Make submission index lockable.

Author: Vecvec

wgpu-core/src/device/queue.rs

@@ -1068,11 +1068,10 @@ impl Queue {
 
             // Fence lock must be acquired after the snatch lock everywhere to avoid deadlocks.
             let mut fence = self.device.fence.write();
-            submit_index = self
-                .device
-                .active_submission_index
-                .fetch_add(1, Ordering::SeqCst)
-                + 1;
+
+            let mut command_index_guard = self.device.command_indices.write();
+            command_index_guard.active_submission_index += 1;
+            submit_index = command_index_guard.active_submission_index;
             let mut active_executions = Vec::new();
 
             let mut used_surface_textures = track::TextureUsageScope::default();
@@ -1292,6 +1291,8 @@ impl Queue {
                     break 'error Err(e.into());
                 }
 
+                drop(command_index_guard);
+
                 // Advance the successful submission index.
                 self.device
                     .last_successful_submission_index

wgpu-core/src/device/resource.rs

@@ -62,6 +62,17 @@ use core::sync::atomic::AtomicU64;
 #[cfg(not(supports_64bit_atomics))]
 use portable_atomic::AtomicU64;
 
+pub(crate) struct CommandIndices {
+    /// The index of the last command submission that was attempted.
+    ///
+    /// Note that `fence` may never be signalled with this value, if the command
+    /// submission failed. If you need to wait for everything running on a
+    /// `Queue` to complete, wait for [`last_successful_submission_index`].
+    ///
+    /// [`last_successful_submission_index`]: Device::last_successful_submission_index
+    pub(crate) active_submission_index: hal::FenceValue,
+}
+
 /// Structure describing a logical device. Some members are internally mutable,
 /// stored behind mutexes.
 pub struct Device {
@@ -74,14 +85,7 @@ pub struct Device {
 
     pub(crate) command_allocator: command::CommandAllocator,
 
-    /// The index of the last command submission that was attempted.
-    ///
-    /// Note that `fence` may never be signalled with this value, if the command
-    /// submission failed. If you need to wait for everything running on a
-    /// `Queue` to complete, wait for [`last_successful_submission_index`].
-    ///
-    /// [`last_successful_submission_index`]: Device::last_successful_submission_index
-    pub(crate) active_submission_index: hal::AtomicFenceValue,
+    pub(crate) command_indices: RwLock<CommandIndices>,
 
     /// The index of the last successful submission to this device's
     /// [`hal::Queue`].
@@ -91,7 +95,7 @@ pub struct Device {
     /// so waiting for this value won't hang waiting for work that was never
     /// submitted.
     ///
-    /// [`active_submission_index`]: Device::active_submission_index
+    /// [`active_submission_index`]: CommandIndices::active_submission_index
     pub(crate) last_successful_submission_index: hal::AtomicFenceValue,
 
     // NOTE: if both are needed, the `snatchable_lock` must be consistently acquired before the
@@ -276,7 +280,13 @@ impl Device {
             zero_buffer: ManuallyDrop::new(zero_buffer),
             label: desc.label.to_string(),
             command_allocator,
-            active_submission_index: AtomicU64::new(0),
+            command_indices: RwLock::new(
+                rank::DEVICE_COMMAND_INDICES,
+                CommandIndices {
+                    active_submission_index: 0,
+                    // By starting at one, we can put the result in a NonZeroU64.
+                },
+            ),
             last_successful_submission_index: AtomicU64::new(0),
             fence: RwLock::new(rank::DEVICE_FENCE, ManuallyDrop::new(fence)),
             snatchable_lock: unsafe { SnatchLock::new(rank::DEVICE_SNATCHABLE_LOCK) },

wgpu-core/src/lock/rank.rs

@@ -130,7 +130,8 @@ define_lock_ranks! {
 
     rank BUFFER_BIND_GROUPS "Buffer::bind_groups" followed by { }
     rank BUFFER_INITIALIZATION_STATUS "Buffer::initialization_status" followed by { }
-    rank DEVICE_DEFERRED_DESTROY "Device::deferred_destroy" followed by { }
+    rank DEVICE_COMMAND_INDICES "Device::command_indices" followed by {}
+    rank DEVICE_DEFERRED_DESTROY "Device::deferred_destroy" followed by {}
     rank DEVICE_FENCE "Device::fence" followed by { }
     #[allow(dead_code)]
     rank DEVICE_TRACE "Device::trace" followed by { }