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=-8.6 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=unavailable 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 01267C433E5 for ; Wed, 22 Jul 2020 14:49:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A834C20729 for ; Wed, 22 Jul 2020 14:49:57 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=axis.com header.i=@axis.com header.b="V3gnVArd" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732668AbgGVOtz (ORCPT ); Wed, 22 Jul 2020 10:49:55 -0400 Received: from smtp1.axis.com ([195.60.68.17]:14468 "EHLO smtp1.axis.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729642AbgGVOtz (ORCPT ); Wed, 22 Jul 2020 10:49:55 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=axis.com; l=1497; q=dns/txt; s=axis-central1; t=1595429393; x=1626965393; h=date:from:to:cc:subject:message-id:references: mime-version:in-reply-to; bh=baYZLtX3aKwOTSmhfy5KuJLM6gJoW1ANGxx/SmqyNeM=; b=V3gnVArd1m0aNyepSqn7Ey0d0PRqam8QQOllnszO43nPZug/MzR5Rskw wYM4t5UFnFMmAKg39rd/g8MiUt+m14D4bdXkKP2AaPDsk/SPcfHwNonIF MnfK3AzOV5dM4tk4g5gFvo1weodgRUMuIa2zq+NFHPAQoQlATsv61+oo0 CFhlueCtdRRrCQlsIP+VVk9Giu5sbXqRTnULHIiwtgSZFuNaxtVSyDWlC ZcwbnqjZAYHTa0CfyKaYDT9EVnGBeHtIfBNeSh6U0w1no2XbDL8x/Y7EH Y95vN4L4sRkSWidzIPa81JsiT1zjE6jFSr9D1ty/Bdw5pkGwllfV02gRm w==; IronPort-SDR: mbTTJiW2W07rlCfh+N3FwpryhyE49fPLBLEbRRDKrFN9xWDIL9d5SYwEzDGYo843hu+yRO09OZ 4iaikNhwCBXuryiyAulLv211P85iWTszHr5xP86bH/zm+LhhivbpRQQ/9iKgRbH/21shZD6Ycu VLysSAqi/QGKM7J0sHYfAib2WYpqcHcMluQ/HgidsjoDLMi0uDFIq6I9QGj+qirIuok7ULCPrC dcp67YgMUEpa1rGY+iDxlaP7fGtvjWts72Re/IaE4YzuXWAsLFgaKGbhJJTS2zOR4Hv2INWakp HLw= X-IronPort-AV: E=Sophos;i="5.75,383,1589234400"; d="scan'208";a="11110818" Date: Wed, 22 Jul 2020 16:49:52 +0200 From: Vincent Whitchurch To: John Ogness CC: Steven Rostedt , "jbaron@akamai.com" , "mingo@redhat.com" , kernel , "corbet@lwn.net" , "linux-kernel@vger.kernel.org" , Petr Mladek , Sergey Senozhatsky Subject: Re: [PATCH] dynamic debug: allow printing to trace event Message-ID: <20200722144952.2mewrgebgkyr2zyf@axis.com> References: <20200721141105.16034-1-vincent.whitchurch@axis.com> <20200721173045.540ae500@oasis.local.home> <87eep3zmg9.fsf@jogness.linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <87eep3zmg9.fsf@jogness.linutronix.de> User-Agent: NeoMutt/20170113 (1.7.2) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jul 22, 2020 at 03:52:22PM +0200, John Ogness wrote: > On 2020-07-21, Steven Rostedt wrote: > >> diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c > >> index 321437bbf87d..9f6d8867af7c 100644 > >> --- a/lib/dynamic_debug.c > >> +++ b/lib/dynamic_debug.c > [..] > >> +static void dynamic_printk(unsigned int flags, const char *fmt, ...) > >> +{ > >> + if (flags & _DPRINTK_FLAGS_TRACE) { > >> + va_list args; > >> + > >> + va_start(args, fmt); > >> + /* > >> + * All callers include the KERN_DEBUG prefix to keep the > >> + * vprintk case simple; strip it out for tracing. > >> + */ > >> + dynamic_trace(fmt + strlen(KERN_DEBUG), args); > > Do we really need a separate tracing event for this? Why not just: > > ftrace_vprintk(fmt + strlen(KERN_DEBUG), args); Thanks, I tried that out now and it seems to work, but it results in the trace_printk() splat (even if the feature is not used), though: ********************************************************** ** NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE ** ** ** ** trace_printk() being used. Allocating extra memory. ** ** ** ** This means that this is a DEBUG kernel and it is ** ** unsafe for production use. ** ** ** ** If you see this message and you are not debugging ** ** the kernel, report this immediately to your vendor! ** ** ** ** NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE ** **********************************************************