[patch 1/3] [PATCH] qeth: exploit HW TX checksumming

frank.blaschka
2010-05-12T05:34:45Z

[-- Attachment #1: 601-qeth-hw-tx-checksum.diff --]
[-- Type: text/plain, Size: 6549 bytes --]

From: Frank Blaschka <frank.blaschka@de.ibm.com>

OSA supports HW TX checksumming in layer 3 mode. Enable this
feature and remove software fallback used for TSO. Cleanup
checksum bits to indicate OSA can do checksumming only for
IPv4 TCP and UDP.

Signed-off-by: Frank Blaschka <frank.blaschka@de.ibm.com>
---

drivers/s390/net/qeth_core.h | 3 -
drivers/s390/net/qeth_l3_main.c | 92 +++++++++++++++++++++++++++++-----------
2 files changed, 69 insertions(+), 26 deletions(-)

diff -urpN linux-2.6/drivers/s390/net/qeth_core.h linux-2.6-patched/drivers/s390/net/qeth_core.h
--- linux-2.6/drivers/s390/net/qeth_core.h 2010-05-11 22:10:12.000000000 +0200
+++ linux-2.6-patched/drivers/s390/net/qeth_core.h 2010-05-11 22:10:34.000000000 +0200
@@ -351,7 +351,7 @@ enum qeth_header_ids {
#define QETH_HDR_EXT_SRC_MAC_ADDR 0x08
#define QETH_HDR_EXT_CSUM_HDR_REQ 0x10
#define QETH_HDR_EXT_CSUM_TRANSP_REQ 0x20
-#define QETH_HDR_EXT_UDP_TSO 0x40 /*bit off for TCP*/
+#define QETH_HDR_EXT_UDP 0x40 /*bit off for TCP*/

static inline int qeth_is_last_sbale(struct qdio_buffer_element *sbale)
{
@@ -630,6 +630,7 @@ struct qeth_card_info {
int unique_id;
struct qeth_card_blkt blkt;
__u32 csum_mask;
+ __u32 tx_csum_mask;
enum qeth_ipa_promisc_modes promisc_mode;
};

diff -urpN linux-2.6/drivers/s390/net/qeth_l3_main.c linux-2.6-patched/drivers/s390/net/qeth_l3_main.c
--- linux-2.6/drivers/s390/net/qeth_l3_main.c 2010-05-11 22:10:12.000000000 +0200
+++ linux-2.6-patched/drivers/s390/net/qeth_l3_main.c 2010-05-11 22:10:34.000000000 +0200
@@ -54,16 +54,16 @@ int qeth_l3_set_large_send(struct qeth_c
if (card->options.large_send == QETH_LARGE_SEND_TSO) {
if (qeth_is_supported(card, IPA_OUTBOUND_TSO)) {
card->dev->features |= NETIF_F_TSO | NETIF_F_SG |
- NETIF_F_HW_CSUM;
+ NETIF_F_IP_CSUM;
} else {
card->dev->features &= ~(NETIF_F_TSO | NETIF_F_SG |
- NETIF_F_HW_CSUM);
+ NETIF_F_IP_CSUM);
card->options.large_send = QETH_LARGE_SEND_NO;
rc = -EOPNOTSUPP;
}
} else {
card->dev->features &= ~(NETIF_F_TSO | NETIF_F_SG |
- NETIF_F_HW_CSUM);
+ NETIF_F_IP_CSUM);
card->options.large_send = QETH_LARGE_SEND_NO;
}
return rc;
@@ -1108,6 +1108,13 @@ static int qeth_l3_default_setassparms_c
card->info.csum_mask = cmd->data.setassparms.data.flags_32bit;
QETH_DBF_TEXT_(TRACE, 3, "csum:%d", card->info.csum_mask);
}
+ if (cmd->data.setassparms.hdr.assist_no == IPA_OUTBOUND_CHECKSUM &&
+ cmd->data.setassparms.hdr.command_code == IPA_CMD_ASS_START) {
+ card->info.tx_csum_mask =
+ cmd->data.setassparms.data.flags_32bit;
+ QETH_DBF_TEXT_(TRACE, 3, "tcsu:%d", card->info.tx_csum_mask);
+ }
+
return 0;
}

@@ -1536,6 +1543,28 @@ static int qeth_l3_start_ipa_checksum(st
return rc;
}

+static int qeth_l3_start_ipa_tx_checksum(struct qeth_card *card)
+{
+ int rc = 0;
+
+ if (!qeth_is_supported(card, IPA_OUTBOUND_CHECKSUM))
+ return rc;
+ rc = qeth_l3_send_simple_setassparms(card, IPA_OUTBOUND_CHECKSUM,
+ IPA_CMD_ASS_START, 0);
+ if (rc)
+ goto err_out;
+ rc = qeth_l3_send_simple_setassparms(card, IPA_OUTBOUND_CHECKSUM,
+ IPA_CMD_ASS_ENABLE, card->info.tx_csum_mask);
+ if (rc)
+ goto err_out;
+ dev_info(&card->gdev->dev, "HW TX Checksumming enabled\n");
+ return rc;
+err_out:
+ dev_warn(&card->gdev->dev, "Enabling HW TX checksumming for %s "
+ "failed, using SW TX checksumming\n", QETH_CARD_IFNAME(card));
+ return rc;
+}
+
static int qeth_l3_start_ipa_tso(struct qeth_card *card)
{
int rc;
@@ -1578,6 +1607,7 @@ static int qeth_l3_start_ipassists(struc
qeth_l3_start_ipa_ipv6(card); /* go on*/
qeth_l3_start_ipa_broadcast(card); /* go on*/
qeth_l3_start_ipa_checksum(card); /* go on*/
+ qeth_l3_start_ipa_tx_checksum(card);
qeth_l3_start_ipa_tso(card); /* go on*/
return 0;
}
@@ -2817,6 +2847,21 @@ static void qeth_l3_fill_header(struct q
}
}

+static inline void qeth_l3_hdr_csum(struct qeth_card *card,
+ struct qeth_hdr *hdr, struct sk_buff *skb)
+{
+ struct iphdr *iph = ip_hdr(skb);
+
+ /* tcph->check contains already the pseudo hdr checksum
+ * so just set the header flags
+ */
+ if (iph->protocol == IPPROTO_UDP)
+ hdr->hdr.l3.ext_flags |= QETH_HDR_EXT_UDP;
+ hdr->hdr.l3.ext_flags |= QETH_HDR_EXT_CSUM_TRANSP_REQ;
+ if (card->options.performance_stats)
+ card->perf_stats.tx_csum++;
+}
+
static void qeth_tso_fill_header(struct qeth_card *card,
struct qeth_hdr *qhdr, struct sk_buff *skb)
{
@@ -2852,21 +2897,6 @@ static void qeth_tso_fill_header(struct
}
}

-static void qeth_tx_csum(struct sk_buff *skb)
-{
- __wsum csum;
- int offset;
-
- skb_set_transport_header(skb, skb->csum_start - skb_headroom(skb));
- offset = skb->csum_start - skb_headroom(skb);
- BUG_ON(offset >= skb_headlen(skb));
- csum = skb_checksum(skb, offset, skb->len - offset, 0);
-
- offset += skb->csum_offset;
- BUG_ON(offset + sizeof(__sum16) > skb_headlen(skb));
- *(__sum16 *)(skb->data + offset) = csum_fold(csum);
-}
-
static inline int qeth_l3_tso_elements(struct sk_buff *skb)
{
unsigned long tcpd = (unsigned long)tcp_hdr(skb) +
@@ -2923,12 +2953,6 @@ static int qeth_l3_hard_start_xmit(struc

if (skb_is_gso(skb))
large_send = card->options.large_send;
- else
- if (skb->ip_summed == CHECKSUM_PARTIAL) {
- qeth_tx_csum(skb);
- if (card->options.performance_stats)
- card->perf_stats.tx_csum++;
- }

if ((card->info.type == QETH_CARD_TYPE_IQD) && (!large_send) &&
(skb_shinfo(skb)->nr_frags == 0)) {
@@ -3007,6 +3031,9 @@ static int qeth_l3_hard_start_xmit(struc
cast_type);
hdr->hdr.l3.length = new_skb->len - data_offset;
}
+
+ if (skb->ip_summed == CHECKSUM_PARTIAL)
+ qeth_l3_hdr_csum(card, hdr, new_skb);
}

elems = qeth_get_elements_no(card, (void *)hdr, new_skb,
@@ -3132,10 +3159,25 @@ static int qeth_l3_ethtool_set_tso(struc
return rc;
}

+static int qeth_l3_ethtool_set_tx_csum(struct net_device *dev, u32 data)
+{
+ struct qeth_card *card = dev->ml_priv;
+
+ if (data) {
+ if (qeth_is_supported(card, IPA_OUTBOUND_CHECKSUM))
+ dev->features |= NETIF_F_IP_CSUM;
+ else
+ return -EPERM;
+ } else
+ dev->features &= ~NETIF_F_IP_CSUM;
+
+ return 0;
+}
+
static const struct ethtool_ops qeth_l3_ethtool_ops = {
.get_link = ethtool_op_get_link,
.get_tx_csum = ethtool_op_get_tx_csum,
- .set_tx_csum = ethtool_op_set_tx_hw_csum,
+ .set_tx_csum = qeth_l3_ethtool_set_tx_csum,
.get_rx_csum = qeth_l3_ethtool_get_rx_csum,
.set_rx_csum = qeth_l3_ethtool_set_rx_csum,
.get_sg = ethtool_op_get_sg,