Nouveau - Sep 2025 - [PATCH v2] gpu: nova-core: take advantage of pci::Device::unbind()

Now that we have pci::Device::unbind() we can unregister the sysmem
flush page with a direct access the I/O resource, i.e. without RCU read
side critical section.

Signed-off-by: Danilo Krummrich <dakr at kernel.org>
---
Changes in v2:
  - Use Device<Core>.
  - Add doc-comment.
---
 drivers/gpu/nova-core/driver.rs |  4 ++++
 drivers/gpu/nova-core/gpu.rs    | 22 ++++++++++++----------
 2 files changed, 16 insertions(+), 10 deletions(-)

diff --git a/drivers/gpu/nova-core/driver.rs b/drivers/gpu/nova-core/driver.rs
index 274989ea1fb4..02b3edd7bbdc 100644
--- a/drivers/gpu/nova-core/driver.rs
+++ b/drivers/gpu/nova-core/driver.rs
@@ -54,4 +54,8 @@ fn probe(pdev: &pci::Device<Core>, _info:
&Self::IdInfo) -> Result<Pin<KBox<Self
 
         Ok(this)
     }
+
+    fn unbind(pdev: &pci::Device<Core>, this: Pin<&Self>) {
+        this.gpu.unbind(pdev.as_ref());
+    }
 }
diff --git a/drivers/gpu/nova-core/gpu.rs b/drivers/gpu/nova-core/gpu.rs
index 8caecaf7dfb4..80a54e303663 100644
--- a/drivers/gpu/nova-core/gpu.rs
+++ b/drivers/gpu/nova-core/gpu.rs
@@ -163,7 +163,7 @@ fn new(bar: &Bar0) -> Result<Spec> {
 }
 
 /// Structure holding the resources required to operate the GPU.
-#[pin_data(PinnedDrop)]
+#[pin_data]
 pub(crate) struct Gpu {
     spec: Spec,
     /// MMIO mapping of PCI BAR 0
@@ -174,15 +174,6 @@ pub(crate) struct Gpu {
     sysmem_flush: SysmemFlush,
 }
 
-#[pinned_drop]
-impl PinnedDrop for Gpu {
-    fn drop(self: Pin<&mut Self>) {
-        // Unregister the sysmem flush page before we release it.
-        self.bar
-            .try_access_with(|b| self.sysmem_flush.unregister(b));
-    }
-}
-
 impl Gpu {
     /// Helper function to load and run the FWSEC-FRTS firmware and confirm
that it has properly
     /// created the WPR2 region.
@@ -309,4 +300,15 @@ pub(crate) fn new(
             sysmem_flush,
         }))
     }
+
+    /// Called when the corresponding [`Device`](device::Device) is unbound.
+    ///
+    /// Note: This method must only be called from `Driver::unbind`.
+    pub(crate) fn unbind(&self, dev:
&device::Device<device::Core>) {
+        kernel::warn_on!(self
+            .bar
+            .access(dev)
+            .inspect(|bar| self.sysmem_flush.unregister(bar))
+            .is_err());
+    }
 }

base-commit: 09f90256e8902793f594517ef440698585eb3595
-- 
2.51.0

On Tue Sep 2, 2025 at 12:01 AM JST, Danilo Krummrich
wrote:
> Now that we have pci::Device::unbind() we can unregister the sysmem
> flush page with a direct access the I/O resource, i.e. without RCU read
> side critical section.
>
> Signed-off-by: Danilo Krummrich <dakr at kernel.org>
Reviewed-by: Alexandre Courbot <acourbot at nvidia.com>

On Tue Sep 2, 2025 at 12:01 AM JST, Danilo Krummrich
wrote:
> Now that we have pci::Device::unbind() we can unregister the sysmem
> flush page with a direct access the I/O resource, i.e. without RCU read
> side critical section.
>
> Signed-off-by: Danilo Krummrich <dakr at kernel.org>
Pushed to drm-rust-next, thanks!