From patchwork Mon Nov 23 03:17:42 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: 11924291 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=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable 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 7AA15C64E7A for ; Mon, 23 Nov 2020 03:18:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5AECD21973 for ; Mon, 23 Nov 2020 03:18:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727957AbgKWDSC (ORCPT ); Sun, 22 Nov 2020 22:18:02 -0500 Received: from mail-pf1-f196.google.com ([209.85.210.196]:42831 "EHLO mail-pf1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727924AbgKWDSC (ORCPT ); Sun, 22 Nov 2020 22:18:02 -0500 Received: by mail-pf1-f196.google.com with SMTP id 131so13584346pfb.9; Sun, 22 Nov 2020 19:18:01 -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=bOfYmfsf36OR7FSqOTiU9QwdQh/3+RIr0zxLiRH6Y84=; b=HFhIDE8IdNVBbhncY7jufVV5Iv/9jjIGMpkMlBry/CxByZAa/Fgz2p1iJNleO54zod 2pLlegdfQTN+0Si3OCaYVjsdfXedCkY2VTbEtOYC2r7XRSBLN9jDNpZXfcASh9rcuMdA 7ZzxiY9AXYxJ9tQN/Uv4hdoxSzq9Eyu6GAJWcxZnKUPE9F39MZFmxqecmTQo+A7O2Vxx GEjW1PougkEhNmbi/45Ty9eLgEa1c0E0h4jHA1RnWwY9CdKIBA4g8iIYi9+zHojncOkc FK0Uu+9V4v62u8XR1BaodCZJzhDogdfBlGmlaYHDhr110Vb6aq7fBVFHj/xM32O6LT92 7rjg== X-Gm-Message-State: AOAM530/ZJIBJsgxFSE0uSAJHFlMhNEmmr8fYPT2WybGmY0mvJ/h/uLe CwxUWDW53oaFr/g+O6KDHJE= X-Google-Smtp-Source: ABdhPJytLEqSaxApi7/AIt3WBo4glghWDB7ywozCAVbkVFuvqHi1hYUUGhS6vlb6E4loPYtaIg/D4w== X-Received: by 2002:a62:7e14:0:b029:18a:d515:dc47 with SMTP id z20-20020a627e140000b029018ad515dc47mr24461696pfc.78.1606101481169; Sun, 22 Nov 2020 19:18:01 -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 w12sm3578751pfn.136.2020.11.22.19.17.59 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 22 Nov 2020 19:18:00 -0800 (PST) From: Bart Van Assche To: "Martin K . Petersen" Cc: "James E . J . Bottomley" , Jens Axboe , Christoph Hellwig , Ming Lei , linux-scsi@vger.kernel.org, linux-block@vger.kernel.org, Bart Van Assche , "David S . Miller" , Alan Stern , Can Guo , Stanley Chu , "Rafael J . Wysocki" Subject: [PATCH v3 2/9] ide: Do not set the RQF_PREEMPT flag for sense requests Date: Sun, 22 Nov 2020 19:17:42 -0800 Message-Id: <20201123031749.14912-3-bvanassche@acm.org> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20201123031749.14912-1-bvanassche@acm.org> References: <20201123031749.14912-1-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. Reviewed-by: Christoph Hellwig 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: Hannes Reinecke --- 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;