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=-9.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 F24ACC388F9 for ; Thu, 12 Nov 2020 01:38:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AC349206F1 for ; Thu, 12 Nov 2020 01:38:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729270AbgKLBiZ (ORCPT ); Wed, 11 Nov 2020 20:38:25 -0500 Received: from mail.kernel.org ([198.145.29.99]:38972 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728088AbgKLAfh (ORCPT ); Wed, 11 Nov 2020 19:35:37 -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 AD803207DE; Thu, 12 Nov 2020 00:33:35 +0000 (UTC) Received: from rostedt by gandalf.local.home with local (Exim 4.94) (envelope-from ) id 1kd0YQ-0002AK-ED; Wed, 11 Nov 2020 19:33:34 -0500 Message-ID: <20201112003334.324587576@goodmis.org> User-Agent: quilt/0.66 Date: Wed, 11 Nov 2020 19:32:52 -0500 From: Steven Rostedt To: linux-kernel@vger.kernel.org Cc: Ingo Molnar , Andrew Morton , Peter Zijlstra , Josh Poimboeuf , Jiri Kosina , Miroslav Benes , Petr Mladek , Masami Hiramatsu , Jiri Olsa Subject: [for-next][PATCH 08/17] perf/ftrace: Add recursion protection to the ftrace callback References: <20201112003244.764326960@goodmis.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: "Steven Rostedt (VMware)" If a ftrace callback does not supply its own recursion protection and does not set the RECURSION_SAFE flag in its ftrace_ops, then ftrace will make a helper trampoline to do so before calling the callback instead of just calling the callback directly. The default for ftrace_ops is going to change. It will expect that handlers provide their own recursion protection, unless its ftrace_ops states otherwise. Link: https://lkml.kernel.org/r/20201028115613.444477858@goodmis.org Link: https://lkml.kernel.org/r/20201106023547.466892083@goodmis.org Cc: Peter Zijlstra Cc: Ingo Molnar Cc: Josh Poimboeuf Cc: Jiri Kosina Cc: Miroslav Benes Cc: Petr Mladek Cc: Masami Hiramatsu Cc: Andrew Morton Cc: Jiri Olsa Signed-off-by: Steven Rostedt (VMware) --- kernel/trace/trace_event_perf.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/kernel/trace/trace_event_perf.c b/kernel/trace/trace_event_perf.c index 643e0b19920d..fd58d83861d8 100644 --- a/kernel/trace/trace_event_perf.c +++ b/kernel/trace/trace_event_perf.c @@ -439,10 +439,15 @@ perf_ftrace_function_call(unsigned long ip, unsigned long parent_ip, struct hlist_head head; struct pt_regs regs; int rctx; + int bit; if ((unsigned long)ops->private != smp_processor_id()) return; + bit = ftrace_test_recursion_trylock(); + if (bit < 0) + return; + event = container_of(ops, struct perf_event, ftrace_ops); /* @@ -463,13 +468,15 @@ perf_ftrace_function_call(unsigned long ip, unsigned long parent_ip, entry = perf_trace_buf_alloc(ENTRY_SIZE, NULL, &rctx); if (!entry) - return; + goto out; entry->ip = ip; entry->parent_ip = parent_ip; perf_trace_buf_submit(entry, ENTRY_SIZE, rctx, TRACE_FN, 1, ®s, &head, NULL); +out: + ftrace_test_recursion_unlock(bit); #undef ENTRY_SIZE } -- 2.28.0