From 2e9fdbe5ec7a65b66da9c202cac621a3a366fde3 Mon Sep 17 00:00:00 2001 From: Danilo Krummrich Date: Sun, 29 Jun 2025 17:37:42 +0200 Subject: [PATCH] rust: drm: device: drop_in_place() the drm::Device in release() In drm::Device::new() we allocate with __drm_dev_alloc() and return an ARef. When the reference count of the drm::Device falls to zero, the C code automatically calls drm_dev_release(), which eventually frees the memory allocated in drm::Device::new(). However, due to that, drm::Device::drop() is never called. As a result the destructor of the user's private data, i.e. drm::Device::data is never called. Hence, fix this by calling drop_in_place() from the DRM device's release callback. Fixes: 1e4b8896c0f3 ("rust: drm: add device abstraction") Reviewed-by: Alice Ryhl Signed-off-by: Danilo Krummrich Link: https://lore.kernel.org/r/20250629153747.72536-1-dakr@kernel.org --- rust/kernel/drm/device.rs | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-) diff --git a/rust/kernel/drm/device.rs b/rust/kernel/drm/device.rs index 624d7a4c83ead..14c1aa402951a 100644 --- a/rust/kernel/drm/device.rs +++ b/rust/kernel/drm/device.rs @@ -66,7 +66,7 @@ impl Device { open: Some(drm::File::::open_callback), postclose: Some(drm::File::::postclose_callback), unload: None, - release: None, + release: Some(Self::release), master_set: None, master_drop: None, debugfs_init: None, @@ -162,6 +162,16 @@ impl Device { // SAFETY: `ptr` is valid by the safety requirements of this function. unsafe { &*ptr.cast() } } + + extern "C" fn release(ptr: *mut bindings::drm_device) { + // SAFETY: `ptr` is a valid pointer to a `struct drm_device` and embedded in `Self`. + let this = unsafe { Self::from_drm_device(ptr) }; + + // SAFETY: + // - When `release` runs it is guaranteed that there is no further access to `this`. + // - `this` is valid for dropping. + unsafe { core::ptr::drop_in_place(this) }; + } } impl Deref for Device { -- 2.47.2