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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 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 C3872C4724C for ; Fri, 1 May 2020 04:59:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9923120836 for ; Fri, 1 May 2020 04:59:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728118AbgEAE7b (ORCPT ); Fri, 1 May 2020 00:59:31 -0400 Received: from mail-pg1-f196.google.com ([209.85.215.196]:38268 "EHLO mail-pg1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727922AbgEAE7a (ORCPT ); Fri, 1 May 2020 00:59:30 -0400 Received: by mail-pg1-f196.google.com with SMTP id l25so1769187pgc.5 for ; Thu, 30 Apr 2020 21:59:30 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:autocrypt :message-id:date:user-agent:mime-version:in-reply-to :content-language:content-transfer-encoding; bh=797sU4LAdXCzhMsENqTA8qVJ7grAr85MoE5SEIRXZdY=; b=g2we/zvdgnJov4o7XwUd7/g8hbHT8oUOZoCBHOoTOn2elxOu3KTMvqyeQZiMyjAxmj NC7aHVLqp1ZA8tK8vYgY0r/z1daOGAXB5OwF3mvSzOP987pjNlcquuKvHz11FRnCkp2F 102joSwC3eewziJwXS9Nc3G7tPH9/ClkitX7WZcuJcpfYykDb/BY9u+ZitCbfvZ4WyXv Ck8YVKxp3WtUfXrhVozxCZMlTH0poi+RLmx0rdR2T6ifNGCwJFwkTBMdjFPUE8graCWA JI/ChaY+x+ZMJpEYqAbiH30WXDQf/ENJkU7MSFsE4OBOAUN0qWx0jx1l5Mm0ni6iwne0 kWoQ== X-Gm-Message-State: AGi0PuZ4xTajrFZLYDbVlQqMc82jjVtvT6LttrTI9q70xSPStwxP+khB 1Z/cRXLH30+r+Nnz+NpElCW1gQ6W4Yo= X-Google-Smtp-Source: APiQypIwIeesvr1lNKhS95dIlEnChml5V11cjedJ4KjnMk+Cx36u+jdtroFBPSrws+s3hNi6dBISiQ== X-Received: by 2002:a63:5552:: with SMTP id f18mr2406624pgm.366.1588309169385; Thu, 30 Apr 2020 21:59:29 -0700 (PDT) Received: from ?IPv6:2601:647:4000:d7:6909:5f45:32d1:8e51? ([2601:647:4000:d7:6909:5f45:32d1:8e51]) by smtp.gmail.com with ESMTPSA id z1sm1052593pjn.43.2020.04.30.21.59.27 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 30 Apr 2020 21:59:28 -0700 (PDT) Subject: Re: [PATCH RFC v3 22/41] block: implement persistent commands To: Hannes Reinecke , "Martin K. Petersen" Cc: Christoph Hellwig , James Bottomley , John Garry , Ming Lei , linux-scsi@vger.kernel.org References: <20200430131904.5847-1-hare@suse.de> <20200430131904.5847-23-hare@suse.de> From: Bart Van Assche Autocrypt: addr=bvanassche@acm.org; prefer-encrypt=mutual; keydata= mQENBFSOu4oBCADcRWxVUvkkvRmmwTwIjIJvZOu6wNm+dz5AF4z0FHW2KNZL3oheO3P8UZWr LQOrCfRcK8e/sIs2Y2D3Lg/SL7qqbMehGEYcJptu6mKkywBfoYbtBkVoJ/jQsi2H0vBiiCOy fmxMHIPcYxaJdXxrOG2UO4B60Y/BzE6OrPDT44w4cZA9DH5xialliWU447Bts8TJNa3lZKS1 AvW1ZklbvJfAJJAwzDih35LxU2fcWbmhPa7EO2DCv/LM1B10GBB/oQB5kvlq4aA2PSIWkqz4 3SI5kCPSsygD6wKnbRsvNn2mIACva6VHdm62A7xel5dJRfpQjXj2snd1F/YNoNc66UUTABEB AAG0JEJhcnQgVmFuIEFzc2NoZSA8YnZhbmFzc2NoZUBhY20ub3JnPokBOQQTAQIAIwUCVI67 igIbAwcLCQgHAwIBBhUIAgkKCwQWAgMBAh4BAheAAAoJEHFcPTXFzhAJ8QkH/1AdXblKL65M Y1Zk1bYKnkAb4a98LxCPm/pJBilvci6boefwlBDZ2NZuuYWYgyrehMB5H+q+Kq4P0IBbTqTa jTPAANn62A6jwJ0FnCn6YaM9TZQjM1F7LoDX3v+oAkaoXuq0dQ4hnxQNu792bi6QyVdZUvKc macVFVgfK9n04mL7RzjO3f+X4midKt/s+G+IPr4DGlrq+WH27eDbpUR3aYRk8EgbgGKvQFdD CEBFJi+5ZKOArmJVBSk21RHDpqyz6Vit3rjep7c1SN8s7NhVi9cjkKmMDM7KYhXkWc10lKx2 RTkFI30rkDm4U+JpdAd2+tP3tjGf9AyGGinpzE2XY1K5AQ0EVI67igEIAKiSyd0nECrgz+H5 PcFDGYQpGDMTl8MOPCKw/F3diXPuj2eql4xSbAdbUCJzk2ETif5s3twT2ER8cUTEVOaCEUY3 eOiaFgQ+nGLx4BXqqGewikPJCe+UBjFnH1m2/IFn4T9jPZkV8xlkKmDUqMK5EV9n3eQLkn5g lco+FepTtmbkSCCjd91EfThVbNYpVQ5ZjdBCXN66CKyJDMJ85HVr5rmXG/nqriTh6cv1l1Js T7AFvvPjUPknS6d+BETMhTkbGzoyS+sywEsQAgA+BMCxBH4LvUmHYhpS+W6CiZ3ZMxjO8Hgc ++w1mLeRUvda3i4/U8wDT3SWuHcB3DWlcppECLkAEQEAAYkBHwQYAQIACQUCVI67igIbDAAK CRBxXD01xc4QCZ4dB/0QrnEasxjM0PGeXK5hcZMT9Eo998alUfn5XU0RQDYdwp6/kMEXMdmT oH0F0xB3SQ8WVSXA9rrc4EBvZruWQ+5/zjVrhhfUAx12CzL4oQ9Ro2k45daYaonKTANYG22y //x8dLe2Fv1By4SKGhmzwH87uXxbTJAUxiWIi1np0z3/RDnoVyfmfbbL1DY7zf2hYXLLzsJR mSsED/1nlJ9Oq5fALdNEPgDyPUerqHxcmIub+pF0AzJoYHK5punqpqfGmqPbjxrJLPJfHVKy goMj5DlBMoYqEgpbwdUYkH6QdizJJCur4icy8GUNbisFYABeoJ91pnD4IGei3MTdvINSZI5e Message-ID: <4cd47cec-90cf-8e3b-c3f8-8dc9d4d22c80@acm.org> Date: Thu, 30 Apr 2020 21:59:27 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.7.0 MIME-Version: 1.0 In-Reply-To: <20200430131904.5847-23-hare@suse.de> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-scsi-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-scsi@vger.kernel.org On 2020-04-30 06:18, Hannes Reinecke wrote: > Some LLDDs implement event handling by sending a command to the > firmware, which then will be completed once the firmware wants > to register an event. ^^^^^^^^ report? > So worst case a command is being sent to the firmware then the ^^^^ when? > driver initializes, and will be returned once the driver unloads. > To avoid these commands to block the queues during freezing or > quiescing this patch implements support for 'persistent' commands, > which will be excluded from blk_queue_enter() and blk_queue_exit() > calls. How is it prevented that the SCSI timeout handler is activated for persistent commands? > Signed-off-by: Hannes Reinecke > --- > block/blk-mq.c | 12 +++++++++--- > include/linux/blk-mq.h | 2 ++ > include/linux/blk_types.h | 4 ++++ > 3 files changed, 15 insertions(+), 3 deletions(-) > > diff --git a/block/blk-mq.c b/block/blk-mq.c > index 44482aaed11e..402cf104d183 100644 > --- a/block/blk-mq.c > +++ b/block/blk-mq.c > @@ -402,9 +402,14 @@ struct request *blk_mq_alloc_request(struct request_queue *q, unsigned int op, > { > struct blk_mq_alloc_data alloc_data = { .flags = flags, .cmd_flags = op }; > struct request *rq; > - int ret; > + int ret = 0; > > - ret = blk_queue_enter(q, flags); > + if (flags & BLK_MQ_REQ_PERSISTENT) { > + if (blk_queue_dying(q)) > + ret = -ENODEV; > + alloc_data.cmd_flags |= REQ_PERSISTENT; > + } else > + ret = blk_queue_enter(q, flags); > if (ret) > return ERR_PTR(ret); > I think that not calling blk_queue_enter() for persistent commands means opening a giant can of worms. There is quite some code in the block layer that assumes that neither .queue_rq() nor the request completion code will be called if q_usage_counter == 0. Skipping the blk_queue_enter() call for persistent commands breaks that assumption. I think we need a better solution. Thanks, Bart.