From 8cace3f05003c6cb4d38c36890055f03151c2ad4 Mon Sep 17 00:00:00 2001
From: Richard Qin <richard.qin.x@gmail.com>
Date: Fri, 16 Oct 2026 02:39:56 +0800
Subject: Remove old code

Signed-off-by: Richard Qin <richard.qin.x@gmail.com>
---
 kernel/sync/mutex.cc | 156 ---------------------------------------------------
 1 file changed, 156 deletions(-)
 delete mode 100644 kernel/sync/mutex.cc

(limited to 'kernel/sync/mutex.cc')

diff --git a/kernel/sync/mutex.cc b/kernel/sync/mutex.cc
deleted file mode 100644
index c4d3e9d..0000000
--- a/kernel/sync/mutex.cc
+++ /dev/null
@@ -1,156 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0-or-later */
-/* Copyright (C) 2026 Richard Qin */
-
-/*
- * Mutex — Linux-style sleeping mutex (no PI).
- *
- * Implementation notes (mirroring kernel/locking/mutex.c, simplified):
- *
- *  - Fast path (uncontended): wait_lock_ -> see owner_==null -> claim -> unlock.
- *  - Slow path (contended): enqueue MutexWaiter on stack, sleep, race for
- *    ownership after each wake. unlock() wakes only the head waiter.
- *  - No optimistic spin, no handoff anti-starvation, no interruptible wait.
- *    These belong to follow-up work (see mutex.md §5).
- *
- * Reference: docs/specs/mutex.md
- */
-
-#include <lume/mutex.h>
-#include <lume/task.h>
-#include <lume/sched.h>
-#include <lume/klog.h>
-#include <arch/cpu.h>
-
-namespace {
-
-struct MutexWaiter {
-    list_node          link;
-    TaskControlBlock*  task;
-};
-
-} // namespace
-
-/* ------------------------------------------------------------------ */
-/*  init                                                              */
-/* ------------------------------------------------------------------ */
-
-void Mutex::init(const char* name)
-{
-    owner_ = nullptr;
-    name_  = name;
-    wait_lock_.init(name != nullptr ? name : "mutex");
-    wait_list_.init();
-}
-
-/* ------------------------------------------------------------------ */
-/*  try_lock — non-blocking, safe from any context                    */
-/* ------------------------------------------------------------------ */
-
-bool Mutex::try_lock()
-{
-    LockGuard g(wait_lock_);
-    if (owner_ != nullptr) {
-        return false;
-    }
-    owner_ = current_task();
-    return true;
-}
-
-/* ------------------------------------------------------------------ */
-/*  lock — blocking, must be called in schedulable context            */
-/* ------------------------------------------------------------------ */
-
-void Mutex::lock()
-{
-    TaskControlBlock* curr = current_task();
-
-    if (curr == nullptr) {
-        kernel_panic("Mutex::lock: no current task");
-    }
-    if (curr->preempt_count > 0) {
-        kernel_panic("Mutex::lock: preemption disabled (holding spinlock?)");
-    }
-
-    wait_lock_.acquire();
-
-    if (owner_ == nullptr) {
-        owner_ = curr;
-        wait_lock_.release();
-        return;
-    }
-
-    if (owner_ == curr) {
-        wait_lock_.release();
-        kernel_panic("Mutex::lock: recursive acquire by same task");
-    }
-
-    /* Slow path: enqueue ourselves and sleep until we are head + lock free. */
-    MutexWaiter waiter;
-    waiter.link.init();
-    waiter.task = curr;
-    list_add_tail(&waiter.link, &wait_list_);
-
-    for (;;) {
-        /* Set state inside wait_lock_ so unlock-side sees a coherent view:
-         * either we are on the list AND Sleeping (will be woken), or we
-         * already took ownership above (not in this loop). */
-        curr->state = TaskState::Sleeping;
-        wait_lock_.release();
-
-        schedule();
-
-        wait_lock_.acquire();
-
-        if (owner_ == nullptr && wait_list_.next == &waiter.link) {
-            owner_ = curr;
-            list_del_init(&waiter.link);
-            wait_lock_.release();
-            return;
-        }
-        /* Spurious wake / lost race — keep waiting. */
-    }
-}
-
-/* ------------------------------------------------------------------ */
-/*  unlock                                                            */
-/* ------------------------------------------------------------------ */
-
-void Mutex::unlock()
-{
-    TaskControlBlock* curr = current_task();
-
-    wait_lock_.acquire();
-
-    if (owner_ != curr) {
-        wait_lock_.release();
-        kernel_panic("Mutex::unlock: not the owner");
-    }
-
-    owner_ = nullptr;
-
-    if (!wait_list_.is_empty()) {
-        list_node*   first  = wait_list_.next;
-        MutexWaiter* w      = list_entry<MutexWaiter, &MutexWaiter::link>(first);
-        TaskControlBlock* victim = w->task;
-
-        /* Race-tolerant wake: only enqueue if still sleeping. If the
-         * waiter is already Runnable (e.g. it was already woken by a
-         * timer-driven schedule reentry and didn't yet retry the lock),
-         * sched_enqueue would double-link it. */
-        if (victim->state == TaskState::Sleeping) {
-            victim->state = TaskState::Runnable;
-            sched_enqueue(victim);
-        }
-    }
-
-    wait_lock_.release();
-}
-
-/* ------------------------------------------------------------------ */
-/*  Debug accessors                                                   */
-/* ------------------------------------------------------------------ */
-
-bool Mutex::is_owned_by_current() const
-{
-    return owner_ == current_task();
-}
-- 
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