From patchwork Mon Jun 12 15:03:07 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Martin Wilck X-Patchwork-Id: 13276800 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id B0E57C88CBA for ; Mon, 12 Jun 2023 15:03:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238931AbjFLPDf (ORCPT ); Mon, 12 Jun 2023 11:03:35 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36670 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239190AbjFLPDY (ORCPT ); Mon, 12 Jun 2023 11:03:24 -0400 Received: from smtp-out1.suse.de (smtp-out1.suse.de [195.135.220.28]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 730B112A; Mon, 12 Jun 2023 08:03:23 -0700 (PDT) Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by smtp-out1.suse.de (Postfix) with ESMTPS id 2B5072282A; Mon, 12 Jun 2023 15:03:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1686582202; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=nQtfZJb2iOoz97Vsm41VrMzITB4wE6/fhEpha6ktEtw=; b=MmjEHd6Rr5rIDrOCfVLj7rraOxXEbTHFWq5Ts3fhY4kH1h9kCmQLKkDUrvTZJbNZ4oEsU9 BqQayZqQdNycvvQ+UFmwUYm0TVv/gMYmXd1qPTPrPGDFPBog0Pn1pf+01h5YKgPSzVn04B gQd4f/lbZPVMo3UsOfdeEcIizsmZ6po= Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id BFA99138EC; Mon, 12 Jun 2023 15:03:21 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id qPznLLkzh2RMMAAAMHmgww (envelope-from ); Mon, 12 Jun 2023 15:03:21 +0000 From: mwilck@suse.com To: "Martin K. Petersen" , Christoph Hellwig , Ming Lei , Bart Van Assche Cc: James Bottomley , linux-scsi@vger.kernel.org, linux-block@vger.kernel.org, Hannes Reinecke , Martin Wilck Subject: [PATCH v4 4/6] scsi: don't wait for quiesce in scsi_stop_queue() Date: Mon, 12 Jun 2023 17:03:07 +0200 Message-Id: <20230612150309.18103-5-mwilck@suse.com> X-Mailer: git-send-email 2.40.1 In-Reply-To: <20230612150309.18103-1-mwilck@suse.com> References: <20230612150309.18103-1-mwilck@suse.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org From: Martin Wilck scsi_stop_queue() has just two callers, one with and one without "nowait". As blk_mq_quiesce_queue() comes down to blk_mq_quiesce_queue_nowait() followed by blk_mq_wait_quiesce_done(), we might as well open-code this in scsi_device_block(). Also, add a comment explaining why blk_mq_quiesce_queue_nowait() must be called with the state_mutex held, see https://lore.kernel.org/linux-scsi/3b8b13bf-a458-827a-b916-07d7eee8ae00@acm.org/. Signed-off-by: Martin Wilck --- drivers/scsi/scsi_lib.c | 32 ++++++++++++++++---------------- 1 file changed, 16 insertions(+), 16 deletions(-) diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c index 69fb7a9d8883..b4cc1501dc36 100644 --- a/drivers/scsi/scsi_lib.c +++ b/drivers/scsi/scsi_lib.c @@ -2731,24 +2731,16 @@ void scsi_start_queue(struct scsi_device *sdev) blk_mq_unquiesce_queue(sdev->request_queue); } -static void scsi_stop_queue(struct scsi_device *sdev, bool nowait) +static void scsi_stop_queue(struct scsi_device *sdev) { /* * The atomic variable of ->queue_stopped covers that * blk_mq_quiesce_queue* is balanced with blk_mq_unquiesce_queue. * - * However, we still need to wait until quiesce is done - * in case that queue has been stopped. + * After return, we still need to wait until quiesce is done. */ - if (!cmpxchg(&sdev->queue_stopped, 0, 1)) { - if (nowait) - blk_mq_quiesce_queue_nowait(sdev->request_queue); - else - blk_mq_quiesce_queue(sdev->request_queue); - } else { - if (!nowait) - blk_mq_wait_quiesce_done(sdev->request_queue->tag_set); - } + if (!cmpxchg(&sdev->queue_stopped, 0, 1)) + blk_mq_quiesce_queue_nowait(sdev->request_queue); } /** @@ -2775,7 +2767,7 @@ int scsi_internal_device_block_nowait(struct scsi_device *sdev) * request queue. */ if (!ret) - scsi_stop_queue(sdev, true); + scsi_stop_queue(sdev); return ret; } EXPORT_SYMBOL_GPL(scsi_internal_device_block_nowait); @@ -2800,9 +2792,17 @@ static void scsi_device_block(struct scsi_device *sdev, void *data) mutex_lock(&sdev->state_mutex); err = __scsi_internal_device_block_nowait(sdev); - if (err == 0) - scsi_stop_queue(sdev, false); - mutex_unlock(&sdev->state_mutex); + if (err == 0) { + /* + * scsi_stop_queue() must be called with the state_mutex + * held. Otherwise a simultaneous scsi_start_queue() call + * might unquiesce the queue before we quiesce it. + */ + scsi_stop_queue(sdev); + mutex_unlock(&sdev->state_mutex); + blk_mq_wait_quiesce_done(sdev->request_queue->tag_set); + } else + mutex_unlock(&sdev->state_mutex); WARN_ONCE(err, "__scsi_internal_device_block_nowait(%s) failed: err = %d\n", dev_name(&sdev->sdev_gendev), err);