From 293a992133d4f9482a726658c8870d27d6d76f34 Mon Sep 17 00:00:00 2001
From: apio <blobs.trading@gmail.com>
Date: Thu, 4 May 2023 23:43:00 +0200
Subject: [PATCH] kernel: Add a kernel_wait_for_event() function to avoid weird
 calls to kernel_wait in kthreads

---
 kernel/src/arch/x86_64/CPU.cpp  | 4 ++--
 kernel/src/main.cpp             | 2 +-
 kernel/src/thread/Scheduler.cpp | 6 ++++++
 kernel/src/thread/Scheduler.h   | 3 +++
 4 files changed, 12 insertions(+), 3 deletions(-)

diff --git a/kernel/src/arch/x86_64/CPU.cpp b/kernel/src/arch/x86_64/CPU.cpp
index 30a28324..19901b5e 100644
--- a/kernel/src/arch/x86_64/CPU.cpp
+++ b/kernel/src/arch/x86_64/CPU.cpp
@@ -128,10 +128,10 @@ void io_thread()
     while (true)
     {
         u8 scancode;
-        while (!scancode_queue.try_pop(scancode)) { kernel_wait(0); }
+        while (!scancode_queue.try_pop(scancode)) kernel_wait_for_event();
 
         char key;
-        if (Keyboard::decode_scancode(scancode).try_set_value(key)) { ConsoleDevice::did_press_key(key); }
+        if (Keyboard::decode_scancode(scancode).try_set_value(key)) ConsoleDevice::did_press_key(key);
     }
 }
 
diff --git a/kernel/src/main.cpp b/kernel/src/main.cpp
index 26fd999a..f6729c5a 100644
--- a/kernel/src/main.cpp
+++ b/kernel/src/main.cpp
@@ -30,7 +30,7 @@ void reap_thread()
 
         dying_threads.consume([](Thread* thread) { Scheduler::reap_thread(thread); });
 
-        kernel_wait(0);
+        kernel_wait_for_event();
     }
 }
 
diff --git a/kernel/src/thread/Scheduler.cpp b/kernel/src/thread/Scheduler.cpp
index cfbf8f20..45887a76 100644
--- a/kernel/src/thread/Scheduler.cpp
+++ b/kernel/src/thread/Scheduler.cpp
@@ -365,6 +365,12 @@ void kernel_wait(pid_t pid)
     kernel_yield();
 }
 
+void kernel_wait_for_event()
+{
+    g_current->state = ThreadState::Waiting;
+    kernel_yield();
+}
+
 [[noreturn]] void kernel_exit()
 {
     g_current->state = ThreadState::Dying;
diff --git a/kernel/src/thread/Scheduler.h b/kernel/src/thread/Scheduler.h
index f34a731d..4816b459 100644
--- a/kernel/src/thread/Scheduler.h
+++ b/kernel/src/thread/Scheduler.h
@@ -56,3 +56,6 @@ extern "C" void kernel_yield();
 void kernel_wait(pid_t pid);
 void kernel_sleep(u64 ms);
 [[noreturn]] void kernel_exit();
+
+// Freezes the current thread until someone else calls wake_up() on this thread.
+void kernel_wait_for_event();