From mboxrd@z Thu Jan 1 00:00:00 1970 From: Wei Liu Subject: [PATCH net-next V2 2/3] xen-netback: avoid allocating variable size array on stack Date: Thu, 2 May 2013 11:43:58 +0100 Message-ID: <1367491439-27629-3-git-send-email-wei.liu2@citrix.com> References: <1367491439-27629-1-git-send-email-wei.liu2@citrix.com> Mime-Version: 1.0 Content-Type: text/plain Cc: , , Wei Liu To: , Return-path: Received: from smtp.citrix.com ([66.165.176.89]:56579 "EHLO SMTP.CITRIX.COM" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757951Ab3EBKoC (ORCPT ); Thu, 2 May 2013 06:44:02 -0400 In-Reply-To: <1367491439-27629-1-git-send-email-wei.liu2@citrix.com> Sender: netdev-owner@vger.kernel.org List-ID: Tune xen_netbk_count_requests to not touch working array beyond limit, so that we can make working array size constant. Suggested-by: Jan Beulich Signed-off-by: Wei Liu --- drivers/net/xen-netback/netback.c | 16 ++++++++++++++-- 1 file changed, 14 insertions(+), 2 deletions(-) diff --git a/drivers/net/xen-netback/netback.c b/drivers/net/xen-netback/netback.c index c44772d..ce8109f 100644 --- a/drivers/net/xen-netback/netback.c +++ b/drivers/net/xen-netback/netback.c @@ -934,11 +934,14 @@ static int netbk_count_requests(struct xenvif *vif, RING_IDX cons = vif->tx.req_cons; int slots = 0; int drop_err = 0; + int more_data; if (!(first->flags & XEN_NETTXF_more_data)) return 0; do { + struct xen_netif_tx_request dropped_tx = { 0 }; + if (slots >= work_to_do) { netdev_err(vif->dev, "Asked for %d slots but exceeds this limit\n", @@ -972,6 +975,9 @@ static int netbk_count_requests(struct xenvif *vif, drop_err = -E2BIG; } + if (drop_err) + txp = &dropped_tx; + memcpy(txp, RING_GET_REQUEST(&vif->tx, cons + slots), sizeof(*txp)); @@ -1001,7 +1007,13 @@ static int netbk_count_requests(struct xenvif *vif, netbk_fatal_tx_err(vif); return -EINVAL; } - } while ((txp++)->flags & XEN_NETTXF_more_data); + + more_data = txp->flags & XEN_NETTXF_more_data; + + if (!drop_err) + txp++; + + } while (more_data); if (drop_err) { netbk_tx_err(vif, first, cons + slots); @@ -1408,7 +1420,7 @@ static unsigned xen_netbk_tx_build_gops(struct xen_netbk *netbk) !list_empty(&netbk->net_schedule_list)) { struct xenvif *vif; struct xen_netif_tx_request txreq; - struct xen_netif_tx_request txfrags[max_skb_slots]; + struct xen_netif_tx_request txfrags[XEN_NETIF_NR_SLOTS_MIN]; struct page *page; struct xen_netif_extra_info extras[XEN_NETIF_EXTRA_TYPE_MAX-1]; u16 pending_idx; -- 1.7.10.4