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=-11.5 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,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 8B5E0C433DF for ; Thu, 6 Aug 2020 16:58:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DEF252086A for ; Thu, 6 Aug 2020 16:58:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729893AbgHFQ6F (ORCPT ); Thu, 6 Aug 2020 12:58:05 -0400 Received: from mail.kernel.org ([198.145.29.99]:59368 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729876AbgHFQ5N (ORCPT ); Thu, 6 Aug 2020 12:57:13 -0400 Received: from oasis.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 C3F4C2086A; Thu, 6 Aug 2020 16:57:12 +0000 (UTC) Date: Thu, 6 Aug 2020 12:57:10 -0400 From: Steven Rostedt To: LKML Cc: Sean Paul Subject: tracing: Add trace_array_init_printk() to initialize instance trace_printk() buffers Message-ID: <20200806125710.3e9bd355@oasis.local.home> 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 From: "Steven Rostedt (VMware)" As trace_array_printk() used with not global instances will not add noise to the main buffer, they are OK to have in the kernel (unlike trace_printk()). This require the subsystem to create their own tracing instance, and the trace_array_printk() only writes into those instances. Add trace_array_init_printk() to initialize the trace_printk() buffers without printing out the WARNING message. Reported-by: Sean Paul Signed-off-by: Steven Rostedt (VMware) --- kernel/trace/trace.c | 43 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 43 insertions(+) diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 06c0feae5ff9..48b608d9c5b1 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -3129,6 +3129,9 @@ static int alloc_percpu_trace_buffer(void) { struct trace_buffer_struct *buffers; + if (trace_percpu_buffer) + return 0; + buffers = alloc_percpu(struct trace_buffer_struct); if (MEM_FAIL(!buffers, "Could not allocate percpu trace_printk buffer")) return -ENOMEM; @@ -3331,6 +3334,26 @@ int trace_array_vprintk(struct trace_array *tr, return __trace_array_vprintk(tr->array_buffer.buffer, ip, fmt, args); } +/** + * trace_array_printk - Print a message to a specific instance + * @tr: The instance trace_array descriptor + * @ip: The instruction pointer that this is called from. + * @fmt: The format to print (printf format) + * + * If a subsystem sets up its own instance, they have the right to + * printk strings into their tracing instance buffer using this + * function. Note, this function will not write into the top level + * buffer (use trace_printk() for that), as writing into the top level + * buffer should only have events that can be individually disabled. + * trace_printk() is only used for debugging a kernel, and should not + * be ever encorporated in normal use. + * + * trace_array_printk() can be used, as it will not add noise to the + * top level tracing buffer. + * + * Note, trace_array_init_printk() must be called on @tr before this + * can be used. + */ __printf(3, 0) int trace_array_printk(struct trace_array *tr, unsigned long ip, const char *fmt, ...) @@ -3355,6 +3378,26 @@ int trace_array_printk(struct trace_array *tr, } EXPORT_SYMBOL_GPL(trace_array_printk); +/** + * trace_array_init_printk - Initialize buffers for trace_array_printk() + * @tr: The trace array to initialize the buffers for + * + * As trace_array_printk() only writes into instances, they are OK to + * have in the kernel (unlike trace_printk()). This needs to be called + * before trace_array_printk() can be used on a trace_array. + */ +int trace_array_init_printk(struct trace_array *tr) +{ + if (!tr) + return -ENOENT; + + /* This is only allowed for created instances */ + if (tr == &global_trace) + return -EINVAL; + + return alloc_percpu_trace_buffer(); +} + __printf(3, 4) int trace_array_printk_buf(struct trace_buffer *buffer, unsigned long ip, const char *fmt, ...) -- 2.25.4