The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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

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    1 /*-
    2  * Copyright (c) 1997, Stefan Esser <se@freebsd.org>
    3  * All rights reserved.
    4  *
    5  * Redistribution and use in source and binary forms, with or without
    6  * modification, are permitted provided that the following conditions
    7  * are met:
    8  * 1. Redistributions of source code must retain the above copyright
    9  *    notice unmodified, this list of conditions, and the following
   10  *    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 ``AS IS'' AND ANY EXPRESS OR
   16  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
   17  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
   18  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
   19  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
   20  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
   21  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
   22  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
   23  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
   24  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   25  */
   26 
   27 #include <sys/cdefs.h>
   28 __FBSDID("$FreeBSD$");
   29 
   30 #include "opt_ddb.h"
   31 
   32 #include <sys/param.h>
   33 #include <sys/bus.h>
   34 #include <sys/conf.h>
   35 #include <sys/rtprio.h>
   36 #include <sys/systm.h>
   37 #include <sys/interrupt.h>
   38 #include <sys/kernel.h>
   39 #include <sys/kthread.h>
   40 #include <sys/ktr.h>
   41 #include <sys/limits.h>
   42 #include <sys/lock.h>
   43 #include <sys/malloc.h>
   44 #include <sys/mutex.h>
   45 #include <sys/proc.h>
   46 #include <sys/random.h>
   47 #include <sys/resourcevar.h>
   48 #include <sys/sched.h>
   49 #include <sys/sysctl.h>
   50 #include <sys/unistd.h>
   51 #include <sys/vmmeter.h>
   52 #include <machine/atomic.h>
   53 #include <machine/cpu.h>
   54 #include <machine/md_var.h>
   55 #include <machine/stdarg.h>
   56 #ifdef DDB
   57 #include <ddb/ddb.h>
   58 #include <ddb/db_sym.h>
   59 #endif
   60 
   61 /*
   62  * Describe an interrupt thread.  There is one of these per interrupt event.
   63  */
   64 struct intr_thread {
   65         struct intr_event *it_event;
   66         struct thread *it_thread;       /* Kernel thread. */
   67         int     it_flags;               /* (j) IT_* flags. */
   68         int     it_need;                /* Needs service. */
   69 };
   70 
   71 /* Interrupt thread flags kept in it_flags */
   72 #define IT_DEAD         0x000001        /* Thread is waiting to exit. */
   73 
   74 struct  intr_entropy {
   75         struct  thread *td;
   76         uintptr_t event;
   77 };
   78 
   79 struct  intr_event *clk_intr_event;
   80 struct  intr_event *tty_intr_event;
   81 void    *softclock_ih;
   82 void    *vm_ih;
   83 
   84 static MALLOC_DEFINE(M_ITHREAD, "ithread", "Interrupt Threads");
   85 
   86 static int intr_storm_threshold = 1000;
   87 TUNABLE_INT("hw.intr_storm_threshold", &intr_storm_threshold);
   88 SYSCTL_INT(_hw, OID_AUTO, intr_storm_threshold, CTLFLAG_RW,
   89     &intr_storm_threshold, 0,
   90     "Number of consecutive interrupts before storm protection is enabled");
   91 static TAILQ_HEAD(, intr_event) event_list =
   92     TAILQ_HEAD_INITIALIZER(event_list);
   93 
   94 static void     intr_event_update(struct intr_event *ie);
   95 static struct intr_thread *ithread_create(const char *name);
   96 static void     ithread_destroy2(struct intr_thread *ithread);
   97 static void     ithread_execute_handlers(struct proc *p, struct intr_event *ie);
   98 static void     ithread_loop(void *);
   99 static void     ithread_update(struct intr_thread *ithd);
  100 static void     start_softintr(void *);
  101 
  102 u_char
  103 intr_priority(enum intr_type flags)
  104 {
  105         u_char pri;
  106 
  107         flags &= (INTR_TYPE_TTY | INTR_TYPE_BIO | INTR_TYPE_NET |
  108             INTR_TYPE_CAM | INTR_TYPE_MISC | INTR_TYPE_CLK | INTR_TYPE_AV);
  109         switch (flags) {
  110         case INTR_TYPE_TTY:
  111                 pri = PI_TTYLOW;
  112                 break;
  113         case INTR_TYPE_BIO:
  114                 /*
  115                  * XXX We need to refine this.  BSD/OS distinguishes
  116                  * between tape and disk priorities.
  117                  */
  118                 pri = PI_DISK;
  119                 break;
  120         case INTR_TYPE_NET:
  121                 pri = PI_NET;
  122                 break;
  123         case INTR_TYPE_CAM:
  124                 pri = PI_DISK;          /* XXX or PI_CAM? */
  125                 break;
  126         case INTR_TYPE_AV:              /* Audio/video */
  127                 pri = PI_AV;
  128                 break;
  129         case INTR_TYPE_CLK:
  130                 pri = PI_REALTIME;
  131                 break;
  132         case INTR_TYPE_MISC:
  133                 pri = PI_DULL;          /* don't care */
  134                 break;
  135         default:
  136                 /* We didn't specify an interrupt level. */
  137                 panic("intr_priority: no interrupt type in flags");
  138         }
  139 
  140         return pri;
  141 }
  142 
  143 /*
  144  * Update an ithread based on the associated intr_event.
  145  */
  146 static void
  147 ithread_update(struct intr_thread *ithd)
  148 {
  149         struct intr_event *ie;
  150         struct thread *td;
  151         u_char pri;
  152 
  153         ie = ithd->it_event;
  154         td = ithd->it_thread;
  155 
  156         /* Determine the overall priority of this event. */
  157         if (TAILQ_EMPTY(&ie->ie_handlers))
  158                 pri = PRI_MAX_ITHD;
  159         else
  160                 pri = TAILQ_FIRST(&ie->ie_handlers)->ih_pri;
  161 
  162         /* Update name and priority. */
  163         strlcpy(td->td_proc->p_comm, ie->ie_fullname,
  164             sizeof(td->td_proc->p_comm));
  165         mtx_lock_spin(&sched_lock);
  166         sched_prio(td, pri);
  167         mtx_unlock_spin(&sched_lock);
  168 }
  169 
  170 /*
  171  * Regenerate the full name of an interrupt event and update its priority.
  172  */
  173 static void
  174 intr_event_update(struct intr_event *ie)
  175 {
  176         struct intr_handler *ih;
  177         char *last;
  178         int missed, space;
  179 
  180         /* Start off with no entropy and just the name of the event. */
  181         mtx_assert(&ie->ie_lock, MA_OWNED);
  182         strlcpy(ie->ie_fullname, ie->ie_name, sizeof(ie->ie_fullname));
  183         ie->ie_flags &= ~IE_ENTROPY;
  184         missed = 0;
  185         space = 1;
  186 
  187         /* Run through all the handlers updating values. */
  188         TAILQ_FOREACH(ih, &ie->ie_handlers, ih_next) {
  189                 if (strlen(ie->ie_fullname) + strlen(ih->ih_name) + 1 <
  190                     sizeof(ie->ie_fullname)) {
  191                         strcat(ie->ie_fullname, " ");
  192                         strcat(ie->ie_fullname, ih->ih_name);
  193                         space = 0;
  194                 } else
  195                         missed++;
  196                 if (ih->ih_flags & IH_ENTROPY)
  197                         ie->ie_flags |= IE_ENTROPY;
  198         }
  199 
  200         /*
  201          * If the handler names were too long, add +'s to indicate missing
  202          * names. If we run out of room and still have +'s to add, change
  203          * the last character from a + to a *.
  204          */
  205         last = &ie->ie_fullname[sizeof(ie->ie_fullname) - 2];
  206         while (missed-- > 0) {
  207                 if (strlen(ie->ie_fullname) + 1 == sizeof(ie->ie_fullname)) {
  208                         if (*last == '+') {
  209                                 *last = '*';
  210                                 break;
  211                         } else
  212                                 *last = '+';
  213                 } else if (space) {
  214                         strcat(ie->ie_fullname, " +");
  215                         space = 0;
  216                 } else
  217                         strcat(ie->ie_fullname, "+");
  218         }
  219 
  220         /*
  221          * If this event has an ithread, update it's priority and
  222          * name.
  223          */
  224         if (ie->ie_thread != NULL)
  225                 ithread_update(ie->ie_thread);
  226         CTR2(KTR_INTR, "%s: updated %s", __func__, ie->ie_fullname);
  227 }
  228 
  229 int
  230 intr_event_create(struct intr_event **event, void *source, int flags,
  231     void (*enable)(void *), const char *fmt, ...)
  232 {
  233         struct intr_event *ie;
  234         va_list ap;
  235 
  236         /* The only valid flag during creation is IE_SOFT. */
  237         if ((flags & ~IE_SOFT) != 0)
  238                 return (EINVAL);
  239         ie = malloc(sizeof(struct intr_event), M_ITHREAD, M_WAITOK | M_ZERO);
  240         ie->ie_source = source;
  241         ie->ie_enable = enable;
  242         ie->ie_flags = flags;
  243         TAILQ_INIT(&ie->ie_handlers);
  244         mtx_init(&ie->ie_lock, "intr event", NULL, MTX_DEF);
  245 
  246         va_start(ap, fmt);
  247         vsnprintf(ie->ie_name, sizeof(ie->ie_name), fmt, ap);
  248         va_end(ap);
  249         strlcpy(ie->ie_fullname, ie->ie_name, sizeof(ie->ie_fullname));
  250         mtx_pool_lock(mtxpool_sleep, &event_list);
  251         TAILQ_INSERT_TAIL(&event_list, ie, ie_list);
  252         mtx_pool_unlock(mtxpool_sleep, &event_list);
  253         if (event != NULL)
  254                 *event = ie;
  255         CTR2(KTR_INTR, "%s: created %s", __func__, ie->ie_name);
  256         return (0);
  257 }
  258 
  259 int
  260 intr_event_destroy(struct intr_event *ie)
  261 {
  262 
  263         mtx_lock(&ie->ie_lock);
  264         if (!TAILQ_EMPTY(&ie->ie_handlers)) {
  265                 mtx_unlock(&ie->ie_lock);
  266                 return (EBUSY);
  267         }
  268         mtx_pool_lock(mtxpool_sleep, &event_list);
  269         TAILQ_REMOVE(&event_list, ie, ie_list);
  270         mtx_pool_unlock(mtxpool_sleep, &event_list);
  271 #ifndef notyet
  272         if (ie->ie_thread != NULL) {
  273                 ithread_destroy2(ie->ie_thread);
  274                 ie->ie_thread = NULL;
  275         }
  276 #endif
  277         mtx_unlock(&ie->ie_lock);
  278         mtx_destroy(&ie->ie_lock);
  279         free(ie, M_ITHREAD);
  280         return (0);
  281 }
  282 
  283 static struct intr_thread *
  284 ithread_create(const char *name)
  285 {
  286         struct intr_thread *ithd;
  287         struct thread *td;
  288         struct proc *p;
  289         int error;
  290 
  291         ithd = malloc(sizeof(struct intr_thread), M_ITHREAD, M_WAITOK | M_ZERO);
  292 
  293         error = kthread_create(ithread_loop, ithd, &p, RFSTOPPED | RFHIGHPID,
  294             0, "%s", name);
  295         if (error)
  296                 panic("kthread_create() failed with %d", error);
  297         td = FIRST_THREAD_IN_PROC(p);   /* XXXKSE */
  298         mtx_lock_spin(&sched_lock);
  299         td->td_ksegrp->kg_pri_class = PRI_ITHD;
  300         TD_SET_IWAIT(td);
  301         mtx_unlock_spin(&sched_lock);
  302         td->td_pflags |= TDP_ITHREAD;
  303         ithd->it_thread = td;
  304         CTR2(KTR_INTR, "%s: created %s", __func__, name);
  305         return (ithd);
  306 }
  307 
  308 static void
  309 ithread_destroy2(struct intr_thread *ithread)
  310 {
  311         struct thread *td;
  312 
  313         CTR2(KTR_INTR, "%s: killing %s", __func__, ithread->it_event->ie_name);
  314         td = ithread->it_thread;
  315         mtx_lock_spin(&sched_lock);
  316         ithread->it_flags |= IT_DEAD;
  317         if (TD_AWAITING_INTR(td)) {
  318                 TD_CLR_IWAIT(td);
  319                 setrunqueue(td, SRQ_INTR);
  320         }
  321         mtx_unlock_spin(&sched_lock);
  322 }
  323 
  324 int
  325 intr_event_add_handler(struct intr_event *ie, const char *name,
  326     driver_intr_t handler, void *arg, u_char pri, enum intr_type flags,
  327     void **cookiep)
  328 {
  329         struct intr_handler *ih, *temp_ih;
  330         struct intr_thread *it;
  331 
  332         if (ie == NULL || name == NULL || handler == NULL)
  333                 return (EINVAL);
  334 
  335         /* Allocate and populate an interrupt handler structure. */
  336         ih = malloc(sizeof(struct intr_handler), M_ITHREAD, M_WAITOK | M_ZERO);
  337         ih->ih_handler = handler;
  338         ih->ih_argument = arg;
  339         ih->ih_name = name;
  340         ih->ih_event = ie;
  341         ih->ih_pri = pri;
  342         if (flags & INTR_FAST)
  343                 ih->ih_flags = IH_FAST;
  344         else if (flags & INTR_EXCL)
  345                 ih->ih_flags = IH_EXCLUSIVE;
  346         if (flags & INTR_MPSAFE)
  347                 ih->ih_flags |= IH_MPSAFE;
  348         if (flags & INTR_ENTROPY)
  349                 ih->ih_flags |= IH_ENTROPY;
  350 
  351         /* We can only have one exclusive handler in a event. */
  352         mtx_lock(&ie->ie_lock);
  353         if (!TAILQ_EMPTY(&ie->ie_handlers)) {
  354                 if ((flags & INTR_EXCL) ||
  355                     (TAILQ_FIRST(&ie->ie_handlers)->ih_flags & IH_EXCLUSIVE)) {
  356                         mtx_unlock(&ie->ie_lock);
  357                         free(ih, M_ITHREAD);
  358                         return (EINVAL);
  359                 }
  360         }
  361 
  362         /* Add the new handler to the event in priority order. */
  363         TAILQ_FOREACH(temp_ih, &ie->ie_handlers, ih_next) {
  364                 if (temp_ih->ih_pri > ih->ih_pri)
  365                         break;
  366         }
  367         if (temp_ih == NULL)
  368                 TAILQ_INSERT_TAIL(&ie->ie_handlers, ih, ih_next);
  369         else
  370                 TAILQ_INSERT_BEFORE(temp_ih, ih, ih_next);
  371         intr_event_update(ie);
  372 
  373         /* Create a thread if we need one. */
  374         while (ie->ie_thread == NULL && !(flags & INTR_FAST)) {
  375                 if (ie->ie_flags & IE_ADDING_THREAD)
  376                         msleep(ie, &ie->ie_lock, 0, "ithread", 0);
  377                 else {
  378                         ie->ie_flags |= IE_ADDING_THREAD;
  379                         mtx_unlock(&ie->ie_lock);
  380                         it = ithread_create("intr: newborn");
  381                         mtx_lock(&ie->ie_lock);
  382                         ie->ie_flags &= ~IE_ADDING_THREAD;
  383                         ie->ie_thread = it;
  384                         it->it_event = ie;
  385                         ithread_update(it);
  386                         wakeup(ie);
  387                 }
  388         }
  389         CTR3(KTR_INTR, "%s: added %s to %s", __func__, ih->ih_name,
  390             ie->ie_name);
  391         mtx_unlock(&ie->ie_lock);
  392 
  393         if (cookiep != NULL)
  394                 *cookiep = ih;
  395         return (0);
  396 }
  397 
  398 int
  399 intr_event_remove_handler(void *cookie)
  400 {
  401         struct intr_handler *handler = (struct intr_handler *)cookie;
  402         struct intr_event *ie;
  403 #ifdef INVARIANTS
  404         struct intr_handler *ih;
  405 #endif
  406 #ifdef notyet
  407         int dead;
  408 #endif
  409 
  410         if (handler == NULL)
  411                 return (EINVAL);
  412         ie = handler->ih_event;
  413         KASSERT(ie != NULL,
  414             ("interrupt handler \"%s\" has a NULL interrupt event",
  415                 handler->ih_name));
  416         mtx_lock(&ie->ie_lock);
  417         CTR3(KTR_INTR, "%s: removing %s from %s", __func__, handler->ih_name,
  418             ie->ie_name);
  419 #ifdef INVARIANTS
  420         TAILQ_FOREACH(ih, &ie->ie_handlers, ih_next)
  421                 if (ih == handler)
  422                         goto ok;
  423         mtx_unlock(&ie->ie_lock);
  424         panic("interrupt handler \"%s\" not found in interrupt event \"%s\"",
  425             ih->ih_name, ie->ie_name);
  426 ok:
  427 #endif
  428         /*
  429          * If there is no ithread, then just remove the handler and return.
  430          * XXX: Note that an INTR_FAST handler might be running on another
  431          * CPU!
  432          */
  433         if (ie->ie_thread == NULL) {
  434                 TAILQ_REMOVE(&ie->ie_handlers, handler, ih_next);
  435                 mtx_unlock(&ie->ie_lock);
  436                 free(handler, M_ITHREAD);
  437                 return (0);
  438         }
  439 
  440         /*
  441          * If the interrupt thread is already running, then just mark this
  442          * handler as being dead and let the ithread do the actual removal.
  443          *
  444          * During a cold boot while cold is set, msleep() does not sleep,
  445          * so we have to remove the handler here rather than letting the
  446          * thread do it.
  447          */
  448         mtx_lock_spin(&sched_lock);
  449         if (!TD_AWAITING_INTR(ie->ie_thread->it_thread) && !cold) {
  450                 handler->ih_flags |= IH_DEAD;
  451 
  452                 /*
  453                  * Ensure that the thread will process the handler list
  454                  * again and remove this handler if it has already passed
  455                  * it on the list.
  456                  */
  457                 ie->ie_thread->it_need = 1;
  458         } else
  459                 TAILQ_REMOVE(&ie->ie_handlers, handler, ih_next);
  460         mtx_unlock_spin(&sched_lock);
  461         while (handler->ih_flags & IH_DEAD)
  462                 msleep(handler, &ie->ie_lock, 0, "iev_rmh", 0);
  463         intr_event_update(ie);
  464 #ifdef notyet
  465         /*
  466          * XXX: This could be bad in the case of ppbus(8).  Also, I think
  467          * this could lead to races of stale data when servicing an
  468          * interrupt.
  469          */
  470         dead = 1;
  471         TAILQ_FOREACH(ih, &ie->ie_handlers, ih_next) {
  472                 if (!(ih->ih_flags & IH_FAST)) {
  473                         dead = 0;
  474                         break;
  475                 }
  476         }
  477         if (dead) {
  478                 ithread_destroy2(ie->ie_thread);
  479                 ie->ie_thread = NULL;
  480         }
  481 #endif
  482         mtx_unlock(&ie->ie_lock);
  483         free(handler, M_ITHREAD);
  484         return (0);
  485 }
  486 
  487 int
  488 intr_event_schedule_thread(struct intr_event *ie)
  489 {
  490         struct intr_entropy entropy;
  491         struct intr_thread *it;
  492         struct thread *td;
  493         struct thread *ctd;
  494         struct proc *p;
  495 
  496         /*
  497          * If no ithread or no handlers, then we have a stray interrupt.
  498          */
  499         if (ie == NULL || TAILQ_EMPTY(&ie->ie_handlers) ||
  500             ie->ie_thread == NULL)
  501                 return (EINVAL);
  502 
  503         ctd = curthread;
  504         it = ie->ie_thread;
  505         td = it->it_thread;
  506         p = td->td_proc;
  507 
  508         /*
  509          * If any of the handlers for this ithread claim to be good
  510          * sources of entropy, then gather some.
  511          */
  512         if (harvest.interrupt && ie->ie_flags & IE_ENTROPY) {
  513                 CTR3(KTR_INTR, "%s: pid %d (%s) gathering entropy", __func__,
  514                     p->p_pid, p->p_comm);
  515                 entropy.event = (uintptr_t)ie;
  516                 entropy.td = ctd;
  517                 random_harvest(&entropy, sizeof(entropy), 2, 0,
  518                     RANDOM_INTERRUPT);
  519         }
  520 
  521         KASSERT(p != NULL, ("ithread %s has no process", ie->ie_name));
  522 
  523         /*
  524          * Set it_need to tell the thread to keep running if it is already
  525          * running.  Then, grab sched_lock and see if we actually need to
  526          * put this thread on the runqueue.
  527          */
  528         it->it_need = 1;
  529         mtx_lock_spin(&sched_lock);
  530         if (TD_AWAITING_INTR(td)) {
  531                 CTR3(KTR_INTR, "%s: schedule pid %d (%s)", __func__, p->p_pid,
  532                     p->p_comm);
  533                 TD_CLR_IWAIT(td);
  534                 setrunqueue(td, SRQ_INTR);
  535         } else {
  536                 CTR5(KTR_INTR, "%s: pid %d (%s): it_need %d, state %d",
  537                     __func__, p->p_pid, p->p_comm, it->it_need, td->td_state);
  538         }
  539         mtx_unlock_spin(&sched_lock);
  540 
  541         return (0);
  542 }
  543 
  544 /*
  545  * Add a software interrupt handler to a specified event.  If a given event
  546  * is not specified, then a new event is created.
  547  */
  548 int
  549 swi_add(struct intr_event **eventp, const char *name, driver_intr_t handler,
  550             void *arg, int pri, enum intr_type flags, void **cookiep)
  551 {
  552         struct intr_event *ie;
  553         int error;
  554 
  555         if (flags & (INTR_FAST | INTR_ENTROPY))
  556                 return (EINVAL);
  557 
  558         ie = (eventp != NULL) ? *eventp : NULL;
  559 
  560         if (ie != NULL) {
  561                 if (!(ie->ie_flags & IE_SOFT))
  562                         return (EINVAL);
  563         } else {
  564                 error = intr_event_create(&ie, NULL, IE_SOFT, NULL,
  565                     "swi%d:", pri);
  566                 if (error)
  567                         return (error);
  568                 if (eventp != NULL)
  569                         *eventp = ie;
  570         }
  571         return (intr_event_add_handler(ie, name, handler, arg,
  572                     (pri * RQ_PPQ) + PI_SOFT, flags, cookiep));
  573                     /* XXKSE.. think of a better way to get separate queues */
  574 }
  575 
  576 /*
  577  * Schedule a software interrupt thread.
  578  */
  579 void
  580 swi_sched(void *cookie, int flags)
  581 {
  582         struct intr_handler *ih = (struct intr_handler *)cookie;
  583         struct intr_event *ie = ih->ih_event;
  584         int error;
  585 
  586         PCPU_LAZY_INC(cnt.v_intr);
  587 
  588         CTR3(KTR_INTR, "swi_sched: %s %s need=%d", ie->ie_name, ih->ih_name,
  589             ih->ih_need);
  590 
  591         /*
  592          * Set ih_need for this handler so that if the ithread is already
  593          * running it will execute this handler on the next pass.  Otherwise,
  594          * it will execute it the next time it runs.
  595          */
  596         atomic_store_rel_int(&ih->ih_need, 1);
  597         if (!(flags & SWI_DELAY)) {
  598                 error = intr_event_schedule_thread(ie);
  599                 KASSERT(error == 0, ("stray software interrupt"));
  600         }
  601 }
  602 
  603 /*
  604  * Remove a software interrupt handler.  Currently this code does not
  605  * remove the associated interrupt event if it becomes empty.  Calling code
  606  * may do so manually via intr_event_destroy(), but that's not really
  607  * an optimal interface.
  608  */
  609 int
  610 swi_remove(void *cookie)
  611 {
  612 
  613         return (intr_event_remove_handler(cookie));
  614 }
  615 
  616 /* ABI compatibility shims. */
  617 #undef ithread_remove_handler
  618 #undef ithread_destroy
  619 int     ithread_remove_handler(void *);
  620 int     ithread_destroy(struct ithd *);
  621 
  622 int
  623 ithread_remove_handler(void *cookie)
  624 {
  625 
  626         return (intr_event_remove_handler(cookie));
  627 }
  628 
  629 int
  630 ithread_destroy(struct ithd *ithread)
  631 {
  632 
  633         return (intr_event_destroy(ithread));
  634 }
  635 
  636 static void
  637 ithread_execute_handlers(struct proc *p, struct intr_event *ie)
  638 {
  639         struct intr_handler *ih, *ihn;
  640 
  641         /* Interrupt handlers should not sleep. */
  642         if (!(ie->ie_flags & IE_SOFT))
  643                 THREAD_NO_SLEEPING();
  644         TAILQ_FOREACH_SAFE(ih, &ie->ie_handlers, ih_next, ihn) {
  645 
  646                 /*
  647                  * If this handler is marked for death, remove it from
  648                  * the list of handlers and wake up the sleeper.
  649                  */
  650                 if (ih->ih_flags & IH_DEAD) {
  651                         mtx_lock(&ie->ie_lock);
  652                         TAILQ_REMOVE(&ie->ie_handlers, ih, ih_next);
  653                         ih->ih_flags &= ~IH_DEAD;
  654                         wakeup(ih);
  655                         mtx_unlock(&ie->ie_lock);
  656                         continue;
  657                 }
  658 
  659                 /*
  660                  * For software interrupt threads, we only execute
  661                  * handlers that have their need flag set.  Hardware
  662                  * interrupt threads always invoke all of their handlers.
  663                  */
  664                 if (ie->ie_flags & IE_SOFT) {
  665                         if (!ih->ih_need)
  666                                 continue;
  667                         else
  668                                 atomic_store_rel_int(&ih->ih_need, 0);
  669                 }
  670 
  671                 /* Fast handlers are handled in primary interrupt context. */
  672                 if (ih->ih_flags & IH_FAST)
  673                         continue;
  674 
  675                 /* Execute this handler. */
  676                 CTR6(KTR_INTR, "%s: pid %d exec %p(%p) for %s flg=%x",
  677                     __func__, p->p_pid, (void *)ih->ih_handler, ih->ih_argument,
  678                     ih->ih_name, ih->ih_flags);
  679 
  680                 if (!(ih->ih_flags & IH_MPSAFE))
  681                         mtx_lock(&Giant);
  682                 ih->ih_handler(ih->ih_argument);
  683                 if (!(ih->ih_flags & IH_MPSAFE))
  684                         mtx_unlock(&Giant);
  685         }
  686         if (!(ie->ie_flags & IE_SOFT))
  687                 THREAD_SLEEPING_OK();
  688 
  689         /*
  690          * Interrupt storm handling:
  691          *
  692          * If this interrupt source is currently storming, then throttle
  693          * it to only fire the handler once  per clock tick.
  694          *
  695          * If this interrupt source is not currently storming, but the
  696          * number of back to back interrupts exceeds the storm threshold,
  697          * then enter storming mode.
  698          */
  699         if (intr_storm_threshold != 0 && ie->ie_count >= intr_storm_threshold &&
  700             !(ie->ie_flags & IE_SOFT)) {
  701                 /* Report the message only once every second. */
  702                 if (ppsratecheck(&ie->ie_warntm, &ie->ie_warncnt, 1)) {
  703                         printf(
  704         "interrupt storm detected on \"%s\"; throttling interrupt source\n",
  705                             ie->ie_name);
  706                 }
  707                 tsleep(&ie->ie_count, 0, "istorm", 1);
  708         } else
  709                 ie->ie_count++;
  710 
  711         /*
  712          * Now that all the handlers have had a chance to run, reenable
  713          * the interrupt source.
  714          */
  715         if (ie->ie_enable != NULL)
  716                 ie->ie_enable(ie->ie_source);
  717 }
  718 
  719 /*
  720  * This is the main code for interrupt threads.
  721  */
  722 static void
  723 ithread_loop(void *arg)
  724 {
  725         struct intr_thread *ithd;
  726         struct intr_event *ie;
  727         struct thread *td;
  728         struct proc *p;
  729 
  730         td = curthread;
  731         p = td->td_proc;
  732         ithd = (struct intr_thread *)arg;
  733         KASSERT(ithd->it_thread == td,
  734             ("%s: ithread and proc linkage out of sync", __func__));
  735         ie = ithd->it_event;
  736         ie->ie_count = 0;
  737 
  738         /*
  739          * As long as we have interrupts outstanding, go through the
  740          * list of handlers, giving each one a go at it.
  741          */
  742         for (;;) {
  743                 /*
  744                  * If we are an orphaned thread, then just die.
  745                  */
  746                 if (ithd->it_flags & IT_DEAD) {
  747                         CTR3(KTR_INTR, "%s: pid %d (%s) exiting", __func__,
  748                             p->p_pid, p->p_comm);
  749                         free(ithd, M_ITHREAD);
  750                         kthread_exit(0);
  751                 }
  752 
  753                 /*
  754                  * Service interrupts.  If another interrupt arrives while
  755                  * we are running, it will set it_need to note that we
  756                  * should make another pass.
  757                  */
  758                 while (ithd->it_need) {
  759                         /*
  760                          * This might need a full read and write barrier
  761                          * to make sure that this write posts before any
  762                          * of the memory or device accesses in the
  763                          * handlers.
  764                          */
  765                         atomic_store_rel_int(&ithd->it_need, 0);
  766                         ithread_execute_handlers(p, ie);
  767                 }
  768                 WITNESS_WARN(WARN_PANIC, NULL, "suspending ithread");
  769                 mtx_assert(&Giant, MA_NOTOWNED);
  770 
  771                 /*
  772                  * Processed all our interrupts.  Now get the sched
  773                  * lock.  This may take a while and it_need may get
  774                  * set again, so we have to check it again.
  775                  */
  776                 mtx_lock_spin(&sched_lock);
  777                 if (!ithd->it_need && !(ithd->it_flags & IT_DEAD)) {
  778                         TD_SET_IWAIT(td);
  779                         ie->ie_count = 0;
  780                         mi_switch(SW_VOL, NULL);
  781                 }
  782                 mtx_unlock_spin(&sched_lock);
  783         }
  784 }
  785 
  786 #ifdef DDB
  787 /*
  788  * Dump details about an interrupt handler
  789  */
  790 static void
  791 db_dump_intrhand(struct intr_handler *ih)
  792 {
  793         int comma;
  794 
  795         db_printf("\t%-10s ", ih->ih_name);
  796         switch (ih->ih_pri) {
  797         case PI_REALTIME:
  798                 db_printf("CLK ");
  799                 break;
  800         case PI_AV:
  801                 db_printf("AV  ");
  802                 break;
  803         case PI_TTYHIGH:
  804         case PI_TTYLOW:
  805                 db_printf("TTY ");
  806                 break;
  807         case PI_TAPE:
  808                 db_printf("TAPE");
  809                 break;
  810         case PI_NET:
  811                 db_printf("NET ");
  812                 break;
  813         case PI_DISK:
  814         case PI_DISKLOW:
  815                 db_printf("DISK");
  816                 break;
  817         case PI_DULL:
  818                 db_printf("DULL");
  819                 break;
  820         default:
  821                 if (ih->ih_pri >= PI_SOFT)
  822                         db_printf("SWI ");
  823                 else
  824                         db_printf("%4u", ih->ih_pri);
  825                 break;
  826         }
  827         db_printf(" ");
  828         db_printsym((uintptr_t)ih->ih_handler, DB_STGY_PROC);
  829         db_printf("(%p)", ih->ih_argument);
  830         if (ih->ih_need ||
  831             (ih->ih_flags & (IH_FAST | IH_EXCLUSIVE | IH_ENTROPY | IH_DEAD |
  832             IH_MPSAFE)) != 0) {
  833                 db_printf(" {");
  834                 comma = 0;
  835                 if (ih->ih_flags & IH_FAST) {
  836                         db_printf("FAST");
  837                         comma = 1;
  838                 }
  839                 if (ih->ih_flags & IH_EXCLUSIVE) {
  840                         if (comma)
  841                                 db_printf(", ");
  842                         db_printf("EXCL");
  843                         comma = 1;
  844                 }
  845                 if (ih->ih_flags & IH_ENTROPY) {
  846                         if (comma)
  847                                 db_printf(", ");
  848                         db_printf("ENTROPY");
  849                         comma = 1;
  850                 }
  851                 if (ih->ih_flags & IH_DEAD) {
  852                         if (comma)
  853                                 db_printf(", ");
  854                         db_printf("DEAD");
  855                         comma = 1;
  856                 }
  857                 if (ih->ih_flags & IH_MPSAFE) {
  858                         if (comma)
  859                                 db_printf(", ");
  860                         db_printf("MPSAFE");
  861                         comma = 1;
  862                 }
  863                 if (ih->ih_need) {
  864                         if (comma)
  865                                 db_printf(", ");
  866                         db_printf("NEED");
  867                 }
  868                 db_printf("}");
  869         }
  870         db_printf("\n");
  871 }
  872 
  873 /*
  874  * Dump details about a event.
  875  */
  876 void
  877 db_dump_intr_event(struct intr_event *ie, int handlers)
  878 {
  879         struct intr_handler *ih;
  880         struct intr_thread *it;
  881         int comma;
  882 
  883         db_printf("%s ", ie->ie_fullname);
  884         it = ie->ie_thread;
  885         if (it != NULL)
  886                 db_printf("(pid %d)", it->it_thread->td_proc->p_pid);
  887         else
  888                 db_printf("(no thread)");
  889         if ((ie->ie_flags & (IE_SOFT | IE_ENTROPY | IE_ADDING_THREAD)) != 0 ||
  890             (it != NULL && it->it_need)) {
  891                 db_printf(" {");
  892                 comma = 0;
  893                 if (ie->ie_flags & IE_SOFT) {
  894                         db_printf("SOFT");
  895                         comma = 1;
  896                 }
  897                 if (ie->ie_flags & IE_ENTROPY) {
  898                         if (comma)
  899                                 db_printf(", ");
  900                         db_printf("ENTROPY");
  901                         comma = 1;
  902                 }
  903                 if (ie->ie_flags & IE_ADDING_THREAD) {
  904                         if (comma)
  905                                 db_printf(", ");
  906                         db_printf("ADDING_THREAD");
  907                         comma = 1;
  908                 }
  909                 if (it != NULL && it->it_need) {
  910                         if (comma)
  911                                 db_printf(", ");
  912                         db_printf("NEED");
  913                 }
  914                 db_printf("}");
  915         }
  916         db_printf("\n");
  917 
  918         if (handlers)
  919                 TAILQ_FOREACH(ih, &ie->ie_handlers, ih_next)
  920                     db_dump_intrhand(ih);
  921 }
  922 
  923 /*
  924  * Dump data about interrupt handlers
  925  */
  926 DB_SHOW_COMMAND(intr, db_show_intr)
  927 {
  928         struct intr_event *ie;
  929         int quit, all, verbose;
  930 
  931         quit = 0;
  932         verbose = index(modif, 'v') != NULL;
  933         all = index(modif, 'a') != NULL;
  934         db_setup_paging(db_simple_pager, &quit, db_lines_per_page);
  935         TAILQ_FOREACH(ie, &event_list, ie_list) {
  936                 if (!all && TAILQ_EMPTY(&ie->ie_handlers))
  937                         continue;
  938                 db_dump_intr_event(ie, verbose);
  939         }
  940 }
  941 #endif /* DDB */
  942 
  943 /*
  944  * Start standard software interrupt threads
  945  */
  946 static void
  947 start_softintr(void *dummy)
  948 {
  949         struct proc *p;
  950 
  951         if (swi_add(&clk_intr_event, "clock", softclock, NULL, SWI_CLOCK,
  952                 INTR_MPSAFE, &softclock_ih) ||
  953             swi_add(NULL, "vm", swi_vm, NULL, SWI_VM, INTR_MPSAFE, &vm_ih))
  954                 panic("died while creating standard software ithreads");
  955 
  956         p = clk_intr_event->ie_thread->it_thread->td_proc;
  957         PROC_LOCK(p);
  958         p->p_flag |= P_NOLOAD;
  959         PROC_UNLOCK(p);
  960 }
  961 SYSINIT(start_softintr, SI_SUB_SOFTINTR, SI_ORDER_FIRST, start_softintr, NULL)
  962 
  963 /*
  964  * Sysctls used by systat and others: hw.intrnames and hw.intrcnt.
  965  * The data for this machine dependent, and the declarations are in machine
  966  * dependent code.  The layout of intrnames and intrcnt however is machine
  967  * independent.
  968  *
  969  * We do not know the length of intrcnt and intrnames at compile time, so
  970  * calculate things at run time.
  971  */
  972 static int
  973 sysctl_intrnames(SYSCTL_HANDLER_ARGS)
  974 {
  975         return (sysctl_handle_opaque(oidp, intrnames, eintrnames - intrnames,
  976            req));
  977 }
  978 
  979 SYSCTL_PROC(_hw, OID_AUTO, intrnames, CTLTYPE_OPAQUE | CTLFLAG_RD,
  980     NULL, 0, sysctl_intrnames, "", "Interrupt Names");
  981 
  982 static int
  983 sysctl_intrcnt(SYSCTL_HANDLER_ARGS)
  984 {
  985         return (sysctl_handle_opaque(oidp, intrcnt,
  986             (char *)eintrcnt - (char *)intrcnt, req));
  987 }
  988 
  989 SYSCTL_PROC(_hw, OID_AUTO, intrcnt, CTLTYPE_OPAQUE | CTLFLAG_RD,
  990     NULL, 0, sysctl_intrcnt, "", "Interrupt Counts");
  991 
  992 #ifdef DDB
  993 /*
  994  * DDB command to dump the interrupt statistics.
  995  */
  996 DB_SHOW_COMMAND(intrcnt, db_show_intrcnt)
  997 {
  998         u_long *i;
  999         char *cp;
 1000         int quit;
 1001 
 1002         cp = intrnames;
 1003         db_setup_paging(db_simple_pager, &quit, db_lines_per_page);
 1004         for (i = intrcnt, quit = 0; i != eintrcnt && !quit; i++) {
 1005                 if (*cp == '\0')
 1006                         break;
 1007                 if (*i != 0)
 1008                         db_printf("%s\t%lu\n", cp, *i);
 1009                 cp += strlen(cp) + 1;
 1010         }
 1011 }
 1012 #endif

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