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=-4.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS autolearn=no 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 C29FEC47257 for ; Fri, 1 May 2020 15:50:28 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 7E6FF24953 for ; Fri, 1 May 2020 15:50:28 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="uGDkmD3a" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 7E6FF24953 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 283EB8E0005; Fri, 1 May 2020 11:50:28 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 20C158E0001; Fri, 1 May 2020 11:50:28 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 0D5148E0005; Fri, 1 May 2020 11:50:28 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0004.hostedemail.com [216.40.44.4]) by kanga.kvack.org (Postfix) with ESMTP id E5F338E0001 for ; Fri, 1 May 2020 11:50:27 -0400 (EDT) Received: from smtpin18.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id AA9C6180AD804 for ; Fri, 1 May 2020 15:50:27 +0000 (UTC) X-FDA: 76768587294.18.toy62_2113cc343a745 X-HE-Tag: toy62_2113cc343a745 X-Filterd-Recvd-Size: 4597 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf08.hostedemail.com (Postfix) with ESMTP for ; Fri, 1 May 2020 15:50:27 +0000 (UTC) Received: from mail-vs1-f48.google.com (mail-vs1-f48.google.com [209.85.217.48]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 4402E2495C for ; Fri, 1 May 2020 15:50:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1588348226; bh=YTlbyd22lW351FilA/KSFmzAlvvZiIEuJWjP9lpav3U=; h=References:In-Reply-To:From:Date:Subject:To:Cc:From; b=uGDkmD3aUzWp5s3Bk9kOjsnSUiEvL3+WOHuQ0kaySIuRgbaXzbSo0K2N2nXVJqwhV o68DMxq943WhesG+RmBL0x3sZFBKxUoTIkcnBII+iwzKAZlJ5CKAx0VW1is3bzPb/I xpTQmlNBttn7LbF1Ofa0uIBzmXYvtzUQoa+gWICU= Received: by mail-vs1-f48.google.com with SMTP id e10so3863235vsp.12 for ; Fri, 01 May 2020 08:50:26 -0700 (PDT) X-Gm-Message-State: AGi0PuYZkJIPgWjinwLOhclFAKjoOmiephvYL0UbZNR6nRDq7nyo+NbZ uo4GiFNoumnVV2Wkg1LCgJVIqFfW4luIpm5l7Fs= X-Google-Smtp-Source: APiQypJbOU1tzkElYzCMzOtBkc0xemlNQUEM7LIN7khWr9hk9tce6YOeVMK5Jv8FjbWgEihKivk+2XAj9/JVC79QwZA= X-Received: by 2002:a05:6102:4d:: with SMTP id k13mr3850833vsp.198.1588348225200; Fri, 01 May 2020 08:50:25 -0700 (PDT) MIME-Version: 1.0 References: <20200429074627.5955-1-mcgrof@kernel.org> <20200429074627.5955-6-mcgrof@kernel.org> <20200429094937.GB2081185@kroah.com> <20200501150626.GM11244@42.do-not-panic.com> <20200501153423.GA12469@infradead.org> <20200501154050.GO11244@42.do-not-panic.com> In-Reply-To: <20200501154050.GO11244@42.do-not-panic.com> From: Luis Chamberlain Date: Fri, 1 May 2020 09:50:17 -0600 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH v3 5/6] blktrace: break out of blktrace setup on concurrent calls To: Christoph Hellwig , Christof Schmitt Cc: Greg KH , Jens Axboe , Al Viro , Bart Van Assche , Steven Rostedt , Ingo Molnar , Jan Kara , Ming Lei , Nicolai Stange , Andrew Morton , Michal Hocko , yu kuai , linux-block@vger.kernel.org, Linux FS Devel , linux-mm , "linux-kernel@vger.kernel.org" Content-Type: text/plain; charset="UTF-8" X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Fri, May 1, 2020 at 9:40 AM Luis Chamberlain wrote: > > On Fri, May 01, 2020 at 08:34:23AM -0700, Christoph Hellwig wrote: > > On Fri, May 01, 2020 at 03:06:26PM +0000, Luis Chamberlain wrote: > > > > You have access to a block device here, please use dev_warn() instead > > > > here for that, that makes it obvious as to what device a "concurrent > > > > blktrace" was attempted for. > > > > > > The block device may be empty, one example is for scsi-generic, but I'll > > > use buts->name. > > > > Is blktrace on /dev/sg something we intentionally support, or just by > > some accident of history? Given all the pains it causes I'd be tempted > > to just remove the support and see if anyone screams. > > From what I can tell I think it was a historic and brutal mistake. I am > more than happy to remove it. I take that back: commit 6da127ad0918f93ea93678dad62ce15ffed18797 Author: Christof Schmitt Date: Fri Jan 11 10:09:43 2008 +0100 blktrace: Add blktrace ioctls to SCSI generic devices Since the SCSI layer uses the request queues from the block layer, blktrace can also be used to trace the requests to all SCSI devices (like SCSI tape drives), not only disks. The only missing part is the ioctl interface to start and stop tracing. This patch adds the SETUP, START, STOP and TEARDOWN ioctls from blktrace to the sg device files. With this change, blktrace can be used for SCSI devices like for disks, e.g.: blktrace -d /dev/sg1 -o - | blkparse -i - Signed-off-by: Christof Schmitt Signed-off-by: Jens Axboe Christof, any thoughts on removing this support? Luis