Fix D3D12 Surface Leak

wgpu-core/src/device/global.rs

@@ -2134,7 +2134,7 @@ impl<G: GlobalIdentityHandlerFactory> Global<G> {
 
         let (mut surface_guard, mut token) = self.surfaces.write(&mut token);
         let (adapter_guard, mut token) = hub.adapters.read(&mut token);
-        let (device_guard, _token) = hub.devices.read(&mut token);
+        let (device_guard, mut token) = hub.devices.read(&mut token);
 
         let error = 'outer: loop {
             let device = match device_guard.get(device_id) {
@@ -2207,6 +2207,24 @@ impl<G: GlobalIdentityHandlerFactory> Global<G> {
                 break error;
             }
 
+            // Wait for all work to finish before configuring the surface.
+            if let Err(e) = device.maintain(hub, wgt::Maintain::Wait, &mut token) {
+                break e.into();
+            }
+
+            // All textures must be destroyed before the surface can be re-configured.
+            if let Some(present) = surface.presentation.take() {
+                if present.acquired_texture.is_some() {
+                    break E::PreviousOutputExists;
+                }
+            }
+
+            // TODO: Texture views may still be alive that point to the texture.
+            // this will allow the user to render to the surface texture, long after
+            // it has been removed.
+            //
+            // https://github.com/gfx-rs/wgpu/issues/4105
+
             match unsafe {
                 A::get_surface_mut(surface)
                     .unwrap()
@@ -2226,12 +2244,6 @@ impl<G: GlobalIdentityHandlerFactory> Global<G> {
                 }
             }
 
-            if let Some(present) = surface.presentation.take() {
-                if present.acquired_texture.is_some() {
-                    break E::PreviousOutputExists;
-                }
-            }
-
             surface.presentation = Some(present::Presentation {
                 device_id: Stored {
                     value: id::Valid(device_id),

wgpu-core/src/device/mod.rs

@@ -1,6 +1,5 @@
 use crate::{
     binding_model,
-    device::life::WaitIdleError,
     hal_api::HalApi,
     hub::Hub,
     id,
@@ -24,7 +23,7 @@ pub mod queue;
 pub mod resource;
 #[cfg(any(feature = "trace", feature = "replay"))]
 pub mod trace;
-pub use resource::Device;
+pub use {life::WaitIdleError, resource::Device};
 
 pub const SHADER_STAGE_COUNT: usize = 3;
 // Should be large enough for the largest possible texture row. This

wgpu-core/src/present.rs

@@ -15,7 +15,7 @@ use std::borrow::Borrow;
 use crate::device::trace::Action;
 use crate::{
     conv,
-    device::{DeviceError, MissingDownlevelFlags},
+    device::{DeviceError, MissingDownlevelFlags, WaitIdleError},
     global::Global,
     hal_api::HalApi,
     hub::Token,
@@ -96,6 +96,18 @@ pub enum ConfigureSurfaceError {
     },
     #[error("Requested usage is not supported")]
     UnsupportedUsage,
+    #[error("Gpu got stuck :(")]
+    StuckGpu,
+}
+
+impl From<WaitIdleError> for ConfigureSurfaceError {
+    fn from(e: WaitIdleError) -> Self {
+        match e {
+            WaitIdleError::Device(d) => ConfigureSurfaceError::Device(d),
+            WaitIdleError::WrongSubmissionIndex(..) => unreachable!(),
+            WaitIdleError::StuckGpu => ConfigureSurfaceError::StuckGpu,
+        }
+    }
 }
 
 #[repr(C)]

wgpu-hal/src/dx12/device.rs

@@ -181,7 +181,10 @@ impl super::Device {
         })
     }
 
-    pub(super) unsafe fn wait_idle(&self) -> Result<(), crate::DeviceError> {
+    // Blocks until the dedicated present queue is finished with all of its work.
+    //
+    // Once this method completes, the surface is able to be resized or deleted.
+    pub(super) unsafe fn wait_for_present_queue_idle(&self) -> Result<(), crate::DeviceError> {
         let cur_value = self.idler.fence.get_value();
         if cur_value == !0 {
             return Err(crate::DeviceError::Lost);

wgpu-hal/src/dx12/mod.rs

@@ -613,19 +613,23 @@ impl crate::Surface<Api> for Surface {
         let mut flags = dxgi::DXGI_SWAP_CHAIN_FLAG_FRAME_LATENCY_WAITABLE_OBJECT;
         // We always set ALLOW_TEARING on the swapchain no matter
         // what kind of swapchain we want because ResizeBuffers
-        // cannot change if ALLOW_TEARING is applied to the swapchain.
+        // cannot change the swapchain's ALLOW_TEARING flag.
+        //
+        // This does not change the behavior of the swapchain, just
+        // allow present calls to use tearing.
         if self.supports_allow_tearing {
             flags |= dxgi::DXGI_SWAP_CHAIN_FLAG_ALLOW_TEARING;
         }
 
+        // While `configure`s contract ensures that no work on the GPU's main queues
+        // are in flight, we still need to wait for the present queue to be idle.
+        unsafe { device.wait_for_present_queue_idle() }?;
+
         let non_srgb_format = auxil::dxgi::conv::map_texture_format_nosrgb(config.format);
 
         let swap_chain = match self.swap_chain.take() {
             //Note: this path doesn't properly re-initialize all of the things
             Some(sc) => {
-                // can't have image resources in flight used by GPU
-                let _ = unsafe { device.wait_idle() };
-
                 let raw = unsafe { sc.release_resources() };
                 let result = unsafe {
                     raw.ResizeBuffers(
@@ -773,12 +777,16 @@ impl crate::Surface<Api> for Surface {
     }
 
     unsafe fn unconfigure(&mut self, device: &Device) {
-        if let Some(mut sc) = self.swap_chain.take() {
+        if let Some(sc) = self.swap_chain.take() {
             unsafe {
-                let _ = sc.wait(None);
-                //TODO: this shouldn't be needed,
-                // but it complains that the queue is still used otherwise
-                let _ = device.wait_idle();
+                // While `unconfigure`s contract ensures that no work on the GPU's main queues
+                // are in flight, we still need to wait for the present queue to be idle.
+
+                // The major failure mode of this function is device loss,
+                // which if we have lost the device, we should just continue
+                // cleaning up, without error.
+                let _ = device.wait_for_present_queue_idle();
+
                 let _raw = sc.release_resources();
             }
         }
@@ -837,6 +845,13 @@ impl crate::Queue<Api> for Queue {
                 .signal(&fence.raw, value)
                 .into_device_result("Signal fence")?;
         }
+
+        // Note the lack of synchronization here between the main Direct queue
+        // and the dedicated presentation queue. This is automatically handled
+        // by the D3D runtime by detecting uses of resources derived from the
+        // swapchain. This automatic detection is why you cannot use a swapchain
+        // as an UAV in D3D12.
+
         Ok(())
     }
     unsafe fn present(

wgpu-hal/src/lib.rs

@@ -194,12 +194,28 @@ pub trait Instance<A: Api>: Sized + WasmNotSend + WasmNotSync {
 }
 
 pub trait Surface<A: Api>: WasmNotSend + WasmNotSync {
+    /// Configures the surface to use the given device.
+    ///
+    /// # Safety
+    ///
+    /// - All gpu work that uses the surface must have been completed.
+    /// - All [`AcquiredSurfaceTexture`]s must have been destroyed.
+    /// - All [`Api::TextureView`]s derived from the [`AcquiredSurfaceTexture`]s must have been destroyed.
+    /// - All surfaces created using other devices must have been unconfigured before this call.
     unsafe fn configure(
         &mut self,
         device: &A::Device,
         config: &SurfaceConfiguration,
     ) -> Result<(), SurfaceError>;
 
+    /// Unconfigures the surface on the given device.
+    ///
+    /// # Safety
+    ///
+    /// - All gpu work that uses the surface must have been completed.
+    /// - All [`AcquiredSurfaceTexture`]s must have been destroyed.
+    /// - All [`Api::TextureView`]s derived from the [`AcquiredSurfaceTexture`]s must have been destroyed.
+    /// - The surface must have been configured on the given device.
     unsafe fn unconfigure(&mut self, device: &A::Device);
 
     /// Returns the next texture to be presented by the swapchain for drawing

wgpu-hal/src/vulkan/device.rs

@@ -1143,7 +1143,7 @@ impl crate::Device<super::Api> for super::Device {
         }
 
         if desc.anisotropy_clamp != 1 {
-            // We only enable anisotropy if it is supported, and wgpu-hal interface guarentees
+            // We only enable anisotropy if it is supported, and wgpu-hal interface guarantees
             // the clamp is in the range [1, 16] which is always supported if anisotropy is.
             vk_info = vk_info
                 .anisotropy_enable(true)

wgpu-hal/src/vulkan/instance.rs

@@ -152,12 +152,11 @@ unsafe extern "system" fn debug_utils_messenger_callback(
 }
 
 impl super::Swapchain {
+    /// # Safety
+    ///
+    /// - The device must have been made idle before calling this function.
     unsafe fn release_resources(self, device: &ash::Device) -> Self {
         profiling::scope!("Swapchain::release_resources");
-        {
-            profiling::scope!("vkDeviceWaitIdle");
-            let _ = unsafe { device.device_wait_idle() };
-        };
         unsafe { device.destroy_fence(self.fence, None) };
         self
     }
@@ -794,6 +793,7 @@ impl crate::Surface<super::Api> for super::Surface {
         device: &super::Device,
         config: &crate::SurfaceConfiguration,
     ) -> Result<(), crate::SurfaceError> {
+        // Safety: `configure`'s contract guarantees there are no resources derived from the swapchain in use.
         let old = self
             .swapchain
             .take()
@@ -807,6 +807,7 @@ impl crate::Surface<super::Api> for super::Surface {
 
     unsafe fn unconfigure(&mut self, device: &super::Device) {
         if let Some(sc) = self.swapchain.take() {
+            // Safety: `unconfigure`'s contract guarantees there are no resources derived from the swapchain in use.
             let swapchain = unsafe { sc.release_resources(&device.shared.raw) };
             unsafe { swapchain.functor.destroy_swapchain(swapchain.raw, None) };
         }