From: Danilo Krummrich <dakr@kernel.org>
Date: Mon, 25 May 2026 20:21:11 +0000 (+0200)
Subject: samples: rust: rust_driver_auxiliary: showcase lifetime-bound registration data
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=d18f3646184fc805d213fc049fc3b5d9fb9a6a27;p=thirdparty%2Fkernel%2Flinux.git

samples: rust: rust_driver_auxiliary: showcase lifetime-bound registration data

Make the Data struct lifetime-parameterized, storing a reference to the
parent pci::Device<Bound>. This demonstrates that registration data can
hold device resources tied to the parent driver's lifetime.

In connect(), retrieve the parent PCI device from the registration data
rather than casting through adev.parent().

Reviewed-by: Eliot Courtney <ecourtney@nvidia.com>
Reviewed-by: Gary Guo <gary@garyguo.net>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Alexandre Courbot <acourbot@nvidia.com>
Link: https://patch.msgid.link/20260525202921.124698-25-dakr@kernel.org
Signed-off-by: Danilo Krummrich <dakr@kernel.org>
---

diff --git a/samples/rust/rust_driver_auxiliary.rs b/samples/rust/rust_driver_auxiliary.rs
index e3e811a14110c..2c1351040e45e 100644
--- a/samples/rust/rust_driver_auxiliary.rs
+++ b/samples/rust/rust_driver_auxiliary.rs
@@ -51,16 +51,17 @@ impl auxiliary::Driver for AuxiliaryDriver {
     }
 }
 
-struct Data {
+struct Data<'bound> {
     index: u32,
+    parent: &'bound pci::Device<Bound>,
 }
 
 struct ParentDriver;
 
 #[allow(clippy::type_complexity)]
 struct ParentData<'bound> {
-    _reg0: auxiliary::Registration<'bound, ForLt!(Data)>,
-    _reg1: auxiliary::Registration<'bound, ForLt!(Data)>,
+    _reg0: auxiliary::Registration<'bound, ForLt!(Data<'_>)>,
+    _reg1: auxiliary::Registration<'bound, ForLt!(Data<'_>)>,
 }
 
 kernel::pci_device_table!(
@@ -81,33 +82,44 @@ impl pci::Driver for ParentDriver {
         _info: &'bound Self::IdInfo,
     ) -> impl PinInit<Self::Data<'bound>, Error> + 'bound {
         Ok(ParentData {
-            _reg0: auxiliary::Registration::new(
-                pdev.as_ref(),
-                AUXILIARY_NAME,
-                0,
-                MODULE_NAME,
-                Data { index: 0 },
-            )?,
-            _reg1: auxiliary::Registration::new(
-                pdev.as_ref(),
-                AUXILIARY_NAME,
-                1,
-                MODULE_NAME,
-                Data { index: 1 },
-            )?,
+            // SAFETY: `ParentData` is the driver's private data, which is dropped when the
+            // device is unbound; i.e. `mem::forget()` is never called on it.
+            _reg0: unsafe {
+                auxiliary::Registration::new_with_lt(
+                    pdev.as_ref(),
+                    AUXILIARY_NAME,
+                    0,
+                    MODULE_NAME,
+                    Data {
+                        index: 0,
+                        parent: pdev,
+                    },
+                )?
+            },
+            // SAFETY: See `_reg0` above.
+            _reg1: unsafe {
+                auxiliary::Registration::new_with_lt(
+                    pdev.as_ref(),
+                    AUXILIARY_NAME,
+                    1,
+                    MODULE_NAME,
+                    Data {
+                        index: 1,
+                        parent: pdev,
+                    },
+                )?
+            },
         })
     }
 }
 
 impl ParentDriver {
     fn connect(adev: &auxiliary::Device<Bound>) -> Result {
-        let dev = adev.parent();
-        let pdev: &pci::Device<Bound> = dev.try_into()?;
-
-        let data = adev.registration_data::<ForLt!(Data)>()?;
+        let data = adev.registration_data::<ForLt!(Data<'_>)>()?;
+        let pdev = data.parent;
 
         dev_info!(
-            dev,
+            pdev,
             "Connect auxiliary {} with parent: VendorID={}, DeviceID={:#x}\n",
             adev.id(),
             pdev.vendor_id(),
@@ -115,7 +127,7 @@ impl ParentDriver {
         );
 
         dev_info!(
-            dev,
+            pdev,
             "Connected to auxiliary device with index {}.\n",
             data.index
         );