Fix the underlying problem that caused the issue of running threads being

enqueued into the run_queue again. Modified the workaround to a panic in the
scheduler so we notice when something else does the same.

git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@23731 a95241bf-73f2-0310-859d-f6bbb57e9c96

src/system/kernel/scheduler.cpp

@@ -219,17 +219,9 @@ scheduler_reschedule(void)
 
 			if (nextThread->cpu
 				&& nextThread->cpu->cpu_num != oldThread->cpu->cpu_num) {
-				// ToDo: This thread is still running on another CPU. The
+				panic("thread in run queue that's still running on another CPU!\n");
-				// thread just missed a semaphore, put itself into the notify
+				// ToDo: remove this check completely when we're sure that this
-				// queue but was not yet rescheduled. During this time frame
+				// cannot happen anymore.
-				// release_sem_etc() was called for said semaphore and put the
-				// thread into the run queue to notify it.
-				// Therefore it is now _still_ running on one CPU and _already_
-				// part of the run queue again. We have to skip this thread
-				// here because otherwise we would overwrite the thread->cpu
-				// pointer with the current CPU which would make both CPUs
-				// "think" they are the same one and kill off the scheduler
-				// logic in here as well as all calls to smp_get_current_cpu().
 				prevThread = nextThread;
 				nextThread = nextThread->queue_next;
 				continue;

src/system/kernel/sem.cpp

@@ -1065,7 +1065,6 @@ release_sem_etc(sem_id id, int32 count, uint32 flags)
 				// release this thread
 				thread = thread_dequeue(&sSems[slot].u.used.queue);
 				thread_enqueue(thread, &releaseQueue);
-				thread->state = B_THREAD_READY;
 				thread->sem.count = 0;
 			}
 		} else if (flags & B_RELEASE_IF_WAITING_ONLY)
@@ -1091,7 +1090,12 @@ release_sem_etc(sem_id id, int32 count, uint32 flags)
 			thread->next_priority = thread->priority >= B_FIRST_REAL_TIME_PRIORITY ?
 				thread->priority : thread->priority + 1;
 #endif
-			scheduler_enqueue_in_run_queue(thread);
+			if (thread->state == B_THREAD_RUNNING)
+				thread->next_state = B_THREAD_READY;
+			else {
+				thread->state = B_THREAD_READY;
+				scheduler_enqueue_in_run_queue(thread);
+			}
 		}
 		if ((flags & B_DO_NOT_RESCHEDULE) == 0)
 			scheduler_reschedule();