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Fri, 30 Jul 2021 10:38:57 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap1.suse-dmz.suse.de with ESMTPSA id EBrIIcHWA2HPOAAAGKfGzw (envelope-from ); Fri, 30 Jul 2021 10:38:57 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version X-BeenThere: xen-devel@lists.xenproject.org List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xenproject.org Precedence: list Sender: "Xen-devel" X-Inumbo-ID: da803bd9-b066-4d9b-a1f8-7503904a5116 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1627641537; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=W95cbauG07UE5MXy/pX7569F2n6zVdQ3MffM9g12IwM=; b=LomOsk913X41D6qB6XhpN71WDo5ikRSfS7EGiNTAyCwrhlOWUpLbYu1pAByNIXE5D6PlPE dF43zwmH0cjHh6uNnxT+1pHauIuf1f/5f1wvFKHV90qN/p79VFKGE3gABKt9uuWeBLnDtm G6qQiospr4xgQvQSZOwAsedHKB4OyhE= From: Juergen Gross To: xen-devel@lists.xenproject.org, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Juergen Gross , Boris Ostrovsky , Stefano Stabellini , Konrad Rzeszutek Wilk , =?UTF-8?q?Roger=20Pau=20Monn=C3=A9?= , Jens Axboe , Jan Beulich Subject: [PATCH v3 1/3] xen/blkfront: read response from backend only once Date: Fri, 30 Jul 2021 12:38:52 +0200 Message-Id: <20210730103854.12681-2-jgross@suse.com> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20210730103854.12681-1-jgross@suse.com> References: <20210730103854.12681-1-jgross@suse.com> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable X-ZohoMail-DKIM: pass (identity @suse.com) X-ZM-MESSAGEID: 1627641568810100003 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 Acked-by: Roger Pau Monn=C3=A9 --- 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 d83fee21f6c5..15e840287734 100644 --- a/drivers/block/xen-blkfront.c +++ b/drivers/block/xen-blkfront.c @@ -1496,7 +1496,7 @@ 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 =3D (struct blkfront_ring_info *)dev_id; @@ -1513,8 +1513,9 @@ static irqreturn_t blkif_interrupt(int irq, void *dev= _id) for (i =3D rinfo->ring.rsp_cons; i !=3D rp; i++) { unsigned long id; =20 - bret =3D RING_GET_RESPONSE(&rinfo->ring, i); - id =3D bret->id; + RING_COPY_RESPONSE(&rinfo->ring, i, &bret); + id =3D 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 - @@ -1522,39 +1523,39 @@ static irqreturn_t blkif_interrupt(int irq, void *d= ev_id) */ if (id >=3D 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 =3D rinfo->shadow[id].request; =20 - if (bret->operation !=3D BLKIF_OP_DISCARD) { + if (bret.operation !=3D 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; } =20 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; } =20 - if (bret->status =3D=3D BLKIF_RSP_OKAY) + if (bret.status =3D=3D BLKIF_RSP_OKAY) blkif_req(req)->error =3D BLK_STS_OK; else blkif_req(req)->error =3D BLK_STS_IOERR; =20 - switch (bret->operation) { + switch (bret.operation) { case BLKIF_OP_DISCARD: - if (unlikely(bret->status =3D=3D BLKIF_RSP_EOPNOTSUPP)) { + if (unlikely(bret.status =3D=3D BLKIF_RSP_EOPNOTSUPP)) { struct request_queue *rq =3D 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 =3D BLK_STS_NOTSUPP; info->feature_discard =3D 0; info->feature_secdiscard =3D 0; @@ -1564,15 +1565,15 @@ static irqreturn_t blkif_interrupt(int irq, void *d= ev_id) break; case BLKIF_OP_FLUSH_DISKCACHE: case BLKIF_OP_WRITE_BARRIER: - if (unlikely(bret->status =3D=3D BLKIF_RSP_EOPNOTSUPP)) { + if (unlikely(bret.status =3D=3D 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 =3D BLK_STS_NOTSUPP; } - if (unlikely(bret->status =3D=3D BLKIF_RSP_ERROR && + if (unlikely(bret.status =3D=3D BLKIF_RSP_ERROR && rinfo->shadow[id].req.u.rw.nr_segments =3D=3D 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 =3D BLK_STS_NOTSUPP; } if (unlikely(blkif_req(req)->error)) { @@ -1585,9 +1586,9 @@ static irqreturn_t blkif_interrupt(int irq, void *dev= _id) fallthrough; case BLKIF_OP_READ: case BLKIF_OP_WRITE: - if (unlikely(bret->status !=3D BLKIF_RSP_OKAY)) + if (unlikely(bret.status !=3D BLKIF_RSP_OKAY)) dev_dbg(&info->xbdev->dev, "Bad return from blkdev data " - "request: %x\n", bret->status); + "request: %x\n", bret.status); =20 break; default: --=20 2.26.2