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hv_netvsc: Fix a bug in netvsc_start_xmit()

Browse source 
Commit b08cc79155 eliminated memory
allocation in the packet send path:

    "hv_netvsc: Eliminate memory allocation in the packet send path

    The network protocol used to communicate with the host is the remote ndis (rndis)
    protocol. We need to decorate each outgoing packet with a rndis header and
    additional rndis state (rndis per-packet state). To manage this state, we
    currently allocate memory in the transmit path. Eliminate this allocation by
    requesting additional head room in the skb."

This commit introduced a bug since it did not account for the case if the skb
was cloned. Fix this bug.

Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Tested-by: Dexuan Cui <decui@microsoft.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
KY Srinivasan 2015-04-28 17:59:48 -07:00 committed by David S. Miller
parent 48734994ac
commit b56fc3c536
3 changed files with 7 additions and 26 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

1
drivers/net/hyperv/hyperv_net.h
View file

@ -128,7 +128,6 @@ struct ndis_tcp_ip_checksum_info;
struct hv_netvsc_packet { struct hv_netvsc_packet {
/* Bookkeeping stuff */ /* Bookkeeping stuff */
u32 status; u32 status;
bool part_of_skb;
bool is_data_pkt; bool is_data_pkt;
bool xmit_more; /* from skb */ bool xmit_more; /* from skb */

5
drivers/net/hyperv/netvsc.c
View file

@ -889,11 +889,6 @@ int netvsc_send(struct hv_device *device,
} else { } else {
packet->page_buf_cnt = 0; packet->page_buf_cnt = 0;
packet->total_data_buflen += msd_len; packet->total_data_buflen += msd_len;
if (!packet->part_of_skb) {
skb = (struct sk_buff *)(unsigned long)packet->
send_completion_tid;
packet->send_completion_tid = 0;
}
} }
if (msdp->pkt) if (msdp->pkt)

27
drivers/net/hyperv/netvsc_drv.c
View file

@ -238,9 +238,6 @@ void netvsc_xmit_completion(void *context)
struct sk_buff *skb = (struct sk_buff *) struct sk_buff *skb = (struct sk_buff *)
(unsigned long)packet->send_completion_tid; (unsigned long)packet->send_completion_tid;
if (!packet->part_of_skb)
kfree(packet);
if (skb) if (skb)
dev_kfree_skb_any(skb); dev_kfree_skb_any(skb);
} }
@ -392,7 +389,6 @@ static int netvsc_start_xmit(struct sk_buff *skb, struct net_device *net)
u32 net_trans_info; u32 net_trans_info;
u32 hash; u32 hash;
u32 skb_length; u32 skb_length;
u32 head_room;
u32 pkt_sz; u32 pkt_sz;
struct hv_page_buffer page_buf[MAX_PAGE_BUFFER_COUNT]; struct hv_page_buffer page_buf[MAX_PAGE_BUFFER_COUNT];
@ -405,7 +401,6 @@ static int netvsc_start_xmit(struct sk_buff *skb, struct net_device *net)
check_size: check_size:
skb_length = skb->len; skb_length = skb->len;
head_room = skb_headroom(skb);
num_data_pgs = netvsc_get_slots(skb) + 2; num_data_pgs = netvsc_get_slots(skb) + 2;
if (num_data_pgs > MAX_PAGE_BUFFER_COUNT && linear) { if (num_data_pgs > MAX_PAGE_BUFFER_COUNT && linear) {
net_alert_ratelimited("packet too big: %u pages (%u bytes)\n", net_alert_ratelimited("packet too big: %u pages (%u bytes)\n",
@ -424,20 +419,14 @@ static int netvsc_start_xmit(struct sk_buff *skb, struct net_device *net)
pkt_sz = sizeof(struct hv_netvsc_packet) + RNDIS_AND_PPI_SIZE; pkt_sz = sizeof(struct hv_netvsc_packet) + RNDIS_AND_PPI_SIZE;
if (head_room < pkt_sz) { ret = skb_cow_head(skb, pkt_sz);
packet = kmalloc(pkt_sz, GFP_ATOMIC); if (ret) {
if (!packet) { netdev_err(net, "unable to alloc hv_netvsc_packet\n");
/* out of memory, drop packet */ ret = -ENOMEM;
netdev_err(net, "unable to alloc hv_netvsc_packet\n"); goto drop;
ret = -ENOMEM;
goto drop;
}
packet->part_of_skb = false;
} else {
/* Use the headroom for building up the packet */
packet = (struct hv_netvsc_packet *)skb->head;
packet->part_of_skb = true;
} }
/* Use the headroom for building up the packet */
packet = (struct hv_netvsc_packet *)skb->head;
packet->status = 0; packet->status = 0;
packet->xmit_more = skb->xmit_more; packet->xmit_more = skb->xmit_more;
@ -594,8 +583,6 @@ static int netvsc_start_xmit(struct sk_buff *skb, struct net_device *net)
net->stats.tx_bytes += skb_length; net->stats.tx_bytes += skb_length;
net->stats.tx_packets++; net->stats.tx_packets++;
} else { } else {
if (packet && !packet->part_of_skb)
kfree(packet);
if (ret != -EAGAIN) { if (ret != -EAGAIN) {
dev_kfree_skb_any(skb); dev_kfree_skb_any(skb);
net->stats.tx_dropped++; net->stats.tx_dropped++;