zwp_pointer_constraints_v1#19: error 1: the surface is already constrained

[Jupeyy]

Description

Hello together, on wayland I experience a bug where when I change the cursor grab mode it crashes the client.
This can be reproduced by going ingame (e.g. on a LAN server) and then tab out and in again.

It's very likely related to the game ungrabbing the mouse when tabbing in/out:
https://github.com/ddnet/ddnet-rs/blob/ee7e250a57f4262023ad0ce1e45ca2e6286815a3/lib/native/src/native/winit_wrapper.rs#L558-L573

Full code can be found here:
https://github.com/ddnet/ddnet-rs

Debugging output

[1625677.395] {mesa vk display queue}  -> wl_surface#27.commit()
[1625677.403] {mesa vk display queue} discarded wl_buffer#178.release()
[1625678.993] wl_pointer#23.enter(32798, wl_surface#27, 1347.05468750, 843.08984375)
[1625679.010] wl_pointer#23.frame()
[1625679.016] zwp_locked_pointer_v1#190.locked()
[1625679.021] zwp_relative_pointer_v1#26.relative_motion(2, 2404437958, -0.80078125, -1.60546875, -1.00000000, -2.00000000)
[1625679.029] wl_pointer#23.frame()
[1625679.033] zwp_relative_pointer_v1#26.relative_motion(2, 2404438960, -1.60546875, -3.21484375, -2.00000000, -4.00000000)
[1625679.040] wl_pointer#23.frame()
[1625679.080]  -> wl_pointer#23.set_cursor(32798, nil, 0, 0)
[1625679.093][rs][discarded] -> zwp_confined_pointer_v1@85.destroy()
[1625679.140]  -> zwp_pointer_constraints_v1#19.confine_pointer(new id zwp_confined_pointer_v1#85, wl_surface#27, wl_pointer#23, nil, 2)
[1625679.387] {Display Queue} wl_display#1.error(zwp_pointer_constraints_v1#19, 1, "the surface is already constrained")
zwp_pointer_constraints_v1#19: error 1: the surface is already constrained
[2025-01-04T14:40:36Z WARN  graphics_backend::backends::vulkan::vulkan] error during swap chain recreation, trying to recover by creating a fake surface: get_physical_device_surface_present_modes failed: ERROR_SURFACE_LOST_KHR
Protocol error 1 on object zwp_pointer_constraints_v1@19: 
Protocol error 1 on object zwp_pointer_constraints_v1@19:

Window isn't shown unless you draw

• I understand that windows aren't shown on Wayland unless I draw and present to them.

Winit version

0.30.7

Small site note: Multiple users from our community with different window managers experienced it

[Jupeyy]

I am (more or less) able to reproduce this with this patch to the window.rs example:

diff --git a/examples/window.rs b/examples/window.rs
index b6077270..9ebc243b 100644
--- a/examples/window.rs
+++ b/examples/window.rs
@@ -17,6 +17,7 @@ mod tracing;
 #[derive(Default, Debug)]
 struct App {
     window: Option<Box<dyn Window>>,
+    i: usize,
 }
 
 impl ApplicationHandler for App {
@@ -36,7 +37,24 @@ impl ApplicationHandler for App {
     }
 
     fn window_event(&mut self, event_loop: &dyn ActiveEventLoop, _: WindowId, event: WindowEvent) {
-        println!("{event:?}");
+        //println!("{event:?}");
+
+        if let Some(window) = &self.window {
+            match (self.i / 1) % 3 {
+                0 => {
+                    window.set_cursor_grab(winit::window::CursorGrabMode::Confined);
+                },
+                1 => {
+                    window.set_cursor_grab(winit::window::CursorGrabMode::Locked);
+                },
+                _ => {
+                    window.set_cursor_grab(winit::window::CursorGrabMode::None);
+                },
+            }
+            self.i += 1;
+            dbg!(self.i);
+        }
+
         match event {
             WindowEvent::CloseRequested => {
                 println!("Close was requested; stopping");
@@ -61,7 +79,7 @@ impl ApplicationHandler for App {
                 fill::fill_window(window.as_ref());
 
                 // For contiguous redraw loop you can request a redraw from here.
-                // window.request_redraw();
+                window.request_redraw();
             },
             _ => (),
         }
@@ -75,6 +93,7 @@ fn main() -> Result<(), Box<dyn Error>> {
     tracing::init();
 
     let event_loop = EventLoop::new()?;
+    event_loop.set_control_flow(winit::event_loop::ControlFlow::Poll);
 
     // For alternative loop run options see `pump_events` and `run_on_demand` examples.
     event_loop.run_app(App::default())?;

Steps to reproduce:

• Move the cursor out and into the window quickly (apparently it's very important for the bug to move the cursor out and in)
• If no crash after ~10 seconds, try unfocus the window

For me it crashes consistently after at most 10 seconds.

[kchibisov]

provide full uncut WAYLAND_DEBUG=1 output.

[Jupeyy]

provide full uncut WAYLAND_DEBUG=1 output.

log too long for github comment:
log.txt

[kchibisov]

Could you test something like that:

diff --git a/src/platform_impl/linux/wayland/window/state.rs b/src/platform_impl/linux/wayland/window/state.rs
index 5e74f7c8..9e943dc2 100644
--- a/src/platform_impl/linux/wayland/window/state.rs
+++ b/src/platform_impl/linux/wayland/window/state.rs
@@ -591,6 +591,7 @@ impl WindowState {
         }

         self.pointers = new_pointers;
+        let _ = self.set_cursor_grab_inner(CursorGrabMode::None);
     }

     /// Refresh the decorations frame if it's present returning whether the client should redraw.

It's in pointer_left function in the same file in case of apply fail to 0.30.

[Jupeyy]

Could you test something like that

Doesn't seem to help

[kchibisov]

diff --git a/src/platform_impl/linux/wayland/window/state.rs b/src/platform_impl/linux/wayland/window/state.rs
index 5e74f7c8..5b628046 100644
--- a/src/platform_impl/linux/wayland/window/state.rs
+++ b/src/platform_impl/linux/wayland/window/state.rs
@@ -591,6 +591,7 @@ impl WindowState {
         }
 
         self.pointers = new_pointers;
+        let _ = self.set_cursor_grab_inner(CursorGrabMode::None);
     }
 
     /// Refresh the decorations frame if it's present returning whether the client should redraw.
@@ -830,6 +831,11 @@ impl WindowState {
             },
         };
 
+        // Don't try to change cursor when we don't have any pointer over the window.
+        if self.pointers.is_empty() {
+            return Ok(());
+        }
+
         // Replace the current mode.
         let old_mode = std::mem::replace(&mut self.cursor_grab_mode.current_grab_mode, mode);
 

If this doesn't help, please provide a WAYLAND_DEBUG=1 log with this patch applied.

[Jupeyy]

Yep that seems to fix it. To me more precise the second half of the patch fixes it, I can comment out the first one and it seems to still work. Thanks!