From nobody Mon Nov 25 22:36:03 2024 Received: from mail-pg1-f181.google.com (mail-pg1-f181.google.com [209.85.215.181]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C68A31ACDF0; Fri, 25 Oct 2024 03:34:33 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.215.181 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1729827276; cv=none; b=FqMSCJRWcY9H5ELAbuIqWJIdGN/beYt1rPvEx2Hegle9dTCHkc/4XWW+v49odj/sLbPRPFVffA/m/FsdJz6N/OSlQI3uKlE2haDBzk3D778HB6kcizq6xv9Aj5RD5qtnODI/EGyhF/HkYmAX7PSQJzHOZLXbQ9WJf/5SJBmbgj4= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1729827276; c=relaxed/simple; bh=pZsVeffyezjeq+ZCP4S1Z1TvMIkWwVO0ML0qhzsHTg8=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Bf4hxavTUwKjbNnJTt543Xm1MA/p0XXuXpp4qt0zSbXVz8u/EAAmYEEoxVotTsqhmCG24qrUzaSdy24QREeecv2yqRQx0F7SepWvg0za2kt2Z3EuwiV0DPACcxZGmmaA0BUPFzCeDQiRwDGBvaYl7b4E6CjuqQPV8tf6i860HsU= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=Nz7XP32d; arc=none smtp.client-ip=209.85.215.181 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="Nz7XP32d" Received: by mail-pg1-f181.google.com with SMTP id 41be03b00d2f7-7e9e38dd5f1so1152372a12.0; Thu, 24 Oct 2024 20:34:33 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1729827273; x=1730432073; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=Z1q9ggByLgvF29xNghA+oLeekFn/dFvbYSRczZS/Rr0=; b=Nz7XP32dmmFSFZ4i2h7KnfPiYY7l8Z/T5F0YDuXnedc4VFICoBSOdW1gxw/Hbgvgl3 gDC/sX7P5cbaa1YlgVsP1qpmwlDi4YBI1rjHlJ1GpMbQZ+1HoDQIhxjBCNM3vxA7WhLd ze/V0JyI3OfS20D776J6rxhm8AU+qwBU2rydDX8QEvY67CI+uSWC3euJ1v9KAmwpNpEy B1BRM72YHmniMvimCuoioSxMSZPFSeNh7GY1eRZaQZmji3kQg3ooxnlspFe8PC1OlfqC w6crVx+Z45OeyXnYZUSJK9SyKNz434pjWRZDWkbp/keSbFCXZaWHLAw/HteKFDP8uaF4 s7fQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1729827273; x=1730432073; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=Z1q9ggByLgvF29xNghA+oLeekFn/dFvbYSRczZS/Rr0=; b=mrBJ1CiEYGoV40J5RIgFNdArzGO4rrJPGr8TRz0qVGDLOJi256ADV40WpFvxBYkocu sYclpVzUDZ5R+PVHp1OeqLEQ1BnniBZrmAZPj2kVx10LQvLf6mXEOyAEUmqTQOafi82E qbfbOQ1WEuDnRPZNCkHZgj5Z69TSJ1tehJyBcdgXs1A7+t1B32A+gOfodLp8iiXm/zER qwtBGn201f+EmYc5b67oIVFT1sshz1jBXdn3QWqD/ykHgUxqy+ogipHR/bVckTmZMHW4 NyCxzIJAUEOixBmL+F9hIvuktA4m4COonSIaU4jjQg68SR4H5GBNUZ5xEL5Dlxn/r8Sk qIlg== X-Forwarded-Encrypted: i=1; AJvYcCUXMrlhgkxlVSOZsz5ojhDm5MMIC9uYmfNKbEDo63KSjlJB0AR8uKMSghluNRN8PxSMsKSXTWZNaY9j5KQ=@vger.kernel.org, AJvYcCWNZsYu7PX7TAhlbD7ykn6B8gg0vn/f4einP+smBAu1Cf/ORK1mXe5xLiLqlhc6Nga06U9B7r3dBjmWrvCtkYg=@vger.kernel.org X-Gm-Message-State: AOJu0YyPSWObFYKFYv/LDwjrRk3tpGygJHJbc+S/Myk/90/wvKLOIL9+ u1swub5IbrBUFXaRjKoGZbm5PBiRv6Jp34n1yAy1anyOe6XujQif X-Google-Smtp-Source: AGHT+IGIUPkN+OqnxUUcmRWusqknbhO05BPVVFPbEuKkJIMkAd+D/2fn/uzB7S5maSTcz6zJeA8RPA== X-Received: by 2002:a05:6a20:db0a:b0:1d9:a9b:28f0 with SMTP id adf61e73a8af0-1d989cc8f66mr5807282637.34.1729827272976; Thu, 24 Oct 2024 20:34:32 -0700 (PDT) Received: from mew.. (p4007189-ipxg22601hodogaya.kanagawa.ocn.ne.jp. [180.53.81.189]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-7205791db5fsm180188b3a.11.2024.10.24.20.34.29 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 24 Oct 2024 20:34:32 -0700 (PDT) From: FUJITA Tomonori To: anna-maria@linutronix.de, frederic@kernel.org, tglx@linutronix.de, jstultz@google.com, sboyd@kernel.org, linux-kernel@vger.kernel.org Cc: netdev@vger.kernel.org, rust-for-linux@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, arnd@arndb.de Subject: [PATCH v4 6/7] rust: Add read_poll_timeout functions Date: Fri, 25 Oct 2024 12:31:17 +0900 Message-ID: <20241025033118.44452-7-fujita.tomonori@gmail.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20241025033118.44452-1-fujita.tomonori@gmail.com> References: <20241025033118.44452-1-fujita.tomonori@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Add read_poll_timeout functions which poll periodically until a condition is met or a timeout is reached. 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. For the proper debug info, readx_poll_timeout() and __might_sleep() are implemented as a macro. We could implement them as a normal function if there is a clean way to get a null-terminated string without allocation from core::panic::Location::file(). readx_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/error.rs | 1 + rust/kernel/io.rs | 5 +++ rust/kernel/io/poll.rs | 93 ++++++++++++++++++++++++++++++++++++++++ rust/kernel/lib.rs | 2 + rust/kernel/processor.rs | 13 ++++++ 7 files changed, 128 insertions(+) create mode 100644 rust/helpers/kernel.c create mode 100644 rust/kernel/io.rs create mode 100644 rust/kernel/io/poll.rs create mode 100644 rust/kernel/processor.rs diff --git a/rust/helpers/helpers.c b/rust/helpers/helpers.c index c274546bcf78..f9569ff1717e 100644 --- a/rust/helpers/helpers.c +++ b/rust/helpers/helpers.c @@ -12,6 +12,7 @@ #include "build_assert.c" #include "build_bug.c" #include "err.c" +#include "kernel.c" #include "kunit.c" #include "mutex.c" #include "page.c" diff --git a/rust/helpers/kernel.c b/rust/helpers/kernel.c new file mode 100644 index 000000000000..da847059260b --- /dev/null +++ b/rust/helpers/kernel.c @@ -0,0 +1,13 @@ +// SPDX-License-Identifier: GPL-2.0 + +#include + +void rust_helper_cpu_relax(void) +{ + cpu_relax(); +} + +void rust_helper___might_sleep(const char *file, int line) +{ + __might_sleep(file, line); +} diff --git a/rust/kernel/error.rs b/rust/kernel/error.rs index 6f1587a2524e..d571b9587ed6 100644 --- a/rust/kernel/error.rs +++ b/rust/kernel/error.rs @@ -58,6 +58,7 @@ macro_rules! declare_err { declare_err!(EPIPE, "Broken pipe."); declare_err!(EDOM, "Math argument out of domain of func."); declare_err!(ERANGE, "Math result not representable."); + declare_err!(ETIMEDOUT, "Connection timed out."); declare_err!(ERESTARTSYS, "Restart the system call."); declare_err!(ERESTARTNOINTR, "System call was interrupted by a signal = and will be restarted."); declare_err!(ERESTARTNOHAND, "Restart if no handler."); diff --git a/rust/kernel/io.rs b/rust/kernel/io.rs new file mode 100644 index 000000000000..033f3c4e4adf --- /dev/null +++ b/rust/kernel/io.rs @@ -0,0 +1,5 @@ +// SPDX-License-Identifier: GPL-2.0 + +//! Input and Output. + +pub mod poll; diff --git a/rust/kernel/io/poll.rs b/rust/kernel/io/poll.rs new file mode 100644 index 000000000000..ef1f38b59fda --- /dev/null +++ b/rust/kernel/io/poll.rs @@ -0,0 +1,93 @@ +// SPDX-License-Identifier: GPL-2.0 + +//! IO polling. +//! +//! C header: [`include/linux/iopoll.h`](srctree/include/linux/iopoll.h). + +use crate::{ + error::{code::*, Result}, + processor::cpu_relax, + time::{delay::fsleep, Delta, Instant}, +}; + +/// Polls periodically until a condition is met or a timeout is reached. +/// +/// Public but hidden since it should only be used from public macros. +#[doc(hidden)] +pub fn read_poll_timeout( + mut op: Op, + cond: Cond, + sleep_delta: Delta, + timeout_delta: Delta, +) -> Result +where + Op: FnMut() -> Result, + Cond: Fn(T) -> bool, +{ + let start =3D Instant::now(); + let sleep =3D !sleep_delta.is_zero(); + let timeout =3D !timeout_delta.is_zero(); + + let val =3D loop { + let val =3D op()?; + if cond(val) { + // Unlike the C version, we immediately return. + // We know a condition is met so we don't need to check again. + return Ok(val); + } + if timeout && start.elapsed() > timeout_delta { + // Should we return Err(ETIMEDOUT) here instead of call op() a= gain + // wihout a sleep between? But we follow the C version. op() c= ould + // take some time so might be worth checking again. + break op()?; + } + if sleep { + fsleep(sleep_delta); + } + // fsleep() could be busy-wait loop so we always call cpu_relax(). + cpu_relax(); + }; + + if cond(val) { + Ok(val) + } else { + Err(ETIMEDOUT) + } +} + +/// Print debug information if it's called inside atomic sections. +#[macro_export] +macro_rules! __might_sleep { + () =3D> { + #[cfg(CONFIG_DEBUG_ATOMIC_SLEEP)] + // SAFETY: FFI call. + unsafe { + $crate::bindings::__might_sleep( + c_str!(::core::file!()).as_char_ptr(), + ::core::line!() as i32, + ) + } + }; +} + +/// Polls periodically until a condition is met or a timeout is reached. +/// +/// `op` is called repeatedly until `cond` returns `true` or the timeout is +/// reached. The return value of `op` is passed to `cond`. +/// +/// `sleep_delta` is the duration to sleep between calls to `op`. +/// If `sleep_delta` is less than one microsecond, the function will busy-= wait. +/// +/// `timeout_delta` is the maximum time to wait for `cond` to return `true= `. +/// +/// This macro can only be used in a nonatomic context. +#[macro_export] +macro_rules! readx_poll_timeout { + ($op:expr, $cond:expr, $sleep_delta:expr, $timeout_delta:expr) =3D> {{ + if !$sleep_delta.is_zero() { + $crate::__might_sleep!(); + } + + $crate::io::poll::read_poll_timeout($op, $cond, $sleep_delta, $tim= eout_delta) + }}; +} diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs index 22a3bfa5a9e9..b775fd1c9be0 100644 --- a/rust/kernel/lib.rs +++ b/rust/kernel/lib.rs @@ -35,6 +35,7 @@ #[cfg(CONFIG_RUST_FW_LOADER_ABSTRACTIONS)] pub mod firmware; pub mod init; +pub mod io; pub mod ioctl; #[cfg(CONFIG_KUNIT)] pub mod kunit; @@ -44,6 +45,7 @@ pub mod page; pub mod prelude; pub mod print; +pub mod processor; pub mod sizes; pub mod rbtree; mod static_assert; diff --git a/rust/kernel/processor.rs b/rust/kernel/processor.rs new file mode 100644 index 000000000000..eeeff4be84fa --- /dev/null +++ b/rust/kernel/processor.rs @@ -0,0 +1,13 @@ +// SPDX-License-Identifier: GPL-2.0 + +//! Processor related primitives. +//! +//! C header: [`include/linux/processor.h`](srctree/include/linux/processo= r.h). + +/// Lower CPU power consumption or yield to a hyperthreaded twin processor. +/// +/// It also happens to serve as a compiler barrier. +pub fn cpu_relax() { + // SAFETY: FFI call. + unsafe { bindings::cpu_relax() } +} --=20 2.43.0