kernel: bootstrap device_number_registry

Previously, the device number registry would only receive devices from
the interface registry that where published **after** the device number
registry was constructed. This introduced a subtle state race, in which
the device number registry would miss devices that already had
published interfaces.

2 files changed, 54 insertions, 37 deletions

diff --git a/kernel/kernel/filesystem/device_number_registry.cpp b/kernel/kernel/filesystem/device_number_registry.cpp
index 92f59bc5..aca0c64c 100644
--- a/kernel/kernel/filesystem/device_number_registry.cpp
+++ b/kernel/kernel/filesystem/device_number_registry.cpp
@@ -37,6 +37,14 @@ namespace kernel::filesystem
   device_number_registry::device_number_registry(kapi::devices::interface_registry & interface_registry)
       : m_interface_registry{&interface_registry}
   {
+    for (auto const & binding : file_type_bindings)
+    {
+      for (auto const & published : interface_registry.all(binding.interface))
+      {
+        try_number(binding.interface, published);
+      }
+    }
+
     m_interface_registry->subscribe(*this);
   }
 
@@ -110,6 +118,49 @@ namespace kernel::filesystem
                                                       kapi::devices::interface_registry::entry const & published)
       -> void
   {
+    try_number(interface, published);
+  }
+
+  auto device_number_registry::on_interface_withdrawn(kapi::devices::interface_id interface,
+                                                      kapi::devices::device & device) -> void
+  {
+    // Check if there even is a binding defined for the given interface.
+    auto binding =
+        std::ranges::find_if(file_type_bindings, [&](auto const & binding) { return binding.interface == interface; });
+    if (binding == std::ranges::cend(file_type_bindings))
+    {
+      return;
+    }
+
+    // TODO: lock registry
+
+    auto found = std::ranges::find_if(m_entries, [&](auto entry) {
+      auto locked = entry.device.lock();
+      return entry.type == binding->posix_type && locked.get() == &device;
+    });
+
+    if (found == std::ranges::cend(m_entries))
+    {
+      m_entries.erase(found);
+    }
+
+    auto unnumbered = *found;
+    m_entries.erase(found);
+
+    // TODO: drop lock
+
+    std::ranges::for_each(m_observers, [&](auto const & weak_observer) {
+      auto observer = weak_observer.lock();
+      if (observer)
+      {
+        observer->on_device_unnumbered(unnumbered);
+      }
+    });
+  }
+
+  auto device_number_registry::try_number(kapi::devices::interface_id interface,
+                                          kapi::devices::interface_registry::entry const & published) -> void
+  {
     // Check if there even is a binding defined for the given interface.
     auto binding =
         std::ranges::find_if(file_type_bindings, [&](auto const & binding) { return binding.interface == interface; });
@@ -171,43 +222,6 @@ namespace kernel::filesystem
       }
     });
   }
-
-  auto device_number_registry::on_interface_withdrawn(kapi::devices::interface_id interface,
-                                                      kapi::devices::device & device) -> void
-  {
-    // Check if there even is a binding defined for the given interface.
-    auto binding =
-        std::ranges::find_if(file_type_bindings, [&](auto const & binding) { return binding.interface == interface; });
-    if (binding == std::ranges::cend(file_type_bindings))
-    {
-      return;
-    }
-
-    // TODO: lock registry
-
-    auto found = std::ranges::find_if(m_entries, [&](auto entry) {
-      auto locked = entry.device.lock();
-      return entry.type == binding->posix_type && locked.get() == &device;
-    });
-
-    if (found == std::ranges::cend(m_entries))
-    {
-      m_entries.erase(found);
-    }
-
-    auto unnumbered = *found;
-    m_entries.erase(found);
-
-    // TODO: drop lock
-
-    std::ranges::for_each(m_observers, [&](auto const & weak_observer) {
-      auto observer = weak_observer.lock();
-      if (observer)
-      {
-        observer->on_device_unnumbered(unnumbered);
-      }
-    });
-  }
 }  // namespace kernel::filesystem
 
 namespace kernel::tests::filesystem::device_number_registry
diff --git a/kernel/kernel/filesystem/device_number_registry.hpp b/kernel/kernel/filesystem/device_number_registry.hpp
index 949d7bba..20a26c22 100644
--- a/kernel/kernel/filesystem/device_number_registry.hpp
+++ b/kernel/kernel/filesystem/device_number_registry.hpp
@@ -83,6 +83,9 @@ namespace kernel::filesystem
 
     auto on_interface_withdrawn(kapi::devices::interface_id interface, kapi::devices::device & device) -> void override;
 
+    auto try_number(kapi::devices::interface_id interface, kapi::devices::interface_registry::entry const & published)
+        -> void;
+
     kstd::observer_ptr<kapi::devices::interface_registry> m_interface_registry;
     mutable kstd::vector<entry> m_entries{};
     kstd::flat_map<kapi::devices::driver const *, std::uint8_t> m_next_minor;