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-rw-r--r--sys/kern/subr_eventhandler.c241
1 files changed, 241 insertions, 0 deletions
diff --git a/sys/kern/subr_eventhandler.c b/sys/kern/subr_eventhandler.c
new file mode 100644
index 0000000..b1c6f65
--- /dev/null
+++ b/sys/kern/subr_eventhandler.c
@@ -0,0 +1,241 @@
+/*-
+ * Copyright (c) 1999 Michael Smith <msmith@freebsd.org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include <sys/param.h>
+#include <sys/kernel.h>
+#include <sys/lock.h>
+#include <sys/malloc.h>
+#include <sys/mutex.h>
+#include <sys/proc.h>
+#include <sys/systm.h>
+#include <sys/eventhandler.h>
+
+static MALLOC_DEFINE(M_EVENTHANDLER, "eventhandler", "Event handler records");
+
+/* List of 'slow' lists */
+static TAILQ_HEAD(, eventhandler_list) eventhandler_lists;
+static int eventhandler_lists_initted = 0;
+static struct mtx eventhandler_mutex;
+
+struct eventhandler_entry_generic
+{
+ struct eventhandler_entry ee;
+ void (* func)(void);
+};
+
+static struct eventhandler_list *_eventhandler_find_list(char *name);
+
+/*
+ * Initialize the eventhandler mutex and list.
+ */
+static void
+eventhandler_init(void *dummy __unused)
+{
+ TAILQ_INIT(&eventhandler_lists);
+ mtx_init(&eventhandler_mutex, "eventhandler", NULL, MTX_DEF);
+ atomic_store_rel_int(&eventhandler_lists_initted, 1);
+}
+SYSINIT(eventhandlers, SI_SUB_EVENTHANDLER, SI_ORDER_FIRST, eventhandler_init,
+ NULL)
+
+/*
+ * Insertion is O(n) due to the priority scan, but optimises to O(1)
+ * if all priorities are identical.
+ */
+eventhandler_tag
+eventhandler_register(struct eventhandler_list *list, char *name,
+ void *func, void *arg, int priority)
+{
+ struct eventhandler_list *new_list;
+ struct eventhandler_entry_generic *eg;
+ struct eventhandler_entry *ep;
+
+ KASSERT(eventhandler_lists_initted, ("eventhandler registered too early"));
+
+ /* lock the eventhandler lists */
+ mtx_lock(&eventhandler_mutex);
+
+ /* Do we need to find/create the (slow) list? */
+ if (list == NULL) {
+ /* look for a matching, existing list */
+ list = _eventhandler_find_list(name);
+
+ /* Do we need to create the list? */
+ if (list == NULL) {
+ mtx_unlock(&eventhandler_mutex);
+
+ new_list = malloc(sizeof(struct eventhandler_list) +
+ strlen(name) + 1, M_EVENTHANDLER, M_WAITOK);
+
+ /* If someone else created it already, then use that one. */
+ mtx_lock(&eventhandler_mutex);
+ list = _eventhandler_find_list(name);
+ if (list != NULL) {
+ free(new_list, M_EVENTHANDLER);
+ } else {
+ CTR2(KTR_EVH, "%s: creating list \"%s\"", __func__, name);
+ list = new_list;
+ list->el_flags = 0;
+ list->el_runcount = 0;
+ bzero(&list->el_lock, sizeof(list->el_lock));
+ list->el_name = (char *)list + sizeof(struct eventhandler_list);
+ strcpy(list->el_name, name);
+ TAILQ_INSERT_HEAD(&eventhandler_lists, list, el_link);
+ }
+ }
+ }
+ if (!(list->el_flags & EHL_INITTED)) {
+ TAILQ_INIT(&list->el_entries);
+ mtx_init(&list->el_lock, name, "eventhandler list", MTX_DEF);
+ atomic_store_rel_int(&list->el_flags, EHL_INITTED);
+ }
+ mtx_unlock(&eventhandler_mutex);
+
+ /* allocate an entry for this handler, populate it */
+ eg = malloc(sizeof(struct eventhandler_entry_generic), M_EVENTHANDLER,
+ M_WAITOK | M_ZERO);
+ eg->func = func;
+ eg->ee.ee_arg = arg;
+ eg->ee.ee_priority = priority;
+ KASSERT(priority != EHE_DEAD_PRIORITY,
+ ("%s: handler for %s registered with dead priority", __func__, name));
+
+ /* sort it into the list */
+ CTR4(KTR_EVH, "%s: adding item %p (function %p) to \"%s\"", __func__, eg,
+ func, name);
+ EHL_LOCK(list);
+ TAILQ_FOREACH(ep, &list->el_entries, ee_link) {
+ if (ep->ee_priority != EHE_DEAD_PRIORITY &&
+ eg->ee.ee_priority < ep->ee_priority) {
+ TAILQ_INSERT_BEFORE(ep, &eg->ee, ee_link);
+ break;
+ }
+ }
+ if (ep == NULL)
+ TAILQ_INSERT_TAIL(&list->el_entries, &eg->ee, ee_link);
+ EHL_UNLOCK(list);
+ return(&eg->ee);
+}
+
+void
+eventhandler_deregister(struct eventhandler_list *list, eventhandler_tag tag)
+{
+ struct eventhandler_entry *ep = tag;
+
+ EHL_LOCK_ASSERT(list, MA_OWNED);
+ if (ep != NULL) {
+ /* remove just this entry */
+ if (list->el_runcount == 0) {
+ CTR3(KTR_EVH, "%s: removing item %p from \"%s\"", __func__, ep,
+ list->el_name);
+ TAILQ_REMOVE(&list->el_entries, ep, ee_link);
+ free(ep, M_EVENTHANDLER);
+ } else {
+ CTR3(KTR_EVH, "%s: marking item %p from \"%s\" as dead", __func__,
+ ep, list->el_name);
+ ep->ee_priority = EHE_DEAD_PRIORITY;
+ }
+ } else {
+ /* remove entire list */
+ if (list->el_runcount == 0) {
+ CTR2(KTR_EVH, "%s: removing all items from \"%s\"", __func__,
+ list->el_name);
+ TAILQ_REMOVE(&list->el_entries, ep, ee_link);
+ while (!TAILQ_EMPTY(&list->el_entries)) {
+ ep = TAILQ_FIRST(&list->el_entries);
+ TAILQ_REMOVE(&list->el_entries, ep, ee_link);
+ free(ep, M_EVENTHANDLER);
+ }
+ } else {
+ CTR2(KTR_EVH, "%s: marking all items from \"%s\" as dead",
+ __func__, list->el_name);
+ TAILQ_FOREACH(ep, &list->el_entries, ee_link)
+ ep->ee_priority = EHE_DEAD_PRIORITY;
+ }
+ }
+ EHL_UNLOCK(list);
+}
+
+/*
+ * Internal version for use when eventhandler list is already locked.
+ */
+static struct eventhandler_list *
+_eventhandler_find_list(char *name)
+{
+ struct eventhandler_list *list;
+
+ mtx_assert(&eventhandler_mutex, MA_OWNED);
+ TAILQ_FOREACH(list, &eventhandler_lists, el_link) {
+ if (!strcmp(name, list->el_name))
+ break;
+ }
+ return (list);
+}
+
+/*
+ * Lookup a "slow" list by name. Returns with the list locked.
+ */
+struct eventhandler_list *
+eventhandler_find_list(char *name)
+{
+ struct eventhandler_list *list;
+
+ if (!eventhandler_lists_initted)
+ return(NULL);
+
+ /* scan looking for the requested list */
+ mtx_lock(&eventhandler_mutex);
+ list = _eventhandler_find_list(name);
+ if (list != NULL)
+ EHL_LOCK(list);
+ mtx_unlock(&eventhandler_mutex);
+
+ return(list);
+}
+
+/*
+ * Prune "dead" entries from an eventhandler list.
+ */
+void
+eventhandler_prune_list(struct eventhandler_list *list)
+{
+ struct eventhandler_entry *ep, *en;
+
+ CTR2(KTR_EVH, "%s: pruning list \"%s\"", __func__, list->el_name);
+ EHL_LOCK_ASSERT(list, MA_OWNED);
+ ep = TAILQ_FIRST(&list->el_entries);
+ while (ep != NULL) {
+ en = TAILQ_NEXT(ep, ee_link);
+ if (ep->ee_priority == EHE_DEAD_PRIORITY) {
+ TAILQ_REMOVE(&list->el_entries, ep, ee_link);
+ free(ep, M_EVENTHANDLER);
+ }
+ ep = en;
+ }
+}
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