kern/bulletin: new module

1 files changed, 83 insertions, 0 deletions

diff --git a/kern/bulletin.c b/kern/bulletin.c
new file mode 100644
index 00000000..bbb1bfc3
--- /dev/null
+++ b/kern/bulletin.c
@@ -0,0 +1,83 @@
+/*
+ * Copyright (c) 2017-2018 Richard Braun.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <assert.h>
+#include <stdint.h>
+
+#include <kern/bulletin.h>
+#include <kern/list.h>
+#include <kern/rcu.h>
+#include <kern/spinlock.h>
+#include <kern/thread.h>
+
+static void
+bulletin_sub_init(struct bulletin_sub *sub,
+                  bulletin_notif_fn_t notif_fn, void *arg)
+{
+    sub->notif_fn = notif_fn;
+    sub->arg = arg;
+}
+
+static void
+bulletin_sub_notify(const struct bulletin_sub *sub, uintptr_t value)
+{
+    sub->notif_fn(value, sub->arg);
+}
+
+void
+bulletin_init(struct bulletin *bulletin)
+{
+    spinlock_init(&bulletin->lock);
+    list_init(&bulletin->subs);
+}
+
+void
+bulletin_subscribe(struct bulletin *bulletin, struct bulletin_sub *sub,
+                   bulletin_notif_fn_t notif_fn, void *arg)
+{
+    bulletin_sub_init(sub, notif_fn, arg);
+
+    spinlock_lock(&bulletin->lock);
+    list_rcu_insert_tail(&bulletin->subs, &sub->node);
+    spinlock_unlock(&bulletin->lock);
+}
+
+void
+bulletin_unsubscribe(struct bulletin *bulletin, struct bulletin_sub *sub)
+{
+    spinlock_lock(&bulletin->lock);
+    list_rcu_remove(&sub->node);
+    spinlock_unlock(&bulletin->lock);
+
+    rcu_wait();
+}
+
+void
+bulletin_publish(struct bulletin *bulletin, uintptr_t value)
+{
+    struct bulletin_sub *sub;
+
+    assert(!thread_interrupted());
+
+    rcu_read_enter();
+
+    list_rcu_for_each_entry(&bulletin->subs, sub, node) {
+        bulletin_sub_notify(sub, value);
+    }
+
+    rcu_read_leave();
+}