From: Steven Rostedt <rostedt@goodmis.org>
To: Zhu Jun <zhujun2@cmss.chinamobile.com>
Cc: vdonnefort@google.com, mhiramat@kernel.org,
mathieu.desnoyers@efficios.com,
linux-trace-kernel@vger.kernel.org, linux-kernel@vger.kernel.org,
syzbot+53ab168fdda7fba508ba@syzkaller.appspotmail.com
Subject: Re: [PATCH] ring-buffer: Mark concurrent accesses to waiter flags
Date: Thu, 12 Nov 2026 05:45:42 -0500 [thread overview]
Message-ID: <20261112054542.63b29e3d@fedora> (raw)
In-Reply-To: <20261111084137.80941-1-zhujun2@cmss.chinamobile.com>
On Wed, 11 Nov 2026 16:41:37 +0800
Zhu Jun <zhujun2@cmss.chinamobile.com> wrote:
> Poll and wait paths set the pending waiter flags while ring buffer
> writers test and clear them without a common lock. The irq_work callback
> also accesses the full-buffer wakeup flags concurrently. These plain
> accesses cause KCSAN reports.
>
> Use READ_ONCE() and WRITE_ONCE() for the shared waiter and wakeup flags.
> Keep the existing barriers and irq_work wakeup protocol unchanged.
>
> Fixes: 15693458c4bc ("tracing/ring-buffer: Move poll wake ups into ring buffer code")
> Fixes: 1e0d6714aceb ("ring-buffer: Do not wake up a splice waiter when page is not full")
> Signed-off-by: Zhu Jun <zhujun2@cmss.chinamobile.com>
Is this simply to prevent read/write tearing?
-- Steve
prev parent reply other threads:[~2026-11-12 10:46 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-11-11 8:41 Zhu Jun
2026-11-12 10:45 ` Steven Rostedt [this message]
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