From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C1D511A3A80; Tue, 1 Oct 2024 17:01:40 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1727802100; cv=none; b=PE8rIES66WO0LTWeu8IRwi3Y8E6fiYaXhp/8M5b4v5Gy3G8Z108l/w8JbRvfUtp+PeNLmPGQhJR35VW65zxb+X9SxVgqVMmqbgsDWZm+SCnA6ZLo6Grhovhj8UrZ7q3X1VdsjSUqpIrNdJyWTVHUpnD2nSTDE5ABf7ASs4A8/sA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1727802100; c=relaxed/simple; bh=teSRd6Ope2DM1P70Vhor8hV4zEZunc3MBpZztCPf6/o=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=SZ4UE6QEZsm/Uqjkf+tD/HbyG1TZJkMfsglKSxG+8IAjl9Uwnl+rilSGdpmTuzQYmLX6j+J5r9BzUMH0VKTzqxn+o6MwQ6fGBCSK6mN5ojgvNNcuwjKnJk0O4uLG50szPtrJ6oGPH2YZ6EFLgm8EFlgqkeQf8ZH24Ln5THxv9uk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=eSPifnfK; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="eSPifnfK" Received: by smtp.kernel.org (Postfix) with ESMTPSA id C3552C4CEC7; Tue, 1 Oct 2024 17:01:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1727802100; bh=teSRd6Ope2DM1P70Vhor8hV4zEZunc3MBpZztCPf6/o=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=eSPifnfKeiEM9VuZQsBfEGNVmWslyQGIsKySPeluxkX7A6zJ6oGrmibGVLIEhr9I8 t2NQRTLMU5WIZHlXADkAm8RL3Q4oZIh8Xd8Ik/qa45wTO6NMZMliujIAJ5HaCv2Hhb qdQssS4RdQgTS+C57bSoHnQ2cVCvaDpCjNez3MeM= Date: Tue, 1 Oct 2024 19:01:32 +0200 From: Greg KH To: Guilherme Giacomo Simoes Cc: rafael@kernel.org, ojeda@kernel.org, alex.gaynor@gmail.com, boqun.feng@gmail.com, gary@garyguo.net, bjorn3_gh@protonmail.com, benno.lossin@proton.me, aliceryhl@google.com, mcgrof@kernel.org, russ.weight@linux.dev, dakr@redhat.com, a.hindborg@kernel.org, rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2] rust: device: change the from_raw() function Message-ID: <2024100150-panther-human-0a46@gregkh> References: <20241001164355.104918-1-trintaeoitogc@gmail.com> Precedence: bulk X-Mailing-List: rust-for-linux@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20241001164355.104918-1-trintaeoitogc@gmail.com> On Tue, Oct 01, 2024 at 01:43:38PM -0300, Guilherme Giacomo Simoes wrote: > The function Device::from_raw() increments a refcount by a call to > bindings::get_device(ptr). This can be confused because usually > from_raw() functions don't increment a refcount. > Hence, rename Device::from_raw() to avoid confuion with other "from_raw" > semantics. > > The new name of function should be "get_device" to be consistent with > the function get_device() already exist in .c files. > > This function body also changed, because the `into()` will convert the > `&'a Device` into `ARef` and also call `inc_ref` from the > `AlwaysRefCounted` trait implemented for Device. > > Signed-off-by: Guilherme Giacomo Simoes > --- > rust/kernel/device.rs | 15 +++------------ > rust/kernel/firmware.rs | 2 +- > 2 files changed, 4 insertions(+), 13 deletions(-) > > diff --git a/rust/kernel/device.rs b/rust/kernel/device.rs > index 851018eef885..c8199ee079ef 100644 > --- a/rust/kernel/device.rs > +++ b/rust/kernel/device.rs > @@ -51,18 +51,9 @@ impl Device { > /// > /// It must also be ensured that `bindings::device::release` can be called from any thread. > /// While not officially documented, this should be the case for any `struct device`. > - pub unsafe fn from_raw(ptr: *mut bindings::device) -> ARef { > - // SAFETY: By the safety requirements, ptr is valid. > - // Initially increase the reference count by one to compensate for the final decrement once > - // this newly created `ARef` instance is dropped. > - unsafe { bindings::get_device(ptr) }; > - > - // CAST: `Self` is a `repr(transparent)` wrapper around `bindings::device`. > - let ptr = ptr.cast::(); > - > - // SAFETY: `ptr` is valid by the safety requirements of this function. By the above call to > - // `bindings::get_device` we also own a reference to the underlying `struct device`. > - unsafe { ARef::from_raw(ptr::NonNull::new_unchecked(ptr)) } > + pub unsafe fn get_device(ptr: *mut bindings::device) -> ARef { > + // SAFETY: By the safety requirements ptr is valid > + unsafe { Self::as_ref(ptr) }.into() > } > > /// Obtain the raw `struct device *`. > diff --git a/rust/kernel/firmware.rs b/rust/kernel/firmware.rs > index dee5b4b18aec..13a374a5cdb7 100644 > --- a/rust/kernel/firmware.rs > +++ b/rust/kernel/firmware.rs > @@ -44,7 +44,7 @@ fn request_nowarn() -> Self { > /// > /// # fn no_run() -> Result<(), Error> { > /// # // SAFETY: *NOT* safe, just for the example to get an `ARef` instance > -/// # let dev = unsafe { Device::from_raw(core::ptr::null_mut()) }; > +/// # let dev = unsafe { Device::get_device(core::ptr::null_mut()) }; > /// > /// let fw = Firmware::request(c_str!("path/to/firmware.bin"), &dev)?; > /// let blob = fw.data(); > -- > > differences from v1: > - this version don't have 0/1 patch anymore. > - this version contains a refactor get_device() function > > The motivation from this change was will discussion in: > https://rust-for-linux.zulipchat.com/#narrow/stream/291566-Library/topic/Inconsistency.20of.20.60from_raw.60.2E > > I would like to thanks for Greg , Danilo > and Alice for help me with this > patch. This information goes below the _first_ --- line, not down here at the bottom of the patch. The documentation should explain all of this, you did read that, right? :) v3 please? thanks, greg k-h