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Message-ID: <20241107163223.2092690-1-ezulian@redhat.com>
Date: Thu, 7 Nov 2024 17:32:22 +0100
From: Eder Zulian <ezulian@...hat.com>
To: linux-kernel@...r.kernel.org,
linux-next@...r.kernel.org,
rust-for-linux@...r.kernel.org
Cc: miguel.ojeda.sandonis@...il.com,
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Subject: [PATCH v3 0/1] rust: helpers: Avoid raw_spin_lock initialization for PREEMPT_RT
Hello!
When PREEMPT_RT=y, spin locks are mapped to rt_mutex types, so using
spinlock_check() + __raw_spin_lock_init() to initialize spin locks is
incorrect, and would cause build errors.
This v3 patch introduces __spin_lock_init() to initialize a spin lock with
lockdep rquired information for PREEMPT_RT builds, and use it in the Rust
helper.
This patch was developed on top of linux-next/master.
As a note, at the time of writing, RUST support for x86_64 depends on
!(MITIGATION_RETHUNK && KASAN) || RUSTC_VERSION >= 108300. Miguel Ojeda
pointed out that this can be avoided with Rust 1.83, to be released in 3
weeks (2024-11-28).
In order to reproduce the problem rust must be available on the system.
$ make LLVM=1 rustavailable
With CONFIG_PREEMPT_RT=y, CONFIG_RUST=y, and CONFIG_DEBUG_SPINLOCK=y a
x86_64 kernel can be built with
$ make LLVM=1 -j$(nproc) bzImage
The problem was reported at least in:
https://lore.kernel.org/oe-kbuild-all/202409251238.vetlgXE9-lkp@intel.com/
https://lore.kernel.org/all/20241107182411.57e2b418@canb.auug.org.au/
Links to v1 and v2 where improvement suggestions were made:
https://lore.kernel.org/all/20241014195253.1704625-1-ezulian@redhat.com/
https://lore.kernel.org/all/20241106211215.2005909-1-ezulian@redhat.com/
Version 2 changes:
- Cleaned up style and incorporated feedback from reviewers Boqun Feng and
Miguel Ojeda.
Version 3 changes:
- Addressed review comments from Boqun Feng. Improved commit title and
description and used a proper 'Fixed:' tag.
Thanks,
Eder Zulian (1):
rust: helpers: Avoid raw_spin_lock initialization for PREEMPT_RT
include/linux/spinlock_rt.h | 15 +++++++--------
rust/helpers/spinlock.c | 8 ++++++--
2 files changed, 13 insertions(+), 10 deletions(-)
--
2.47.0
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