)p * 31 + line;
  506         hash &= LPROF_HASH_MASK;
  507         type = &lp_cpu[PCPU_GET(cpuid)]->lpc_types[spin];
  508         head = &type->lpt_hash[hash];
  509         SLIST_FOREACH(lp, head, link) {
  510                 if (lp->line == line && lp->file == p &&
  511                     lp->name == lo->lo_name)
  512                         return (lp);
  513 
  514         }
  515         lp = SLIST_FIRST(&type->lpt_lpalloc);
  516         if (lp == NULL) {
  517                 lock_prof_rejected++;
  518                 return (lp);
  519         }
  520         SLIST_REMOVE_HEAD(&type->lpt_lpalloc, link);
  521         lp->file = p;
  522         lp->line = line;
  523         lp->class = LOCK_CLASS(lo);
  524         lp->name = lo->lo_name;
  525         SLIST_INSERT_HEAD(&type->lpt_hash[hash], lp, link);
  526         return (lp);
  527 }
  528 
  529 static struct lock_profile_object *
  530 lock_profile_object_lookup(struct lock_object *lo, int spin, const char *file,
  531     int line)
  532 {
  533         struct lock_profile_object *l;
  534         struct lock_prof_type *type;
  535         struct lpohead *head;
  536 
  537         head = &curthread->td_lprof[spin];
  538         LIST_FOREACH(l, head, lpo_link)
  539                 if (l->lpo_obj == lo && l->lpo_file == file &&
  540                     l->lpo_line == line)
  541                         return (l);
  542         type = &lp_cpu[PCPU_GET(cpuid)]->lpc_types[spin];
  543         l = LIST_FIRST(&type->lpt_lpoalloc);
  544         if (l == NULL) {
  545                 lock_prof_rejected++;
  546                 return (NULL);
  547         }
  548         LIST_REMOVE(l, lpo_link);
  549         l->lpo_obj = lo;
  550         l->lpo_file = file;
  551         l->lpo_line = line;
  552         l->lpo_cnt = 0;
  553         LIST_INSERT_HEAD(head, l, lpo_link);
  554 
  555         return (l);
  556 }
  557 
  558 void
  559 lock_profile_obtain_lock_success(struct lock_object *lo, int contested,
  560     uint64_t waittime, const char *file, int line)
  561 {
  562         static int lock_prof_count;
  563         struct lock_profile_object *l;
  564         int spin;
  565 
  566         if (SCHEDULER_STOPPED())
  567                 return;
  568 
  569         /* don't reset the timer when/if recursing */
  570         if (!lock_prof_enable || (lo->lo_flags & LO_NOPROFILE))
  571                 return;
  572         if (lock_prof_skipcount &&
  573             (++lock_prof_count % lock_prof_skipcount) != 0)
  574                 return;
  575         spin = (LOCK_CLASS(lo)->lc_flags & LC_SPINLOCK) ? 1 : 0;
  576         if (spin && lock_prof_skipspin == 1)
  577                 return;
  578         critical_enter();
  579         /* Recheck enabled now that we're in a critical section. */
  580         if (lock_prof_enable == 0)
  581                 goto out;
  582         l = lock_profile_object_lookup(lo, spin, file, line);
  583         if (l == NULL)
  584                 goto out;
  585         l->lpo_cnt++;
  586         if (++l->lpo_ref > 1)
  587                 goto out;
  588         l->lpo_contest_locking = contested;
  589         l->lpo_acqtime = nanoseconds(); 
  590         if (waittime && (l->lpo_acqtime > waittime))
  591                 l->lpo_waittime = l->lpo_acqtime - waittime;
  592         else
  593                 l->lpo_waittime = 0;
  594 out:
  595         critical_exit();
  596 }
  597 
  598 void
  599 lock_profile_thread_exit(struct thread *td)
  600 {
  601 #ifdef INVARIANTS
  602         struct lock_profile_object *l;
  603 
  604         MPASS(curthread->td_critnest == 0);
  605 #endif
  606         /*
  607          * If lock profiling was disabled we have to wait for reset to
  608          * clear our pointers before we can exit safely.
  609          */
  610         lock_prof_reset_wait();
  611 #ifdef INVARIANTS
  612         LIST_FOREACH(l, &td->td_lprof[0], lpo_link)
  613                 printf("thread still holds lock acquired at %s:%d\n",
  614                     l->lpo_file, l->lpo_line);
  615         LIST_FOREACH(l, &td->td_lprof[1], lpo_link)
  616                 printf("thread still holds lock acquired at %s:%d\n",
  617                     l->lpo_file, l->lpo_line);
  618 #endif
  619         MPASS(LIST_FIRST(&td->td_lprof[0]) == NULL);
  620         MPASS(LIST_FIRST(&td->td_lprof[1]) == NULL);
  621 }
  622 
  623 void
  624 lock_profile_release_lock(struct lock_object *lo)
  625 {
  626         struct lock_profile_object *l;
  627         struct lock_prof_type *type;
  628         struct lock_prof *lp;
  629         uint64_t curtime, holdtime;
  630         struct lpohead *head;
  631         int spin;
  632 
  633         if (SCHEDULER_STOPPED())
  634                 return;
  635         if (lo->lo_flags & LO_NOPROFILE)
  636                 return;
  637         spin = (LOCK_CLASS(lo)->lc_flags & LC_SPINLOCK) ? 1 : 0;
  638         head = &curthread->td_lprof[spin];
  639         if (LIST_FIRST(head) == NULL)
  640                 return;
  641         critical_enter();
  642         /* Recheck enabled now that we're in a critical section. */
  643         if (lock_prof_enable == 0 && lock_prof_resetting == 1)
  644                 goto out;
  645         /*
  646          * If lock profiling is not enabled we still want to remove the
  647          * lpo from our queue.
  648          */
  649         LIST_FOREACH(l, head, lpo_link)
  650                 if (l->lpo_obj == lo)
  651                         break;
  652         if (l == NULL)
  653                 goto out;
  654         if (--l->lpo_ref > 0)
  655                 goto out;
  656         lp = lock_profile_lookup(lo, spin, l->lpo_file, l->lpo_line);
  657         if (lp == NULL)
  658                 goto release;
  659         curtime = nanoseconds();
  660         if (curtime < l->lpo_acqtime)
  661                 goto release;
  662         holdtime = curtime - l->lpo_acqtime;
  663 
  664         /*
  665          * Record if the lock has been held longer now than ever
  666          * before.
  667          */
  668         if (holdtime > lp->cnt_max)
  669                 lp->cnt_max = holdtime;
  670         if (l->lpo_waittime > lp->cnt_wait_max)
  671                 lp->cnt_wait_max = l->lpo_waittime;
  672         lp->cnt_tot += holdtime;
  673         lp->cnt_wait += l->lpo_waittime;
  674         lp->cnt_contest_locking += l->lpo_contest_locking;
  675         lp->cnt_cur += l->lpo_cnt;
  676 release:
  677         LIST_REMOVE(l, lpo_link);
  678         type = &lp_cpu[PCPU_GET(cpuid)]->lpc_types[spin];
  679         LIST_INSERT_HEAD(&type->lpt_lpoalloc, l, lpo_link);
  680 out:
  681         critical_exit();
  682 }
  683 
  684 static SYSCTL_NODE(_debug_lock, OID_AUTO, prof, CTLFLAG_RD, NULL,
  685     "lock profiling");
  686 SYSCTL_INT(_debug_lock_prof, OID_AUTO, skipspin, CTLFLAG_RW,
  687     &lock_prof_skipspin, 0, "Skip profiling on spinlocks.");
  688 SYSCTL_INT(_debug_lock_prof, OID_AUTO, skipcount, CTLFLAG_RW,
  689     &lock_prof_skipcount, 0, "Sample approximately every N lock acquisitions.");
  690 SYSCTL_INT(_debug_lock_prof, OID_AUTO, rejected, CTLFLAG_RD,
  691     &lock_prof_rejected, 0, "Number of rejected profiling records");
  692 SYSCTL_PROC(_debug_lock_prof, OID_AUTO, stats, CTLTYPE_STRING | CTLFLAG_RD,
  693     NULL, 0, dump_lock_prof_stats, "A", "Lock profiling statistics");
  694 SYSCTL_PROC(_debug_lock_prof, OID_AUTO, reset, CTLTYPE_INT | CTLFLAG_RW,
  695     NULL, 0, reset_lock_prof_stats, "I", "Reset lock profiling statistics");
  696 SYSCTL_PROC(_debug_lock_prof, OID_AUTO, enable, CTLTYPE_INT | CTLFLAG_RW,
  697     NULL, 0, enable_lock_prof, "I", "Enable lock profiling");
  698 
  699 #endif
Cache object: 0bc6914c347d0a56a9f301250000be25
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FreeBSD/Linux Kernel Cross Reference sys/kern/subr_lock.c

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