[PATCH net-next 11/11] s390/qeth: speed up L2 IQD xmit

Julian Wiedmann
2018-07-19T10:43:58Z

Modify the L2 OSA xmit path so that it also supports L2 IQD devices
(in particular, their HW header requirements). This allows IQD devices
to advertise NETIF_F_SG support, and eliminates the allocation overhead
for the HW header.

Signed-off-by: Julian Wiedmann <jwi@linux.ibm.com>
---
drivers/s390/net/qeth_core_main.c | 7 ++++
drivers/s390/net/qeth_l2_main.c | 76 ++++++++++++---------------------------
drivers/s390/net/qeth_l3_main.c | 3 --
3 files changed, 30 insertions(+), 56 deletions(-)

diff --git a/drivers/s390/net/qeth_core_main.c b/drivers/s390/net/qeth_core_main.c
index 732b517369c7..d09a7110b381 100644
--- a/drivers/s390/net/qeth_core_main.c
+++ b/drivers/s390/net/qeth_core_main.c
@@ -5731,6 +5731,13 @@ static struct net_device *qeth_alloc_netdev(struct qeth_card *card)
dev->mtu = 0;
SET_NETDEV_DEV(dev, &card->gdev->dev);
netif_carrier_off(dev);
+
+ if (!IS_OSN(card)) {
+ dev->priv_flags &= ~IFF_TX_SKB_SHARING;
+ dev->hw_features |= NETIF_F_SG;
+ dev->vlan_features |= NETIF_F_SG;
+ }
+
return dev;
}

diff --git a/drivers/s390/net/qeth_l2_main.c b/drivers/s390/net/qeth_l2_main.c
index c302002e422f..c1829a4b955d 100644
--- a/drivers/s390/net/qeth_l2_main.c
+++ b/drivers/s390/net/qeth_l2_main.c
@@ -641,37 +641,13 @@ static void qeth_l2_set_rx_mode(struct net_device *dev)
qeth_promisc_to_bridge(card);
}

-static int qeth_l2_xmit_iqd(struct qeth_card *card, struct sk_buff *skb,
- struct qeth_qdio_out_q *queue, int cast_type)
-{
- unsigned int data_offset = ETH_HLEN;
- struct qeth_hdr *hdr;
- int rc;
-
- hdr = kmem_cache_alloc(qeth_core_header_cache, GFP_ATOMIC);
- if (!hdr)
- return -ENOMEM;
- qeth_l2_fill_header(hdr, skb, cast_type, skb->len);
- skb_copy_from_linear_data(skb, ((char *)hdr) + sizeof(*hdr),
- data_offset);
-
- if (!qeth_get_elements_no(card, skb, 1, data_offset)) {
- rc = -E2BIG;
- goto out;
- }
- rc = qeth_do_send_packet_fast(queue, skb, hdr, data_offset,
- sizeof(*hdr) + data_offset);
-out:
- if (rc)
- kmem_cache_free(qeth_core_header_cache, hdr);
- return rc;
-}
-
-static int qeth_l2_xmit_osa(struct qeth_card *card, struct sk_buff *skb,
- struct qeth_qdio_out_q *queue, int cast_type,
- int ipv)
+static int qeth_l2_xmit(struct qeth_card *card, struct sk_buff *skb,
+ struct qeth_qdio_out_q *queue, int cast_type, int ipv)
{
+ const unsigned int proto_len = IS_IQD(card) ? ETH_HLEN : 0;
const unsigned int hw_hdr_len = sizeof(struct qeth_hdr);
+ unsigned int frame_len = skb->len;
+ unsigned int data_offset = 0;
struct qeth_hdr *hdr = NULL;
unsigned int hd_len = 0;
unsigned int elements;
@@ -682,15 +658,16 @@ static int qeth_l2_xmit_osa(struct qeth_card *card, struct sk_buff *skb,
if (rc)
return rc;

- push_len = qeth_add_hw_header(card, skb, &hdr, hw_hdr_len, 0,
+ push_len = qeth_add_hw_header(card, skb, &hdr, hw_hdr_len, proto_len,
&elements);
if (push_len < 0)
return push_len;
if (!push_len) {
- /* hdr was allocated from cache */
- hd_len = sizeof(*hdr);
+ /* HW header needs its own buffer element. */
+ hd_len = hw_hdr_len + proto_len;
+ data_offset = proto_len;
}
- qeth_l2_fill_header(hdr, skb, cast_type, skb->len - push_len);
+ qeth_l2_fill_header(hdr, skb, cast_type, frame_len);
if (skb->ip_summed == CHECKSUM_PARTIAL) {
qeth_tx_csum(skb, &hdr->hdr.l2.flags[1], ipv);
if (card->options.performance_stats)
@@ -698,9 +675,15 @@ static int qeth_l2_xmit_osa(struct qeth_card *card, struct sk_buff *skb,
}

is_sg = skb_is_nonlinear(skb);
- /* TODO: remove the skb_orphan() once TX completion is fast enough */
- skb_orphan(skb);
- rc = qeth_do_send_packet(card, queue, skb, hdr, 0, hd_len, elements);
+ if (IS_IQD(card)) {
+ rc = qeth_do_send_packet_fast(queue, skb, hdr, data_offset,
+ hd_len);
+ } else {
+ /* TODO: drop skb_orphan() once TX completion is fast enough */
+ skb_orphan(skb);
+ rc = qeth_do_send_packet(card, queue, skb, hdr, data_offset,
+ hd_len, elements);
+ }

if (!rc) {
if (card->options.performance_stats) {
@@ -759,16 +742,10 @@ static netdev_tx_t qeth_l2_hard_start_xmit(struct sk_buff *skb,
}
netif_stop_queue(dev);

- switch (card->info.type) {
- case QETH_CARD_TYPE_OSN:
+ if (IS_OSN(card))
rc = qeth_l2_xmit_osn(card, skb, queue);
- break;
- case QETH_CARD_TYPE_IQD:
- rc = qeth_l2_xmit_iqd(card, skb, queue, cast_type);
- break;
- default:
- rc = qeth_l2_xmit_osa(card, skb, queue, cast_type, ipv);
- }
+ else
+ rc = qeth_l2_xmit(card, skb, queue, cast_type, ipv);

if (!rc) {
card->stats.tx_packets++;
@@ -927,6 +904,7 @@ static int qeth_l2_setup_netdev(struct qeth_card *card)
card->dev->flags |= IFF_NOARP;
} else {
card->dev->ethtool_ops = &qeth_l2_ethtool_ops;
+ card->dev->needed_headroom = sizeof(struct qeth_hdr);
}

if (card->info.type == QETH_CARD_TYPE_OSM)
@@ -934,14 +912,6 @@ static int qeth_l2_setup_netdev(struct qeth_card *card)
else
card->dev->features |= NETIF_F_HW_VLAN_CTAG_FILTER;

- if (card->info.type != QETH_CARD_TYPE_OSN &&
- card->info.type != QETH_CARD_TYPE_IQD) {
- card->dev->priv_flags &= ~IFF_TX_SKB_SHARING;
- card->dev->needed_headroom = sizeof(struct qeth_hdr);
- card->dev->hw_features |= NETIF_F_SG;
- card->dev->vlan_features |= NETIF_F_SG;
- }
-
if (card->info.type == QETH_CARD_TYPE_OSD && !card->info.guestlan) {
card->dev->features |= NETIF_F_SG;
/* OSA 3S and earlier has no RX/TX support */
diff --git a/drivers/s390/net/qeth_l3_main.c b/drivers/s390/net/qeth_l3_main.c
index b8e828556cf6..1833e7505aca 100644
--- a/drivers/s390/net/qeth_l3_main.c
+++ b/drivers/s390/net/qeth_l3_main.c
@@ -2556,13 +2556,10 @@ static int qeth_l3_setup_netdev(struct qeth_card *card)
return -ENODEV;

card->dev->ethtool_ops = &qeth_l3_ethtool_ops;
- card->dev->priv_flags &= ~IFF_TX_SKB_SHARING;
card->dev->needed_headroom = sizeof(struct qeth_hdr) - ETH_HLEN;
card->dev->features |= NETIF_F_HW_VLAN_CTAG_TX |
NETIF_F_HW_VLAN_CTAG_RX |
NETIF_F_HW_VLAN_CTAG_FILTER;
- card->dev->hw_features |= NETIF_F_SG;
- card->dev->vlan_features |= NETIF_F_SG;

netif_keep_dst(card->dev);
if (card->dev->hw_features & NETIF_F_TSO)
--
2.16.4