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authorChristian Cunningham <cc@localhost>2022-03-16 15:36:09 -0700
committerChristian Cunningham <cc@localhost>2022-03-16 15:36:09 -0700
commit18b205cc3498e81136107b383618f92df5ef1380 (patch)
tree787ed194b1b52a1c05c459e3af0d817dec2018c3 /src/sys
parentb7590870cfd909baca7b5dc1d954e233ec92092e (diff)
Fixed Boundary Constraints
Diffstat (limited to 'src/sys')
-rw-r--r--src/sys/schedule.c279
1 files changed, 162 insertions, 117 deletions
diff --git a/src/sys/schedule.c b/src/sys/schedule.c
index 4366b1a..ea677e4 100644
--- a/src/sys/schedule.c
+++ b/src/sys/schedule.c
@@ -66,6 +66,115 @@ void init_scheduler(void)
}
}
+void push_to_queue(struct Thread* t, unsigned char type, unsigned char priority)
+{
+ struct ThreadEntry* entry = &thread_entries[t->offset];
+ struct ThreadQueue* queue;
+ if (type == THREAD_READY) {
+ queue = &scheduler.ready[priority];
+ } else if (type == THREAD_MWAIT) {
+ queue = &scheduler.mwait[priority];
+ } else if (type == THREAD_SWAIT) {
+ queue = &scheduler.swait[priority];
+ } else {
+ return;
+ }
+ queue->end.next->next = entry;
+ queue->end.next = entry;
+ entry->next = &queue->end;
+}
+
+struct ThreadEntry* pop_from_queue(unsigned char type, unsigned char priority)
+{
+ struct ThreadEntry* entry = 0;
+ struct ThreadQueue* queue;
+ if (type == THREAD_READY) {
+ queue = &scheduler.ready[priority];
+ } else if (type == THREAD_MWAIT) {
+ queue = &scheduler.mwait[priority];
+ } else if (type == THREAD_SWAIT) {
+ queue = &scheduler.swait[priority];
+ } else {
+ return entry;
+ }
+ if (queue->start.next->entry_type == END_ENTRY)
+ return entry;
+ entry = queue->start.next;
+ queue->start.next = entry->next;
+ if (entry->next->entry_type == END_ENTRY)
+ queue->end.next = &queue->start;
+ return entry;
+}
+
+struct ThreadEntry* remove_next_from_queue(struct ThreadEntry* te)
+{
+ struct ThreadEntry* prev = te;
+ struct ThreadEntry* remove = te->next;
+ struct ThreadEntry* next = remove->next;
+ if (remove->entry_type == END_ENTRY || remove->entry_type == START_ENTRY)
+ return 0;
+ prev->next = next;
+ if (next->entry_type == END_ENTRY)
+ next->next = prev;
+ return remove;
+}
+
+struct ThreadEntry* find_pid(unsigned long pid)
+{
+ for (unsigned char p = 0; p < PRIORITIES; p++) {
+ struct ThreadQueue* queue;
+ struct ThreadEntry* prev;
+ struct ThreadEntry* entry;
+
+ queue = &scheduler.ready[p];
+ prev = &queue->start;
+ entry = prev->next;
+ while (entry->entry_type != END_ENTRY) {
+ if (entry->thread->pid == pid)
+ return prev;
+ prev = entry;
+ entry = entry->next;
+ }
+
+ queue = &scheduler.mwait[p];
+ prev = &queue->start;
+ entry = prev->next;
+ while (entry->entry_type != END_ENTRY) {
+ if (entry->thread->pid == pid)
+ return prev;
+ prev = entry;
+ entry = entry->next;
+ }
+
+ queue = &scheduler.swait[p];
+ prev = &queue->start;
+ entry = prev->next;
+ while (entry->entry_type != END_ENTRY) {
+ if (entry->thread->pid == pid)
+ return prev;
+ prev = entry;
+ entry = entry->next;
+ }
+ }
+ return 0;
+}
+
+struct ThreadEntry* find_mutex_wait_next(void* m)
+{
+ for (unsigned char p = 0; p < PRIORITIES; p++) {
+ struct ThreadQueue* queue = &scheduler.mwait[p];
+ struct ThreadEntry* prev = &queue->start;
+ struct ThreadEntry* entry = prev->next;
+ while (entry->entry_type != END_ENTRY) {
+ if (entry->thread->mptr == m)
+ return prev;
+ prev = entry;
+ entry = entry->next;
+ }
+ }
+ return 0;
+}
+
struct Thread* get_unused_thread(void)
{
for(unsigned long i = 0; i < MAX_THREADS; i++) {
@@ -108,15 +217,7 @@ unsigned char add_thread(void* pc, void* arg, unsigned char priority)
// Reserved for non-preemptible tasking
thread->preempt = 0;
/// Add Thread to Scheduler
- // Get the Ready Queue
- struct ThreadQueue* ready_queue = &scheduler.ready[thread->priority];
- // Get thread's entry
- struct ThreadEntry* new_t_entry = &thread_entries[thread->offset];
- // Append to the end of the thread
- ready_queue->end.next->next = new_t_entry;
- ready_queue->end.next = new_t_entry;
- // Link thread's next entry to end of queue
- new_t_entry->next = &ready_queue->end;
+ push_to_queue(thread, THREAD_READY, thread->priority);
// Schedule if this was called in usermode
unsigned long mode = getmode() & 0x1F;
if (mode == 0x10) {
@@ -189,12 +290,7 @@ void c_cleanup(void)
struct Thread* rt = scheduler.rthread;
struct ThreadEntry* rte = &thread_entries[rt->offset];
struct ThreadQueue* queue = &scheduler.ready[rt->priority];
- // Move head forward
- queue->start.next = rte->next;
- if (rte->next->entry_type == END_ENTRY)
- rte->next->next = &queue->start;
- // Clear thread entry's next
- rte->next = 0;
+ pop_from_queue(THREAD_READY, rt->priority);
// Mark Thread Unused
thread_table[rt->offset] = 0;
}
@@ -208,123 +304,72 @@ void yield(void)
// Put current thread at the end of its ready queue,
// thus any threads of the same priority can be run first
unsigned char priority = rthread->priority;
- struct ThreadQueue* trq = &scheduler.ready[priority];
- struct ThreadEntry* te = &thread_entries[rthread->offset];
- // Move head forward
- trq->start.next = te->next;
- if (te->next->entry_type == END_ENTRY)
- te->next->next = &trq->start;
- // Add to tail
- trq->end.next->next = te;
- trq->end.next = te;
- te->next = &trq->end;
+ struct ThreadEntry* tq;
+ // Remove from top of queue
+ tq = pop_from_queue(THREAD_READY, priority);
+ if (tq != 0) {
+ // Add to bottom of queue
+ push_to_queue(tq->thread, THREAD_READY, priority);
+ }
}
-// TODO: Figure out why two things are appearing in the wait queue by the end of this
void sched_mutex_yield(void* m)
{
struct Thread* rthread = scheduler.rthread;
- struct ThreadEntry* rthread_e = &thread_entries[rthread->offset];
// usrloopthread should not be yielded
if (rthread == &usrloopthread)
return;
unsigned char priority = rthread->priority;
// Signify which lock this thread is waiting for
rthread->mptr = m;
- struct ThreadQueue* trq = &scheduler.ready[priority];
- struct ThreadQueue* tmq = &scheduler.mwait[priority];
- // Move to next thread in the current thread priority's ready queue
- trq->start.next = trq->start.next->next;
- if (trq->start.next->next->entry_type == END_ENTRY)
- trq->end.next = &trq->start;
- // Add thread to waiting queue
- tmq->end.next->next = rthread_e;
- tmq->end.next = rthread_e;
- rthread_e->next = &tmq->end;
- /// Find the thread with the mutex
- // Search through each priority
- for (unsigned long p = 0; p < PRIORITIES; p++) {
- struct ThreadQueue* queue = &scheduler.ready[p];
- // Keep track of the previous entry
- struct ThreadEntry* prev = &queue->start;
- struct ThreadEntry* entry = prev->next;
- while (entry->entry_type != END_ENTRY) {
- // Check if it is the Mutex's thread
- if (entry->thread->pid == ((struct Mutex*)m)->pid) {
- uart_scheduler();
- // Promote the thread's priority
- if (entry->thread->priority > priority) {
- struct ThreadQueue* new_queue = &scheduler.ready[priority];
- // Add it to the higher priority queue
- new_queue->end.next->next = entry;
- new_queue->end.next = entry;
- // Set the old priority if not set
- if (entry->thread->old_priority == 0xFF)
- entry->thread->old_priority = p;
- // Set the new priority
- entry->thread->priority = priority;
- // Remove it from the lower priority queue
- prev->next = entry->next;
- if (entry->next->entry_type == END_ENTRY) {
- entry->next->next = prev;
- }
- // Set the entry's next entry
- entry->next = &new_queue->end;
- }
- return;
- }
- // Continue forward
- prev = entry;
- entry = entry->next;
- }
+ struct ThreadEntry* rt;
+ // Remove from top of running queue
+ rt = pop_from_queue(THREAD_READY, priority);
+ if (rt != 0)
+ // Push to bottom of wait queue
+ push_to_queue(rt->thread, THREAD_MWAIT, priority);
+ // Find the thread that has the mutex locked
+ struct Mutex* mtex = m;
+ struct ThreadEntry* mutex_next = find_pid(mtex->pid);
+ if (mutex_next == 0)
+ return;
+ // The next thread is the one with the lock
+ struct ThreadEntry* mutex_thread_entry = mutex_next->next;
+ // Check if it is lower priority
+ if (mutex_thread_entry->thread->priority > priority) {
+ // Remove it from the old priority queue
+ remove_next_from_queue(mutex_next);
+ struct Thread* t = mutex_thread_entry->thread;
+ // Preserve the old priority
+ if (t->old_priority == 0xFF)
+ t->old_priority = t->priority;
+ t->priority = priority;
+ // Add it to the higher priority queue
+ push_to_queue(t, THREAD_READY, priority);
}
}
void sched_mutex_resurrect(void* m)
{
- // Look through each priority
- for (int p = 0; p < PRIORITIES; p++) {
- struct ThreadQueue* wait_queue = &scheduler.mwait[p];
- struct ThreadEntry* prev = &wait_queue->start;
- struct ThreadEntry* entry = prev->next;
- // Look through the lock wait queue
- while (entry->entry_type != END_ENTRY) {
- // Check if the thread is waiting for the release mutex
- if (entry->thread->mptr == m) {
- // Resurrect the thread
- entry->thread->mptr = 0;
- struct ThreadEntry* end = &scheduler.ready[entry->thread->priority].end;
- // Remove from old list
- prev->next = entry->next;
- if (entry->next->entry_type == END_ENTRY) {
- prev->next->next = prev;
- }
- // Add to new list
- end->next->next = entry;
- end->next = entry;
- entry->next = end;
- struct Thread* rthread = scheduler.rthread;
- struct ThreadEntry* rthread_e = &thread_entries[rthread->offset];
- // Move current thread to old thread if applicable
- if (rthread->old_priority != 0xFF) {
- struct ThreadQueue* cqueue = &scheduler.ready[rthread->priority];
- struct ThreadQueue* oqueue = &scheduler.ready[rthread->old_priority];
- // Move current queue up
- cqueue->start.next = cqueue->start.next->next;
- if (cqueue->start.next->next->entry_type == END_ENTRY)
- cqueue->end.next = &cqueue->start;
- // Add to old queue
- oqueue->end.next->next = rthread_e;
- oqueue->end.next = rthread_e;
- rthread_e->next = &oqueue->end;
- // Reset priority
- rthread->priority = rthread->old_priority;
- rthread->old_priority = 0xFF;
- }
- return;
- }
- prev = entry;
- entry = entry->next;
- }
+ struct ThreadEntry* prev = find_mutex_wait_next(m);
+ if (prev == 0)
+ return;
+ struct ThreadEntry* entry = prev->next;
+ struct Thread* thread = entry->thread;
+ // Resurrect the thread
+ thread->mptr = 0;
+ // Remove from wait queue
+ entry = remove_next_from_queue(prev);
+ if (entry == 0)
+ return;
+ // Add to ready queue
+ push_to_queue(entry->thread, THREAD_READY, entry->thread->priority);
+ // Demote current thread
+ struct Thread* rthread = scheduler.rthread;
+ unsigned long p = rthread->priority;
+ unsigned long op = rthread->old_priority;
+ if (op != 0xFF) {
+ struct ThreadEntry* tentry = pop_from_queue(THREAD_READY, p);
+ push_to_queue(tentry->thread, THREAD_READY, p);
}
}