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=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 00D1DC00449 for ; Fri, 5 Oct 2018 22:35:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B0D2821473 for ; Fri, 5 Oct 2018 22:35:42 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B0D2821473 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linuxfoundation.org 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 S1729244AbeJFFg2 (ORCPT ); Sat, 6 Oct 2018 01:36:28 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:50776 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726399AbeJFFg2 (ORCPT ); Sat, 6 Oct 2018 01:36:28 -0400 Received: from localhost (unknown [104.153.224.168]) by mail.linuxfoundation.org (Postfix) with ESMTPSA id EF28F1356; Fri, 5 Oct 2018 22:35:38 +0000 (UTC) Date: Fri, 5 Oct 2018 15:35:26 -0700 From: Greg KH To: Dror Levin Cc: torvalds@linux-foundation.org, Richard Weinberger , linux-kernel@vger.kernel.org, linux-block@vger.kernel.org, linux-scsi@vger.kernel.org, hch@infradead.org, axboe@kernel.dk Subject: Re: Recent removal of bsg read/write support Message-ID: <20181005223526.GF13613@kroah.com> References: 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) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Oct 04, 2018 at 09:58:37AM +0300, Dror Levin wrote: > CC'ing Greg. > > On Mon, Sep 3, 2018 at 11:34 AM Dror Levin wrote: > > > > On Sun, Sep 2, 2018 at 8:55 PM Linus Torvalds > > wrote: > > > > > > On Sun, Sep 2, 2018 at 4:44 AM Richard Weinberger > > > wrote: > > > > > > > > CC'ing relevant people. Otherwise your mail might get lost. > > > > > > Indeed. > > > > Sorry for that. > > > > > > On Sun, Sep 2, 2018 at 1:37 PM Dror Levin wrote: > > > > > > > > > > We have an internal tool that uses the bsg read/write interface to > > > > > issue SCSI commands as part of a test suite for a storage device. > > > > > > > > > > After recently reading on LWN that this interface is to be removed we > > > > > tried porting our code to use sg instead. However, that raises new > > > > > issues - mainly getting ENOMEM over iSCSI for unknown reasons. > > > > > > Is there any chance that you can make more data available? > > > > Sure, I can try. > > > > We use writev() to send up to SG_MAX_QUEUE tasks at a time. Occasionally not > > all tasks are written at which point we wait for tasks to return before > > sending more, but then writev() fails with ENOMEM and we see this in the syslog: > > > > Sep 1 20:58:14 gdc-qa-io-017 kernel: sd 441:0:0:5: [sg73] > > sg_common_write: start_req err=-12 > > > > Failing tasks are reads of 128KiB. > > > > > I'd rather fix the sg interface (which while also broken garbage, we > > > can't get rid of) than re-surrect the bsg interface. > > Discussion seems to have died down but release of 4.19 is drawing near. > > Is there still any chance removal of bsg can be reconsidered? Maybe > postponed to the > next version to allow more time to adjust? > > I'm especially concerned about the possibility of this being > backported to stable kernels > which might leave us very little time to fix our code. What is being backported to what stable kernels and why? Is there sg patches? totally confused, greg k-h