linux-kernel - Re: [PATCH] rcu-tasks: Update show_rcu_tasks_trace_gp

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Message-ID: <20240326152230.3e692d83@gandalf.local.home>
Date: Tue, 26 Mar 2024 15:22:30 -0400
From: Steven Rostedt <rostedt@...dmis.org>
To: Nikita Kiryushin <kiryushin@...ud.ru>
Cc: "Paul E. McKenney" <paulmck@...nel.org>, Frederic Weisbecker
 <frederic@...nel.org>, Neeraj Upadhyay <quic_neeraju@...cinc.com>, Joel
 Fernandes <joel@...lfernandes.org>, Josh Triplett <josh@...htriplett.org>,
 Boqun Feng <boqun.feng@...il.com>, Mathieu Desnoyers
 <mathieu.desnoyers@...icios.com>, Lai Jiangshan <jiangshanlai@...il.com>,
 Zqiang <qiang.zhang1211@...il.com>, rcu@...r.kernel.org,
 linux-kernel@...r.kernel.org, lvc-project@...uxtesting.org
Subject: Re: [PATCH] rcu-tasks: Update show_rcu_tasks_trace_gp_kthread
 buffer size

On Tue, 26 Mar 2024 20:48:39 +0300
Nikita Kiryushin <kiryushin@...ud.ru> wrote:

> diff --git a/kernel/rcu/tasks.h b/kernel/rcu/tasks.h
> index 147b5945d67a..13ac514489c0 100644
> --- a/kernel/rcu/tasks.h
> +++ b/kernel/rcu/tasks.h
> @@ -1992,7 +1992,7 @@ static int __init rcu_spawn_tasks_trace_kthread(void)
>  #if !defined(CONFIG_TINY_RCU)
>  void show_rcu_tasks_trace_gp_kthread(void)
>  {
> -	char buf[64];
> +	char buf[87];

Why 87? as it's not even word size, and this is on the stack.

>  
>  	sprintf(buf, "N%lu h:%lu/%lu/%lu",

Better yet, why not just use snprintf()?

	snprintf(buf, 64, "N%lu h:%lu/%lu/%lu",

-- Steve

>  		data_race(n_trc_holdouts),
> --