Kernel/x86 - Clean up some of the task switching code (possibly a little broken)
[tpg/acess2.git] / KernelLand / Kernel / threads.c
index 0961f8d..469c5ec 100644 (file)
@@ -4,18 +4,23 @@
  * threads.c
  * - Common Thread Control
  */
+#define DEBUG  0
 #include <acess.h>
 #include <threads.h>
 #include <threads_int.h>
 #include <errno.h>
 #include <hal_proc.h>
 #include <semaphore.h>
+#include <rwlock.h>
 #include <vfs_threads.h>       // VFS Handle maintainence
 #include <events.h>
+#include <debug_hooks.h>
 
 // Configuration
+#define DEBUG_TRACE_ACTIVEQUEUE        0       // Trace adds/removals from the active queue
 #define DEBUG_TRACE_TICKETS    0       // Trace ticket counts
 #define DEBUG_TRACE_STATE      0       // Trace state changes (sleep/wake)
+#define DEBUG_TRACE_SCHEDULE   0       // Trace scheduling
 
 // --- Schedulers ---
 #define SCHED_UNDEF    0
 #define        DEFAULT_PRIORITY        5
 #define MIN_PRIORITY           10
 
+#define PRIthread_fmt  "%p(%i %s)"
+#define PRIthread_args(t)      (t), ((t)?(t)->TID:-1), ((t)?(t)->ThreadName:"-")
+
 // === IMPORTS ===
+extern void    User_Signal_Kill(int SigNum);
 
 // === TYPE ===
 typedef struct
@@ -48,7 +57,7 @@ void  Threads_Delete(tThread *Thread);
 char   *Threads_GetName(tTID ID);
 #if 0
 void   Threads_SetPriority(tThread *Thread, int Pri);
-tThread        *Threads_CloneTCB(Uint *Err, Uint Flags);
+tThread        *Threads_CloneTCB(Uint Flags);
  int   Threads_WaitTID(int TID, int *status);
 tThread        *Threads_GetThread(Uint TID);
 #endif
@@ -58,15 +67,20 @@ void        Threads_int_AddToList(tThreadList *List, tThread *Thread);
 void   Threads_Exit(int TID, int Status);
 void   Threads_Kill(tThread *Thread, int Status);
 void   Threads_Yield(void);
+ int   Threads_int_Sleep(enum eThreadStatus Status, void *Ptr, int Num, tThread **ListHead, tThread **ListTail, tShortSpinlock *Lock);
 void   Threads_Sleep(void);
  int   Threads_Wake(tThread *Thread);
 void   Threads_AddActive(tThread *Thread);
 tThread        *Threads_RemActive(void);
-#endif
 void   Threads_ToggleTrace(int TID);
+#endif
 void   Threads_Fault(int Num);
 void   Threads_SegFault(tVAddr Addr);
+void   Threads_PostSignalTo(tThread *Thread, int SignalNum);
+#if 0
 void   Threads_PostSignal(int SignalNum);
+void   Threads_SignalGroup(tPGID PGID, int SignalNum);
+#endif
  int   Threads_GetPendingSignal(void);
 void   Threads_SetSignalHandler(int SignalNum, void *Handler);
 void   *Threads_GetSignalHandler(int SignalNum);
@@ -79,12 +93,15 @@ tGID        Threads_GetGID(void);
  int   Threads_SetGID(Uint *Errno, tUID ID);
 #endif
 void   Threads_int_DumpThread(tThread *thread);
+#if 0
 void   Threads_Dump(void);
+#endif
 void   Threads_DumpActive(void);
+tThread        *Threads_int_GetRunnable(void);
 
 // === GLOBALS ===
 // -- Core Thread --
-struct sProcess        gProcessZero = {
+tProcess       gProcessZero = {
        };
 // Only used for the core kernel
 tThread        gThreadZero = {
@@ -95,6 +112,7 @@ tThread      gThreadZero = {
        .Priority       = DEFAULT_PRIORITY      // Number of tickets
        };
 // -- Processes --
+tProcess       *gAllProcesses = &gProcessZero;
 // --- Locks ---
 tShortSpinlock glThreadListLock;       ///\note NEVER use a heap function while locked
 // --- Current State ---
@@ -170,8 +188,18 @@ void Threads_Delete(tThread *Thread)
        if( Thread->Process->nThreads == 0 )
        {
                tProcess        *proc = Thread->Process;
+
+               // Remove from global process list
+               // TODO: RWLock
+               if(proc->Prev)
+                       proc->Prev->Next = proc->Next;
+               else
+                       gAllProcesses = proc->Next;
+               if(proc->Next)
+                       proc->Next->Prev = proc->Prev;
+
                // VFS Cleanup
-               VFS_CloseAllUserHandles();
+               VFS_CloseAllUserHandles( proc );
                // Architecture cleanup
                Proc_ClearProcess( proc );
                // VFS Configuration strings
@@ -302,11 +330,10 @@ void Threads_SetPriority(tThread *Thread, int Pri)
  */
 tThread *Threads_CloneTCB(Uint Flags)
 {
-       tThread *cur, *new;
-       cur = Proc_GetCurThread();
+       tThread *cur = Proc_GetCurThread();
        
        // Allocate and duplicate
-       new = malloc(sizeof(tThread));
+       tThread *new = malloc(sizeof(tThread));
        if(new == NULL) { errno = -ENOMEM; return NULL; }
        memcpy(new, cur, sizeof(tThread));
        
@@ -328,7 +355,7 @@ tThread *Threads_CloneTCB(Uint Flags)
        if(Flags & CLONE_VM) {
                tProcess        *newproc, *oldproc;
                oldproc = cur->Process;
-               new->Process = malloc( sizeof(struct sProcess) );
+               new->Process = calloc( sizeof(struct sProcess), 1 );
                newproc = new->Process;
                newproc->PID = new->TID;
                if( Flags & CLONE_PGID )
@@ -338,17 +365,17 @@ tThread *Threads_CloneTCB(Uint Flags)
                newproc->UID = oldproc->UID;
                newproc->GID = oldproc->GID;
                newproc->MaxFD = oldproc->MaxFD;
-               if( oldproc->CurrentWorkingDir )
-                       newproc->CurrentWorkingDir = strdup( oldproc->CurrentWorkingDir );
-               else
-                       newproc->CurrentWorkingDir = NULL;
-               if( oldproc->RootDir )
-                       newproc->RootDir = strdup( oldproc->RootDir );
-               else
-                       newproc->RootDir = NULL;
+               newproc->CurrentWorkingDir = oldproc->CurrentWorkingDir ? strdup( oldproc->CurrentWorkingDir ) : NULL;
+               newproc->RootDir = oldproc->RootDir ? strdup( oldproc->RootDir ) : NULL;
                newproc->nThreads = 1;
                // Reference all handles in the VFS
                VFS_ReferenceUserHandles();
+               
+               // Add to global list
+               newproc->Prev = NULL;
+               // TODO: RWLock
+               newproc->Next = gAllProcesses;
+               gAllProcesses = newproc;
 
                newproc->FirstThread = new;
                new->ProcessNext = NULL;
@@ -453,18 +480,26 @@ tTID Threads_WaitTID(int TID, int *Status)
                tTID    ret = -1;
                if( ev & THREAD_EVENT_DEADCHILD )
                {
+                       tThread * const us = Proc_GetCurThread();
                        // A child died, get the TID
-                       tThread *us = Proc_GetCurThread();
                        ASSERT(us->LastDeadChild);
-                       ret = us->LastDeadChild->TID;
+                       tThread *dead_thread = us->LastDeadChild;
+                       us->LastDeadChild = dead_thread->Next;
+                       if( us->LastDeadChild )
+                               Threads_PostEvent( us, THREAD_EVENT_DEADCHILD );
+                       else
+                               Threads_ClearEvent( THREAD_EVENT_DEADCHILD );
+                       Mutex_Release(&us->DeadChildLock);
+                       
+                       ret = dead_thread->TID;
                        // - Mark as dead (as opposed to undead)
-                       ASSERT(us->LastDeadChild->Status == THREAD_STAT_ZOMBIE);
-                       us->LastDeadChild->Status = THREAD_STAT_DEAD;
+                       ASSERTC(dead_thread->Status, ==, THREAD_STAT_ZOMBIE);
+                       dead_thread->Status = THREAD_STAT_DEAD;
                        // - Set return status
                        if(Status)
-                               *Status = us->LastDeadChild->RetStatus;
-                       us->LastDeadChild = NULL;
-                       Mutex_Release(&us->DeadChildLock);
+                               *Status = dead_thread->RetStatus;
+                       
+                       Threads_Delete( dead_thread );
                }
                else
                {
@@ -488,6 +523,7 @@ tTID Threads_WaitTID(int TID, int *Status)
        // Specific Thread
        if(TID > 0)
        {
+               // TODO: Register on thread to be poked when it dies
                tTID    ret;
                // NOTE: Race condition - Other child dies, desired child dies, first death is 'lost'
                while( (ret = Threads_WaitTID(-1, Status)) != TID )
@@ -694,9 +730,11 @@ void Threads_Kill(tThread *Thread, int Status)
        SHORTREL( &glThreadListLock );
        // TODO: It's possible that we could be timer-preempted here, should disable that... somehow
        Mutex_Acquire( &Thread->Parent->DeadChildLock );        // released by parent
+       Thread->Next = Thread->Parent->LastDeadChild;
        Thread->Parent->LastDeadChild = Thread;
        Threads_PostEvent( Thread->Parent, THREAD_EVENT_DEADCHILD );
        
+       // Process cleanup happens on reaping
        Log("Thread %i went *hurk* (%i)", Thread->TID, Status);
        
        // And, reschedule
@@ -722,14 +760,56 @@ void Threads_Yield(void)
 void Threads_int_WaitForStatusEnd(enum eThreadStatus Status)
 {
        tThread *us = Proc_GetCurThread();
+       LOG("us = %p(%i %s), status=%i", us, us->TID, us->ThreadName, Status);
        ASSERT(Status != THREAD_STAT_ACTIVE);
        ASSERT(Status != THREAD_STAT_DEAD);
        while( us->Status == Status )
        {
                Proc_Reschedule();
                if( us->Status == Status )
-                       Debug("Thread %p(%i %s) rescheduled while in %s state", casTHREAD_STAT[Status]);
+                       Debug("Thread %p(%i %s) rescheduled while in %s state for %p",
+                               us, us->TID, us->ThreadName,
+                               casTHREAD_STAT[Status],
+                               __builtin_return_address(0));
+       }
+}
+
+int Threads_int_Sleep(enum eThreadStatus Status, void *Ptr, int Num, tThread **ListHead, tThread **ListTail, tShortSpinlock *Lock)
+{
+       SHORTLOCK( &glThreadListLock );
+       tThread *us = Threads_RemActive();
+       us->Next = NULL;
+       // - Mark as sleeping
+       us->Status = Status;
+       us->WaitPointer = Ptr;
+       us->RetStatus = Num;    // Use RetStatus as a temp variable
+               
+       // - Add to waiting
+       if( ListTail ) {
+               if(*ListTail) {
+                       (*ListTail)->Next = us;
+               }
+               else {
+                       *ListHead = us;
+               }
+               *ListTail = us;
        }
+       else if( ListHead ) {
+               us->Next = *ListHead;
+               *ListHead = us;
+       }
+       else {
+               // Nothing
+       }
+       
+       //if( Proc_ThreadSync(us) )
+       //      return ;
+       SHORTREL( &glThreadListLock );
+       if( Lock )
+               SHORTREL( Lock );
+       Threads_int_WaitForStatusEnd(Status);
+       us->WaitPointer = NULL;
+       return us->RetStatus;
 }
 
 /**
@@ -888,27 +968,40 @@ void Threads_ToggleTrace(int TID)
  */
 void Threads_AddActive(tThread *Thread)
 {
+       #if DEBUG_TRACE_ACTIVEQUEUE
+       Debug("Threads_AddActive("PRIthread_fmt")", PRIthread_args(Thread));
+       #endif
        SHORTLOCK( &glThreadListLock );
        
-       if( Thread->Status == THREAD_STAT_ACTIVE ) {
+       if( Thread->Status == THREAD_STAT_ACTIVE )
+       {
                tThread *cur = Proc_GetCurThread();
-               Log_Warning("Threads", "WTF, %p CPU%i %p (%i %s) is adding %p (%i %s) when it is active",
+               Log_KernelPanic("Threads",
+                       "ret=%p CPU%i "PRIthread_fmt" is adding "PRIthread_fmt" when it is active",
                        __builtin_return_address(0),
-                       GetCPUNum(), cur, cur->TID, cur->ThreadName, Thread, Thread->TID, Thread->ThreadName);
+                       GetCPUNum(), PRIthread_args(cur), PRIthread_args(Thread));
                SHORTREL( &glThreadListLock );
                return ;
        }
        
        // Set state
        Thread->Status = THREAD_STAT_ACTIVE;
-//     Thread->CurCPU = -1;
        // Add to active list
+       // - Thread can be the current thread if we're interrupted just before
+       //   Proc_Reschedule in a sleep state.
+       if( Thread != Proc_GetCurThread() )
        {
                #if SCHEDULER_TYPE == SCHED_RR_PRI
                tThreadList     *list = &gaActiveThreads[Thread->Priority];
                #else
                tThreadList     *list = &gActiveThreads;
                #endif
+               #if DEBUG_TRACE_ACTIVEQUEUE
+               Debug(" - Head="PRIthread_fmt",Tail="PRIthread_fmt"",
+                       PRIthread_args(list->Head),
+                       PRIthread_args(list->Tail)
+                       );
+               #endif
                Threads_int_AddToList( list, Thread );
        }
        
@@ -944,8 +1037,12 @@ void Threads_AddActive(tThread *Thread)
  */
 tThread *Threads_RemActive(void)
 {
+       tThread *us = Proc_GetCurThread();
+       #if DEBUG_TRACE_ACTIVEQUEUE
+       Debug("Threads_RemActive(%p(%i %s))", us, us->TID, us->ThreadName);
+       #endif
        giNumActiveThreads --;
-       return Proc_GetCurThread();
+       return us;
 }
 
 /**
@@ -1009,11 +1106,27 @@ void Threads_SegFault(tVAddr Addr)
 }
 
 
+void Threads_PostSignalTo(tThread *Thread, int SignalNum)
+{
+       ASSERT(Thread);
+       Log_Debug("Threads", "Signalling %i(%s) with %i", Thread->TID, Thread->ThreadName, SignalNum);
+       Thread->PendingSignal = SignalNum;
+       Threads_PostEvent(Thread, THREAD_EVENT_SIGNAL);
+}
 void Threads_PostSignal(int SignalNum)
 {
-       tThread *cur = Proc_GetCurThread();
-       cur->PendingSignal = SignalNum;
-       Threads_PostEvent(cur, THREAD_EVENT_SIGNAL);
+       Threads_PostSignalTo( Proc_GetCurThread(), SignalNum );
+}
+
+void Threads_SignalGroup(tPGID PGID, int Signal)
+{
+       for( tProcess *proc = gAllProcesses; proc; proc = proc->Next )
+       {
+               if(proc->PGID == PGID)
+               {
+                       Threads_PostSignalTo(proc->FirstThread, Signal);
+               }
+       }
 }
 
 /**
@@ -1023,7 +1136,13 @@ int Threads_GetPendingSignal(void)
        tThread *cur = Proc_GetCurThread();
        
        // Atomic AND with 0 fetches and clears in one operation
-       return __sync_fetch_and_and( &cur->PendingSignal, 0 );
+       int ret = __sync_fetch_and_and( &cur->PendingSignal, 0 );
+       if( ret )
+       {
+               Log_Debug("Threads", "Thread %i(%s) has signal %i pending",
+                       cur->TID, cur->ThreadName, ret);
+       }
+       return ret;
 }
 
 /*
@@ -1039,28 +1158,49 @@ void Threads_SetSignalHandler(int SignalNum, void *Handler)
 }
 
 /**
- * \return 0  Ignore
+ * \brief Gets the registered (or default, if none set) handler for a signal.
+ * \return Handler function pointer, OR NULL if no signal to be ignored
  */
 void *Threads_GetSignalHandler(int SignalNum)
 {
+       // TODO: Core dump
+       void *User_Signal_Core = User_Signal_Kill;
+       
        if( SignalNum <= 0 || SignalNum >= NSIGNALS )
                return NULL;
        void *ret = Proc_GetCurThread()->Process->SignalHandlers[SignalNum];
-       if( !ret )
+       if( !ret || (SignalNum == SIGKILL || SignalNum == SIGSTOP) )
        {
                // Defaults
                switch(SignalNum)
                {
+               case SIGHUP:
                case SIGINT:
+                       ret = User_Signal_Kill;
+                       break;
+               case SIGQUIT:
+               case SIGILL:
+               case SIGABRT:
+               case SIGFPE:
+                       ret = User_Signal_Core;
+                       break;
                case SIGKILL:
+                       ret = User_Signal_Kill;
+                       break;
                case SIGSEGV:
-//                     ret = User_Signal_Kill;
+                       ret = User_Signal_Core;
+                       break;
+               case SIGPIPE:
+               case SIGALRM:
+               case SIGTERM:
+                       ret = User_Signal_Kill;
                        break;
                default:
                        ret = NULL;
                        break;
                }
        }
+       Log_Debug("Threads", "Handler %p for signal %i", ret, SignalNum);
        return ret;
 }
 
@@ -1117,31 +1257,50 @@ int *Threads_GetErrno(void)
 }
 
 // --- Configuration ---
-int *Threads_GetMaxFD(void)
+int *Threads_GetMaxFD(tProcess *Process)
 {
-       return &Proc_GetCurThread()->Process->MaxFD;
+       if(!Process)    Process = Proc_GetCurThread()->Process;
+       return &Process->MaxFD;
 }
-char **Threads_GetChroot(void)
+char **Threads_GetChroot(tProcess *Process)
 {
-       return &Proc_GetCurThread()->Process->RootDir;
+       if(!Process)    Process = Proc_GetCurThread()->Process;
+       return &Process->RootDir;
 }
-char **Threads_GetCWD(void)
+char **Threads_GetCWD(tProcess *Process)
 {
-       return &Proc_GetCurThread()->Process->CurrentWorkingDir;
+       if(!Process)    Process = Proc_GetCurThread()->Process;
+       return &Process->CurrentWorkingDir;
 }
 // ---
 
 void Threads_int_DumpThread(tThread *thread)
 {
+       if( !thread ) {
+               Log(" %p NULL", thread);
+               return ;
+       }
+       if( !CheckMem(thread, sizeof(tThread)) ) {
+               Log(" %p INVAL", thread);
+               return ;
+       }
+       tPID    pid = (thread->Process ? thread->Process->PID : -1);
+       const char      *statstr = (thread->Status < sizeof(casTHREAD_STAT)/sizeof(casTHREAD_STAT[0])
+               ? casTHREAD_STAT[thread->Status] : "");
        Log(" %p %i (%i) - %s (CPU %i) - %i (%s)",
-               thread, thread->TID, thread->Process->PID, thread->ThreadName, thread->CurCPU,
-               thread->Status, casTHREAD_STAT[thread->Status]
+               thread, thread->TID, pid, thread->ThreadName, thread->CurCPU,
+               thread->Status, statstr
                );
        switch(thread->Status)
        {
        case THREAD_STAT_MUTEXSLEEP:
                Log("  Mutex Pointer: %p", thread->WaitPointer);
                break;
+       case THREAD_STAT_RWLOCKSLEEP:
+               Log("  Lock Pointer: %p", thread->WaitPointer);
+               Log("  Lock Name: %s",
+                       ((tRWLock*)thread->WaitPointer)->Name);
+               break;
        case THREAD_STAT_SEMAPHORESLEEP:
                Log("  Semaphore Pointer: %p", thread->WaitPointer);
                Log("  Semaphore Name: %s:%s", 
@@ -1149,6 +1308,9 @@ void Threads_int_DumpThread(tThread *thread)
                        ((tSemaphore*)thread->WaitPointer)->Name
                        );
                break;
+       case THREAD_STAT_EVENTSLEEP:
+               Log("  Event Mask: %x", thread->RetStatus);
+               break;
        case THREAD_STAT_ZOMBIE:
                Log("  Return Status: %i", thread->RetStatus);
                break;
@@ -1166,22 +1328,16 @@ void Threads_int_DumpThread(tThread *thread)
  */
 void Threads_DumpActive(void)
 {
-       tThread *thread;
-       tThreadList     *list;
-       #if SCHEDULER_TYPE == SCHED_RR_PRI
-        int    i;
-       #endif
-       
        Log("Active Threads: (%i reported)", giNumActiveThreads);
        
        #if SCHEDULER_TYPE == SCHED_RR_PRI
-       for( i = 0; i < MIN_PRIORITY+1; i++ )
+       for( int i = 0; i < MIN_PRIORITY+1; i++ )
        {
-               list = &gaActiveThreads[i];
+               tThreadList *list = &gaActiveThreads[i];
        #else
-               list = &gActiveThreads;
+               tThreadList *list = &gActiveThreads;
        #endif
-               for(thread=list->Head;thread;thread=thread->Next)
+               for(tThread *thread = list->Head; thread; thread = thread->Next)
                {
                        Threads_int_DumpThread(thread);
                        if(thread->Status != THREAD_STAT_ACTIVE)
@@ -1200,18 +1356,138 @@ void Threads_DumpActive(void)
  */
 void Threads_Dump(void)
 {
-       tThread *thread;
-       
        Log("--- Thread Dump ---");
        Threads_DumpActive();
        
        Log("All Threads:");
-       for(thread=gAllThreads;thread;thread=thread->GlobalNext)
+       for(tThread *thread = gAllThreads; thread; thread = thread->GlobalNext)
        {
                Threads_int_DumpThread(thread);
        }
 }
 
+tThread *Threads_int_GetRunnable(void)
+{
+       #if SCHEDULER_TYPE == SCHED_LOTTERY
+       // -----------------------------------
+       // Lottery Scheduler
+       // -----------------------------------
+       #if DEBUG_VALIDATE_TICKET_COUNTS
+       {
+               int total_tickets = 0;
+               for(const tThread *thread = gActiveThreads.Head; thread; thread = thread->Next)
+               {
+                       if(thread->Status != THREAD_STAT_ACTIVE)
+                               Panic("Bookkeeping fail - %p %i(%s) is on the active queue with a status of %i",
+                                       thread, thread->TID, thread->ThreadName, thread->Status);
+                       if(thread->Next == thread) {
+                               Panic("Bookkeeping fail - %p %i(%s) loops back on itself",
+                                       thread, thread->TID, thread->ThreadName, thread->Status);
+                       }
+                       total_tickets += caiTICKET_COUNTS[ thread->Priority ];
+               }
+               if(total_tickets != giFreeTickets)
+               {
+                       Panic("Bookkeeping fail (giFreeTickets(%i) != number(%i)) - CPU%i",
+                               giFreeTickets, total_tickets, CPU);
+               }
+       }
+       # endif
+       
+       // No free tickets (all tasks delegated to cores)
+       if( giFreeTickets == 0 )
+       {
+               return NULL;
+       }
+       
+       // Get the ticket number
+       int ticket = rand() % giFreeTickets;
+       int number = ticket;
+       
+       // Find the next thread
+       tThread **pnp = &gActiveThreads.Head;
+       tThread *thread;
+       for(thread = gActiveThreads.Head; thread; pnp = &thread->Next, thread = thread->Next )
+       {
+               if( caiTICKET_COUNTS[ thread->Priority ] > number)
+                       break;
+               number -= caiTICKET_COUNTS[ thread->Priority ];
+       }
+       
+       // If we didn't find a thread, something went wrong
+       if(thread == NULL)
+       {
+               int total_tickets = 0;
+               for(thread=gActiveThreads;thread;thread=thread->Next) {
+                       if(thread->CurCPU >= 0) continue;
+                       total_tickets += caiTICKET_COUNTS[ thread->Priority ];
+               }
+               Panic("Bookeeping Failed - giFreeTickets(%i) > true count (%i)",
+                       giFreeTickets, total_tickets);
+       }
+
+       // Remove
+       *pnp = thread->Next;
+       if( !thread->Next )
+               gActiveThreads.Tail = prev;             
+
+       giFreeTickets -= caiTICKET_COUNTS[ thread->Priority ];
+       # if DEBUG_TRACE_TICKETS
+       LogF("Log: CPU%i allocated %p (%i %s), (%i [-%i] tickets in pool), \n",
+               CPU, thread, thread->TID, thread->ThreadName,
+               giFreeTickets, caiTICKET_COUNTS[ thread->Priority ]);
+       # endif
+       return thread;
+       
+       #elif SCHEDULER_TYPE == SCHED_RR_PRI
+       
+       // -----------------------------------
+       // Priority based round robin scheduler
+       // -----------------------------------
+       for( int i = 0; i < MIN_PRIORITY + 1; i ++ )
+       {
+               if( gaActiveThreads[i].Head == NULL )
+                       continue ;
+       
+               tThread *thread = gaActiveThreads[i].Head;
+
+               if( thread->Status != THREAD_STAT_ACTIVE ) {
+                       for( const tThread *t = gaActiveThreads[i].Head; t; t = t->Next )
+                               LogF("- %p(%i %s)\n", t, t->TID, t->ThreadName);
+                       Panic("Thread %p(%i %s) from pqueue %i is active!",
+                               thread, thread->TID, thread->ThreadName, i);
+               }
+
+               // Remove from head
+               gaActiveThreads[i].Head = thread->Next;
+               if(!thread->Next)
+                       gaActiveThreads[i].Tail = NULL;
+               thread->Next = NULL;
+               return thread;
+       }
+       return NULL;
+       
+       #elif SCHEDULER_TYPE == SCHED_RR_SIM
+       
+       // -----------------------------------
+       // Single-list round-robin
+       // -----------------------------------
+       tThread *thread = gActiveThreads.Head;
+       LOG("thread = %p", thread);
+       if( thread )
+       {
+               gActiveThreads.Head = thread->Next;
+               if(!thread->Next)
+                       gaActiveThreads.Tail = NULL;
+               thread->Next = NULL;
+       }
+       return thread;
+       #else
+       # error "Unimplemented scheduling algorithm"
+       return NULL;
+       #endif
+}
+
 /**
  * \brief Gets the next thread to run
  * \param CPU  Current CPU
@@ -1219,50 +1495,29 @@ void Threads_Dump(void)
  */
 tThread *Threads_GetNextToRun(int CPU, tThread *Last)
 {
-       tThread *thread;
-       
-       // If this CPU has the lock, we must let it complete
-       if( CPU_HAS_LOCK( &glThreadListLock ) )
-               return Last;
+       ASSERT( CPU_HAS_LOCK(&glThreadListLock) );
        
        // Don't change threads if the current CPU has switches disabled
-       if( gaThreads_NoTaskSwitch[CPU] )
+       if( gaThreads_NoTaskSwitch[CPU] ) {
+               LOG("- Denied");
                return Last;
-
-       // Lock thread list
-       SHORTLOCK( &glThreadListLock );
+       }
        
        // Make sure the current (well, old) thread is marked as de-scheduled   
        if(Last)        Last->CurCPU = -1;
 
        // No active threads, just take a nap
        if(giNumActiveThreads == 0) {
-               SHORTREL( &glThreadListLock );
+               LOG("- No active");
                #if DEBUG_TRACE_TICKETS
                Log("No active threads");
                #endif
                return NULL;
        }
 
-       #if 0   
-       #if SCHEDULER_TYPE != SCHED_RR_PRI
-       // Special case: 1 thread
-       if(giNumActiveThreads == 1) {
-               if( gActiveThreads.Head->CurCPU == -1 )
-                       gActiveThreads.Head->CurCPU = CPU;
-               
-               SHORTREL( &glThreadListLock );
-               
-               if( gActiveThreads.Head->CurCPU == CPU )
-                       return gActiveThreads.Head;
-               
-               return NULL;    // CPU has nothing to do
-       }
-       #endif
-       #endif  
-
        // Allow the old thread to be scheduled again
-       if( Last ) {
+       if( Last )
+       {
                if( Last->Status == THREAD_STAT_ACTIVE ) {
                        tThreadList     *list;
                        #if SCHEDULER_TYPE == SCHED_LOTTERY
@@ -1281,6 +1536,10 @@ tThread *Threads_GetNextToRun(int CPU, tThread *Last)
                        #endif
                        // Add to end of list
                        Threads_int_AddToList( list, Last );
+                       #if DEBUG_TRACE_ACTIVEQUEUE > 1
+                       Debug("Threads_GetNextToRun: Append thread %p(%i %s)",
+                               Last, Last->TID, Last->ThreadName);
+                       #endif
                }
                #if SCHEDULER_TYPE == SCHED_LOTTERY && DEBUG_TRACE_TICKETS
                else
@@ -1289,131 +1548,34 @@ tThread *Threads_GetNextToRun(int CPU, tThread *Last)
                #endif
                Last->CurCPU = -1;
        }
-       
-       // ---
-       // Lottery Scheduler
-       // ---
-       #if SCHEDULER_TYPE == SCHED_LOTTERY
-       {
-                int    ticket, number;
-               # if 1
-               number = 0;
-               for(thread = gActiveThreads.Head; thread; thread = thread->Next)
-               {
-                       if(thread->Status != THREAD_STAT_ACTIVE)
-                               Panic("Bookkeeping fail - %p %i(%s) is on the active queue with a status of %i",
-                                       thread, thread->TID, thread->ThreadName, thread->Status);
-                       if(thread->Next == thread) {
-                               Panic("Bookkeeping fail - %p %i(%s) loops back on itself",
-                                       thread, thread->TID, thread->ThreadName, thread->Status);
-                       }
-                       number += caiTICKET_COUNTS[ thread->Priority ];
-               }
-               if(number != giFreeTickets) {
-                       Panic("Bookkeeping fail (giFreeTickets(%i) != number(%i)) - CPU%i",
-                               giFreeTickets, number, CPU);
-               }
-               # endif
-               
-               // No free tickets (all tasks delegated to cores)
-               if( giFreeTickets == 0 ) {
-                       SHORTREL(&glThreadListLock);
-                       return NULL;
-               }
-               
-               // Get the ticket number
-               ticket = number = rand() % giFreeTickets;
-               
-               // Find the next thread
-               for(thread = gActiveThreads.Head; thread; prev = thread, thread = thread->Next )
-               {
-                       if( caiTICKET_COUNTS[ thread->Priority ] > number)      break;
-                       number -= caiTICKET_COUNTS[ thread->Priority ];
-               }
-               
-               // If we didn't find a thread, something went wrong
-               if(thread == NULL)
-               {
-                       number = 0;
-                       for(thread=gActiveThreads;thread;thread=thread->Next) {
-                               if(thread->CurCPU >= 0) continue;
-                               number += caiTICKET_COUNTS[ thread->Priority ];
-                       }
-                       Panic("Bookeeping Failed - giFreeTickets(%i) > true count (%i)",
-                               giFreeTickets, number);
-               }
-
-               // Remove
-               if(prev)
-                       prev->Next = thread->Next;
-               else
-                       gActiveThreads.Head = thread->Next;
-               if(!thread->Next)
-                       gActiveThreads.Tail = prev;             
 
-               giFreeTickets -= caiTICKET_COUNTS[ thread->Priority ];
-               # if DEBUG_TRACE_TICKETS
-               LogF("Log: CPU%i allocated %p (%i %s), (%i [-%i] tickets in pool), \n",
-                       CPU, thread, thread->TID, thread->ThreadName,
-                       giFreeTickets, caiTICKET_COUNTS[ thread->Priority ]);
-               # endif
-       }
+       // Call actual scheduler        
+       tThread *thread = Threads_int_GetRunnable();
        
-       // ---
-       // Priority based round robin scheduler
-       // ---
-       #elif SCHEDULER_TYPE == SCHED_RR_PRI
+       // Anything to do?
+       if( thread )
        {
-                int    i;
-               thread = NULL;
-               for( i = 0; i < MIN_PRIORITY + 1; i ++ )
+               if( thread->Status != THREAD_STAT_ACTIVE )
                {
-                       if( !gaActiveThreads[i].Head )
-                               continue ;
-       
-                       thread = gaActiveThreads[i].Head;
-                       
-                       // Remove from head
-                       gaActiveThreads[i].Head = thread->Next;
-                       if(!thread->Next)
-                               gaActiveThreads[i].Tail = NULL;
-                       thread->Next = NULL;
-                       break;
+                       LogF("Thread %p(%i %s) scheduled while not active\n",
+                               thread, thread->TID, thread->ThreadName);
                }
+
+               // Make the new thread non-schedulable
+               thread->CurCPU = CPU;
+               thread->Remaining = thread->Quantum;
                
-               // Anything to do?
-               if( !thread ) {
-                       SHORTREL(&glThreadListLock);
-                       return NULL;
-               }
-               if( thread->Status != THREAD_STAT_ACTIVE ) {
-                       LogF("Oops, Thread %i (%s) is not active\n", thread->TID, thread->ThreadName);
-               }
+               #if DEBUG_TRACE_SCHEDULE
+               Debug("Scheduled "PRIthread_fmt", next = %p",
+                       PRIthread_args(thread),
+                       thread->Next);
+               #endif
        }
-       #elif SCHEDULER_TYPE == SCHED_RR_SIM
+       else
        {
-               // Get the next thread off the list
-               thread = gActiveThreads.Head;   
-               gActiveThreads.Head = thread->Next;
-               if(!thread->Next)
-                       gaActiveThreads.Tail = NULL;
-               thread->Next = NULL;
-               
-               // Anything to do?
-               if( !thread ) {
-                       SHORTREL(&glThreadListLock);
-                       return NULL;
-               }
+               // No thread possible, warning condition (idle thread should be runnable)
+               Warning("No runnable thread for CPU%i", CPU);
        }
-       #else
-       # error "Unimplemented scheduling algorithm"
-       #endif
-       
-       // Make the new thread non-schedulable
-       thread->CurCPU = CPU;
-       thread->Remaining = thread->Quantum;
-       
-       SHORTREL( &glThreadListLock );
        
        return thread;
 }

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