SRP: record owner in semaphores

1 files changed, 26 insertions, 24 deletions

diff --git a/litmus/litmus_sem.c b/litmus/litmus_sem.c
index 486fb3bef7..8151087c1a 100644
--- a/litmus/litmus_sem.c
+++ b/litmus/litmus_sem.c
@@ -319,21 +319,35 @@ DEFINE_PER_CPU(struct srp, srp);
 
 #define system_ceiling(srp) list2prio(srp->ceiling.next)
 
+
+#define UNDEF_SEM -2
+
+
+/* struct for uniprocessor SRP "semaphore" */
+struct srp_semaphore {
+        struct srp_priority ceiling;
+        struct task_struct* owner;
+        int cpu; /* cpu associated with this "semaphore" and resource */
+};
+
+#define ceiling2sem(c) container_of(c, struct srp_semaphore, ceiling) 
+
 static int srp_exceeds_ceiling(struct task_struct* first,
                                struct srp* srp)
 {
         return list_empty(&srp->ceiling) ||
                get_rt_period(first) < system_ceiling(srp)->period ||
                (get_rt_period(first) == system_ceiling(srp)->period &&
-                first->pid < system_ceiling(srp)->pid);
+                first->pid < system_ceiling(srp)->pid) || 
+                ceiling2sem(system_ceiling(srp))->owner == first;
 }
 
 static void srp_add_prio(struct srp* srp, struct srp_priority* prio)
 {
         struct list_head *pos;
         if (in_list(&prio->list)) {
-                TRACE_CUR("WARNING: SRP violation detected, prio is already in "
-                          "ceiling list!\n");
+                printk(KERN_CRIT "WARNING: SRP violation detected, prio is already in "
+                       "ceiling list!\n");
                 return;
         }
         list_for_each(pos, &srp->ceiling)
@@ -345,16 +359,6 @@ static void srp_add_prio(struct srp* srp, struct srp_priority* prio)
         list_add_tail(&prio->list, &srp->ceiling);
 }
 
-#define UNDEF_SEM -2
-
-
-/* struct for uniprocessor SRP "semaphore" */
-struct srp_semaphore {
-        struct srp_priority ceiling;
-        int cpu; /* cpu associated with this "semaphore" and resource */
-        int claimed; /* is the resource claimed (ceiling should be used)? */
-};
-
 
 static void* create_srp_semaphore(void)
 {
@@ -366,8 +370,8 @@ static void* create_srp_semaphore(void)
 
         INIT_LIST_HEAD(&sem->ceiling.list);
         sem->ceiling.period = 0;
-        sem->claimed = 0;
         sem->cpu     = UNDEF_SEM;
+        sem->owner   = NULL;
         atomic_inc(&srp_objects_in_use);
         return sem;
 }
@@ -430,22 +434,20 @@ __initcall(srp_sema_boot_init);
 
 void do_srp_down(struct srp_semaphore* sem)
 {
-        /* claim... */
-        sem->claimed = 1;
-        /* ...and update ceiling */
+        /* Update ceiling. */
         srp_add_prio(&__get_cpu_var(srp), &sem->ceiling);
+        WARN_ON(sem->owner != NULL);
+        sem->owner = current;
 }
 
 void do_srp_up(struct srp_semaphore* sem)
-{
-        sem->claimed = 0;
-
+{       
         /* Determine new system priority ceiling for this CPU. */
-        if (in_list(&sem->ceiling.list))
+        WARN_ON(!in_list(&sem->ceiling.list));
+        if (!in_list(&sem->ceiling.list))
                 list_del(&sem->ceiling.list);
-        else
-                TRACE_CUR("WARNING: SRP violation detected, prio not in ceiling"
-                          " list!\n");
+
+        sem->owner = NULL;
 
         /* Wake tasks on this CPU, if they exceed current ceiling. */
         wake_up_all(&__get_cpu_var(srp).ceiling_blocked);