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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9DE1AC433EF for ; Tue, 19 Jul 2022 20:33:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238865AbiGSUdS (ORCPT ); Tue, 19 Jul 2022 16:33:18 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46830 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233670AbiGSUdR (ORCPT ); Tue, 19 Jul 2022 16:33:17 -0400 Received: from mga06.intel.com (mga06b.intel.com [134.134.136.31]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C3A884506B; Tue, 19 Jul 2022 13:33:16 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1658262796; x=1689798796; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=20RPDLm8Al5aPVJySa70I/GMs19LDvZGqa/P5oQG5pU=; b=ZjdXZBMFkHzsyEHX0nm7bK965LXL7jOWVgETuC6M6IY3CDdLEzeVu+pZ 5LFsyznpsCPvBt/o1b8NS5EZe2XS4rmHEtfCGiTAnJ22pCRlMQPAmaqPH QlIjJlXvDsIzHRbpf4XsNoanO63Ts8ZwJkRpWhdE5dLU1LeB5x7ChPS+T PBJinHesu0xJ15WWslWOtvUV/vRylzTQXboBDSjoJdD5ty6nFvSu14Y9T 9bS92dPXQDSqHxFYysC7tCKZdL4kYOxdLbY6ROl58287PebOwRJgFWrBa bot6/te/qc86zdEs8JLRE09wm+O1DJLiLLxInPNHqcjNsh3rMY+XXUg1X w==; X-IronPort-AV: E=McAfee;i="6400,9594,10413"; a="348287280" X-IronPort-AV: E=Sophos;i="5.92,285,1650956400"; d="scan'208";a="348287280" Received: from fmsmga006.fm.intel.com ([10.253.24.20]) by orsmga104.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 19 Jul 2022 13:33:16 -0700 X-IronPort-AV: E=Sophos;i="5.92,285,1650956400"; d="scan'208";a="843784574" Received: from avandeve-mobl.amr.corp.intel.com (HELO [10.209.102.45]) ([10.209.102.45]) by fmsmga006-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 19 Jul 2022 13:33:13 -0700 Message-ID: Date: Tue, 19 Jul 2022 13:33:13 -0700 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101 Thunderbird/91.11.0 Subject: Re: [PATCH v2 09/13] notifier: Show function names on notifier routines if DEBUG_NOTIFIERS is set Content-Language: en-US To: "Guilherme G. Piccoli" , akpm@linux-foundation.org, bhe@redhat.com, pmladek@suse.com, kexec@lists.infradead.org Cc: linux-kernel@vger.kernel.org, linux-hyperv@vger.kernel.org, netdev@vger.kernel.org, x86@kernel.org, kernel-dev@igalia.com, kernel@gpiccoli.net, halves@canonical.com, fabiomirmar@gmail.com, alejandro.j.jimenez@oracle.com, andriy.shevchenko@linux.intel.com, arnd@arndb.de, bp@alien8.de, corbet@lwn.net, d.hatayama@jp.fujitsu.com, dave.hansen@linux.intel.com, dyoung@redhat.com, feng.tang@intel.com, gregkh@linuxfoundation.org, mikelley@microsoft.com, hidehiro.kawai.ez@hitachi.com, jgross@suse.com, john.ogness@linutronix.de, keescook@chromium.org, luto@kernel.org, mhiramat@kernel.org, mingo@redhat.com, paulmck@kernel.org, peterz@infradead.org, rostedt@goodmis.org, senozhatsky@chromium.org, stern@rowland.harvard.edu, tglx@linutronix.de, vgoyal@redhat.com, vkuznets@redhat.com, will@kernel.org, Cong Wang , Sebastian Andrzej Siewior , Valentin Schneider , Xiaoming Ni References: <20220719195325.402745-1-gpiccoli@igalia.com> <20220719195325.402745-10-gpiccoli@igalia.com> From: Arjan van de Ven In-Reply-To: <20220719195325.402745-10-gpiccoli@igalia.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-hyperv@vger.kernel.org On 7/19/2022 12:53 PM, Guilherme G. Piccoli wrote: > Currently we have a debug infrastructure in the notifiers file, but > it's very simple/limited. Extend it by: > > (a) Showing all registered/unregistered notifiers' callback names; I'm not yet convinced that this is the right direction. The original intent for this "debug" feature was to be lightweight enough that it could run in production, since at the time, rootkits liked to clobber/hijack notifiers and there were also some other signs of corruption at the time. By making something print (even at pr_info) for what are probably frequent non-error operations, you turn something that is light into something that's a lot more heavy and generally that's not a great idea... it'll be a performance surprise.