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 AD999C433EF for ; Mon, 29 Nov 2021 18:29:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1379147AbhK2Scl (ORCPT ); Mon, 29 Nov 2021 13:32:41 -0500 Received: from sin.source.kernel.org ([145.40.73.55]:50190 "EHLO sin.source.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1348075AbhK2Sai (ORCPT ); Mon, 29 Nov 2021 13:30:38 -0500 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by sin.source.kernel.org (Postfix) with ESMTPS id 4396DCE13D5; Mon, 29 Nov 2021 18:27:19 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id E26C5C53FC7; Mon, 29 Nov 2021 18:27:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1638210437; bh=G6BMZrOdbyo4PsmfRthi8NxaM97GTDCU7aQjjXWhzmw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Q4jnZbx3YZjCabNpR1FveJjnz1dLmX/JLUxraWrxnh+yjpnSZhjcxGN7hH7JOd8z6 XrWUfvIU+faZh7FIv0r3GY9X6NOXUtnMtB/TK0MIKakp9rRCg5kSYKHfuR+KRplg3t muBN5a0b9pRVcqGbRQFFjiC3MFXKZpZgzrcp0vZ8= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Juergen Gross , Jan Beulich , "David S. Miller" Subject: [PATCH 5.4 88/92] xen/netfront: read response from backend only once Date: Mon, 29 Nov 2021 19:18:57 +0100 Message-Id: <20211129181710.328397857@linuxfoundation.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20211129181707.392764191@linuxfoundation.org> References: <20211129181707.392764191@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Juergen Gross commit 8446066bf8c1f9f7b7412c43fbea0fb87464d75b upstream. 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 Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- drivers/net/xen-netfront.c | 38 +++++++++++++++++++------------------- 1 file changed, 19 insertions(+), 19 deletions(-) --- a/drivers/net/xen-netfront.c +++ b/drivers/net/xen-netfront.c @@ -387,13 +387,13 @@ static void xennet_tx_buf_gc(struct netf rmb(); /* Ensure we see responses up to 'rp'. */ for (cons = queue->tx.rsp_cons; cons != prod; cons++) { - struct xen_netif_tx_response *txrsp; + struct xen_netif_tx_response txrsp; - txrsp = RING_GET_RESPONSE(&queue->tx, cons); - if (txrsp->status == XEN_NETIF_RSP_NULL) + RING_COPY_RESPONSE(&queue->tx, cons, &txrsp); + if (txrsp.status == XEN_NETIF_RSP_NULL) continue; - id = txrsp->id; + id = txrsp.id; skb = queue->tx_skbs[id].skb; if (unlikely(gnttab_query_foreign_access( queue->grant_tx_ref[id]) != 0)) { @@ -741,7 +741,7 @@ static int xennet_get_extras(struct netf RING_IDX rp) { - struct xen_netif_extra_info *extra; + struct xen_netif_extra_info extra; struct device *dev = &queue->info->netdev->dev; RING_IDX cons = queue->rx.rsp_cons; int err = 0; @@ -757,24 +757,22 @@ static int xennet_get_extras(struct netf break; } - extra = (struct xen_netif_extra_info *) - RING_GET_RESPONSE(&queue->rx, ++cons); + RING_COPY_RESPONSE(&queue->rx, ++cons, &extra); - if (unlikely(!extra->type || - extra->type >= XEN_NETIF_EXTRA_TYPE_MAX)) { + if (unlikely(!extra.type || + extra.type >= XEN_NETIF_EXTRA_TYPE_MAX)) { if (net_ratelimit()) dev_warn(dev, "Invalid extra type: %d\n", - extra->type); + extra.type); err = -EINVAL; } else { - memcpy(&extras[extra->type - 1], extra, - sizeof(*extra)); + extras[extra.type - 1] = extra; } skb = xennet_get_rx_skb(queue, cons); ref = xennet_get_rx_ref(queue, cons); xennet_move_rx_slot(queue, skb, ref); - } while (extra->flags & XEN_NETIF_EXTRA_FLAG_MORE); + } while (extra.flags & XEN_NETIF_EXTRA_FLAG_MORE); queue->rx.rsp_cons = cons; return err; @@ -784,7 +782,7 @@ static int xennet_get_responses(struct n struct netfront_rx_info *rinfo, RING_IDX rp, struct sk_buff_head *list) { - struct xen_netif_rx_response *rx = &rinfo->rx; + struct xen_netif_rx_response *rx = &rinfo->rx, rx_local; struct xen_netif_extra_info *extras = rinfo->extras; struct device *dev = &queue->info->netdev->dev; RING_IDX cons = queue->rx.rsp_cons; @@ -842,7 +840,8 @@ next: break; } - rx = RING_GET_RESPONSE(&queue->rx, cons + slots); + RING_COPY_RESPONSE(&queue->rx, cons + slots, &rx_local); + rx = &rx_local; skb = xennet_get_rx_skb(queue, cons + slots); ref = xennet_get_rx_ref(queue, cons + slots); slots++; @@ -897,10 +896,11 @@ static int xennet_fill_frags(struct netf struct sk_buff *nskb; while ((nskb = __skb_dequeue(list))) { - struct xen_netif_rx_response *rx = - RING_GET_RESPONSE(&queue->rx, ++cons); + struct xen_netif_rx_response rx; skb_frag_t *nfrag = &skb_shinfo(nskb)->frags[0]; + RING_COPY_RESPONSE(&queue->rx, ++cons, &rx); + if (skb_shinfo(skb)->nr_frags == MAX_SKB_FRAGS) { unsigned int pull_to = NETFRONT_SKB_CB(skb)->pull_to; @@ -915,7 +915,7 @@ static int xennet_fill_frags(struct netf skb_add_rx_frag(skb, skb_shinfo(skb)->nr_frags, skb_frag_page(nfrag), - rx->offset, rx->status, PAGE_SIZE); + rx.offset, rx.status, PAGE_SIZE); skb_shinfo(nskb)->nr_frags = 0; kfree_skb(nskb); @@ -1013,7 +1013,7 @@ static int xennet_poll(struct napi_struc i = queue->rx.rsp_cons; work_done = 0; while ((i != rp) && (work_done < budget)) { - memcpy(rx, RING_GET_RESPONSE(&queue->rx, i), sizeof(*rx)); + RING_COPY_RESPONSE(&queue->rx, i, rx); memset(extras, 0, sizeof(rinfo.extras)); err = xennet_get_responses(queue, &rinfo, rp, &tmpq);