Base scheduler queues off linked lists and do cleanup/consolidation

Abstracts threading from itself a bit, changes the way its queues are
handled and does type hiding for that as well.

Do alot here due to already required major brain surgery.

Threads may now be on a run queue and a wait queue simultaneously so
that the expired timer only has to wake the thread but not remove it
from the wait queue which simplifies the implicit wake handling.

List formats change for wait queues-- doubly-linked, not circular.
Timeout queue is now singly-linked. The run queue is still circular
as before.

Adds a better thread slot allocator that may keep the slot marked as
used regardless of the thread state. Assists in dumping special tasks
that switch_thread was tasked to perform (blocking tasks).

Deletes alot of code yet surprisingly, gets larger than expected.
Well, I'm not not minding that for the time being-- omlettes and break
a few eggs and all that.

Change-Id: I0834d7bb16b2aecb2f63b58886eeda6ae4f29d59

1 files changed, 15 insertions, 66 deletions

diff --git a/firmware/kernel/pthread/thread.c b/firmware/kernel/pthread/thread.c
index 354a946698..71cbd1d136 100644
--- a/firmware/kernel/pthread/thread.c
+++ b/firmware/kernel/pthread/thread.c
@@ -3,8 +3,8 @@
 #include <errno.h>
 #include <pthread.h>
 #include "/usr/include/semaphore.h"
+#include "thread-internal.h"
 #include "kernel.h"
-#include "thread.h"
 
 #define NSEC_PER_SEC 1000000000L
 static inline void timespec_add_ns(struct timespec *a, uint64_t ns)
@@ -25,11 +25,6 @@ struct thread_init_data {
 
 __thread struct thread_entry *_current;
 
-struct thread_entry* thread_self_entry(void)
-{
-    return _current;
-}
-
 unsigned int thread_self(void)
 {
     return (unsigned) pthread_self();
@@ -70,12 +65,10 @@ static void *trampoline(void *arg)
     if (data->start_frozen)
     {
         struct corelock thaw_lock;
-        struct thread_entry *queue = NULL;
         corelock_init(&thaw_lock);
         corelock_lock(&thaw_lock);
 
         _current->lock = &thaw_lock;
-        _current->bqp = &queue;
         sem_post(&data->init_sem);
         block_thread_switch(_current, _current->lock);
         _current->lock = NULL;
@@ -97,7 +90,7 @@ void thread_thaw(unsigned int thread_id)
     if (e->lock)
     {
         corelock_lock(e->lock);
-        wakeup_thread(e->bqp);
+        wakeup_thread(e);
         corelock_unlock(e->lock);
     }
     /* else: no lock. must be running already */
@@ -135,7 +128,7 @@ unsigned int create_thread(void (*function)(void),
     data->entry = entry;
     pthread_cond_init(&entry->cond, NULL);         
     entry->runnable = true;
-    entry->l = (struct thread_list) { NULL, NULL };
+
     sem_init(&data->init_sem, 0, 0);
 
     if (pthread_create(&retval, NULL, trampoline, data) < 0)
@@ -153,58 +146,19 @@ unsigned int create_thread(void (*function)(void),
     return retval;
 }
 
-static void add_to_list_l(struct thread_entry **list,
-                          struct thread_entry *thread)
-{
-    if (*list == NULL)
-    {
-        /* Insert into unoccupied list */
-        thread->l.next = thread;
-        thread->l.prev = thread;
-        *list = thread;
-    }
-    else
-    {
-        /* Insert last */
-        thread->l.next = *list;
-        thread->l.prev = (*list)->l.prev;
-        thread->l.prev->l.next = thread;
-        (*list)->l.prev = thread;
-    }
-}
-
-static void remove_from_list_l(struct thread_entry **list,
-                               struct thread_entry *thread)
-{
-    if (thread == thread->l.next)
-    {
-        /* The only item */
-        *list = NULL;
-        return;
-    }
-
-    if (thread == *list)
-    {
-        /* List becomes next item */
-        *list = thread->l.next;
-    }
-
-    /* Fix links to jump over the removed entry. */
-    thread->l.prev->l.next = thread->l.next;
-    thread->l.next->l.prev = thread->l.prev;
-}
-
 /* for block_thread(), _w_tmp() and wakeup_thread() t->lock must point
  * to a corelock instance, and this corelock must be held by the caller */
 void block_thread_switch(struct thread_entry *t, struct corelock *cl)
 {
     t->runnable = false;
-    add_to_list_l(t->bqp, t);
+    if (wait_queue_ptr(t))
+        wait_queue_register(t);
     while(!t->runnable)
         pthread_cond_wait(&t->cond, &cl->mutex);
 }
 
-void block_thread_switch_w_tmo(struct thread_entry *t, int timeout, struct corelock *cl)
+void block_thread_switch_w_tmo(struct thread_entry *t, int timeout,
+                               struct corelock *cl)
 {
     int err = 0;
     struct timespec ts;
@@ -213,30 +167,25 @@ void block_thread_switch_w_tmo(struct thread_entry *t, int timeout, struct corel
     timespec_add_ns(&ts, timeout * (NSEC_PER_SEC/HZ));
 
     t->runnable = false;
-    add_to_list_l(t->bqp, t);
+    wait_queue_register(t->wqp, t);
     while(!t->runnable && !err)
         err = pthread_cond_timedwait(&t->cond, &cl->mutex, &ts);
 
     if (err == ETIMEDOUT)
     {   /* the thread timed out and was not explicitely woken up.
          * we need to do this now to mark it runnable again */
-        remove_from_list_l(t->bqp, t);
         t->runnable = true;
-        if (t->wakeup_ext_cb)
-            t->wakeup_ext_cb(t);
+        /* NOTE: objects do their own removal upon timer expiration */
     }
 }
 
-unsigned int wakeup_thread(struct thread_entry **list)
+unsigned int wakeup_thread(struct thread_entry *t)
 {
-    struct thread_entry *t = *list;
-    if (t)
-    {
-        remove_from_list_l(list, t);
-        t->runnable = true;
-        pthread_cond_signal(&t->cond);
-    }
-    return THREAD_NONE;
+    if (t->wqp)
+        wait_queue_remove(t);
+    t->runnable = true;
+    pthread_cond_signal(&t->cond);
+    return THREAD_OK;
 }