Kernel+LibC+WindowServer: Remove unused thread/process boost mechanism

The priority boosting mechanism has been broken for a very long time.
Let's remove it from the codebase and we can bring it back the day
someone feels like implementing it in a working way. :^)

Kernel/API/Syscall.h

@@ -177,8 +177,6 @@ namespace Kernel {
     S(profiling_enable)       \
     S(profiling_disable)      \
     S(futex)                  \
-    S(set_thread_boost)       \
-    S(set_process_boost)      \
     S(chroot)                 \
     S(pledge)                 \
     S(unveil)                 \

Kernel/Process.h

@@ -350,8 +350,6 @@ public:
     int sys$profiling_enable(pid_t);
     int sys$profiling_disable(pid_t);
     int sys$futex(Userspace<const Syscall::SC_futex_params*>);
-    int sys$set_thread_boost(pid_t tid, int amount);
-    int sys$set_process_boost(pid_t, int amount);
     int sys$chroot(Userspace<const char*> path, size_t path_length, int mount_flags);
     int sys$pledge(Userspace<const Syscall::SC_pledge_params*>);
     int sys$unveil(Userspace<const Syscall::SC_unveil_params*>);
@@ -467,11 +465,6 @@ public:
         return m_big_lock;
     }
 
-    u32 priority_boost() const
-    {
-        return m_priority_boost;
-    }
-
     Custody& root_directory();
     Custody& root_directory_relative_to_global_root();
     void set_root_directory(const Custody&);
@@ -646,8 +639,6 @@ private:
 
     RefPtr<Timer> m_alarm_timer;
 
-    u32 m_priority_boost { 0 };
-
     u32 m_promises { 0 };
     u32 m_execpromises { 0 };
 
@@ -771,7 +762,7 @@ inline const LogStream& operator<<(const LogStream& stream, const Process& proce
 
 inline u32 Thread::effective_priority() const
 {
-    return m_priority + m_process->priority_boost() + m_priority_boost + m_extra_priority;
+    return m_priority + m_extra_priority;
 }
 
 #define REQUIRE_NO_PROMISES                        \

Kernel/Syscalls/sched.cpp

@@ -104,36 +104,4 @@ int Process::sys$sched_getparam(pid_t pid, Userspace<struct sched_param*> user_p
     return 0;
 }
 
-int Process::sys$set_thread_boost(pid_t tid, int amount)
-{
-    REQUIRE_PROMISE(proc);
-    if (amount < 0 || amount > 20)
-        return -EINVAL;
-    ScopedSpinLock lock(g_scheduler_lock);
-    auto thread = Thread::from_tid(tid);
-    if (!thread)
-        return -ESRCH;
-    if (thread->state() == Thread::State::Dead || thread->state() == Thread::State::Dying)
-        return -ESRCH;
-    if (!is_superuser() && thread->process().uid() != euid())
-        return -EPERM;
-    thread->set_priority_boost(amount);
-    return 0;
-}
-
-int Process::sys$set_process_boost(pid_t pid, int amount)
-{
-    REQUIRE_PROMISE(proc);
-    if (amount < 0 || amount > 20)
-        return -EINVAL;
-    ScopedSpinLock lock(g_processes_lock);
-    auto process = Process::from_pid(pid);
-    if (!process || process->is_dead())
-        return -ESRCH;
-    if (!is_superuser() && process->uid() != euid())
-        return -EPERM;
-    process->m_priority_boost = amount;
-    return 0;
-}
-
 }

Kernel/Thread.h

@@ -102,9 +102,6 @@ public:
     void set_priority(u32 p) { m_priority = p; }
     u32 priority() const { return m_priority; }
 
-    void set_priority_boost(u32 boost) { m_priority_boost = boost; }
-    u32 priority_boost() const { return m_priority_boost; }
-
     u32 effective_priority() const;
 
     void detach()
@@ -1199,7 +1196,6 @@ private:
     String m_name;
     u32 m_priority { THREAD_PRIORITY_NORMAL };
     u32 m_extra_priority { 0 };
-    u32 m_priority_boost { 0 };
 
     State m_stop_state { Invalid };
 

Userland/Libraries/LibC/serenity.cpp

@@ -60,18 +60,6 @@ int profiling_disable(pid_t pid)
     __RETURN_WITH_ERRNO(rc, rc, -1);
 }
 
-int set_thread_boost(pid_t tid, int amount)
-{
-    int rc = syscall(SC_set_thread_boost, tid, amount);
-    __RETURN_WITH_ERRNO(rc, rc, -1);
-}
-
-int set_process_boost(pid_t tid, int amount)
-{
-    int rc = syscall(SC_set_process_boost, tid, amount);
-    __RETURN_WITH_ERRNO(rc, rc, -1);
-}
-
 int futex(int32_t* userspace_address, int futex_op, int32_t value, const struct timespec* timeout)
 {
     Syscall::SC_futex_params params { userspace_address, futex_op, value, timeout };

Userland/Libraries/LibC/serenity.h

@@ -52,9 +52,6 @@ int profiling_disable(pid_t);
 #define THREAD_PRIORITY_HIGH 50
 #define THREAD_PRIORITY_MAX 99
 
-int set_thread_boost(pid_t tid, int amount);
-int set_process_boost(pid_t, int amount);
-
 #define FUTEX_WAIT 1
 #define FUTEX_WAKE 2
 

Userland/Services/WindowServer/ClientConnection.cpp

@@ -770,24 +770,6 @@ OwnPtr<Messages::WindowServer::GetSystemThemeResponse> ClientConnection::handle(
     return make<Messages::WindowServer::GetSystemThemeResponse>(name);
 }
 
-void ClientConnection::boost()
-{
-    // FIXME: Re-enable this when we have a solution for boosting.
-#if 0
-    if (set_process_boost(client_pid(), 10) < 0)
-        perror("boost: set_process_boost");
-#endif
-}
-
-void ClientConnection::deboost()
-{
-    // FIXME: Re-enable this when we have a solution for boosting.
-#if 0
-    if (set_process_boost(client_pid(), 0) < 0)
-        perror("deboost: set_process_boost");
-#endif
-}
-
 OwnPtr<Messages::WindowServer::SetWindowBaseSizeAndSizeIncrementResponse> ClientConnection::handle(const Messages::WindowServer::SetWindowBaseSizeAndSizeIncrement& message)
 {
     auto it = m_windows.find(message.window_id());

Userland/Services/WindowServer/ClientConnection.h

@@ -54,9 +54,6 @@ public:
 
     bool is_unresponsive() const { return m_unresponsive; }
 
-    void boost();
-    void deboost();
-
     static ClientConnection* from_client_id(int client_id);
     static void for_each_client(Function<void(ClientConnection&)>);
 

Userland/Services/WindowServer/WindowManager.cpp

@@ -1239,11 +1239,7 @@ void WindowManager::set_active_window(Window* window, bool make_input)
 
     auto* previously_active_window = m_active_window.ptr();
 
-    ClientConnection* previously_active_client = nullptr;
-    ClientConnection* active_client = nullptr;
-
     if (previously_active_window) {
-        previously_active_client = previously_active_window->client();
         Core::EventLoop::current().post_event(*previously_active_window, make<Event>(Event::WindowDeactivated));
         previously_active_window->invalidate();
         m_active_window = nullptr;
@@ -1253,7 +1249,6 @@ void WindowManager::set_active_window(Window* window, bool make_input)
 
     if (window) {
         m_active_window = *window;
-        active_client = m_active_window->client();
         Core::EventLoop::current().post_event(*m_active_window, make<Event>(Event::WindowActivated));
         m_active_window->invalidate();
         if (auto* client = window->client()) {
@@ -1265,13 +1260,6 @@ void WindowManager::set_active_window(Window* window, bool make_input)
     } else {
         MenuManager::the().set_current_menubar(nullptr);
     }
-
-    if (active_client != previously_active_client) {
-        if (previously_active_client)
-            previously_active_client->deboost();
-        if (active_client)
-            active_client->boost();
-    }
 }
 
 void WindowManager::set_hovered_window(Window* window)