1 files changed, 36 insertions, 33 deletions

diff --git a/litmus/sched_psn_edf.c b/litmus/sched_psn_edf.c
index 6f4d4adcec01..466d45d9f6bd 100644
--- a/litmus/sched_psn_edf.c
+++ b/litmus/sched_psn_edf.c
@@ -418,6 +418,9 @@ struct dgl_semaphore {
     /* bitmask of resources that are currently locked. */
     resource_mask_t locked;
 
+    /* bitmask of the resources that are logically locked. */
+    resource_mask_t logically_locked;
+
     /* bitmask of resources in the file descriptor table that are controlled by
      * this dgl_semaphore.
      */
@@ -429,6 +432,11 @@ struct dgl_semaphore {
      */
     bool boosted[NR_CPUS];
 
+    /* Ensure that a task cannot acquire if there is an earlier-issued request
+     * on that processor.
+     */
+    bool logically_boosted[NR_CPUS];
+
     /* FIFO queue of waiting tasks */
     wait_queue_head_t wait;
 };
@@ -644,7 +652,7 @@ bool is_mask_valid(struct litmus_lock* l, resource_mask_t mask)
 #define for_each_bit(field, idx)                                \
         for (idx = find_first_bit(&field, sizeof(field)*8);     \
              idx < sizeof(field)*8;                             \
-             idx = find_next_bit(&field, sizeof(field)*8, idx))
+             idx = find_next_bit(&field, sizeof(field)*8, idx+1))
 
 int psnedf_dgl_dynamic_group_lock(struct litmus_lock* l, resource_mask_t resources)
 {
@@ -665,12 +673,14 @@ int psnedf_dgl_dynamic_group_lock(struct litmus_lock* l, resource_mask_t resourc
     t->resources = resources;
 
     spin_lock_irqsave(&sem->wait.lock, flags);
+    
 
     // if sem->locked & resources == 0, then all resources are available,
     // otherwise we must suspend.
-    if (sem->locked & resources){
+    if (waitqueue_active(&sem->wait) || sem->logically_locked & resources ||
+            sem->logically_boosted[task_cpu(t)]){
 
-        STRACE("Resources locked, suspending\n");
+        STRACE("Resources unavailable, suspending\n");
 
         init_waitqueue_entry(&wait, t);
 
@@ -678,6 +688,9 @@ int psnedf_dgl_dynamic_group_lock(struct litmus_lock* l, resource_mask_t resourc
 
         __add_wait_queue_tail_exclusive(&sem->wait, &wait);
 
+        sem->logically_boosted[task_cpu(t)] = true;
+        sem->logically_locked |= resources;
+
         TS_LOCK_SUSPEND;
 
         spin_unlock_irqrestore(&sem->wait.lock, flags);
@@ -687,9 +700,10 @@ int psnedf_dgl_dynamic_group_lock(struct litmus_lock* l, resource_mask_t resourc
         TS_LOCK_RESUME;
     } else {
 
-        STRACE("Acquired a resource\n");
+        STRACE("Acquired resource(s)\n");
 
-        sem->locked = sem->locked | resources;
+        sem->locked |= resources;
+        sem->logically_locked |= resources;
 
         // if a job requests a resource, then it was scheduled, and therefore
         // there was not another boosted job, so this is safe.
@@ -698,10 +712,12 @@ int psnedf_dgl_dynamic_group_lock(struct litmus_lock* l, resource_mask_t resourc
         boost_priority(t);
 
         sem->boosted[task_cpu(t)] = true;
+        sem->logically_boosted[task_cpu(t)] = true;
 
         spin_unlock_irqrestore(&sem->wait.lock, flags);
     }
 
+    // tracing what resources are used when.
     for_each_bit(resources, resource)
             sched_trace_server_switch_to(resource, 0, t->pid, get_job_no(t),
                                          get_partition(t));
@@ -709,23 +725,12 @@ int psnedf_dgl_dynamic_group_lock(struct litmus_lock* l, resource_mask_t resourc
     return 0;
 }
 
-inline int num_boosted(struct dgl_semaphore *sem)
-{
-    int ret = 0;
-    int i;
-    for(i = 0; i < NR_CPUS; i++){
-        ret += sem->boosted[i];
-    }
-    return ret;
-}
-
 int psnedf_dgl_dynamic_group_unlock(struct litmus_lock* l, resource_mask_t resources)
 {
     struct task_struct *t = current, *tsk;
     struct dgl_semaphore *sem = dgl_from_lock(l);
     unsigned long flags;
-    int err = 0, resource;
-    resource_mask_t logically_locked;
+    int err = 0, resource, i;
     struct list_head *pos, *tmp;
 
     TRACE_CUR("Trying to unlock a DGL\n");
@@ -754,31 +759,26 @@ int psnedf_dgl_dynamic_group_unlock(struct litmus_lock* l, resource_mask_t resou
         STRACE("Released all resources\n");
         unboost_priority(t);
         sem->boosted[task_cpu(t)] = false;
+        //n.b., logically_boosted[task_cpu(t)] may be reset to true in the
+        //subsequent iteration.
+        sem->logically_boosted[task_cpu(t)] = false;
     } else {
         // update t->resources to reflect the resources currently owned.
         STRACE("Unlocked a subset of locked resources\n");
         t->resources = t->resources & ~resources;
     }
 
-    logically_locked = sem->locked;
+    sem->logically_locked = sem->locked;
+    for(i = 0; i < NR_CPUS; i++)
+        sem->logically_boosted[i] = sem->boosted[i];
 
+    // iterate through the waitqueue and unlock ready tasks. Also recreate logically_locked.
         list_for_each_safe(pos, tmp, &sem->wait.task_list) {
                 tsk  = (struct task_struct*) list_entry(pos, wait_queue_t,
                                                            task_list)->private;
-        STRACE_TASK(tsk, "Evaluating\n");
-
-        if ( (logically_locked == -1) || (num_boosted(sem) == NR_CPUS) ){
-            STRACE_TASK(tsk, "All procs boosted, or all resources locked\n");
-            break;
-        }
-
-        //STRACE_TASK(tsk, "Logically locked: %o\n", logically_locked);
-        //STRACE_TASK(tsk, "tsk->resources: %o\n", tsk->resources);
-        //STRACE_TASK(tsk, "!(tsk->resources & logically_locked): %o\n", !(tsk->resources & logically_locked));
-        //STRACE_TASK(tsk, "!sem->boosted: %d\n", !sem->boosted[task_cpu(tsk)]);
 
         // the resources requested are unlocked, tsk acquires its resources
-        if( !(tsk->resources & logically_locked) && !sem->boosted[task_cpu(tsk)]) {
+        if( !(tsk->resources & sem->logically_locked) && !sem->logically_boosted[task_cpu(tsk)]) {
 
             STRACE_TASK(tsk, "Acquired a resource\n");
 
@@ -791,8 +791,8 @@ int psnedf_dgl_dynamic_group_unlock(struct litmus_lock* l, resource_mask_t resou
 
             wake_up_process(tsk);
         }
-
-        logically_locked = logically_locked | tsk->resources;
+        sem->logically_locked |= tsk->resources;
+        sem->logically_boosted[task_cpu(tsk)] = true;
     }
 
     for_each_bit(resources, resource)
@@ -847,10 +847,13 @@ static struct litmus_lock* psnedf_new_dgl(void)
         return NULL;
 
     sem->locked = 0;
+    sem->logically_locked = 0;
     sem->dgl_resources = 0;
 
-    for(i = 0; i < NR_CPUS; i++)
+    for(i = 0; i < NR_CPUS; i++){
         sem->boosted[i] = false;
+        sem->logically_boosted[i] = false;
+    }
 
     init_waitqueue_head(&sem->wait);
     sem->litmus_lock.ops = &psnedf_dgl_lock_ops;