From patchwork Thu May 13 10:02:56 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: =?utf-8?b?SsO8cmdlbiBHcm/Dnw==?= X-Patchwork-Id: 12255475 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=-18.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 1BE9DC433ED for ; Thu, 13 May 2021 10:03:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id EBF2A61260 for ; Thu, 13 May 2021 10:03:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232845AbhEMKE2 (ORCPT ); Thu, 13 May 2021 06:04:28 -0400 Received: from mx2.suse.de ([195.135.220.15]:37416 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232813AbhEMKEQ (ORCPT ); Thu, 13 May 2021 06:04:16 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1620900185; 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=lutTQX8ZA5u3khaAXqUgHLKbfap899noTeivh9Sx9NQ=; b=X9zTq81SYVIejJbZ3hqVnPgnP7pcUDx2BE/zHP4wRq7hBon4FcfafyN+fXITzioqYy+QoR pBz0uhcESpMAUzIdg50l7VW/TsBGw3s6HDsmczQ3YLqYI5+JC1vvrfRDwWsaYqSOxIH89y FBMrmVY8k7hSXXCMQGggw+D5zhxq8r4= Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id B132FAFF5; Thu, 13 May 2021 10:03:05 +0000 (UTC) From: Juergen Gross To: xen-devel@lists.xenproject.org, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Juergen Gross , Konrad Rzeszutek Wilk , =?utf-8?q?Roger_Pau_Monn?= =?utf-8?q?=C3=A9?= , Boris Ostrovsky , Stefano Stabellini , Jens Axboe Subject: [PATCH 2/8] xen/blkfront: read response from backend only once Date: Thu, 13 May 2021 12:02:56 +0200 Message-Id: <20210513100302.22027-3-jgross@suse.com> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20210513100302.22027-1-jgross@suse.com> References: <20210513100302.22027-1-jgross@suse.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org In order to avoid problems in case the backend is modifying a response on the ring page while the frontend has already seen it, just read the response into a local buffer in one go and then operate on that buffer only. Signed-off-by: Juergen Gross Reviewed-by: Jan Beulich --- drivers/block/xen-blkfront.c | 35 ++++++++++++++++++----------------- 1 file changed, 18 insertions(+), 17 deletions(-) diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c index 10df39a8b18d..a8b56c153330 100644 --- a/drivers/block/xen-blkfront.c +++ b/drivers/block/xen-blkfront.c @@ -1557,7 +1557,7 @@ static bool blkif_completion(unsigned long *id, static irqreturn_t blkif_interrupt(int irq, void *dev_id) { struct request *req; - struct blkif_response *bret; + struct blkif_response bret; RING_IDX i, rp; unsigned long flags; struct blkfront_ring_info *rinfo = (struct blkfront_ring_info *)dev_id; @@ -1574,8 +1574,9 @@ static irqreturn_t blkif_interrupt(int irq, void *dev_id) for (i = rinfo->ring.rsp_cons; i != rp; i++) { unsigned long id; - bret = RING_GET_RESPONSE(&rinfo->ring, i); - id = bret->id; + RING_COPY_RESPONSE(&rinfo->ring, i, &bret); + id = bret.id; + /* * The backend has messed up and given us an id that we would * never have given to it (we stamp it up to BLK_RING_SIZE - @@ -1583,39 +1584,39 @@ static irqreturn_t blkif_interrupt(int irq, void *dev_id) */ if (id >= BLK_RING_SIZE(info)) { WARN(1, "%s: response to %s has incorrect id (%ld)\n", - info->gd->disk_name, op_name(bret->operation), id); + info->gd->disk_name, op_name(bret.operation), id); /* We can't safely get the 'struct request' as * the id is busted. */ continue; } req = rinfo->shadow[id].request; - if (bret->operation != BLKIF_OP_DISCARD) { + if (bret.operation != BLKIF_OP_DISCARD) { /* * We may need to wait for an extra response if the * I/O request is split in 2 */ - if (!blkif_completion(&id, rinfo, bret)) + if (!blkif_completion(&id, rinfo, &bret)) continue; } if (add_id_to_freelist(rinfo, id)) { WARN(1, "%s: response to %s (id %ld) couldn't be recycled!\n", - info->gd->disk_name, op_name(bret->operation), id); + info->gd->disk_name, op_name(bret.operation), id); continue; } - if (bret->status == BLKIF_RSP_OKAY) + if (bret.status == BLKIF_RSP_OKAY) blkif_req(req)->error = BLK_STS_OK; else blkif_req(req)->error = BLK_STS_IOERR; - switch (bret->operation) { + switch (bret.operation) { case BLKIF_OP_DISCARD: - if (unlikely(bret->status == BLKIF_RSP_EOPNOTSUPP)) { + if (unlikely(bret.status == BLKIF_RSP_EOPNOTSUPP)) { struct request_queue *rq = info->rq; printk(KERN_WARNING "blkfront: %s: %s op failed\n", - info->gd->disk_name, op_name(bret->operation)); + info->gd->disk_name, op_name(bret.operation)); blkif_req(req)->error = BLK_STS_NOTSUPP; info->feature_discard = 0; info->feature_secdiscard = 0; @@ -1625,15 +1626,15 @@ static irqreturn_t blkif_interrupt(int irq, void *dev_id) break; case BLKIF_OP_FLUSH_DISKCACHE: case BLKIF_OP_WRITE_BARRIER: - if (unlikely(bret->status == BLKIF_RSP_EOPNOTSUPP)) { + if (unlikely(bret.status == BLKIF_RSP_EOPNOTSUPP)) { printk(KERN_WARNING "blkfront: %s: %s op failed\n", - info->gd->disk_name, op_name(bret->operation)); + info->gd->disk_name, op_name(bret.operation)); blkif_req(req)->error = BLK_STS_NOTSUPP; } - if (unlikely(bret->status == BLKIF_RSP_ERROR && + if (unlikely(bret.status == BLKIF_RSP_ERROR && rinfo->shadow[id].req.u.rw.nr_segments == 0)) { printk(KERN_WARNING "blkfront: %s: empty %s op failed\n", - info->gd->disk_name, op_name(bret->operation)); + info->gd->disk_name, op_name(bret.operation)); blkif_req(req)->error = BLK_STS_NOTSUPP; } if (unlikely(blkif_req(req)->error)) { @@ -1646,9 +1647,9 @@ static irqreturn_t blkif_interrupt(int irq, void *dev_id) fallthrough; case BLKIF_OP_READ: case BLKIF_OP_WRITE: - if (unlikely(bret->status != BLKIF_RSP_OKAY)) + if (unlikely(bret.status != BLKIF_RSP_OKAY)) dev_dbg(&info->xbdev->dev, "Bad return from blkdev data " - "request: %x\n", bret->status); + "request: %x\n", bret.status); break; default: