From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_2 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id F125DC2BA83 for ; Wed, 12 Feb 2020 14:26:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C24B12082F for ; Wed, 12 Feb 2020 14:26:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728445AbgBLO07 (ORCPT ); Wed, 12 Feb 2020 09:26:59 -0500 Received: from mail.kernel.org ([198.145.29.99]:44260 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727963AbgBLO06 (ORCPT ); Wed, 12 Feb 2020 09:26:58 -0500 Received: from gandalf.local.home (cpe-66-24-58-225.stny.res.rr.com [66.24.58.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 2A455206D7; Wed, 12 Feb 2020 14:26:57 +0000 (UTC) Date: Wed, 12 Feb 2020 09:26:55 -0500 From: Steven Rostedt To: Peter Zijlstra Cc: linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, 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 Subject: Re: [PATCH 6/8] perf,tracing: Prepare the perf-trace interface for RCU changes Message-ID: <20200212092655.4ba6cd79@gandalf.local.home> In-Reply-To: <20200212094107.951346701@infradead.org> References: <20200212093210.468391728@infradead.org> <20200212094107.951346701@infradead.org> X-Mailer: Claws Mail 3.17.3 (GTK+ 2.24.32; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 12 Feb 2020 10:32:16 +0100 Peter Zijlstra wrote: > The tracepoint interface will stop providing regular RCU context; make > sure we do it ourselves, since perf makes use of regular RCU protected > data. > Suggested-by: Steven Rostedt (VMware) ;-) -- Steve > Signed-off-by: Peter Zijlstra (Intel) > --- > kernel/events/core.c | 5 +++++ > 1 file changed, 5 insertions(+) > > --- a/kernel/events/core.c > +++ b/kernel/events/core.c > @@ -8950,6 +8950,7 @@ void perf_tp_event(u16 event_type, u64 c > { > struct perf_sample_data data; > struct perf_event *event; > + unsigned long rcu_flags; > > struct perf_raw_record raw = { > .frag = { > @@ -8961,6 +8962,8 @@ void perf_tp_event(u16 event_type, u64 c > perf_sample_data_init(&data, 0, 0); > data.raw = &raw; > > + rcu_flags = trace_rcu_enter(); > + > perf_trace_buf_update(record, event_type); > > hlist_for_each_entry_rcu(event, head, hlist_entry) { > @@ -8996,6 +8999,8 @@ void perf_tp_event(u16 event_type, u64 c > } > > perf_swevent_put_recursion_context(rctx); > + > + trace_rcu_exit(rcu_flags); > } > EXPORT_SYMBOL_GPL(perf_tp_event); > >