From cbfb59b828dbd095b27d44e88fc77ac024fdea74 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Marco=20Trevisan=20=28Trevi=C3=B1o=29?= <mail@3v1n0.net>
Date: Mon, 22 Mar 2021 17:44:11 +0100
Subject: [PATCH] backends/native: Ignore udev events while we're paused

When the native backend is paused we still process the udev events
even though this isn't needed and may just cause unneeded events to be
triggered afterwards.

Since we'll resume with full changes on such event, we can just block
the signal hander when paused and restore it afterwards.

As per this we can cleanup also a bit the device adding signal handling
given that now we don't have to disconnect/reconnect it again.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1964>
---
 src/backends/native/meta-backend-native.c | 35 ++++-------------------
 src/backends/native/meta-udev.c           | 12 ++++++++
 src/backends/native/meta-udev.h           |  4 +++
 3 files changed, 21 insertions(+), 30 deletions(-)

diff --git a/src/backends/native/meta-backend-native.c b/src/backends/native/meta-backend-native.c
index 81d9629d0..2cc9add75 100644
--- a/src/backends/native/meta-backend-native.c
+++ b/src/backends/native/meta-backend-native.c
@@ -87,8 +87,6 @@ struct _MetaBackendNative
   MetaKms *kms;
 
   gboolean is_headless;
-
-  gulong udev_device_added_handler_id;
 };
 
 static GInitableIface *initable_parent_iface;
@@ -100,20 +98,11 @@ G_DEFINE_TYPE_WITH_CODE (MetaBackendNative, meta_backend_native, META_TYPE_BACKE
                          G_IMPLEMENT_INTERFACE (G_TYPE_INITABLE,
                                                 initable_iface_init))
 
-static void
-disconnect_udev_device_added_handler (MetaBackendNative *native);
-
 static void
 meta_backend_native_dispose (GObject *object)
 {
   MetaBackendNative *native = META_BACKEND_NATIVE (object);
 
-  if (native->udev_device_added_handler_id)
-    {
-      disconnect_udev_device_added_handler (native);
-      native->udev_device_added_handler_id = 0;
-    }
-
   if (native->kms)
     meta_kms_prepare_shutdown (native->kms);
 
@@ -485,20 +474,6 @@ on_udev_device_added (MetaUdev          *udev,
   meta_backend_add_gpu (backend, META_GPU (new_gpu_kms));
 }
 
-static void
-connect_udev_device_added_handler (MetaBackendNative *native)
-{
-  native->udev_device_added_handler_id =
-    g_signal_connect (native->udev, "device-added",
-                      G_CALLBACK (on_udev_device_added), native);
-}
-
-static void
-disconnect_udev_device_added_handler (MetaBackendNative *native)
-{
-  g_clear_signal_handler (&native->udev_device_added_handler_id, native->udev);
-}
-
 static gboolean
 init_gpus (MetaBackendNative  *native,
            GError            **error)
@@ -549,7 +524,9 @@ init_gpus (MetaBackendNative  *native,
       return FALSE;
     }
 
-  connect_udev_device_added_handler (native);
+  g_signal_connect_object (native->udev, "device-added",
+                           G_CALLBACK (on_udev_device_added), native,
+                           0);
 
   return TRUE;
 }
@@ -724,8 +701,7 @@ meta_backend_native_pause (MetaBackendNative *native)
 
   meta_seat_native_release_devices (seat);
   meta_renderer_pause (renderer);
-
-  disconnect_udev_device_added_handler (native);
+  meta_udev_pause (native->udev);
 
   meta_monitor_manager_native_pause (monitor_manager_native);
 }
@@ -749,10 +725,9 @@ void meta_backend_native_resume (MetaBackendNative *native)
                            "Backend (resume)");
 
   meta_monitor_manager_native_resume (monitor_manager_native);
+  meta_udev_resume (native->udev);
   meta_kms_resume (native->kms);
 
-  connect_udev_device_added_handler (native);
-
   meta_seat_native_reclaim_devices (seat);
   meta_renderer_resume (renderer);
 
diff --git a/src/backends/native/meta-udev.c b/src/backends/native/meta-udev.c
index c0e0e165f..16c44dc13 100644
--- a/src/backends/native/meta-udev.c
+++ b/src/backends/native/meta-udev.c
@@ -222,6 +222,18 @@ meta_udev_new (MetaBackendNative *backend_native)
   return udev;
 }
 
+void
+meta_udev_pause (MetaUdev *udev)
+{
+  g_signal_handler_block (udev->gudev_client, udev->uevent_handler_id);
+}
+
+void
+meta_udev_resume (MetaUdev *udev)
+{
+  g_signal_handler_unblock (udev->gudev_client, udev->uevent_handler_id);
+}
+
 static void
 meta_udev_finalize (GObject *object)
 {
diff --git a/src/backends/native/meta-udev.h b/src/backends/native/meta-udev.h
index 7b179329e..4d85c8f04 100644
--- a/src/backends/native/meta-udev.h
+++ b/src/backends/native/meta-udev.h
@@ -44,6 +44,10 @@ gboolean meta_udev_is_drm_device (MetaUdev    *udev,
 GList * meta_udev_list_drm_devices (MetaUdev  *udev,
                                     GError   **error);
 
+void meta_udev_pause (MetaUdev *udev);
+
+void meta_udev_resume (MetaUdev *udev);
+
 MetaUdev * meta_udev_new (MetaBackendNative *backend_native);
 
 #endif /* META_UDEV_H */