From patchwork Sun Sep 6 01:22:12 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: 11759399 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 216C413B1 for ; Sun, 6 Sep 2020 01:22:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 123FD2078D for ; Sun, 6 Sep 2020 01:22:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728807AbgIFBWb (ORCPT ); Sat, 5 Sep 2020 21:22:31 -0400 Received: from mail-pl1-f195.google.com ([209.85.214.195]:43027 "EHLO mail-pl1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728409AbgIFBWa (ORCPT ); Sat, 5 Sep 2020 21:22:30 -0400 Received: by mail-pl1-f195.google.com with SMTP id y6so2838530plk.10; Sat, 05 Sep 2020 18:22:30 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=WBxpkiMjxwD+IRn41vyX5xWhB8DClldowR9a4K9oHbk=; b=MA0Ziz8djkgkMyA9tOpuf5yFiMjToq2BLlrw6b3P7+lR4RPaAvGGsijopd1EPgeF4Z c34bcgmCznLki1KpKmCITqZNUcpGqWW+vxjDL0yJaSurIhFjpIgkWtkG82axfH7OznpZ joxmbKHBLO2zWMaWR52KUz3lGd0f7SVYlK7QsQ1nQsktoVnKtW9EtCus9i8zMFgY//Qg +5HJpy3/nblyQMn6l6/+deaA8YeuHo9edacsquIlfc1s5wHtmKEWY1ZmtOg0lb0spNqv kG05SBBO47+wG3QS06LVPr86aTVgsteW1KGmCIy97gsk7M+APiI7NqDnDGii4BWqIoQ6 C5mA== X-Gm-Message-State: AOAM532F4EH0JkvoItH34dpu6vTGuQBV1EKu1EF4JTWzqwRJavR8WLKC 8kXkQTNMZm9T4yszGY39ApY= X-Google-Smtp-Source: ABdhPJwoIMtvOpDsg6UTyCd0hUXSX1uEqT9KJWuRMHOj0yEX0nWRCqXjcFmR2sOmzmvcG2ycrSBDXg== X-Received: by 2002:a17:90a:d703:: with SMTP id y3mr14635755pju.183.1599355350066; Sat, 05 Sep 2020 18:22:30 -0700 (PDT) Received: from asus.hsd1.ca.comcast.net ([2601:647:4000:d7:cd46:435a:ac98:84de]) by smtp.gmail.com with ESMTPSA id 25sm3585165pjh.57.2020.09.05.18.22.28 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 05 Sep 2020 18:22:29 -0700 (PDT) From: Bart Van Assche To: Jens Axboe , "Martin K . Petersen" , "James E . J . Bottomley" Cc: linux-block@vger.kernel.org, Christoph Hellwig , linux-scsi@vger.kernel.org, Alan Stern , Bart Van Assche , "David S . Miller" , Can Guo , Stanley Chu , Ming Lei , "Rafael J . Wysocki" Subject: [PATCH 2/9] ide: Do not set the RQF_PREEMPT flag for sense requests Date: Sat, 5 Sep 2020 18:22:12 -0700 Message-Id: <20200906012219.17893-3-bvanassche@acm.org> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20200906012219.17893-1-bvanassche@acm.org> References: <20200906012219.17893-1-bvanassche@acm.org> MIME-Version: 1.0 Sender: linux-scsi-owner@vger.kernel.org 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 --- 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;