[PATCH net-next V2 2/3] xen-netback: avoid allocating variable size array on stack
From: Wei Liu <hidden>
Date: 2013-05-02 10:44:02
Subsystem:
networking drivers, the rest, xen network backend driver · Maintainers:
Andrew Lunn, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds, Wei Liu, Paul Durrant
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 <redacted> Signed-off-by: Wei Liu <redacted> --- 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