Kernel: Fix some problems with Thread::wait_on and Lock

This changes the Thread::wait_on function to not enable interrupts
upon leaving, which caused some problems with page fault handlers
and in other situations. It may now be called from critical
sections, with interrupts enabled or disabled, and returns to the
same state.

This also requires some fixes to Lock. To aid debugging, a new
define LOCK_DEBUG is added that enables checking for Lock leaks
upon finalization of a Thread.

1 files changed, 3 insertions, 4 deletions

diff --git a/Kernel/VM/Region.cpp b/Kernel/VM/Region.cpp
index 9552264eb1..4182dee77c 100644
--- a/Kernel/VM/Region.cpp
+++ b/Kernel/VM/Region.cpp
@@ -474,10 +474,9 @@ PageFaultResponse Region::handle_inode_fault(size_t page_index_in_region)
     ASSERT_INTERRUPTS_DISABLED();
     ASSERT(vmobject().is_inode());
 
-    sti();
     LOCKER(vmobject().m_paging_lock);
-    cli();
 
+    ASSERT_INTERRUPTS_DISABLED();
     auto& inode_vmobject = static_cast<InodeVMObject&>(vmobject());
     auto& vmobject_physical_page_entry = inode_vmobject.physical_pages()[first_page_index() + page_index_in_region];
 
@@ -501,7 +500,7 @@ PageFaultResponse Region::handle_inode_fault(size_t page_index_in_region)
 #ifdef MM_DEBUG
     dbg() << "MM: page_in_from_inode ready to read from inode";
 #endif
-    sti();
+
     u8 page_buffer[PAGE_SIZE];
     auto& inode = inode_vmobject.inode();
     auto buffer = UserOrKernelBuffer::for_kernel_buffer(page_buffer);
@@ -514,7 +513,7 @@ PageFaultResponse Region::handle_inode_fault(size_t page_index_in_region)
         // If we read less than a page, zero out the rest to avoid leaking uninitialized data.
         memset(page_buffer + nread, 0, PAGE_SIZE - nread);
     }
-    cli();
+
     vmobject_physical_page_entry = MM.allocate_user_physical_page(MemoryManager::ShouldZeroFill::No);
     if (vmobject_physical_page_entry.is_null()) {
         klog() << "MM: handle_inode_fault was unable to allocate a physical page";