Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Subject: Re: [PATCH v2 9/9] perf,tracing: Allow function tracing when !RCU
To:     Peter Zijlstra <peterz@infradead.org>,
        linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org,
        rostedt@goodmis.org
Cc:     mingo@kernel.org, joel@joelfernandes.org,
        gregkh@linuxfoundation.org, gustavo@embeddedor.com,
        tglx@linutronix.de, paulmck@kernel.org, josh@joshtriplett.org,
        mathieu.desnoyers@efficios.com, jiangshanlai@gmail.com
References: <20200212210139.382424693@infradead.org>
 <20200212210750.312024711@infradead.org>
From:   Kim Phillips <kim.phillips@amd.com>
Message-ID: <121a6b11-2fe1-6d9b-2861-a8ef8b42c452@amd.com>
Date:   Fri, 14 Feb 2020 14:38:14 -0600
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101
 Thunderbird/68.4.1
In-Reply-To: <20200212210750.312024711@infradead.org>
Content-Type: text/plain; charset=utf-8
Content-Language: en-US
Content-Transfer-Encoding: 7bit
MIME-Version: 1.0
Received-SPF: None (protection.outlook.com: amd.com does not designate
 permitted sender hosts)
X-MS-Exchange-CrossTenant-Network-Message-Id: 4e0d6ce8-4a3a-4d64-7734-08d7b18dd23e
X-MS-Exchange-CrossTenant-OriginalArrivalTime: 14 Feb 2020 20:38:17.4267
 (UTC)
X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted
X-MS-Exchange-CrossTenant-Id: 3dd8961f-e488-4e60-8e11-a82d994e183d
X-MS-Exchange-CrossTenant-MailboxType: HOSTED
X-MS-Exchange-CrossTenant-UserPrincipalName: Iry6BF90gPnNjJ4U3jVdmoH/d8MwLq6gND03y5EgJr7+65mkOoYfe96CRRuVL3aQmsaEU8/AMjt6keZCBz7Qcw==
X-MS-Exchange-Transport-CrossTenantHeadersStamped: SN6PR12MB2687
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On 2/12/20 3:01 PM, Peter Zijlstra wrote:
> Since perf is now able to deal with !rcu_is_watching() contexts,
> remove the restraint.
> 
> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
> ---
>  kernel/trace/trace_event_perf.c |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> --- a/kernel/trace/trace_event_perf.c
> +++ b/kernel/trace/trace_event_perf.c
> @@ -477,7 +477,7 @@ static int perf_ftrace_function_register
>  {
>  	struct ftrace_ops *ops = &event->ftrace_ops;
>  
> -	ops->flags   = FTRACE_OPS_FL_RCU;
> +	ops->flags   = 0;
>  	ops->func    = perf_ftrace_function_call;
>  	ops->private = (void *)(unsigned long)nr_cpu_ids;

If this is the last user of the flag, should all remaining
FTRACE_OPS_FL_RCU references be removed, too?

Thanks,

Kim