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net: Add a software TSO helper API

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Although the implementation probably needs a lot of work, this initial API
allows to implement software TSO in mvneta and mv643xx_eth drivers in a not
so intrusive way.

Signed-off-by: Ezequiel Garcia <ezequiel.garcia@free-electrons.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Ezequiel Garcia 2014-05-19 13:59:52 -03:00 committed by David S. Miller
parent 8af750d739
commit e876f208af
3 changed files with 93 additions and 1 deletions
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20
include/net/tso.h Normal file
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@ -0,0 +1,20 @@
#ifndef _TSO_H
#define _TSO_H
#include <net/ip.h>
struct tso_t {
int next_frag_idx;
void *data;
size_t size;
u16 ip_id;
u32 tcp_seq;
};
int tso_count_descs(struct sk_buff *skb);
void tso_build_hdr(struct sk_buff *skb, char *hdr, struct tso_t *tso,
int size, bool is_last);
void tso_build_data(struct sk_buff *skb, struct tso_t *tso, int size);
void tso_start(struct sk_buff *skb, struct tso_t *tso);
#endif /* _TSO_H */

2
net/core/Makefile
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@ -9,7 +9,7 @@ obj-$(CONFIG_SYSCTL) += sysctl_net_core.o
obj-y += dev.o ethtool.o dev_addr_lists.o dst.o netevent.o \
neighbour.o rtnetlink.o utils.o link_watch.o filter.o \
sock_diag.o dev_ioctl.o
sock_diag.o dev_ioctl.o tso.o
obj-$(CONFIG_XFRM) += flow.o
obj-y += net-sysfs.o

72
net/core/tso.c Normal file
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@ -0,0 +1,72 @@
#include <net/ip.h>
#include <net/tso.h>
/* Calculate expected number of TX descriptors */
int tso_count_descs(struct sk_buff *skb)
{
/* The Marvell Way */
return skb_shinfo(skb)->gso_segs * 2 + skb_shinfo(skb)->nr_frags;
}
void tso_build_hdr(struct sk_buff *skb, char *hdr, struct tso_t *tso,
int size, bool is_last)
{
struct iphdr *iph;
struct tcphdr *tcph;
int hdr_len = skb_transport_offset(skb) + tcp_hdrlen(skb);
int mac_hdr_len = skb_network_offset(skb);
memcpy(hdr, skb->data, hdr_len);
iph = (struct iphdr *)(hdr + mac_hdr_len);
iph->id = htons(tso->ip_id);
iph->tot_len = htons(size + hdr_len - mac_hdr_len);
tcph = (struct tcphdr *)(hdr + skb_transport_offset(skb));
tcph->seq = htonl(tso->tcp_seq);
tso->ip_id++;
if (!is_last) {
/* Clear all special flags for not last packet */
tcph->psh = 0;
tcph->fin = 0;
tcph->rst = 0;
}
}
void tso_build_data(struct sk_buff *skb, struct tso_t *tso, int size)
{
tso->tcp_seq += size;
tso->size -= size;
tso->data += size;
if ((tso->size == 0) &&
(tso->next_frag_idx < skb_shinfo(skb)->nr_frags)) {
skb_frag_t *frag = &skb_shinfo(skb)->frags[tso->next_frag_idx];
/* Move to next segment */
tso->size = frag->size;
tso->data = page_address(frag->page.p) + frag->page_offset;
tso->next_frag_idx++;
}
}
void tso_start(struct sk_buff *skb, struct tso_t *tso)
{
int hdr_len = skb_transport_offset(skb) + tcp_hdrlen(skb);
tso->ip_id = ntohs(ip_hdr(skb)->id);
tso->tcp_seq = ntohl(tcp_hdr(skb)->seq);
tso->next_frag_idx = 0;
/* Build first data */
tso->size = skb_headlen(skb) - hdr_len;
tso->data = skb->data + hdr_len;
if ((tso->size == 0) &&
(tso->next_frag_idx < skb_shinfo(skb)->nr_frags)) {
skb_frag_t *frag = &skb_shinfo(skb)->frags[tso->next_frag_idx];
/* Move to next segment */
tso->size = frag->size;
tso->data = page_address(frag->page.p) + frag->page_offset;
tso->next_frag_idx++;
}
}