1 files changed, 90 insertions, 2 deletions

diff --git a/include/litmus/litmus_softirq.h b/include/litmus/litmus_softirq.h
index 37804fcfe8a3..6d1f85c2e093 100644
--- a/include/litmus/litmus_softirq.h
+++ b/include/litmus/litmus_softirq.h
@@ -1,11 +1,99 @@
-
 #include <linux/interrupt.h>
 
+/*
+   Threaded tasklet handling for Litmus.  Tasklets
+   are scheduled with the priority of the tasklet's
+   owner-- that is, the RT task on behalf the tasklet
+   runs.
+ 
+   Tasklets are current scheduled in FIFO order with
+   NO priority inheritance for "blocked" tasklets.
+ 
+   klitirqd assumes the priority of the owner of the
+   tasklet when the tasklet is next to execute.
+ 
+   Currently, hi-tasklets are scheduled before
+   low-tasklets, regardless of priority of low-tasklets.
+   This priority inversion probably needs to be fixed,
+   though it is not an issue if our work with GPUs as
+   GPUs are owned (and associated klitirqds) for
+   exclusive time periods, thus no inversions can
+   occur.
+ 
+   FIXME: Let low-tasklets with higher Litmus priority
+   be scheduled before hi-tasklets of lower Litmus
+   priority.
+ 
+   TODO: Decide if tasklets should really be scheduled
+   FIFO.  If not, we should probably ensure tasklets with
+   the same owner still execute in FIFO order lest we
+   confuse drivers with out-of-order execution (though
+   they probably should still be able to handle it by
+   tasklet processing design).
+ */
+
+
+
 #define NR_LITMUS_SOFTIRQD CONFIG_NR_LITMUS_SOFTIRQD
 
-void trigger_litirqs(struct task_struct*);
 
+//void trigger_litirqs(struct task_struct*);
+
+/* Spawns NR_LITMUS_SOFTIRQD klitirqd daemons.
+   Actual launch of threads is deffered to kworker's
+   workqueue, so daemons will likely not be immediately
+   running when this function returns, though the required
+   data will be initialized. */
 void spawn_klitirqd(void);
 
+
+/* Raises a flag to tell klitirqds to terminate.
+   Termination is async, so some threads may be running
+   after function return. */
 void kill_klitirqd(void);
 
+
+/* Returns 1 if all NR_LITMUS_SOFTIRQD klitirqs are ready
+   to handle tasklets. 0, otherwise.*/
+int klitirqd_is_ready(void);
+
+
+void __litmus_tasklet_schedule(
+        struct tasklet_struct *t,
+        unsigned int k_id);
+
+/* schedule a tasklet on klitirqd #k_id */
+static inline void litmus_tasklet_schedule(
+    struct tasklet_struct *t,
+    unsigned int k_id)
+{
+        if (!test_and_set_bit(TASKLET_STATE_SCHED, &t->state))
+                __litmus_tasklet_schedule(t, k_id);
+}
+
+
+extern void __litmus_tasklet_hi_schedule(struct tasklet_struct *t,
+                                         unsigned int k_id);
+
+/* schedule a hi tasklet on klitirqd #k_id */
+static inline void litmus_tasklet_hi_schedule(struct tasklet_struct *t,
+                                              unsigned int k_id)
+{
+        if (!test_and_set_bit(TASKLET_STATE_SCHED, &t->state))
+                __litmus_tasklet_hi_schedule(t, k_id);
+}
+
+
+extern void __litmus_tasklet_hi_schedule_first(
+    struct tasklet_struct *t,
+    unsigned int k_id);
+
+/* schedule a hi tasklet on klitirqd #k_id on next go-around */
+/* PRECONDITION: Interrupts must be disabled. */
+static inline void litmus_tasklet_hi_schedule_first(
+    struct tasklet_struct *t,
+    unsigned int k_id)
+{
+        if (!test_and_set_bit(TASKLET_STATE_SCHED, &t->state))
+                __litmus_tasklet_hi_schedule_first(t, k_id);
+}
\ No newline at end of file