diff options
Diffstat (limited to 'freebsd/sys/kern/kern_intr.c')
| -rw-r--r-- | freebsd/sys/kern/kern_intr.c | 193 |
1 files changed, 118 insertions, 75 deletions
diff --git a/freebsd/sys/kern/kern_intr.c b/freebsd/sys/kern/kern_intr.c index 8f6c2a6d..04914e93 100644 --- a/freebsd/sys/kern/kern_intr.c +++ b/freebsd/sys/kern/kern_intr.c @@ -175,12 +175,13 @@ ithread_update(struct intr_thread *ithd) ie = ithd->it_event; td = ithd->it_thread; + mtx_assert(&ie->ie_lock, MA_OWNED); /* Determine the overall priority of this event. */ - if (TAILQ_EMPTY(&ie->ie_handlers)) + if (CK_SLIST_EMPTY(&ie->ie_handlers)) pri = PRI_MAX_ITHD; else - pri = TAILQ_FIRST(&ie->ie_handlers)->ih_pri; + pri = CK_SLIST_FIRST(&ie->ie_handlers)->ih_pri; /* Update name and priority. */ #ifndef __rtems__ @@ -218,7 +219,7 @@ intr_event_update(struct intr_event *ie) space = 1; /* Run through all the handlers updating values. */ - TAILQ_FOREACH(ih, &ie->ie_handlers, ih_next) { + CK_SLIST_FOREACH(ih, &ie->ie_handlers, ih_next) { if (strlen(ie->ie_fullname) + strlen(ih->ih_name) + 1 < sizeof(ie->ie_fullname)) { strcat(ie->ie_fullname, " "); @@ -280,7 +281,7 @@ intr_event_create(struct intr_event **event, void *source, int flags, int irq, ie->ie_flags = flags; ie->ie_irq = irq; ie->ie_cpu = NOCPU; - TAILQ_INIT(&ie->ie_handlers); + CK_SLIST_INIT(&ie->ie_handlers); mtx_init(&ie->ie_lock, "intr event", NULL, MTX_DEF); va_start(ap, fmt); @@ -402,7 +403,7 @@ intr_lookup(int irq) TAILQ_FOREACH(ie, &event_list, ie_list) if (ie->ie_irq == irq && (ie->ie_flags & IE_SOFT) == 0 && - TAILQ_FIRST(&ie->ie_handlers) != NULL) + CK_SLIST_FIRST(&ie->ie_handlers) != NULL) break; mtx_unlock(&event_lock); return (ie); @@ -498,7 +499,7 @@ intr_event_destroy(struct intr_event *ie) mtx_lock(&event_lock); mtx_lock(&ie->ie_lock); - if (!TAILQ_EMPTY(&ie->ie_handlers)) { + if (!CK_SLIST_EMPTY(&ie->ie_handlers)) { mtx_unlock(&ie->ie_lock); mtx_unlock(&event_lock); return (EBUSY); @@ -532,7 +533,7 @@ ithread_create(const char *name) error = kproc_kthread_add(ithread_loop, ithd, &intrproc, &td, RFSTOPPED | RFHIGHPID, - 0, "intr", "%s", name); + 0, "intr", "%s", name); if (error) panic("kproc_create() failed with %d", error); thread_lock(td); @@ -573,6 +574,7 @@ intr_event_add_handler(struct intr_event *ie, const char *name, enum intr_type flags, void **cookiep) { struct intr_handler *ih, *temp_ih; + struct intr_handler **prevptr; struct intr_thread *it; if (ie == NULL || name == NULL || (handler == NULL && filter == NULL)) @@ -595,9 +597,9 @@ intr_event_add_handler(struct intr_event *ie, const char *name, /* We can only have one exclusive handler in a event. */ mtx_lock(&ie->ie_lock); - if (!TAILQ_EMPTY(&ie->ie_handlers)) { + if (!CK_SLIST_EMPTY(&ie->ie_handlers)) { if ((flags & INTR_EXCL) || - (TAILQ_FIRST(&ie->ie_handlers)->ih_flags & IH_EXCLUSIVE)) { + (CK_SLIST_FIRST(&ie->ie_handlers)->ih_flags & IH_EXCLUSIVE)) { mtx_unlock(&ie->ie_lock); free(ih, M_ITHREAD); return (EINVAL); @@ -622,14 +624,12 @@ intr_event_add_handler(struct intr_event *ie, const char *name, } /* Add the new handler to the event in priority order. */ - TAILQ_FOREACH(temp_ih, &ie->ie_handlers, ih_next) { + CK_SLIST_FOREACH_PREVPTR(temp_ih, prevptr, &ie->ie_handlers, ih_next) { if (temp_ih->ih_pri > ih->ih_pri) break; } - if (temp_ih == NULL) - TAILQ_INSERT_TAIL(&ie->ie_handlers, ih, ih_next); - else - TAILQ_INSERT_BEFORE(temp_ih, ih, ih_next); + CK_SLIST_INSERT_PREVPTR(prevptr, temp_ih, ih, ih_next); + intr_event_update(ie); CTR3(KTR_INTR, "%s: added %s to %s", __func__, ih->ih_name, @@ -656,7 +656,7 @@ intr_event_describe_handler(struct intr_event *ie, void *cookie, mtx_lock(&ie->ie_lock); #ifdef INVARIANTS - TAILQ_FOREACH(ih, &ie->ie_handlers, ih_next) { + CK_SLIST_FOREACH(ih, &ie->ie_handlers, ih_next) { if (ih == cookie) break; } @@ -718,6 +718,45 @@ intr_handler_source(void *cookie) } /* + * If intr_event_handle() is running in the ISR context at the time of the call, + * then wait for it to complete. + */ +static void +intr_event_barrier(struct intr_event *ie) +{ + int phase; + + mtx_assert(&ie->ie_lock, MA_OWNED); + phase = ie->ie_phase; + + /* + * Switch phase to direct future interrupts to the other active counter. + * Make sure that any preceding stores are visible before the switch. + */ + KASSERT(ie->ie_active[!phase] == 0, ("idle phase has activity")); + atomic_store_rel_int(&ie->ie_phase, !phase); + + /* + * This code cooperates with wait-free iteration of ie_handlers + * in intr_event_handle. + * Make sure that the removal and the phase update are not reordered + * with the active count check. + * Note that no combination of acquire and release fences can provide + * that guarantee as Store->Load sequences can always be reordered. + */ + atomic_thread_fence_seq_cst(); + + /* + * Now wait on the inactive phase. + * The acquire fence is needed so that that all post-barrier accesses + * are after the check. + */ + while (ie->ie_active[phase] > 0) + cpu_spinwait(); + atomic_thread_fence_acq(); +} + +/* * Sleep until an ithread finishes executing an interrupt handler. * * XXX Doesn't currently handle interrupt filters or fast interrupt @@ -757,16 +796,14 @@ _intr_drain(int irq) } #endif /* __rtems__ */ - #ifndef __rtems__ int intr_event_remove_handler(void *cookie) { struct intr_handler *handler = (struct intr_handler *)cookie; struct intr_event *ie; -#ifdef INVARIANTS struct intr_handler *ih; -#endif + struct intr_handler **prevptr; #ifdef notyet int dead; #endif @@ -777,60 +814,48 @@ intr_event_remove_handler(void *cookie) KASSERT(ie != NULL, ("interrupt handler \"%s\" has a NULL interrupt event", handler->ih_name)); + mtx_lock(&ie->ie_lock); CTR3(KTR_INTR, "%s: removing %s from %s", __func__, handler->ih_name, ie->ie_name); -#ifdef INVARIANTS - TAILQ_FOREACH(ih, &ie->ie_handlers, ih_next) + CK_SLIST_FOREACH_PREVPTR(ih, prevptr, &ie->ie_handlers, ih_next) { if (ih == handler) - goto ok; - mtx_unlock(&ie->ie_lock); - panic("interrupt handler \"%s\" not found in interrupt event \"%s\"", - ih->ih_name, ie->ie_name); -ok: -#endif + break; + } + if (ih == NULL) { + panic("interrupt handler \"%s\" not found in " + "interrupt event \"%s\"", handler->ih_name, ie->ie_name); + } + /* - * If there is no ithread, then just remove the handler and return. - * XXX: Note that an INTR_FAST handler might be running on another - * CPU! + * If there is no ithread, then directly remove the handler. Note that + * intr_event_handle() iterates ie_handlers in a lock-less fashion, so + * care needs to be taken to keep ie_handlers consistent and to free + * the removed handler only when ie_handlers is quiescent. */ if (ie->ie_thread == NULL) { - TAILQ_REMOVE(&ie->ie_handlers, handler, ih_next); + CK_SLIST_REMOVE_PREVPTR(prevptr, ih, ih_next); + intr_event_barrier(ie); + intr_event_update(ie); mtx_unlock(&ie->ie_lock); free(handler, M_ITHREAD); return (0); } /* - * If the interrupt thread is already running, then just mark this - * handler as being dead and let the ithread do the actual removal. - * - * During a cold boot while cold is set, msleep() does not sleep, - * so we have to remove the handler here rather than letting the - * thread do it. + * Let the interrupt thread do the job. + * The interrupt source is disabled when the interrupt thread is + * running, so it does not have to worry about interaction with + * intr_event_handle(). */ - thread_lock(ie->ie_thread->it_thread); - if (!TD_AWAITING_INTR(ie->ie_thread->it_thread) && !cold) { - handler->ih_flags |= IH_DEAD; - - /* - * Ensure that the thread will process the handler list - * again and remove this handler if it has already passed - * it on the list. - * - * The release part of the following store ensures - * that the update of ih_flags is ordered before the - * it_need setting. See the comment before - * atomic_cmpset_acq(&ithd->it_need, ...) operation in - * the ithread_execute_handlers(). - */ - atomic_store_rel_int(&ie->ie_thread->it_need, 1); - } else - TAILQ_REMOVE(&ie->ie_handlers, handler, ih_next); - thread_unlock(ie->ie_thread->it_thread); + KASSERT((handler->ih_flags & IH_DEAD) == 0, + ("duplicate handle remove")); + handler->ih_flags |= IH_DEAD; + intr_event_schedule_thread(ie); while (handler->ih_flags & IH_DEAD) msleep(handler, &ie->ie_lock, 0, "iev_rmh", 0); intr_event_update(ie); + #ifdef notyet /* * XXX: This could be bad in the case of ppbus(8). Also, I think @@ -838,8 +863,8 @@ ok: * interrupt. */ dead = 1; - TAILQ_FOREACH(ih, &ie->ie_handlers, ih_next) { - if (!(ih->ih_flags & IH_FAST)) { + CK_SLIST_FOREACH(ih, &ie->ie_handlers, ih_next) { + if (ih->ih_handler != NULL) { dead = 0; break; } @@ -866,7 +891,7 @@ intr_event_schedule_thread(struct intr_event *ie) /* * If no ithread or no handlers, then we have a stray interrupt. */ - if (ie == NULL || TAILQ_EMPTY(&ie->ie_handlers) || + if (ie == NULL || CK_SLIST_EMPTY(&ie->ie_handlers) || ie->ie_thread == NULL) return (EINVAL); @@ -881,7 +906,7 @@ intr_event_schedule_thread(struct intr_event *ie) if (ie->ie_flags & IE_ENTROPY) { entropy.event = (uintptr_t)ie; entropy.td = ctd; - random_harvest_queue(&entropy, sizeof(entropy), 2, RANDOM_INTERRUPT); + random_harvest_queue(&entropy, sizeof(entropy), RANDOM_INTERRUPT); } #ifndef __rtems__ @@ -981,7 +1006,7 @@ swi_sched(void *cookie, int flags) entropy.event = (uintptr_t)ih; entropy.td = curthread; - random_harvest_queue(&entropy, sizeof(entropy), 1, RANDOM_SWI); + random_harvest_queue(&entropy, sizeof(entropy), RANDOM_SWI); /* * Set ih_need for this handler so that if the ithread is already @@ -1012,32 +1037,37 @@ swi_remove(void *cookie) return (intr_event_remove_handler(cookie)); } - - #endif /* __rtems__ */ -/* - * This is a public function for use by drivers that mux interrupt - * handlers for child devices from their interrupt handler. - */ -void + +static void intr_event_execute_handlers(struct proc *p, struct intr_event *ie) { - struct intr_handler *ih, *ihn; + struct intr_handler *ih, *ihn, *ihp; - TAILQ_FOREACH_SAFE(ih, &ie->ie_handlers, ih_next, ihn) { + ihp = NULL; + CK_SLIST_FOREACH_SAFE(ih, &ie->ie_handlers, ih_next, ihn) { /* * If this handler is marked for death, remove it from * the list of handlers and wake up the sleeper. */ if (ih->ih_flags & IH_DEAD) { mtx_lock(&ie->ie_lock); - TAILQ_REMOVE(&ie->ie_handlers, ih, ih_next); + if (ihp == NULL) + CK_SLIST_REMOVE_HEAD(&ie->ie_handlers, ih_next); + else + CK_SLIST_REMOVE_AFTER(ihp, ih_next); ih->ih_flags &= ~IH_DEAD; wakeup(ih); mtx_unlock(&ie->ie_lock); continue; } + /* + * Now that we know that the current element won't be removed + * update the previous element. + */ + ihp = ih; + /* Skip filter only handlers */ if (ih->ih_handler == NULL) continue; @@ -1226,6 +1256,7 @@ intr_event_handle(struct intr_event *ie, struct trapframe *frame) struct trapframe *oldframe; struct thread *td; int ret, thread; + int phase; td = curthread; @@ -1234,7 +1265,7 @@ intr_event_handle(struct intr_event *ie, struct trapframe *frame) #endif /* An interrupt with no event or handlers is a stray interrupt. */ - if (ie == NULL || TAILQ_EMPTY(&ie->ie_handlers)) + if (ie == NULL || CK_SLIST_EMPTY(&ie->ie_handlers)) return (EINVAL); /* @@ -1249,7 +1280,17 @@ intr_event_handle(struct intr_event *ie, struct trapframe *frame) critical_enter(); oldframe = td->td_intr_frame; td->td_intr_frame = frame; - TAILQ_FOREACH(ih, &ie->ie_handlers, ih_next) { + + phase = ie->ie_phase; + atomic_add_int(&ie->ie_active[phase], 1); + + /* + * This fence is required to ensure that no later loads are + * re-ordered before the ie_active store. + */ + atomic_thread_fence_seq_cst(); + + CK_SLIST_FOREACH(ih, &ie->ie_handlers, ih_next) { if (ih->ih_filter == NULL) { thread = 1; continue; @@ -1286,6 +1327,8 @@ intr_event_handle(struct intr_event *ie, struct trapframe *frame) thread = 1; } } + atomic_add_rel_int(&ie->ie_active[phase], -1); + td->td_intr_frame = oldframe; if (thread) { @@ -1295,7 +1338,7 @@ intr_event_handle(struct intr_event *ie, struct trapframe *frame) if (ie->ie_post_filter != NULL) ie->ie_post_filter(ie->ie_source); } - + /* Schedule the ithread if needed. */ if (thread) { int error __unused; @@ -1441,7 +1484,7 @@ db_dump_intr_event(struct intr_event *ie, int handlers) db_printf("\n"); if (handlers) - TAILQ_FOREACH(ih, &ie->ie_handlers, ih_next) + CK_SLIST_FOREACH(ih, &ie->ie_handlers, ih_next) db_dump_intrhand(ih); } @@ -1456,7 +1499,7 @@ DB_SHOW_COMMAND(intr, db_show_intr) verbose = strchr(modif, 'v') != NULL; all = strchr(modif, 'a') != NULL; TAILQ_FOREACH(ie, &event_list, ie_list) { - if (!all && TAILQ_EMPTY(&ie->ie_handlers)) + if (!all && CK_SLIST_EMPTY(&ie->ie_handlers)) continue; db_dump_intr_event(ie, verbose); if (db_pager_quit) |