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authorEzequiel Garcia <ezequiel.garcia@free-electrons.com>2014-05-19 13:59:52 -0300
committerDavid S. Miller <davem@davemloft.net>2014-05-22 14:57:15 -0400
commite876f208af18b074f800656e4d1b99da75b2135f (patch)
treedaff9963d9fe03343b9dcac38d0dec07881d1db7 /net/core/tso.c
parent8af750d739620a0028dc767b289b0ed1d61fb38b (diff)
downloadlinux-e876f208af18b074f800656e4d1b99da75b2135f.tar.bz2
net: Add a software TSO helper API
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>
Diffstat (limited to 'net/core/tso.c')
-rw-r--r--net/core/tso.c72
1 files changed, 72 insertions, 0 deletions
diff --git a/net/core/tso.c b/net/core/tso.c
new file mode 100644
index 000000000000..097821dd3a8c
--- /dev/null
+++ b/net/core/tso.c
@@ -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++;
+ }
+}