From e88f7e078e47d4261a22e6f20a574620cbfc7a4b Mon Sep 17 00:00:00 2001 From: Vitaly Kuznetsov Date: Wed, 8 Apr 2015 17:54:06 +0200 Subject: [PATCH] hv_netvsc: try linearizing big SKBs before dropping them In netvsc_start_xmit() we can handle packets which are scattered around not more than MAX_PAGE_BUFFER_COUNT-2 pages. It is, however, easy to create a packet which is not big in size but occupies more pages (e.g. if it uses frags on compound pages boundaries). When we drop such packet it cases sender to try resending it but in most cases it will try resending the same packet which will also get dropped, this will cause the particular connection to stick. To solve the issue we can try linearizing skb. Signed-off-by: Vitaly Kuznetsov Signed-off-by: David S. Miller --- drivers/net/hyperv/netvsc_drv.c | 25 ++++++++++++++++++++----- 1 file changed, 20 insertions(+), 5 deletions(-) diff --git a/drivers/net/hyperv/netvsc_drv.c b/drivers/net/hyperv/netvsc_drv.c index 9e4230d81ac0..448716787e73 100644 --- a/drivers/net/hyperv/netvsc_drv.c +++ b/drivers/net/hyperv/netvsc_drv.c @@ -377,27 +377,42 @@ static int netvsc_start_xmit(struct sk_buff *skb, struct net_device *net) struct rndis_packet *rndis_pkt; u32 rndis_msg_size; bool isvlan; + bool linear = false; struct rndis_per_packet_info *ppi; struct ndis_tcp_ip_checksum_info *csum_info; struct ndis_tcp_lso_info *lso_info; int hdr_offset; u32 net_trans_info; u32 hash; - u32 skb_length = skb->len; - u32 head_room = skb_headroom(skb); + u32 skb_length; + u32 head_room; u32 pkt_sz; struct hv_page_buffer page_buf[MAX_PAGE_BUFFER_COUNT]; /* We will atmost need two pages to describe the rndis * header. We can only transmit MAX_PAGE_BUFFER_COUNT number - * of pages in a single packet. + * of pages in a single packet. If skb is scattered around + * more pages we try linearizing it. */ + +check_size: + skb_length = skb->len; + head_room = skb_headroom(skb); num_data_pgs = netvsc_get_slots(skb) + 2; - if (num_data_pgs > MAX_PAGE_BUFFER_COUNT) { - netdev_err(net, "Packet too big: %u\n", skb->len); + if (num_data_pgs > MAX_PAGE_BUFFER_COUNT && linear) { + net_alert_ratelimited("packet too big: %u pages (%u bytes)\n", + num_data_pgs, skb->len); ret = -EFAULT; goto drop; + } else if (num_data_pgs > MAX_PAGE_BUFFER_COUNT) { + if (skb_linearize(skb)) { + net_alert_ratelimited("failed to linearize skb\n"); + ret = -ENOMEM; + goto drop; + } + linear = true; + goto check_size; } pkt_sz = sizeof(struct hv_netvsc_packet) + RNDIS_AND_PPI_SIZE; -- 2.34.1