Added bug ons in case of stack deadlock

3 files changed, 44 insertions, 9 deletions

diff --git a/litmus/Kconfig b/litmus/Kconfig
index 46563edf513c..08f4d5f62a71 100644
--- a/litmus/Kconfig
+++ b/litmus/Kconfig
@@ -110,8 +110,8 @@ config SCHED_TASK_TRACE
 config SCHED_TASK_TRACE_SHIFT
        int "Buffer size for sched_trace_xxx() events"
        depends on SCHED_TASK_TRACE
-       range 8 13
-       default 9
+       range 8 24
+       default 24
        help
 
          Select the buffer size of sched_trace_xxx() events as a power of two.
diff --git a/litmus/sched_edf_hsb.c b/litmus/sched_edf_hsb.c
index d176efca648b..8de315c0774d 100644
--- a/litmus/sched_edf_hsb.c
+++ b/litmus/sched_edf_hsb.c
@@ -262,8 +262,10 @@ static void add_slack(server_t *slack)
 
         TRACE_SERVER_SUB(slack, "slack added");
 
-        if (head_in_list(&slack->list))
+        if (head_in_list(&slack->list)) {
+                TRACE_SERVER_SUB(slack, "already in list");
                 return;
+        }
 
         list_for_each_prev(pos, &slack_queue) {
                 queued = list_entry(pos, server_t, list);
@@ -353,8 +355,9 @@ static noinline void check_donate_slack(server_t *donator, struct task_struct *w
                 return;
         }
 
-        if (donator->type == S_HRT)
+        if (donator->type == S_HRT) {
                 hrt_server = container_of(donator, hrt_server_t, server);
+        }
 
         /* Donate if the server is waiting for a task release */
         if ((donator->type == S_SRT &&
@@ -404,17 +407,19 @@ static void check_slack_candidate(struct task_struct *task)
 static noinline server_t* next_eligible_slack_server(void)
 {
         server_t *next_slack = NULL;
+        lt_t now = litmus_clock();
 
         while (!list_empty(&slack_queue)) {
                 next_slack = list_entry(slack_queue.next, server_t, list);
                 BUG_ON(!next_slack);
 
-                if (lt_after(next_slack->deadline, litmus_clock()) &&
+                if (lt_after(next_slack->deadline, now) &&
                     lt_after(next_slack->budget, SLACK_MIN) &&
                     !is_server_linked(next_slack)) {
                         break;
                 } else {
                         /* Slack has expired or has too little time */
+                        BUG_ON(next_slack->id == 1001);
                         remove_slack(next_slack);
                         next_slack = NULL;
                 }
@@ -628,8 +633,13 @@ static void requeue_server(server_t *server, lt_t now)
         int added = 0;
         hrt_server_t *hrt_server;
 
-        if (server->type == S_SRT || server->type == S_SLACK)
+        if (server->type == S_SRT)
+                return;
+
+        if (server->type == S_SLACK) {
+                add_slack(server);
                 return;
+        }
 
         if (lt_before(now, server->release)) {
                 added = add_server_release(server, &server_domain);
@@ -2206,6 +2216,10 @@ static struct task_struct* edf_hsb_schedule(struct task_struct *prev)
 
         curr = entry->scheduled;
 
+        if (entry->scheduled && !is_realtime(prev)) {
+                TRACE_TASK_SUB(entry->scheduled, "Stack deadlock!");
+        }
+
         TRACE("server_budget: %llu, server_deadline: %llu, "
               "curr_time: %llu, no_slack: %d, ready: %d\n",
               TIME(entry->hrt_server.server.budget),
@@ -2268,6 +2282,10 @@ static struct task_struct* edf_hsb_schedule(struct task_struct *prev)
 
         raw_spin_unlock_irqrestore(global_lock, flags);
 
+        if (!entry->scheduled && !next_eligible_slack_server()) {
+                TRACE_SUB("A slack server has dissapeared!");
+        }
+
         return entry->scheduled;
 }
 
diff --git a/litmus/sched_edf_hsb_noslack.c b/litmus/sched_edf_hsb_noslack.c
index e6e8d7dd0e8b..7782f72ed7ea 100644
--- a/litmus/sched_edf_hsb_noslack.c
+++ b/litmus/sched_edf_hsb_noslack.c
@@ -262,8 +262,10 @@ static void add_slack(server_t *slack)
 
         TRACE_SERVER_SUB(slack, "slack added");
 
-        if (head_in_list(&slack->list))
+        if (head_in_list(&slack->list)) {
+                TRACE_SERVER_SUB(slack, "already in list");
                 return;
+        }
 
         list_for_each_prev(pos, &slack_queue) {
                 queued = list_entry(pos, server_t, list);
@@ -401,17 +403,19 @@ static void check_slack_candidate(struct task_struct *task)
 static noinline server_t* next_eligible_slack_server(void)
 {
         server_t *next_slack = NULL;
+        lt_t now = litmus_clock();
 
         while (!list_empty(&slack_queue)) {
                 next_slack = list_entry(slack_queue.next, server_t, list);
                 BUG_ON(!next_slack);
 
-                if (lt_after(next_slack->deadline, litmus_clock()) &&
+                if (lt_after(next_slack->deadline, now) &&
                     lt_after(next_slack->budget, SLACK_MIN) &&
                     !is_server_linked(next_slack)) {
                         break;
                 } else {
                         /* Slack has expired or has too little time */
+                        BUG_ON(next_slack->id == 1001);
                         remove_slack(next_slack);
                         next_slack = NULL;
                 }
@@ -625,8 +629,13 @@ static void requeue_server(server_t *server, lt_t now)
         int added = 0;
         hrt_server_t *hrt_server;
 
-        if (server->type == S_SRT || server->type == S_SLACK)
+        if (server->type == S_SRT)
+                return;
+
+        if (server->type == S_SLACK) {
+                add_slack(server);
                 return;
+        }
 
         if (lt_before(now, server->release)) {
                 added = add_server_release(server, &server_domain);
@@ -2203,6 +2212,10 @@ static struct task_struct* edf_hsb_schedule(struct task_struct *prev)
 
         curr = entry->scheduled;
 
+        if (entry->scheduled && !is_realtime(prev)) {
+                TRACE_TASK_SUB(entry->scheduled, "Stack deadlock!");
+        }
+
         TRACE("server_budget: %llu, server_deadline: %llu, "
               "curr_time: %llu, no_slack: %d, ready: %d\n",
               TIME(entry->hrt_server.server.budget),
@@ -2265,6 +2278,10 @@ static struct task_struct* edf_hsb_schedule(struct task_struct *prev)
 
         raw_spin_unlock_irqrestore(global_lock, flags);
 
+        if (!entry->scheduled && !next_eligible_slack_server()) {
+                TRACE_SUB("A slack server has dissapeared!");
+        }
+
         return entry->scheduled;
 }