1 files changed, 152 insertions, 0 deletions

diff --git a/litmus/sync.c b/litmus/sync.c
new file mode 100644
index 000000000000..5d180603f46b
--- /dev/null
+++ b/litmus/sync.c
@@ -0,0 +1,152 @@
+/* litmus/sync.c - Support for synchronous and asynchronous task system releases.
+ *
+ *
+ */
+
+#include <asm/atomic.h>
+#include <asm/uaccess.h>
+#include <linux/spinlock.h>
+#include <linux/list.h>
+#include <linux/sched.h>
+#include <linux/completion.h>
+
+#include <litmus/litmus.h>
+#include <litmus/sched_plugin.h>
+#include <litmus/jobs.h>
+
+#include <litmus/sched_trace.h>
+
+struct ts_release_wait {
+        struct list_head list;
+        struct completion completion;
+        lt_t ts_release_time;
+};
+
+#define DECLARE_TS_RELEASE_WAIT(symb)                                   \
+        struct ts_release_wait symb =                                   \
+        {                                                               \
+                LIST_HEAD_INIT(symb.list),                              \
+                COMPLETION_INITIALIZER_ONSTACK(symb.completion),        \
+                0                                                       \
+        }
+
+static LIST_HEAD(task_release_list);
+static DEFINE_MUTEX(task_release_lock);
+
+static long do_wait_for_ts_release(void)
+{
+        DECLARE_TS_RELEASE_WAIT(wait);
+
+        long ret = -ERESTARTSYS;
+
+        if (mutex_lock_interruptible(&task_release_lock))
+                goto out;
+
+        list_add(&wait.list, &task_release_list);
+
+        mutex_unlock(&task_release_lock);
+
+        /* We are enqueued, now we wait for someone to wake us up. */
+        ret = wait_for_completion_interruptible(&wait.completion);
+
+        if (!ret) {
+                /* Completion succeeded, setup release time. */
+                ret = litmus->wait_for_release_at(
+                        wait.ts_release_time + get_rt_phase(current));
+        } else {
+                /* We were interrupted, must cleanup list. */
+                mutex_lock(&task_release_lock);
+                if (!wait.completion.done)
+                        list_del(&wait.list);
+                mutex_unlock(&task_release_lock);
+        }
+
+out:
+        return ret;
+}
+
+int count_tasks_waiting_for_release(void)
+{
+        int task_count = 0;
+        struct list_head *pos;
+
+        mutex_lock(&task_release_lock);
+
+        list_for_each(pos, &task_release_list) {
+                task_count++;
+        }
+
+        mutex_unlock(&task_release_lock);
+
+
+        return task_count;
+}
+
+static long do_release_ts(lt_t start)
+{
+        long  task_count = 0;
+
+        struct list_head        *pos, *safe;
+        struct ts_release_wait  *wait;
+
+        if (mutex_lock_interruptible(&task_release_lock)) {
+                task_count = -ERESTARTSYS;
+                goto out;
+        }
+
+        TRACE("<<<<<< synchronous task system release >>>>>>\n");
+        sched_trace_sys_release(&start);
+        litmus->synchronous_release_at(start);
+
+        task_count = 0;
+        list_for_each_safe(pos, safe, &task_release_list) {
+                wait = (struct ts_release_wait*)
+                        list_entry(pos, struct ts_release_wait, list);
+
+                task_count++;
+                wait->ts_release_time = start;
+                complete(&wait->completion);
+        }
+
+        /* clear stale list */
+        INIT_LIST_HEAD(&task_release_list);
+
+        mutex_unlock(&task_release_lock);
+
+out:
+        return task_count;
+}
+
+
+asmlinkage long sys_wait_for_ts_release(void)
+{
+        long ret = -EPERM;
+        struct task_struct *t = current;
+
+        if (is_realtime(t))
+                ret = do_wait_for_ts_release();
+
+        return ret;
+}
+
+#define ONE_MS 1000000
+
+asmlinkage long sys_release_ts(lt_t __user *__delay)
+{
+        long ret;
+        lt_t delay;
+        lt_t start_time;
+
+        /* FIXME: check capabilities... */
+
+        ret = copy_from_user(&delay, __delay, sizeof(delay));
+        if (ret == 0) {
+                /* round up to next larger integral millisecond */
+                start_time = litmus_clock();
+                do_div(start_time, ONE_MS);
+                start_time *= ONE_MS;
+                ret = do_release_ts(start_time + delay);
+        }
+
+        return ret;
+}