From 3dfb6b5a8cea3724309c1c90cf3d6dc2d3481e76 Mon Sep 17 00:00:00 2001
From: Matheus <matheusuky@gmail.com>
Date: Thu, 16 Apr 2026 22:41:43 -0300
Subject: [PATCH] waitpid: use event instead of busy loop when waiting for
 threads to die

---
 kernel-src/include/kernel/proc.h  |  1 +
 kernel-src/sys/proc.c             | 15 ++++++++++++---
 kernel-src/sys/syscalls/waitpid.c | 15 ++++++++++++---
 kernel-src/sys/thread.c           |  2 ++
 4 files changed, 27 insertions(+), 6 deletions(-)

diff --git a/kernel-src/include/kernel/proc.h b/kernel-src/include/kernel/proc.h
index c251162b..26bf232f 100644
--- a/kernel-src/include/kernel/proc.h
+++ b/kernel-src/include/kernel/proc.h
@@ -36,6 +36,7 @@ typedef struct proc_t {
 	cred_t cred;
 	spinlock_t threadlistlock;
 	thread_t *threadlist;
+	eventheader_t thread_exit_event;
 	bool nomorethreads;
 	size_t runningthreadcount;
 	size_t fdcount;
diff --git a/kernel-src/sys/proc.c b/kernel-src/sys/proc.c
index 6ab27f91..f1fbdaf0 100644
--- a/kernel-src/sys/proc.c
+++ b/kernel-src/sys/proc.c
@@ -107,6 +107,7 @@ proc_t *proc_create() {
 	itimer_init(&proc->timer.profiling, profdpc, proc);
 	SPINLOCK_INIT(proc->threadlistlock);
 	EVENT_INITHEADER(&proc->child_exit_event);
+	EVENT_INITHEADER(&proc->thread_exit_event);
 
 	proc->fd = alloc(sizeof(fd_t) * 3);
 	if (proc->fd == NULL) {
@@ -173,10 +174,18 @@ void proc_stop_other_threads() {
 		threadlist = threadlist->procnext;
 	}
 
-	while (__atomic_load_n(&proc->runningthreadcount, __ATOMIC_SEQ_CST) > 1) {
-		arch_e9_puts("proc_stop_other_threads\n");
-		sched_yield();
+	eventlistener_t listener;
+	EVENT_INITLISTENER(&listener);
+	for (;;) {
+		EVENT_ATTACH(&listener, &proc->thread_exit_event);
+		if (__atomic_load_n(&proc->runningthreadcount, __ATOMIC_SEQ_CST) == 1)
+			break;
+
+		EVENT_WAIT(&listener, 0);
+		EVENT_DETACHALL(&listener);
 	}
+	EVENT_DETACHALL(&listener);
+
 
 	proc->nomorethreads = false;
 }
diff --git a/kernel-src/sys/syscalls/waitpid.c b/kernel-src/sys/syscalls/waitpid.c
index dcb9a885..fb1ab756 100644
--- a/kernel-src/sys/syscalls/waitpid.c
+++ b/kernel-src/sys/syscalls/waitpid.c
@@ -132,10 +132,19 @@ syscallret_t syscall_waitpid(context_t *context, pid_t pid, int *status, int opt
 		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 & THREAD_FLAGS_DEAD) == 0)
-				sched_yield();
+			eventlistener_t listener;
+			EVENT_INITLISTENER(&listener);
+			for (;;) {
+				EVENT_ATTACH(&listener, &iterator->thread_exit_event);
+				if (freethread->flags & THREAD_FLAGS_DEAD) {
+					EVENT_DETACHALL(&listener);
+					break;
+				}
+
+				EVENT_WAIT(&listener, 0);
+				EVENT_DETACHALL(&listener);
+			}
 
 			sched_destroythread(freethread);
 		}
diff --git a/kernel-src/sys/thread.c b/kernel-src/sys/thread.c
index fdbb16f8..e1fee627 100644
--- a/kernel-src/sys/thread.c
+++ b/kernel-src/sys/thread.c
@@ -70,6 +70,8 @@ static void threadexit_internal(context_t *, void *) {
 	current_cpu()->thread = NULL;
 
 	thread->flags |= THREAD_FLAGS_DEAD;
+	if (thread->proc)
+		EVENT_SIGNAL(&thread->proc->thread_exit_event);
 
 	// because a thread deallocating its own data is a nightmare, thread deallocation and such will be left to whoever frees the proc it's tied to
 	// (likely an exit(2) call)