Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Message-ID: <07b8285c-abfc-dcc6-5a20-b6f8c9bc7e1e@igalia.com>
Date:   Tue, 13 Dec 2022 19:04:41 -0300
MIME-Version: 1.0
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101
 Thunderbird/102.5.0
Subject: Re: [PATCH] ftrace: Prevent RCU stall on PREEMPT_VOLUNTARY kernels
Content-Language: en-US
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>
References: <20221115204847.593616-1-gpiccoli@igalia.com>
 <20221116153620.353819e9c6acb1bf39adeca2@kernel.org>
From:   "Guilherme G. Piccoli" <gpiccoli@igalia.com>
In-Reply-To: <20221116153620.353819e9c6acb1bf39adeca2@kernel.org>
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 7bit
Precedence: bulk


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