From a51fbb13e8abcbf7682d5c6fac2a825afc1cc298 Mon Sep 17 00:00:00 2001
From: Tom <tomut@yahoo.com>
Date: Thu, 14 Jan 2021 19:14:10 -0700
Subject: [PATCH] Kernel: Make Locker remember whether the lock is held

This allows temporarily unlocking a lock or re-locking it, and it will
only unlock if it is still being held.

Fixes #4352
---
 Kernel/Lock.h | 21 ++++++++++++++++++---
 1 file changed, 18 insertions(+), 3 deletions(-)

diff --git a/Kernel/Lock.h b/Kernel/Lock.h
index 4d5e8bd6f98..9756587a3ff 100644
--- a/Kernel/Lock.h
+++ b/Kernel/Lock.h
@@ -110,12 +110,27 @@ public:
     {
         m_lock.lock(mode);
     }
-    ALWAYS_INLINE ~Locker() { unlock(); }
-    ALWAYS_INLINE void unlock() { m_lock.unlock(); }
-    ALWAYS_INLINE void lock(Lock::Mode mode = Lock::Mode::Exclusive) { m_lock.lock(mode); }
+    ALWAYS_INLINE ~Locker()
+    {
+        if (m_locked)
+            unlock();
+    }
+    ALWAYS_INLINE void unlock()
+    {
+        ASSERT(m_locked);
+        m_locked = false;
+        m_lock.unlock();
+    }
+    ALWAYS_INLINE void lock(Lock::Mode mode = Lock::Mode::Exclusive)
+    {
+        ASSERT(!m_locked);
+        m_locked = true;
+        m_lock.lock(mode);
+    }
 
 private:
     Lock& m_lock;
+    bool m_locked { true };
 };
 
 #ifdef LOCK_DEBUG