scheduler: use a linked list for threads in a process instead of a table

kernel-src/sys/scheduler.c

@@ -50,23 +50,14 @@ proc_t *sched_getprocfrompid(int pid) {
 }
 
 static void rtdpc(context_t *, dpcarg_t arg) {
-	proc_t *proc = arg;
-	// XXX this can sleep and if it does the entire system burns down sooooooo yeah fix this for the love of god
-	__assert(proc->threadtablesize == 1);
 	signal_signalproc(arg, SIGALRM);
 }
 
 static void vtdpc(context_t *, dpcarg_t arg) {
-	proc_t *proc = arg;
-	// XXX this can sleep and if it does the entire system burns down sooooooo yeah fix this for the love of god
-	__assert(proc->threadtablesize == 1);
 	signal_signalproc(arg, SIGVTALRM);
 }
 
 static void profdpc(context_t *, dpcarg_t arg) {
-	proc_t *proc = arg;
-	// XXX this can sleep and if it does the entire system burns down sooooooo yeah fix this for the love of god
-	__assert(proc->threadtablesize == 1);
 	signal_signalproc(arg, SIGPROF);
 }
 
@@ -77,15 +68,8 @@ proc_t *sched_newproc() {
 
 	memset(proc, 0, sizeof(proc_t));
 
-	proc->threads = alloc(sizeof(thread_t *));
-	if (proc->threads == NULL) {
-		slab_free(processcache, proc);
-		return NULL;
-	}
-
 	// TODO move this to slab
 	proc->state = SCHED_PROC_STATE_NORMAL;
-	proc->threadtablesize = 1;
 	proc->runningthreadcount = 1;
 	MUTEX_INIT(&proc->mutex);
 	SPINLOCK_INIT(proc->nodeslock);
@@ -101,10 +85,10 @@ proc_t *sched_newproc() {
 	itimer_init(&proc->timer.realtime, rtdpc, proc);
 	itimer_init(&proc->timer.virtualtime, vtdpc, proc);
 	itimer_init(&proc->timer.profiling, profdpc, proc);
+	SPINLOCK_INIT(proc->threadlistlock);
 
 	proc->fd = alloc(sizeof(fd_t) * 3);
 	if (proc->fd == NULL) {
-		free(proc->threads);
 		slab_free(processcache, proc);
 		return NULL;
 	}
@@ -117,7 +101,6 @@ proc_t *sched_newproc() {
 	if (hashtable_set(&pidtable, proc, &proc->pid, sizeof(proc->pid), true)) {
 		MUTEX_RELEASE(&sched_pidtablemutex);
 		free(proc->fd);
-		free(proc->threads);
 		slab_free(processcache, proc);
 		return NULL;
 	}
@@ -168,7 +151,6 @@ void sched_destroythread(thread_t *thread) {
 }
 
 void sched_destroyproc(proc_t *proc) {
-	free(proc->threads);
 	free(proc->fd);
 	slab_free(processcache, proc);
 }
@@ -353,8 +335,9 @@ void sched_procexit() {
 	signal_signalproc(proc->parent, SIGCHLD);
 	semaphore_signal(&proc->parent->waitsem);
 	// TODO sigaction flag for this
-	for (int i = 0; i < belowzombiecount; ++i)
+	for (int i = 0; i < belowzombiecount; ++i) {
 		semaphore_signal(&sched_initproc->waitsem);
+	}
 }
 
 void sched_inactiveproc(proc_t *proc) {
@@ -469,21 +452,31 @@ __attribute__((no_caller_saved_registers)) void sched_userspacecheck(context_t *
 void sched_stopotherthreads() {
 	thread_t *thread = _cpu()->thread;
 	proc_t *proc = thread->proc;
-	MUTEX_ACQUIRE(&proc->mutex, false);
+
+	bool intstatus = interrupt_set(false);
+	spinlock_acquire(&proc->threadlistlock);
+
 	proc->nomorethreads = true;
+	thread_t *threadlist = proc->threadlist;
 
-	for (int i = 0; i < proc->threadtablesize; ++i) {
-		if (proc->threads[i] == NULL || proc->threads[i] == thread)
+	spinlock_release(&proc->threadlistlock);
+	interrupt_set(intstatus);
+
+	while (threadlist) {
+		if (threadlist == thread) {
+			threadlist = threadlist->procnext;
 			continue;
+		}
 
-		proc->threads[i]->shouldexit = true;
-		sched_wakeup(proc->threads[i], SCHED_WAKEUP_REASON_INTERRUPTED);
-		proc->threads[i] = NULL;
+		threadlist->shouldexit = true;
+		sched_wakeup(threadlist, SCHED_WAKEUP_REASON_INTERRUPTED);
+		threadlist = threadlist->procnext;
 	}
 
-	MUTEX_RELEASE(&proc->mutex);
-
-	while (__atomic_load_n(&proc->runningthreadcount, __ATOMIC_SEQ_CST) > 1) sched_yield();
+	while (__atomic_load_n(&proc->runningthreadcount, __ATOMIC_SEQ_CST) > 1) {
+		arch_e9_puts("sched_stopotherthreads\n");
+		sched_yield();
+	}
 
 	proc->nomorethreads = false;
 }
@@ -809,7 +802,8 @@ void sched_runinit() {
 	thread_t *uthread = sched_newthread(entry, PAGE_SIZE * 16, 1, proc, stack);
 	__assert(uthread);
 
-	proc->threads[0] = uthread;
+	proc->threadlist = uthread;
+	uthread->procnext = NULL;
 
 	uthread->vmmctx = vmmctx;
 	sched_queue(uthread);

kernel-src/sys/signal.c

@@ -161,7 +161,6 @@ void signal_signalthread(struct thread_t *thread, int signal, bool urgent) {
 
 void signal_signalproc(struct proc_t *proc, int signal) {
 	// first, check if any threads have the signal unmasked, and set as pending for the first one
-	MUTEX_ACQUIRE(&proc->mutex, false);
 	PROCESS_ENTER(proc);
 	void *address = proc->signals.actions[signal].address;
 	bool notignored = address != SIG_IGN && ((address == SIG_DFL && signal_defaultactions[signal] != ACTION_IGN) || address != SIG_DFL);
@@ -172,28 +171,31 @@ void signal_signalproc(struct proc_t *proc, int signal) {
 
 	// TODO is one thread has a stop signal masked, the masked wait breaks completely
 
-	for (int i = 0; i < proc->threadtablesize; ++i) {
-		if (proc->threads[i] == NULL || (proc->threads[i]->flags & SCHED_THREAD_FLAGS_DEAD))
+	thread_t *thread = proc->threadlist;
+	while (thread) {
+		if (thread->flags & SCHED_THREAD_FLAGS_DEAD) {
+			thread = thread->procnext;
 			continue;
+		}
 
-		THREAD_ENTER(proc->threads[i]);
+		THREAD_ENTER(thread);
 
-		if (SIGNAL_GET(&proc->threads[i]->signals.mask, signal) == 0 || notignorable) {
-			SIGNAL_SETON(&proc->threads[i]->signals.pending, signal);
+		if (SIGNAL_GET(&thread->signals.mask, signal) == 0 || notignorable) {
+			SIGNAL_SETON(&thread->signals.pending, signal);
 			if (notignored || notignorable) {
 				int reason = SCHED_WAKEUP_REASON_INTERRUPTED;
-				if (proc->threads[i]->signals.stopped && (signal == SIGCONT || signal == SIGKILL)) {
+				if (thread->signals.stopped && (signal == SIGCONT || signal == SIGKILL)) {
 					// thread is stopped and we have to wake it up
-					proc->threads[i]->signals.stopped = false;
+					thread->signals.stopped = false;
 					reason = 0; // wake it up from the non interruptible sleep
 					threadcontinued = true;
 				} else if (signal == SIGCONT) {
 					// thread is not stopped, ignore SIGCONT
-					SIGNAL_SETOFF(&proc->threads[i]->signals.pending, signal);
+					SIGNAL_SETOFF(&thread->signals.pending, signal);
 					goto threadleave;
 				}
 
-				sched_wakeup(proc->threads[i], reason);
+				sched_wakeup(thread, reason);
 				// TODO ipi if running isn't self
 			}
 
@@ -201,19 +203,23 @@ void signal_signalproc(struct proc_t *proc, int signal) {
 			// XXX possible race condition where a thread will change the process mask or the action of stopping signals
 			// after it was sent to everyone
 			if ((shouldstop || signal == SIGCONT) == false) {
-				THREAD_LEAVE(proc->threads[i]);
+				THREAD_LEAVE(thread);
 				PROCESS_LEAVE(proc);
-				MUTEX_RELEASE(&proc->mutex);
+				spinlock_release(&proc->threadlistlock);
 				return;
 			}
 		}
 
 		threadleave:
-		THREAD_LEAVE(proc->threads[i]);
+		THREAD_LEAVE(thread);
+		thread = thread->procnext;
 	}
 
+	spinlock_release(&proc->threadlistlock);
+
 	// tell the parent that a child stopped
 	// TODO when stopping make sure that a thread was actually stopped
+	// TODO protect parent with a spinlock
 	if ((notignorable || notignored) && signal_defaultactions[signal] == ACTION_STOP) {
 		proc->status = 0x7f;
 		proc->status |= signal << 8;
@@ -229,14 +235,14 @@ void signal_signalproc(struct proc_t *proc, int signal) {
 	if (threadcontinued) {
 		proc->status = 0xffff;
 		proc->signals.continueunwaited = true;
+
 		if (proc->parent && (proc->parent->signals.actions[SIGCHLD].flags & SA_NOCLDSTOP) == 0) {
 			signal_signalproc(proc->parent, SIGCHLD);
 		}
+
 		semaphore_signal(&proc->parent->waitsem);
 	}
 
-	MUTEX_RELEASE(&proc->mutex);
-
 	// if its ignorable and there wasn't any thread with it unmasked, set it as pending for the whole process
 	// not ignorable signals will be sent to all threads individually
 	if (notignorable == false && (threadcontinued || shouldstop) == false) {

kernel-src/sys/syscalls/fork.c

@@ -46,7 +46,8 @@ syscallret_t syscall_fork(context_t *ctx) {
 	nproc->umask = _cpu()->thread->proc->umask;
 	nproc->root = sched_getroot();
 	nproc->cwd = sched_getcwd();
-	nproc->threads[0] = nthread;
+	nproc->threadlist = nthread;
+	nthread->procnext = NULL;
 
 	ARCH_CONTEXT_THREADSAVE(nthread, ctx);
 

kernel-src/sys/syscalls/newthread.c

@@ -8,6 +8,7 @@ syscallret_t syscall_newthread(context_t *, void *entry, void *stack) {
 		.ret = -1
 	};
 
+	// TODO perhaps clean up threads here as well
 	// if the kernel was specified to have no user threading in the cmdline
 	if (cmdline_get("nomultithread")) {
 		ret.errno = ENOSYS;
@@ -16,53 +17,37 @@ syscallret_t syscall_newthread(context_t *, void *entry, void *stack) {
 
 	proc_t *proc = _cpu()->thread->proc;
 
-	MUTEX_ACQUIRE(&proc->mutex, false);
+	thread_t *thread = sched_newthread(entry, 16 * PAGE_SIZE, 1, _cpu()->thread->proc, stack);
+	if (thread == NULL) {
+		ret.errno = ENOMEM;
+		return ret;
+	}
 
-	// if we currently don't want any more threads to start
-	if (proc->nomorethreads == true) {
-		MUTEX_RELEASE(&proc->mutex);
+	thread->vmmctx = _cpu()->thread->vmmctx;
+
+	bool intstatus = interrupt_set(false);
+	spinlock_acquire(&proc->threadlistlock);
+
+	bool shouldntstart = proc->nomorethreads;
+	if (shouldntstart == false) {
+		thread->procnext = proc->threadlist;
+		proc->threadlist = thread;
+		__atomic_fetch_add(&proc->runningthreadcount, 1, __ATOMIC_SEQ_CST);
+	}
+
+	spinlock_release(&proc->threadlistlock);
+	interrupt_set(intstatus);
+
+	if (shouldntstart) {
+		sched_destroythread(thread);
 		ret.errno = EAGAIN;
 		return ret;
 	}
 
-	int i;
-	for (i = 0; i < proc->threadtablesize; ++i) {
-		thread_t *thread = proc->threads[i];
-		if (thread == NULL || (thread->flags & SCHED_THREAD_FLAGS_DEAD) == 0)
-			continue;
-
-		// reuse the slot in the threads table
-		sched_destroythread(thread);
-		break;
-	}
-
-	if (i == proc->threadtablesize) {
-		// resize it
-		void *tmp = realloc(proc->threads, (proc->threadtablesize + 1) * sizeof(thread_t *));
-		if (tmp == NULL) {
-			ret.errno = ENOMEM;
-			goto cleanup;
-		}
-
-		proc->threads = tmp;
-	}
-
-	proc->threads[i] = sched_newthread(entry, 16 * PAGE_SIZE, 1, _cpu()->thread->proc, stack);
-	if (proc->threads[i] == NULL) {
-		ret.errno = ENOMEM;
-		goto cleanup;
-	}
-
-	proc->threads[i]->vmmctx = _cpu()->thread->vmmctx;
-
 	ret.errno = 0;
-	ret.ret = proc->threads[i]->tid;
+	ret.ret = thread->tid;
 
-	__atomic_fetch_add(&proc->runningthreadcount, 1, __ATOMIC_SEQ_CST);
-
-	sched_queue(proc->threads[i]);
-
-	cleanup:
-	MUTEX_RELEASE(&proc->mutex);
+	if (shouldntstart == false)
+		sched_queue(thread);
 	return ret;
 }

kernel-src/sys/syscalls/waitpid.c

@@ -102,16 +102,26 @@ syscallret_t syscall_waitpid(context_t *context, pid_t pid, int *status, int opt
 
 	MUTEX_RELEASE(&proc->mutex);
 
-	for (int i = 0; i < iterator->threadtablesize && zombie; ++i) {
-		if (iterator->threads[i] == NULL)
-			continue;
+	if (zombie) {
+		bool intstatus = interrupt_set(false);
+		spinlock_acquire(&iterator->threadlistlock);
 
-		volatile int *flags = (volatile int *)(&iterator->threads[i]->flags);
-		// wait until the thread can actually be unallocated
-		while ((*flags & SCHED_THREAD_FLAGS_DEAD) == 0)
-			sched_yield();
+		thread_t *threadlist = iterator->threadlist;
+		iterator->threadlist = NULL;
 
-		sched_destroythread(iterator->threads[i]);
+		spinlock_release(&iterator->threadlistlock);
+		interrupt_set(intstatus);
+
+		while (threadlist) {
+			thread_t *freethread = threadlist;
+			threadlist = threadlist->procnext;
+			volatile int *flags = (volatile int *)(&freethread->flags);
+			// wait until the thread can actually be unallocated
+			while ((*flags & SCHED_THREAD_FLAGS_DEAD) == 0)
+				sched_yield();
+
+			sched_destroythread(freethread);
+		}
 	}
 
 	ret.ret = iterator->pid;