Re: [PATCH] ftrace: Prevent RCU stall on PREEMPT_VOLUNTARY kernels

From: "Guilherme G. Piccoli" <gpiccoli@igalia.com>
To: rostedt@goodmis.org
Cc: linux-kernel@vger.kernel.org,
	"Masami Hiramatsu (Google)" <mhiramat@kernel.org>,
	rcu@vger.kernel.org, kernel-dev@igalia.com, kernel@gpiccoli.net,
	"Paul E . McKenney" <paulmck@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>
Subject: Re: [PATCH] ftrace: Prevent RCU stall on PREEMPT_VOLUNTARY kernels
Date: Tue, 13 Dec 2022 19:04:41 -0300	[thread overview]
Message-ID: <07b8285c-abfc-dcc6-5a20-b6f8c9bc7e1e@igalia.com> (raw)
In-Reply-To: <20221116153620.353819e9c6acb1bf39adeca2@kernel.org>

On 16/11/2022 03:36, Masami Hiramatsu (Google) wrote:
> On Tue, 15 Nov 2022 17:48:47 -0300
> "Guilherme G. Piccoli" <gpiccoli@igalia.com> wrote:
> 
>> The function match_records() may take a while due to a large
>> number of string comparisons, so when in PREEMPT_VOLUNTARY
>> kernels we could face RCU stalls due to that.
>>
>> Add a cond_resched() to prevent that.
>>
>> Suggested-by: Steven Rostedt <rostedt@goodmis.org>
>> Acked-by: Paul E. McKenney <paulmck@kernel.org> # from RCU CPU stall warning perspective
>> Cc: Masami Hiramatsu <mhiramat@kernel.org>
>> Cc: Mark Rutland <mark.rutland@arm.com>
>> Signed-off-by: Guilherme G. Piccoli <gpiccoli@igalia.com>
> 
> This looks good to me.
> 
> Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
> 
> Thanks!
> 

Hi Steve, sorry to annoy, just a regular ping to see if we can get this
into 6.2 (if too late, not a huge deal).

Thanks,

Guilherme