6.17-stable review patch. If anyone has any objections, please let me know.
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From: Danilo Krummrich dakr@kernel.org
commit cfec502b3d091ff7c24df6ccf8079470584315a0 upstream.
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 aliceryhl@google.com Reviewed-by: Alexandre Courbot acourbot@nvidia.com Acked-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Danilo Krummrich dakr@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- rust/kernel/auxiliary.rs | 8 +------- rust/kernel/device.rs | 4 ++-- 2 files changed, 3 insertions(+), 9 deletions(-)
--- a/rust/kernel/auxiliary.rs +++ b/rust/kernel/auxiliary.rs @@ -217,13 +217,7 @@ impl<Ctx: device::DeviceContext> 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<Ctx: DeviceContext>` 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() } }
--- a/rust/kernel/device.rs +++ b/rust/kernel/device.rs @@ -250,7 +250,7 @@ impl<Ctx: DeviceContext> Device<Ctx> {
/// 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. @@ -263,7 +263,7 @@ impl<Ctx: DeviceContext> Device<Ctx> { // - 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) }) } }