From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from gimli.kloenk.de (gimli.kloenk.de [49.12.72.200]) (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 B875119DF61; Tue, 28 Jan 2025 10:52:46 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=49.12.72.200 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1738061569; cv=none; b=bmSLRJ+79BLRMTPZ0RJUISpaP7HztEyPGMVKxuF/BEcnbuIrRLXEtQuVo+qeJYr4QPBufPnO0CIuDw32hOrNN+79J0E/xKkC5alyMF579gIoIlEG/yUvCpVggTJeswkX14qZlkz78QPPd/jFEN3H4VuKyqYs6+aYmhvhVpp+jT8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1738061569; c=relaxed/simple; bh=PfCdzxsbws1eBdcw38huDK/jKhGdbdGpeOJKZkwLwKs=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=TMaPiV3TbsLKbUzSiL7EkWyVgl/OeOEBrskcJN2OmtjPHy5amvl6Gvnv8SAL77LsO7kXfEEbS2Ct2eJO1rWuf861uchVl24TkJpqtlN1zguwGI+e8ZgHGf8oABAu3QIap+M/DpgQy7h4uzMG+pu3srU2SaoqcytQce0OZ69S7xQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=kloenk.dev; spf=pass smtp.mailfrom=kloenk.dev; dkim=pass (1024-bit key) header.d=kloenk.dev header.i=@kloenk.dev header.b=i7ZHd+8l; arc=none smtp.client-ip=49.12.72.200 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=kloenk.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=kloenk.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=kloenk.dev header.i=@kloenk.dev header.b="i7ZHd+8l" From: Fiona Behrens DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kloenk.dev; s=mail; t=1738061564; bh=GVAB7md79HnKqybn7MqI9eX/+oFlbzYDCqZBX2HB8cg=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=i7ZHd+8lqRITRgcHAjo9tgTaALap3ECpCiMw2MYGIUehtPe4nkOTf4ZLbXYNBgr5s qqutonTK3jR+3Yk0kXTnPpWMfH9tx9ubASu4P/YlTutXCJbtitkbh4UfiQgOlNQ4Ag YadB3juUQ6yJ1k/QvSiyo5Vi2LoVb+BwvByhOIbA= To: FUJITA Tomonori Cc: linux-kernel@vger.kernel.org, rust-for-linux@vger.kernel.org, netdev@vger.kernel.org, andrew@lunn.ch, hkallweit1@gmail.com, tmgross@umich.edu, ojeda@kernel.org, alex.gaynor@gmail.com, gary@garyguo.net, bjorn3_gh@protonmail.com, benno.lossin@proton.me, a.hindborg@samsung.com, aliceryhl@google.com, anna-maria@linutronix.de, frederic@kernel.org, tglx@linutronix.de, arnd@arndb.de, jstultz@google.com, sboyd@kernel.org, mingo@redhat.com, peterz@infradead.org, juri.lelli@redhat.com, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de, vschneid@redhat.com, tgunders@redhat.com Subject: Re: [PATCH v9 7/8] rust: Add read_poll_timeout functions Date: Tue, 28 Jan 2025 11:52:42 +0100 Message-ID: In-Reply-To: <20250125101854.112261-8-fujita.tomonori@gmail.com> References: <20250125101854.112261-1-fujita.tomonori@gmail.com> <20250125101854.112261-8-fujita.tomonori@gmail.com> Precedence: bulk X-Mailing-List: netdev@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 25 Jan 2025, at 11:18, FUJITA Tomonori wrote: > Add read_poll_timeout functions which poll periodically until a > condition is met or a timeout is reached. > > The C's read_poll_timeout (include/linux/iopoll.h) is a complicated > macro and a simple wrapper for Rust doesn't work. So this implements > the same functionality in Rust. > > The C version uses usleep_range() while the Rust version uses > fsleep(), which uses the best sleep method so it works with spans that > usleep_range() doesn't work nicely with. > > Unlike the C version, __might_sleep() is used instead of might_sleep() > to show proper debug info; the file name and line > number. might_resched() could be added to match what the C version > does but this function works without it. > > The sleep_before_read argument isn't supported since there is no user > for now. It's rarely used in the C version. > > read_poll_timeout() can only be used in a nonatomic context. This > requirement is not checked by these abstractions, but it is intended > that klint [1] or a similar tool will be used to check it in the > future. > > Link: https://rust-for-linux.com/klint [1] > Signed-off-by: FUJITA Tomonori > --- > rust/helpers/helpers.c | 1 + > rust/helpers/kernel.c | 13 +++++++ > rust/kernel/cpu.rs | 13 +++++++ > rust/kernel/error.rs | 1 + > rust/kernel/io.rs | 5 +++ > rust/kernel/io/poll.rs | 79 ++++++++++++++++++++++++++++++++++++++++++= > rust/kernel/lib.rs | 2 ++ > 7 files changed, 114 insertions(+) > create mode 100644 rust/helpers/kernel.c > create mode 100644 rust/kernel/cpu.rs > create mode 100644 rust/kernel/io.rs > create mode 100644 rust/kernel/io/poll.rs > (..) > diff --git a/rust/kernel/io/poll.rs b/rust/kernel/io/poll.rs > new file mode 100644 > index 000000000000..7a503cf643a1 > --- /dev/null > +++ b/rust/kernel/io/poll.rs > @@ -0,0 +1,79 @@ > +// SPDX-License-Identifier: GPL-2.0 > + > +//! IO polling. > +//! > +//! C header: [`include/linux/iopoll.h`](srctree/include/linux/iopoll.= h). > + > +use crate::{ > + cpu::cpu_relax, > + error::{code::*, Result}, > + time::{delay::fsleep, Delta, Instant}, > +}; > + > +use core::panic::Location; > + > +/// Polls periodically until a condition is met or a timeout is reache= d. > +/// > +/// Public but hidden since it should only be used from public macros.= This states the function should be hidden, but I don=E2=80=99t see a `#[d= oc(hidden)]` in here so bit confused by that comment what part now is hid= den. Thanks, Fiona > +/// > +/// ```rust > +/// use kernel::io::poll::read_poll_timeout; > +/// use kernel::time::Delta; > +/// use kernel::sync::{SpinLock, new_spinlock}; > +/// > +/// let lock =3D KBox::pin_init(new_spinlock!(()), kernel::alloc::flag= s::GFP_KERNEL)?; > +/// let g =3D lock.lock(); > +/// read_poll_timeout(|| Ok(()), |()| true, Delta::from_micros(42), De= lta::from_micros(42)); > +/// drop(g); > +/// > +/// # Ok::<(), Error>(()) > +/// ``` > +#[track_caller] > +pub fn read_poll_timeout( > + mut op: Op, > + mut cond: Cond, > + sleep_delta: Delta, > + timeout_delta: Delta, > +) -> Result > +where > + Op: FnMut() -> Result, > + Cond: FnMut(&T) -> bool, > +{ > + let start =3D Instant::now(); > + let sleep =3D !sleep_delta.is_zero(); > + let timeout =3D !timeout_delta.is_zero(); > + > + if sleep { > + might_sleep(Location::caller()); > + } > + > + loop { > + let val =3D op()?; > + if cond(&val) { > + // Unlike the C version, we immediately return. > + // We know the condition is met so we don't need to check = again. > + return Ok(val); > + } > + if timeout && start.elapsed() > timeout_delta { > + // Unlike the C version, we immediately return. > + // We have just called `op()` so we don't need to call it = again. > + return Err(ETIMEDOUT); > + } > + if sleep { > + fsleep(sleep_delta); > + } > + // fsleep() could be busy-wait loop so we always call cpu_rela= x(). > + cpu_relax(); > + } > +} > + > +fn might_sleep(loc: &Location<'_>) { > + // SAFETY: FFI call. > + unsafe { > + crate::bindings::__might_sleep_precision( > + loc.file().as_ptr().cast(), > + loc.file().len() as i32, > + loc.line() as i32, > + ) > + } > +} > diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs > index 545d1170ee63..c477701b2efa 100644 > --- a/rust/kernel/lib.rs > +++ b/rust/kernel/lib.rs > @@ -35,6 +35,7 @@ > pub mod block; > #[doc(hidden)] > pub mod build_assert; > +pub mod cpu; > pub mod cred; > pub mod device; > pub mod error; > @@ -42,6 +43,7 @@ > pub mod firmware; > pub mod fs; > pub mod init; > +pub mod io; > pub mod ioctl; > pub mod jump_label; > #[cfg(CONFIG_KUNIT)] > -- = > 2.43.0