From cfec502b3d091ff7c24df6ccf8079470584315a0 Mon Sep 17 00:00:00 2001 From: Danilo Krummrich Date: Thu, 16 Oct 2025 15:31:44 +0200 Subject: rust: device: fix device context of Device::parent() Regardless of the DeviceContext of a device, we can't give any guarantees about the DeviceContext of its parent device. This is very subtle, since it's only caused by a simple typo, i.e. Self::from_raw(parent) which preserves the DeviceContext in this case, vs. Device::from_raw(parent) which discards the DeviceContext. (I should have noticed it doing the correct thing in auxiliary::Device subsequently, but somehow missed it.) Hence, fix both Device::parent() and auxiliary::Device::parent(). Cc: stable@vger.kernel.org Fixes: a4c9f71e3440 ("rust: device: implement Device::parent()") Reviewed-by: Alice Ryhl Reviewed-by: Alexandre Courbot Acked-by: Greg Kroah-Hartman Signed-off-by: Danilo Krummrich --- rust/kernel/auxiliary.rs | 8 +------- rust/kernel/device.rs | 4 ++-- 2 files changed, 3 insertions(+), 9 deletions(-) (limited to 'rust/kernel') diff --git a/rust/kernel/auxiliary.rs b/rust/kernel/auxiliary.rs index e11848bbf206..7a3b0b9c418e 100644 --- a/rust/kernel/auxiliary.rs +++ b/rust/kernel/auxiliary.rs @@ -217,13 +217,7 @@ impl Device { /// Returns a reference to the parent [`device::Device`], if any. pub fn parent(&self) -> Option<&device::Device> { - let ptr: *const Self = self; - // CAST: `Device` types are transparent to each other. - let ptr: *const Device = ptr.cast(); - // SAFETY: `ptr` was derived from `&self`. - let this = unsafe { &*ptr }; - - this.as_ref().parent() + self.as_ref().parent() } } diff --git a/rust/kernel/device.rs b/rust/kernel/device.rs index 1321e6f0b53c..a849b7dde2fd 100644 --- a/rust/kernel/device.rs +++ b/rust/kernel/device.rs @@ -251,7 +251,7 @@ impl Device { /// Returns a reference to the parent device, if any. #[cfg_attr(not(CONFIG_AUXILIARY_BUS), expect(dead_code))] - pub(crate) fn parent(&self) -> Option<&Self> { + pub(crate) fn parent(&self) -> Option<&Device> { // SAFETY: // - By the type invariant `self.as_raw()` is always valid. // - The parent device is only ever set at device creation. @@ -264,7 +264,7 @@ impl Device { // - Since `parent` is not NULL, it must be a valid pointer to a `struct device`. // - `parent` is valid for the lifetime of `self`, since a `struct device` holds a // reference count of its parent. - Some(unsafe { Self::from_raw(parent) }) + Some(unsafe { Device::from_raw(parent) }) } } -- cgit v1.2.3