linux-kernel - Re: [PATCH v2 15/18] rtla: Make stop

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Message-ID: <20260106110519.40c97efe@gandalf.local.home>
Date: Tue, 6 Jan 2026 11:05:19 -0500
From: Steven Rostedt <rostedt@...dmis.org>
To: Wander Lairson Costa <wander@...hat.com>
Cc: Tomas Glozar <tglozar@...hat.com>, Crystal Wood <crwood@...hat.com>,
 Ivan Pravdin <ipravdin.official@...il.com>, Costa Shulyupin
 <costa.shul@...hat.com>, John Kacur <jkacur@...hat.com>, Tiezhu Yang
 <yangtiezhu@...ngson.cn>, linux-trace-kernel@...r.kernel.org (open
 list:Real-time Linux Analysis (RTLA) tools), linux-kernel@...r.kernel.org
 (open list:Real-time Linux Analysis (RTLA) tools), bpf@...r.kernel.org
 (open list:BPF [MISC]:Keyword:(?:\b|_)bpf(?:\b|_))
Subject: Re: [PATCH v2 15/18] rtla: Make stop_tracing variable volatile

On Tue,  6 Jan 2026 08:49:51 -0300
Wander Lairson Costa <wander@...hat.com> wrote:

> Add the volatile qualifier to stop_tracing in both common.c and
> common.h to ensure all accesses to this variable bypass compiler
> optimizations and read directly from memory. This guarantees that
> when the signal handler sets stop_tracing, the change is immediately
> visible to the main program loop, preventing potential hangs or
> delayed shutdown when termination signals are received.

In the kernel, this is handled via the READ_ONCE() macro. Perhaps rtla
should implement that too.

-- Steve