From 6df87b51f7d0193f2f493dab5a6358bda480a72e Mon Sep 17 00:00:00 2001
From: Tom <tomut@yahoo.com>
Date: Thu, 9 Jul 2020 13:51:58 -0600
Subject: [PATCH] Kernel: Protect Inode list with SpinLock (#2748)

Fixes crashes when a context switch happens in the middle
of modifying it, or when another thread on another processor
modifies it at the same time.
---
 Kernel/FileSystem/Inode.cpp | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/Kernel/FileSystem/Inode.cpp b/Kernel/FileSystem/Inode.cpp
index aa1c97b4fa..ec410bcac3 100644
--- a/Kernel/FileSystem/Inode.cpp
+++ b/Kernel/FileSystem/Inode.cpp
@@ -36,8 +36,12 @@
 
 namespace Kernel {
 
+static SpinLock s_all_inodes_lock;
+
 InlineLinkedList<Inode>& all_inodes()
 {
+    ASSERT(s_all_inodes_lock.is_locked());
+
     static InlineLinkedList<Inode>* list;
     if (!list)
         list = new InlineLinkedList<Inode>;
@@ -48,7 +52,7 @@ void Inode::sync()
 {
     NonnullRefPtrVector<Inode, 32> inodes;
     {
-        InterruptDisabler disabler;
+        ScopedSpinLock all_inodes_lock(s_all_inodes_lock);
         for (auto& inode : all_inodes()) {
             if (inode.is_metadata_dirty())
                 inodes.append(inode);
@@ -111,11 +115,13 @@ Inode::Inode(FS& fs, unsigned index)
     : m_fs(fs)
     , m_index(index)
 {
+    ScopedSpinLock all_inodes_lock(s_all_inodes_lock);
     all_inodes().append(this);
 }
 
 Inode::~Inode()
 {
+    ScopedSpinLock all_inodes_lock(s_all_inodes_lock);
     all_inodes().remove(this);
 }