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Manjarres" Cc: rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org, Matthew Maurer Content-Type: text/plain; charset="utf-8" A common pattern in the kernel is to test whether a file belongs to a particular driver by checking its `f_op` struct against an expected value. This provides a safe way to perform that test for `MiscDevice` implementations without needing to directly expose the vtable. Signed-off-by: Matthew Maurer --- rust/kernel/miscdevice.rs | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/rust/kernel/miscdevice.rs b/rust/kernel/miscdevice.rs index 939278bc7b03489a647b697012e09223871c90cd..5f59eda57c38be5f0d54fa9692fe5b2819e31480 100644 --- a/rust/kernel/miscdevice.rs +++ b/rust/kernel/miscdevice.rs @@ -177,6 +177,14 @@ fn show_fdinfo( } } +/// Determines whether a given `File` is backed by the `T` `MiscDevice` based on vtable matching. +pub fn is_miscdevice_file(file: &File) -> bool { + let vtable = core::ptr::from_ref(&MiscdeviceVTable::::VTABLE); + // SAFETY: `f_op` is not mutated after file creation + let file_vtable = unsafe { (*file.as_ptr()).f_op }; + vtable == file_vtable +} + /// A vtable for the file operations of a Rust miscdevice. struct MiscdeviceVTable(PhantomData); --- base-commit: 86731a2a651e58953fc949573895f2fa6d456841 change-id: 20250627-linux-miscident-7b67db234a5c Best regards, -- Matthew Maurer