From: "Gary Guo" <gary@garyguo.net>
To: "Thomas Weißschuh" <linux@weissschuh.net>,
"Jason Baron" <jbaron@akamai.com>,
"Jim Cromie" <jim.cromie@gmail.com>,
"Miguel Ojeda" <ojeda@kernel.org>,
"Boqun Feng" <boqun@kernel.org>, "Gary Guo" <gary@garyguo.net>,
"Björn Roy Baron" <bjorn3_gh@protonmail.com>,
"Benno Lossin" <lossin@kernel.org>,
"Andreas Hindborg" <a.hindborg@kernel.org>,
"Alice Ryhl" <aliceryhl@google.com>,
"Trevor Gross" <tmgross@umich.edu>,
"Danilo Krummrich" <dakr@kernel.org>,
"Daniel Almeida" <daniel.almeida@collabora.com>,
"Tamir Duberstein" <tamird@kernel.org>,
"Alexandre Courbot" <acourbot@nvidia.com>,
"Onur Özkan" <work@onurozkan.dev>,
"Andrew Morton" <akpm@linux-foundation.org>,
"Will Deacon" <will@kernel.org>,
"Peter Zijlstra" <peterz@infradead.org>,
"Mark Rutland" <mark.rutland@arm.com>,
"Lyude Paul" <lyude@redhat.com>,
"Yury Norov" <yury.norov@gmail.com>,
"Luis Chamberlain" <mcgrof@kernel.org>,
"Petr Pavlu" <petr.pavlu@suse.com>,
"Daniel Gomez" <da.gomez@kernel.org>,
"Sami Tolvanen" <samitolvanen@google.com>,
"Aaron Tomlin" <atomlin@atomlin.com>,
"Brendan Higgins" <brendan.higgins@linux.dev>,
"David Gow" <david@davidgow.net>,
"Rae Moar" <raemoar63@gmail.com>,
"Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
"Rafael J. Wysocki" <rafael@kernel.org>
Cc: <linux-kernel@vger.kernel.org>, <rust-for-linux@vger.kernel.org>,
<linux-modules@vger.kernel.org>,
<linux-kselftest@vger.kernel.org>, <kunit-dev@googlegroups.com>,
<driver-core@lists.linux.dev>
Subject: Re: [PATCH RFC 07/11] dyndbg: use READ_ONCE()/WRITE_ONCE() to access descriptor flags
Date: Sun, 11 Oct 2026 14:16:25 +0100 [thread overview]
Message-ID: <DM21CVIBHTW9.3OHGQ2ME5G89V@garyguo.net> (raw)
In-Reply-To: <20261011-rust-dyndbg-v1-7-832e4039b71f@weissschuh.net>
On Sun Oct 11, 2026 at 1:52 PM BST, Thomas Weißschuh wrote:
> The descriptor flags are accessed concurrently. Use
> READ_ONCE()/WRITE_ONCE() to keep their contents consistent.
>
> Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
>
> ---
> I am not entirely sure about this. We are only using single bits, so
> torn reads/writes should not matter. But LKMM has no guidance on this as
> far as I can see. Also for Rust this seems to be necessary.
Code should assume plain writes to be atomic. Concurrently accessed data should
use READ_ONCE/WRITE_ONCE so you're right on this one.
I think this patch should be merged with the bitfield definition change, though.
Best,
Gary
> ---
> include/linux/dynamic_debug.h | 6 +++---
> lib/dynamic_debug.c | 24 +++++++++++++-----------
> 2 files changed, 16 insertions(+), 14 deletions(-)
>
next prev parent reply other threads:[~2026-10-11 13:16 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-10-11 12:52 [PATCH RFC 00/11] rust: add support for dynamic debug Thomas Weißschuh
2026-10-11 12:52 ` [PATCH RFC 01/11] rust: print: use CStr for __LOG_PREFIX Thomas Weißschuh
2026-10-11 13:01 ` Gary Guo
2026-10-11 14:43 ` Thomas Weißschuh
2026-10-11 12:52 ` [PATCH RFC 02/11] rust: sync: atomic: Add Atomic<u{8,16}> Thomas Weißschuh
2026-10-11 13:00 ` sashiko-bot
2026-10-11 13:04 ` Gary Guo
2026-10-11 12:52 ` [PATCH RFC 03/11] rust: num: Add Bounded::USABLE_BITS Thomas Weißschuh
2026-10-11 12:52 ` [PATCH RFC 04/11] samples: rust_print: add debug messages Thomas Weißschuh
2026-10-11 13:53 ` Miguel Ojeda
2026-10-11 14:48 ` Thomas Weißschuh
2026-10-11 12:52 ` [PATCH RFC 05/11] dyndbg: use u32 for struct _ddebug bitfields Thomas Weißschuh
2026-10-11 12:52 ` [PATCH RFC 06/11] dyndbg: make _ddebug::flags its own field Thomas Weißschuh
2026-10-11 13:23 ` Gary Guo
2026-10-11 14:47 ` Thomas Weißschuh
2026-10-11 15:44 ` Gary Guo
2026-10-11 12:52 ` [PATCH RFC 07/11] dyndbg: use READ_ONCE()/WRITE_ONCE() to access descriptor flags Thomas Weißschuh
2026-10-11 13:16 ` Gary Guo [this message]
2026-10-11 12:52 ` [PATCH RFC 08/11] rust: add support for dynamic debug Thomas Weißschuh
2026-10-11 13:08 ` sashiko-bot
2026-10-11 12:52 ` [PATCH RFC 09/11] rust: print: enable dynamic debug for pr_debug!() Thomas Weißschuh
2026-10-11 13:01 ` sashiko-bot
2026-10-11 12:52 ` [PATCH RFC 10/11] rust: device: remove logging methods Thomas Weißschuh
2026-10-11 13:01 ` sashiko-bot
2026-10-11 12:52 ` [PATCH RFC 11/11] rust: device: enable dynamic debug for dev_dbg!() Thomas Weißschuh
2026-10-11 13:01 ` sashiko-bot
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=DM21CVIBHTW9.3OHGQ2ME5G89V@garyguo.net \
--to=gary@garyguo.net \
--cc=a.hindborg@kernel.org \
--cc=acourbot@nvidia.com \
--cc=akpm@linux-foundation.org \
--cc=aliceryhl@google.com \
--cc=atomlin@atomlin.com \
--cc=bjorn3_gh@protonmail.com \
--cc=boqun@kernel.org \
--cc=brendan.higgins@linux.dev \
--cc=da.gomez@kernel.org \
--cc=dakr@kernel.org \
--cc=daniel.almeida@collabora.com \
--cc=david@davidgow.net \
--cc=driver-core@lists.linux.dev \
--cc=gregkh@linuxfoundation.org \
--cc=jbaron@akamai.com \
--cc=jim.cromie@gmail.com \
--cc=kunit-dev@googlegroups.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-kselftest@vger.kernel.org \
--cc=linux-modules@vger.kernel.org \
--cc=linux@weissschuh.net \
--cc=lossin@kernel.org \
--cc=lyude@redhat.com \
--cc=mark.rutland@arm.com \
--cc=mcgrof@kernel.org \
--cc=ojeda@kernel.org \
--cc=peterz@infradead.org \
--cc=petr.pavlu@suse.com \
--cc=raemoar63@gmail.com \
--cc=rafael@kernel.org \
--cc=rust-for-linux@vger.kernel.org \
--cc=samitolvanen@google.com \
--cc=tamird@kernel.org \
--cc=tmgross@umich.edu \
--cc=will@kernel.org \
--cc=work@onurozkan.dev \
--cc=yury.norov@gmail.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.