From 10574059ce0451c6572c85329c772aa15085f8eb Mon Sep 17 00:00:00 2001 From: Paul Durrant Date: Wed, 11 Dec 2013 10:57:15 +0000 Subject: [PATCH] xen-netback: napi: fix abuse of budget netback seems to be somewhat confused about the napi budget parameter. The parameter is supposed to limit the number of skbs processed in each poll, but netback has this confused with grant operations. This patch fixes that, properly limiting the work done in each poll. Note that this limit makes sure we do not process any more data from the shared ring than we intend to pass back from the poll. This is important to prevent tx_queue potentially growing without bound. Signed-off-by: Paul Durrant Cc: Wei Liu Cc: Ian Campbell Cc: David Vrabel Signed-off-by: David S. Miller --- drivers/net/xen-netback/netback.c | 14 +++++++------- 1 file changed, 7 insertions(+), 7 deletions(-) diff --git a/drivers/net/xen-netback/netback.c b/drivers/net/xen-netback/netback.c index d158fc40cff2..db79e29b3d09 100644 --- a/drivers/net/xen-netback/netback.c +++ b/drivers/net/xen-netback/netback.c @@ -1445,14 +1445,15 @@ static bool tx_credit_exceeded(struct xenvif *vif, unsigned size) return false; } -static unsigned xenvif_tx_build_gops(struct xenvif *vif) +static unsigned xenvif_tx_build_gops(struct xenvif *vif, int budget) { struct gnttab_copy *gop = vif->tx_copy_ops, *request_gop; struct sk_buff *skb; int ret; while ((nr_pending_reqs(vif) + XEN_NETBK_LEGACY_SLOTS_MAX - < MAX_PENDING_REQS)) { + < MAX_PENDING_REQS) && + (skb_queue_len(&vif->tx_queue) < budget)) { struct xen_netif_tx_request txreq; struct xen_netif_tx_request txfrags[XEN_NETBK_LEGACY_SLOTS_MAX]; struct page *page; @@ -1614,14 +1615,13 @@ static unsigned xenvif_tx_build_gops(struct xenvif *vif) } -static int xenvif_tx_submit(struct xenvif *vif, int budget) +static int xenvif_tx_submit(struct xenvif *vif) { struct gnttab_copy *gop = vif->tx_copy_ops; struct sk_buff *skb; int work_done = 0; - while (work_done < budget && - (skb = __skb_dequeue(&vif->tx_queue)) != NULL) { + while ((skb = __skb_dequeue(&vif->tx_queue)) != NULL) { struct xen_netif_tx_request *txp; u16 pending_idx; unsigned data_len; @@ -1696,14 +1696,14 @@ int xenvif_tx_action(struct xenvif *vif, int budget) if (unlikely(!tx_work_todo(vif))) return 0; - nr_gops = xenvif_tx_build_gops(vif); + nr_gops = xenvif_tx_build_gops(vif, budget); if (nr_gops == 0) return 0; gnttab_batch_copy(vif->tx_copy_ops, nr_gops); - work_done = xenvif_tx_submit(vif, nr_gops); + work_done = xenvif_tx_submit(vif); return work_done; }