Kernel: Don't hold the process list lock while destructing the process

Once we remove the process from the process list, we're free to do
whatever we want without any locks.

1 files changed, 5 insertions, 2 deletions

diff --git a/Kernel/Process.cpp b/Kernel/Process.cpp
index 6c225ab345..9b1a05b078 100644
--- a/Kernel/Process.cpp
+++ b/Kernel/Process.cpp
@@ -302,16 +302,19 @@ bool Process::unref() const
     // NOTE: We need to obtain the process list lock before doing anything,
     //       because otherwise someone might get in between us lowering the
     //       refcount and acquiring the lock.
-    return processes().with_exclusive([&](auto& list) {
+    auto did_hit_zero = processes().with_exclusive([&](auto& list) {
         auto new_ref_count = deref_base();
         if (new_ref_count > 0)
             return false;
 
         if (m_list_node.is_in_list())
             list.remove(*const_cast<Process*>(this));
-        delete this;
         return true;
     });
+
+    if (did_hit_zero)
+        delete this;
+    return did_hit_zero;
 }
 
 // Make sure the compiler doesn't "optimize away" this function: