From patchwork Wed Apr 5 02:21:15 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Steven Rostedt X-Patchwork-Id: 13201125 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id C34DFC761AF for ; Wed, 5 Apr 2023 02:23:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236714AbjDECXr (ORCPT ); Tue, 4 Apr 2023 22:23:47 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42320 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236548AbjDECXp (ORCPT ); Tue, 4 Apr 2023 22:23:45 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 39B282106; Tue, 4 Apr 2023 19:23:44 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id C022B60DD5; Wed, 5 Apr 2023 02:23:43 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2A30CC4339E; Wed, 5 Apr 2023 02:23:43 +0000 (UTC) Received: from rostedt by gandalf with local (Exim 4.96) (envelope-from ) id 1pjsoI-000hVn-0E; Tue, 04 Apr 2023 22:23:42 -0400 Message-ID: <20230405022341.895334039@goodmis.org> User-Agent: quilt/0.66 Date: Tue, 04 Apr 2023 22:21:15 -0400 From: Steven Rostedt To: linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org Cc: Masami Hiramatsu , Mark Rutland , Andrew Morton , Ross Zwisler , stable@vger.kernel.org Subject: [PATCH 2/2 v2] tracing: Fix ftrace_boot_snapshot command line logic References: <20230405022113.860447811@goodmis.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-trace-kernel@vger.kernel.org From: "Steven Rostedt (Google)" The kernel command line ftrace_boot_snapshot by itself is supposed to trigger a snapshot at the end of boot up of the main top level trace buffer. A ftrace_boot_snapshot=foo will do the same for an instance called foo that was created by trace_instance=foo,... The logic was broken where if ftrace_boot_snapshot was by itself, it would trigger a snapshot for all instances that had tracing enabled, regardless if it asked for a snapshot or not. When a snapshot is requested for a buffer, the buffer's tr->allocated_snapshot is set to true. Use that to know if a trace buffer wants a snapshot at boot up or not. Since the top level buffer is part of the ftrace_trace_arrays list, there's no reason to treat it differently than the other buffers. Just iterate the list if ftrace_boot_snapshot was specified. Cc: stable@vger.kernel.org Fixes: 9c1c251d670bc ("tracing: Allow boot instances to have snapshot buffers") Signed-off-by: Steven Rostedt (Google) --- Changes since v1: https://lkml.kernel.org/r/20230404230308.501833715@goodmis.org - Protect use of tr->allocated_snapshot around #ifdef TRACER_MAX_TRACE kernel/trace/trace.c | 13 +++++++------ 1 file changed, 7 insertions(+), 6 deletions(-) diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 93740a9370c6..36a6037823cd 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -10394,19 +10394,20 @@ __init static int tracer_alloc_buffers(void) void __init ftrace_boot_snapshot(void) { +#ifdef CONFIG_TRACER_MAX_TRACE struct trace_array *tr; - if (snapshot_at_boot) { - tracing_snapshot(); - internal_trace_puts("** Boot snapshot taken **\n"); - } + if (!snapshot_at_boot) + return; list_for_each_entry(tr, &ftrace_trace_arrays, list) { - if (tr == &global_trace) + if (!tr->allocated_snapshot) continue; - trace_array_puts(tr, "** Boot snapshot taken **\n"); + tracing_snapshot_instance(tr); + trace_array_puts(tr, "** Boot snapshot taken **\n"); } +#endif } void __init early_trace_init(void)