From patchwork Mon Nov 16 03:04:52 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Bart Van Assche X-Patchwork-Id: 11907277 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id E199C1746 for ; Mon, 16 Nov 2020 03:05:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D3D2E206F9 for ; Mon, 16 Nov 2020 03:05:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726739AbgKPDFN (ORCPT ); Sun, 15 Nov 2020 22:05:13 -0500 Received: from mail-pg1-f193.google.com ([209.85.215.193]:39845 "EHLO mail-pg1-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726692AbgKPDFM (ORCPT ); Sun, 15 Nov 2020 22:05:12 -0500 Received: by mail-pg1-f193.google.com with SMTP id p68so1415628pga.6; Sun, 15 Nov 2020 19:05:12 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=WBxpkiMjxwD+IRn41vyX5xWhB8DClldowR9a4K9oHbk=; b=eLDl1MlWT7z6cIUDS9CGNoiT1v1sWg2OTnrpBI+lZ40MRfdqBWuH9p+yK8PF4GSTfT 1fnRqU54g2vXBCr9oAr1TWZ5+iBpfPcgPMLxFJRfA6R99ggGVwAgzYLxekSWoiaiX9jQ HOjR/kC80qVILba9RYCUAgaDbjV8yxLGw60d+J8xRtLR7eYqTd+YbNfcm4s8w0q7q6sc e2g9YMTinQLB52s8EDJjLC/HOQ92CM/wBUxM4Ync9oTafJbl6yMryXGuCIw6boVBzR/c Phz5pKODuXuExstUrGTb65HkbSoo2ytRnQO8GIbiOW+IWFydUzJytO6qejoz+tjv8o9b JtCw== X-Gm-Message-State: AOAM530KHhk3cG6KwVm0/iLoZoFWpOFiwYchFvCOjFoEUEQjxBRJTg+z gDyFZb3mpdQhyvLJdL6WuDw= X-Google-Smtp-Source: ABdhPJxhg5qQ69TckhvT+TZCfSAVkm0WCWj/uHzz6NuQWHDL7LjRtj7uWuM0emzFQO92Ds8oA93zkw== X-Received: by 2002:a63:540c:: with SMTP id i12mr11677491pgb.32.1605495911820; Sun, 15 Nov 2020 19:05:11 -0800 (PST) Received: from asus.hsd1.ca.comcast.net (c-73-241-217-19.hsd1.ca.comcast.net. [73.241.217.19]) by smtp.gmail.com with ESMTPSA id r3sm17148131pjl.23.2020.11.15.19.05.09 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 15 Nov 2020 19:05:10 -0800 (PST) From: Bart Van Assche To: "Martin K . Petersen" Cc: "James E . J . Bottomley" , Jens Axboe , Christoph Hellwig , linux-scsi@vger.kernel.org, linux-block@vger.kernel.org, Bart Van Assche , "David S . Miller" , Alan Stern , Can Guo , Stanley Chu , Ming Lei , "Rafael J . Wysocki" Subject: [PATCH v2 2/9] ide: Do not set the RQF_PREEMPT flag for sense requests Date: Sun, 15 Nov 2020 19:04:52 -0800 Message-Id: <20201116030459.13963-3-bvanassche@acm.org> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20201116030459.13963-1-bvanassche@acm.org> References: <20201116030459.13963-1-bvanassche@acm.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-scsi@vger.kernel.org RQF_PREEMPT is used for two different purposes in the legacy IDE code: 1. To mark power management requests. 2. To mark requests that should preempt another request. An (old) explanation of that feature is as follows: "The IDE driver in the Linux kernel normally uses a series of busywait delays during its initialization. When the driver executes these busywaits, the kernel does nothing for the duration of the wait. The time spent in these waits could be used for other initialization activities, if they could be run concurrently with these waits. More specifically, busywait-style delays such as udelay() in module init functions inhibit kernel preemption because the Big Kernel Lock is held, while yielding APIs such as schedule_timeout() allow preemption. This is true because the kernel handles the BKL specially and releases and reacquires it across reschedules allowed by the current thread. This IDE-preempt specification requires that the driver eliminate these busywaits and replace them with a mechanism that allows other work to proceed while the IDE driver is initializing." Since I haven't found an implementation of (2), do not set the PREEMPT flag for sense requests. This patch causes sense requests to be postponed while a drive is suspended instead of being submitted to ide_queue_rq(). If it would ever be necessary to restore the IDE PREEMPT functionality, that can be done by introducing a new flag in struct ide_request. This patch is a first step towards removing the PREEMPT flag from the block layer. Cc: David S. Miller Cc: Alan Stern Cc: Can Guo Cc: Stanley Chu Cc: Ming Lei Cc: Rafael J. Wysocki Signed-off-by: Bart Van Assche Reviewed-by: Christoph Hellwig --- drivers/ide/ide-atapi.c | 1 - 1 file changed, 1 deletion(-) diff --git a/drivers/ide/ide-atapi.c b/drivers/ide/ide-atapi.c index 2162bc80f09e..013ad33fbbc8 100644 --- a/drivers/ide/ide-atapi.c +++ b/drivers/ide/ide-atapi.c @@ -223,7 +223,6 @@ void ide_prep_sense(ide_drive_t *drive, struct request *rq) sense_rq->rq_disk = rq->rq_disk; sense_rq->cmd_flags = REQ_OP_DRV_IN; ide_req(sense_rq)->type = ATA_PRIV_SENSE; - sense_rq->rq_flags |= RQF_PREEMPT; req->cmd[0] = GPCMD_REQUEST_SENSE; req->cmd[4] = cmd_len;