1 files changed, 146 insertions, 0 deletions
diff --git a/kern/work.h b/kern/work.h
new file mode 100644
index 00000000..b3668df9
--- /dev/null
+++ b/kern/work.h
@@ -0,0 +1,146 @@
+/*
+ * Copyright (c) 2013 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/>.
+ *
+ *
+ * Deferred work queues.
+ *
+ * Works, like threads, are scheduled activities, but they are much shorter
+ * and (usually) consume a lot less resources. They are allowed to block
+ * and must run in thread context. This module provides thread pools to
+ * concurrently handle queued works.
+ */
+
+#ifndef _KERN_WORK_H
+#define _KERN_WORK_H
+
+/*
+ * Work scheduling flags.
+ */
+#define WORK_HIGHPRIO   0x1 /* Use a high priority worker thread */
+
+struct work;
+
+/*
+ * Type for work functions.
+ */
+typedef void (*work_fn_t)(struct work *);
+
+/*
+ * Deferred work.
+ *
+ * This structure should be embedded in objects related to the work. It
+ * stores the work function and is passed to it as its only parameter.
+ * The function can then find the containing object with the structof macro.
+ */
+struct work {
+    struct work *next;
+    work_fn_t fn;
+};
+
+/*
+ * Queue of deferred works for batch scheduling.
+ */
+struct work_queue {
+    struct work *first;
+    struct work *last;
+    unsigned int nr_works;
+};
+
+static inline void
+work_queue_init(struct work_queue *queue)
+{
+    queue->first = NULL;
+    queue->last = NULL;
+    queue->nr_works = 0;
+}
+
+static inline unsigned int
+work_queue_nr_works(const struct work_queue *queue)
+{
+    return queue->nr_works;
+}
+
+static inline void
+work_queue_push(struct work_queue *queue, struct work *work)
+{
+    work->next = NULL;
+
+    if (queue->last == NULL)
+        queue->first = work;
+    else
+        queue->last->next = work;
+
+    queue->last = work;
+    queue->nr_works++;
+}
+
+static inline struct work *
+work_queue_pop(struct work_queue *queue)
+{
+    struct work *work;
+
+    work = queue->first;
+    queue->first = work->next;
+
+    if (queue->last == work)
+        queue->last = NULL;
+
+    queue->nr_works--;
+    return work;
+}
+
+static inline void
+work_queue_transfer(struct work_queue *dest, struct work_queue *src)
+{
+    *dest = *src;
+}
+
+static inline void
+work_queue_concat(struct work_queue *queue1, struct work_queue *queue2)
+{
+    if (queue2->nr_works == 0)
+        return;
+
+    if (queue1->nr_works == 0) {
+        *queue1 = *queue2;
+        return;
+    }
+
+    queue1->last->next = queue2->first;
+    queue1->last = queue2->last;
+    queue1->nr_works += queue2->nr_works;
+}
+
+static inline void
+work_init(struct work *work, work_fn_t fn)
+{
+    work->fn = fn;
+}
+
+/*
+ * Initialize the work module.
+ */
+void work_setup(void);
+
+/*
+ * Schedule work for deferred processing.
+ *
+ * This function may be called from interrupt context.
+ */
+void work_schedule(struct work *work, int flags);
+void work_queue_schedule(struct work_queue *queue, int flags);
+
+#endif /* _KERN_WORK_H */