EDF-WM: handle races between out_of_time and blocks

Also move budget handling functions to top of file.

1 files changed, 53 insertions, 32 deletions

diff --git a/litmus/sched_edf_wm.c b/litmus/sched_edf_wm.c
index e25977a91c8b..c3d241a42566 100644
--- a/litmus/sched_edf_wm.c
+++ b/litmus/sched_edf_wm.c
@@ -90,6 +90,47 @@ static void complete_sliced_job(struct task_struct* t)
         p->semi_part.wm.job_deadline = p->job_params.deadline;
 }
 
+static lt_t slice_exec_time(struct task_struct* t)
+{
+        struct rt_param* p = tsk_rt(t);
+
+        /* Compute how much execution time has been consumed
+         * since last slice advancement. */
+        return p->job_params.exec_time - p->semi_part.wm.exec_time;
+}
+
+static lt_t slice_budget(struct task_struct* t)
+{
+        return tsk_rt(t)->semi_part.wm.slice->budget;
+}
+
+static int slice_budget_exhausted(struct task_struct* t)
+{
+        return slice_exec_time(t) >= slice_budget(t);
+}
+
+/* assumes positive remainder; overflows otherwise */
+static lt_t slice_budget_remaining(struct task_struct* t)
+{
+        return slice_budget(t) - slice_exec_time(t);
+}
+
+static lt_t wm_budget_remaining(struct task_struct* t)
+{
+        if (is_sliced_task(t))
+                return slice_budget_remaining(t);
+        else
+                return budget_remaining(t);
+}
+
+static int wm_budget_exhausted(struct task_struct* t)
+{
+        if (is_sliced_task(t))
+                return slice_budget_exhausted(t);
+        else
+                return budget_exhausted(t);
+}
+
 static void advance_next_slice(struct task_struct* t, int completion_signaled)
 {
         int idx;
@@ -131,34 +172,22 @@ static void advance_next_slice(struct task_struct* t, int completion_signaled)
         compute_slice_params(t);
 }
 
-static lt_t slice_exec_time(struct task_struct* t)
-{
-        struct rt_param* p = tsk_rt(t);
-
-        /* Compute how much execution time has been consumed
-         * since last slice advancement. */
-        return p->job_params.exec_time - p->semi_part.wm.exec_time;
-}
-
-static lt_t slice_budget(struct task_struct* t)
+/* assumes time_passed does not advance past the last slice */
+static void fast_forward_slices(struct task_struct* t, lt_t time_passed)
 {
-        return tsk_rt(t)->semi_part.wm.slice->budget;
-}
+        TRACE_TASK(t, "fast forwarding %lluns\n", time_passed);
 
-static int slice_budget_exhausted(struct task_struct* t)
-{
-        return slice_exec_time(t) >= slice_budget(t);
-}
+        /* this is NOT the slice version */
+        BUG_ON(budget_remaining(t) <= time_passed);
 
-/* assumes positive remainder; overflows otherwise */
-static lt_t slice_budget_remaining(struct task_struct* t)
-{
-        return slice_budget(t) - slice_exec_time(t);
-}
+        if (wm_budget_exhausted(t)) {
+                /* This can happen if a suspension raced
+                 * with a normal slice advancement. wm_schedule()
+                 * does not process out_of_time when a task blocks. */
+                TRACE_TASK(t, "block raced with out_of_time?\n");
+                advance_next_slice(t, 0);
+        }
 
-/* assumes time_passed does not advance past the last slice */
-static void fast_forward_slices(struct task_struct* t, lt_t time_passed)
-{
         while (time_passed &&
                time_passed >= slice_budget_remaining(t)) {
                 /* slice completely exhausted */
@@ -271,14 +300,6 @@ static void wm_job_or_slice_completion(struct task_struct* t,
                 regular_job_completion(t, !completion_signaled);
 }
 
-static int wm_budget_exhausted(struct task_struct* t)
-{
-        if (is_sliced_task(t))
-                return slice_budget_exhausted(t);
-        else
-                return budget_exhausted(t);
-}
-
 static void wm_tick(struct task_struct *t)
 {
         wm_domain_t *dom = local_domain;