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=-2.3 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT 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 951A3C43441 for ; Fri, 16 Nov 2018 17:36:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4E3042086A for ; Fri, 16 Nov 2018 17:36:17 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=thunk.org header.i=@thunk.org header.b="ybb4rWfw" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 4E3042086A Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=mit.edu Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2390083AbeKQDtd (ORCPT ); Fri, 16 Nov 2018 22:49:33 -0500 Received: from imap.thunk.org ([74.207.234.97]:39976 "EHLO imap.thunk.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729036AbeKQDtd (ORCPT ); Fri, 16 Nov 2018 22:49:33 -0500 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=thunk.org; s=ef5046eb; h=In-Reply-To:Content-Type:MIME-Version:References:Message-ID: Subject:Cc:To:From:Date:Sender:Reply-To:Content-Transfer-Encoding:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Id:List-Help:List-Unsubscribe:List-Subscribe: List-Post:List-Owner:List-Archive; bh=a3wvockeyFdBCdANJ0FWpvxXKlsz8M9B+g9hKXIk5ik=; b=ybb4rWfwKs+x0CtNS/ANm6jcZm HlkLi9pgSmluEAPnzeRE6ZNBgZPMyKUPI7VRGf7yd66lt7peGGZpbOqvNIJz7YMTDMb/hun1XkgqT kDj2F+7o9A7dLUhdvNwXGvmoo4xKJG7HbEVGKSaxHdcoBCqoFMDRSfHvX+rE8myiKCkU=; Received: from root (helo=callcc.thunk.org) by imap.thunk.org with local-esmtp (Exim 4.89) (envelope-from ) id 1gNi24-0004sq-KD; Fri, 16 Nov 2018 17:35:52 +0000 Received: by callcc.thunk.org (Postfix, from userid 15806) id 3A5C47A47B5; Fri, 16 Nov 2018 12:35:51 -0500 (EST) Date: Fri, 16 Nov 2018 12:35:51 -0500 From: "Theodore Y. Ts'o" To: Paolo Bonzini Cc: Bart Van Assche , linux-kernel@vger.kernel.org, linux-scsi@vger.kernel.org, Hannes Reinecke , "Martin K. Petersen" , James Bottomley , Christoph Hellwig Subject: Re: [PATCH 0/3] SG_IO command filtering via sysfs Message-ID: <20181116173551.GG20617@thunk.org> Mail-Followup-To: "Theodore Y. Ts'o" , Paolo Bonzini , Bart Van Assche , linux-kernel@vger.kernel.org, linux-scsi@vger.kernel.org, Hannes Reinecke , "Martin K. Petersen" , James Bottomley , Christoph Hellwig References: <1541867733-7836-1-git-send-email-pbonzini@redhat.com> <20181110190521.GA2627@thunk.org> <566bc821-f12a-f7c1-e7c7-99092807ee27@redhat.com> <20181111141426.GA7377@thunk.org> <98fe5cf7-722a-37d6-156d-842e8812e430@redhat.com> <1542328654.100259.18.camel@acm.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) X-SA-Exim-Connect-IP: X-SA-Exim-Mail-From: tytso@thunk.org X-SA-Exim-Scanned: No (on imap.thunk.org); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Nov 16, 2018 at 08:01:29AM +0100, Paolo Bonzini wrote: > On 16/11/18 01:37, Bart Van Assche wrote: > > All user space interfaces in the Linux kernel for storage that I'm familiar > > with not only allow configuration of parameters but also make it easy to > > query which parameters have been configured. The existing sysfs and configfs > > interfaces demonstrate this. Using BPF to configure SG/IO access has a > > significant disadvantage, namely that it is very hard to figure out what has > > been configured. Figuring out what has been configured namely requires > > disassembling BPF. I'm not sure anyone will be enthusiast about this. > > Well, that's a problem with BPF in general. With great power comes > great obscurability. You can also make the same complaint about kernel modules; that it's impossible to figure exactly what a kernel modules does without disassembling them. However, you can a one-line description of what it does using modinfo: % modinfo async_pq filename: /lib/modules/4.19.0-00022-g831156939ae8/kernel/crypto/async_tx/async_pq.ko license: GPL description: asynchronous raid6 syndrome generation/validation srcversion: 529102C736C4FED181C15A8 depends: raid6_pq,async_tx,async_xor retpoline: Y intree: Y name: async_pq vermagic: 4.19.0-00022-g831156939ae8 SMP mod_unload modversions - Ted