From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-40133.protonmail.ch (mail-40133.protonmail.ch [185.70.40.133]) (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 0751918E025; Wed, 12 Mar 2025 17:05:50 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=185.70.40.133 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1741799153; cv=none; b=hzL7iTArs57j8mG550T8QplaI7N4AgF1GW3n5XU/s6Ftq2xX6giMPPVjKvF5Tx+JD1S6RMdM5J712laaOKrCzGt0RC+OG44WZPYnJ4XdVTJBZ81JfA374LS4zYpPRdq6zWaq/+wiWPQowMskEpdOR7nyGbYtNTKAUCPLUE7NdeM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1741799153; c=relaxed/simple; bh=AP2DarFxP1kHmbc1UQ9k/cTreCsRImTcUA6mVTmVGkY=; h=Date:To:From:Cc:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=C++DcwqaEl5Z0oUpJPDZ3ehSJO4jjCzvww1oywZ4bQnMZT3bYe4C6KeIuIC6gW9jFpO/6hsJ3UaYS6XzapTsC3xfJNErjfoV/hxkQarxV7DnSFCyt+cDxEpeiRCoo2ueqchlIGQRtbFL5QvQSnAKFU4eCQMcZBxwgQ9wzjDupds= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=proton.me; spf=pass smtp.mailfrom=proton.me; dkim=pass (2048-bit key) header.d=proton.me header.i=@proton.me header.b=b2jziJiR; arc=none smtp.client-ip=185.70.40.133 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=proton.me Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=proton.me Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=proton.me header.i=@proton.me header.b="b2jziJiR" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=proton.me; s=protonmail; t=1741799147; x=1742058347; bh=H5vl6p6VvHTW8KbGWXzE7B7/l993EE1hKM2A3P0sLhk=; h=Date:To:From:Cc:Subject:Message-ID:In-Reply-To:References: Feedback-ID:From:To:Cc:Date:Subject:Reply-To:Feedback-ID: Message-ID:BIMI-Selector:List-Unsubscribe:List-Unsubscribe-Post; b=b2jziJiRFsmsGXaAH/pfzEpF6rybEcf/p6HsH/3iuVY6V8RgfKPuIaPsdUqv/kk38 jDaRI6UihnNYvD9eCeTozR9RJm6VOcspVF7Jv3U9v1rrWLyyvpcfbQajG+eAw/pa3+ Qnkxgek2raHEZB6LkzhlfCmAp+aN5AQDN5bwptySMixAf84ZVG6nWirq03aKZDNfRO +A4MLcTa9PYJd8Whi1yfBdZ6is1iQMDwpkkuKIhIDmz5YHnpT4B+5qs4BHxSccRrkr TrSccll+fzpnzBOsr/6GIy/APpeqhW+YhhSRzBlglgXWLsVyStn9PTuqzMbg7s/56n MshHrVkdfD/hA== Date: Wed, 12 Mar 2025 17:05:42 +0000 To: Tamir Duberstein From: Benno Lossin Cc: Masahiro Yamada , Nathan Chancellor , Nicolas Schier , Miguel Ojeda , Alex Gaynor , Boqun Feng , Gary Guo , =?utf-8?Q?Bj=C3=B6rn_Roy_Baron?= , Andreas Hindborg , Alice Ryhl , Trevor Gross , Danilo Krummrich , Greg Kroah-Hartman , "Rafael J. Wysocki" , Brendan Higgins , David Gow , Rae Moar , Bjorn Helgaas , Luis Chamberlain , Russ Weight , Rob Herring , Saravana Kannan , linux-kbuild@vger.kernel.org, linux-kernel@vger.kernel.org, rust-for-linux@vger.kernel.org, linux-kselftest@vger.kernel.org, kunit-dev@googlegroups.com, linux-pci@vger.kernel.org, linux-block@vger.kernel.org, devicetree@vger.kernel.org Subject: Re: [PATCH v2 5/5] rust: enable `clippy::as_underscore` lint Message-ID: In-Reply-To: References: <20250309-ptr-as-ptr-v2-0-25d60ad922b7@gmail.com> <20250309-ptr-as-ptr-v2-5-25d60ad922b7@gmail.com> Feedback-ID: 71780778:user:proton X-Pm-Message-ID: e4ddaa38df8cc192110bac9445ef586b5ce36b87 Precedence: bulk X-Mailing-List: devicetree@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable On Wed Mar 12, 2025 at 4:35 PM CET, Tamir Duberstein wrote: > On Wed, Mar 12, 2025 at 11:05=E2=80=AFAM Benno Lossin wrote: >> >> On Sun Mar 9, 2025 at 5:00 PM CET, Tamir Duberstein wrote: >> > diff --git a/rust/kernel/devres.rs b/rust/kernel/devres.rs >> > index 598001157293..20159b7c9293 100644 >> > --- a/rust/kernel/devres.rs >> > +++ b/rust/kernel/devres.rs >> > @@ -45,7 +45,7 @@ struct DevresInner { >> > /// # Example >> > /// >> > /// ```no_run >> > -/// # use kernel::{bindings, c_str, device::Device, devres::Devres, i= o::{Io, IoRaw}}; >> > +/// # use kernel::{bindings, c_str, device::Device, devres::Devres, f= fi::c_void, io::{Io, IoRaw}}; >> > /// # use core::ops::Deref; >> > /// >> > /// // See also [`pci::Bar`] for a real example. >> > @@ -59,19 +59,19 @@ struct DevresInner { >> > /// unsafe fn new(paddr: usize) -> Result{ >> > /// // SAFETY: By the safety requirements of this function [`= paddr`, `paddr` + `SIZE`) is >> > /// // valid for `ioremap`. >> > -/// let addr =3D unsafe { bindings::ioremap(paddr as _, SIZE = as _) }; >> > +/// let addr =3D unsafe { bindings::ioremap(paddr as u64, SIZ= E) }; >> >> The argument of `ioremap` is defined as `resource_size_t` which >> ultimately maps to `u64` on 64 bit systems and `u32` on 32 bit ones. I >> don't think that we should have code like this... Is there another >> option? >> >> Maybe Gary knows something here, do we have a type that represents that >> better? > > Ah yeah the problem is that this type is an alias rather than a > newtype. How do you feel about `as bindings::phys_addr_t`? Yeah that's better. >> > /// if addr.is_null() { >> > /// return Err(ENOMEM); >> > /// } >> > /// >> > -/// Ok(IoMem(IoRaw::new(addr as _, SIZE)?)) >> > +/// Ok(IoMem(IoRaw::new(addr as usize, SIZE)?)) >> >> This should be `addr.addr()` (requires `strict_provenance` on Rust 1.83 >> & before). >> >> (I am assuming that we're never casting the usize back to a pointer, >> since otherwise this change would introduce UB) > > Yeah, we don't have strict provenance APIs (and we can't introduce > them without compiler tooling or bumping MSRV). I'm not sure if we are > casting back to a pointer, but either way this change doesn't change > the semantics - it is only spelling out the type. It's fine to enable the feature, since it's stable in a newer version of the compiler. >> > /// } >> > /// } >> > /// >> > /// impl Drop for IoMem { >> > /// fn drop(&mut self) { >> > /// // SAFETY: `self.0.addr()` is guaranteed to be properly m= apped by `Self::new`. >> > -/// unsafe { bindings::iounmap(self.0.addr() as _); }; >> > +/// unsafe { bindings::iounmap(self.0.addr() as *mut c_void);= }; >> >> Can't this be a `.cast::()`? > > This is an integer-to-pointer cast. `addr` returns `usize`: Oh I missed the `*mut`... In that case, we can't use the `addr` suggestion that I made above, instead we should use `expose_provenance` above and `with_exposed_provenance` here. > impl IoRaw { > [...] > > /// Returns the base address of the MMIO region. > #[inline] > pub fn addr(&self) -> usize { > self.addr > } > > [...] > } > >> >> > /// } >> > /// } >> > /// >> >> > diff --git a/rust/kernel/error.rs b/rust/kernel/error.rs >> > index 8654d52b0bb9..eb8fa52f08ba 100644 >> > --- a/rust/kernel/error.rs >> > +++ b/rust/kernel/error.rs >> > @@ -152,7 +152,7 @@ pub(crate) fn to_blk_status(self) -> bindings::blk= _status_t { >> > /// Returns the error encoded as a pointer. >> > pub fn to_ptr(self) -> *mut T { >> > // SAFETY: `self.0` is a valid error due to its invariant. >> > - unsafe { bindings::ERR_PTR(self.0.get() as _).cast() } >> > + unsafe { bindings::ERR_PTR(self.0.get() as isize).cast() } >> >> Can't this be a `.into()`? > > error[E0277]: the trait bound `isize: core::convert::From` is not sa= tisfied > --> ../rust/kernel/error.rs:155:49 > | > 155 | unsafe { bindings::ERR_PTR(self.0.get().into()).cast() } > | ^^^^ the trait > `core::convert::From` is not implemented for `isize` That's a bummer... I wonder why that doesn't exist. >> > } >> > >> > /// Returns a string representing the error, if one exists. >> >> > @@ -119,7 +119,7 @@ pub fn $name(&self, offset: usize) -> $type_name { >> > let addr =3D self.io_addr_assert::<$type_name>(offset); >> > >> > // SAFETY: By the type invariant `addr` is a valid addres= s for MMIO operations. >> > - unsafe { bindings::$name(addr as _) } >> > + unsafe { bindings::$name(addr as *const c_void) } >> >> Also here, is `.cast::()` enough? (and below) > > It's an integer-to-pointer cast. In the same `impl > IoRaw` as above: > > fn io_addr_assert(&self, offset: usize) -> usize { > build_assert!(Self::offset_valid::(offset, SIZE)); > > self.addr() + offset > } I would prefer we use the strict_provenance API. >> > } >> > >> > /// Read IO data from a given offset. >> >> > diff --git a/rust/kernel/of.rs b/rust/kernel/of.rs >> > index 04f2d8ef29cb..40d1bd13682c 100644 >> > --- a/rust/kernel/of.rs >> > +++ b/rust/kernel/of.rs >> > @@ -22,7 +22,7 @@ unsafe impl RawDeviceId for DeviceId { >> > const DRIVER_DATA_OFFSET: usize =3D core::mem::offset_of!(binding= s::of_device_id, data); >> > >> > fn index(&self) -> usize { >> > - self.0.data as _ >> > + self.0.data as usize >> >> This should also be `self.0.data.addr()`. > > Can't do it without strict_provenance. > >> >> > } >> > } >> > >> > @@ -34,10 +34,10 @@ pub const fn new(compatible: &'static CStr) -> Sel= f { >> > // SAFETY: FFI type is valid to be zero-initialized. >> > let mut of: bindings::of_device_id =3D unsafe { core::mem::ze= roed() }; >> > >> > - // TODO: Use `clone_from_slice` once the corresponding types = do match. >> > + // TODO: Use `copy_from_slice` once stabilized for `const`. >> >> This feature has just been stabilized (5 days ago!): >> >> https://github.com/rust-lang/rust/issues/131415 > > Yep! I know :) > >> @Miguel: Do we already have a target Rust version for dropping the >> `RUSTC_BOOTSTRAP=3D1`? If not, then I think we should use this feature >> now, since it will be stable by the time we bump the minimum version. >> (not in this patch [series] though) >> >> > let mut i =3D 0; >> > while i < src.len() { >> > - of.compatible[i] =3D src[i] as _; >> > + of.compatible[i] =3D src[i]; >> > i +=3D 1; >> > } >> >> > @@ -317,7 +320,7 @@ unsafe fn do_release(pdev: &Device, ioptr: usize, = num: i32) { >> > // `ioptr` is valid by the safety requirements. >> > // `num` is valid by the safety requirements. >> > unsafe { >> > - bindings::pci_iounmap(pdev.as_raw(), ioptr as _); >> > + bindings::pci_iounmap(pdev.as_raw(), ioptr as *mut kernel= ::ffi::c_void); >> >> Again, probably castable. > > How? `ioptr` is a `usize` (you can see the prototype). Sorry, I missed all the `*mut`/`*const` prefixes here. --- Cheers, Benno