Re: [PATCH] s390: qeth tcp segmentation offload
From: Jeff Garzik
Date: Tue Mar 29 2005 - 02:27:18 EST
Linux Kernel Mailing List wrote:
ChangeSet 1.2231.1.121, 2005/03/28 19:50:10-08:00, pavlic@xxxxxxxxxx
[PATCH] s390: qeth tcp segmentation offload
Add support for TCP Segmentation Offload to the qeth network driver.
Signed-off-by: Martin Schwidefsky <schwidefsky@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxx>
+static inline void
+qeth_eddp_copy_data_tcp(char *dst, struct qeth_eddp_data *eddp, int len,
+ u32 *hcsum)
+{
+ struct skb_frag_struct *frag;
+ int left_in_frag;
+ int copy_len;
+ u8 *src;
+
+ QETH_DBF_TEXT(trace, 5, "eddpcdtc");
+ if (skb_shinfo(eddp->skb)->nr_frags == 0) {
+ memcpy(dst, eddp->skb->data + eddp->skb_offset, len);
+ *hcsum = csum_partial(eddp->skb->data + eddp->skb_offset, len,
+ *hcsum);
+ eddp->skb_offset += len;
+ } else {
+ while (len > 0) {
+ if (eddp->frag < 0) {
+ /* we're in skb->data */
+ left_in_frag = qeth_get_skb_data_len(eddp->skb)
+ - eddp->skb_offset;
+ src = eddp->skb->data + eddp->skb_offset;
+ } else {
+ frag = &skb_shinfo(eddp->skb)->
+ frags[eddp->frag];
+ left_in_frag = frag->size - eddp->frag_offset;
+ src = (u8 *)(
+ (page_to_pfn(frag->page) << PAGE_SHIFT)+
+ frag->page_offset + eddp->frag_offset);
+ }
+ if (left_in_frag <= 0) {
+ eddp->frag++;
+ eddp->frag_offset = 0;
+ continue;
+ }
+ copy_len = min(left_in_frag, len);
+ memcpy(dst, src, copy_len);
+ *hcsum = csum_partial(src, copy_len, *hcsum);
+ dst += copy_len;
+ eddp->frag_offset += copy_len;
+ eddp->skb_offset += copy_len;
+ len -= copy_len;
+ }
+ }
+}
Please help me understand: why add all this TSO code (zerocopy), if you
are adding memcpy() under the hood?
Was this reviewed on netdev? or by any network developer?
Overall this patch adds a whole lot of code that must be VERY intimate
with the net stack, a huge maintenance burden that is likely to be rife
with out-of-date code and bugs over time.
+static inline void
+qeth_eddp_create_segment_data_tcp(struct qeth_eddp_context *ctx,
+ struct qeth_eddp_data *eddp, int data_len,
+ u32 hcsum)
+{
+ u8 *page;
+ int page_remainder;
+ int page_offset;
+ struct qeth_eddp_element *element;
+ int first_lap = 1;
+
+ QETH_DBF_TEXT(trace, 5, "eddpcsdt");
+ page = ctx->pages[ctx->offset >> PAGE_SHIFT];
+ page_offset = ctx->offset % PAGE_SIZE;
+ element = &ctx->elements[ctx->num_elements];
+ while (data_len){
+ page_remainder = PAGE_SIZE - page_offset;
+ if (page_remainder < data_len){
+ qeth_eddp_copy_data_tcp(page + page_offset, eddp,
+ page_remainder, &hcsum);
+ element->length += page_remainder;
+ if (first_lap)
+ element->flags = SBAL_FLAGS_FIRST_FRAG;
+ else
+ element->flags = SBAL_FLAGS_MIDDLE_FRAG;
+ ctx->num_elements++;
+ element++;
+ data_len -= page_remainder;
+ ctx->offset += page_remainder;
+ page = ctx->pages[ctx->offset >> PAGE_SHIFT];
+ page_offset = 0;
+ element->addr = page + page_offset;
+ } else {
+ qeth_eddp_copy_data_tcp(page + page_offset, eddp,
+ data_len, &hcsum);
+ element->length += data_len;
+ if (!first_lap)
+ element->flags = SBAL_FLAGS_LAST_FRAG;
+ ctx->num_elements++;
+ ctx->offset += data_len;
+ data_len = 0;
+ }
+ first_lap = 0;
+ }
+ ((struct tcphdr *)eddp->th_in_ctx)->check = csum_fold(hcsum);
+}
+
+static inline u32
+qeth_eddp_check_tcp4_hdr(struct qeth_eddp_data *eddp, int data_len)
+{
+ u32 phcsum; /* pseudo header checksum */
+
+ QETH_DBF_TEXT(trace, 5, "eddpckt4");
+ eddp->th.tcp.h.check = 0;
+ /* compute pseudo header checksum */
+ phcsum = csum_tcpudp_nofold(eddp->nh.ip4.h.saddr, eddp->nh.ip4.h.daddr,
+ eddp->thl + data_len, IPPROTO_TCP, 0);
+ /* compute checksum of tcp header */
+ return csum_partial((u8 *)&eddp->th, eddp->thl, phcsum);
+}
+
+static inline u32
+qeth_eddp_check_tcp6_hdr(struct qeth_eddp_data *eddp, int data_len)
+{
+ u32 proto;
+ u32 phcsum; /* pseudo header checksum */
+
+ QETH_DBF_TEXT(trace, 5, "eddpckt6");
+ eddp->th.tcp.h.check = 0;
+ /* compute pseudo header checksum */
+ phcsum = csum_partial((u8 *)&eddp->nh.ip6.h.saddr,
+ sizeof(struct in6_addr), 0);
+ phcsum = csum_partial((u8 *)&eddp->nh.ip6.h.daddr,
+ sizeof(struct in6_addr), phcsum);
+ proto = htonl(IPPROTO_TCP);
+ phcsum = csum_partial((u8 *)&proto, sizeof(u32), phcsum);
+ return phcsum;
+}
+
+static inline struct qeth_eddp_data *
+qeth_eddp_create_eddp_data(struct qeth_hdr *qh, u8 *nh, u8 nhl, u8 *th, u8 thl)
+{
+ struct qeth_eddp_data *eddp;
+
+ QETH_DBF_TEXT(trace, 5, "eddpcrda");
+ eddp = kmalloc(sizeof(struct qeth_eddp_data), GFP_ATOMIC);
+ if (eddp){
+ memset(eddp, 0, sizeof(struct qeth_eddp_data));
+ eddp->nhl = nhl;
+ eddp->thl = thl;
+ memcpy(&eddp->qh, qh, sizeof(struct qeth_hdr));
+ memcpy(&eddp->nh, nh, nhl);
+ memcpy(&eddp->th, th, thl);
+ eddp->frag = -1; /* initially we're in skb->data */
+ }
+ return eddp;
+}
+
+static inline void
+__qeth_eddp_fill_context_tcp(struct qeth_eddp_context *ctx,
+ struct qeth_eddp_data *eddp)
+{
+ struct tcphdr *tcph;
+ int data_len;
+ u32 hcsum;
+
+ QETH_DBF_TEXT(trace, 5, "eddpftcp");
+ eddp->skb_offset = sizeof(struct qeth_hdr) + eddp->nhl + eddp->thl;
+ tcph = eddp->skb->h.th;
+ while (eddp->skb_offset < eddp->skb->len) {
+ data_len = min((int)skb_shinfo(eddp->skb)->tso_size,
+ (int)(eddp->skb->len - eddp->skb_offset));
+ /* prepare qdio hdr */
+ if (eddp->qh.hdr.l2.id == QETH_HEADER_TYPE_LAYER2){
+ eddp->qh.hdr.l2.pkt_length = data_len + ETH_HLEN +
+ eddp->nhl + eddp->thl -
+ sizeof(struct qeth_hdr);
+#ifdef CONFIG_QETH_VLAN
+ if (eddp->mac.h_proto == __constant_htons(ETH_P_8021Q))
+ eddp->qh.hdr.l2.pkt_length += VLAN_HLEN;
+#endif /* CONFIG_QETH_VLAN */
+ } else
+ eddp->qh.hdr.l3.length = data_len + eddp->nhl +
+ eddp->thl;
+ /* prepare ip hdr */
+ if (eddp->skb->protocol == ETH_P_IP){
+ eddp->nh.ip4.h.tot_len = data_len + eddp->nhl +
+ eddp->thl;
+ eddp->nh.ip4.h.check = 0;
+ eddp->nh.ip4.h.check =
+ ip_fast_csum((u8 *)&eddp->nh.ip4.h,
+ eddp->nh.ip4.h.ihl);
+ } else
+ eddp->nh.ip6.h.payload_len = data_len + eddp->thl;
+ /* prepare tcp hdr */
+ if (data_len == (eddp->skb->len - eddp->skb_offset)){
+ /* last segment -> set FIN and PSH flags */
+ eddp->th.tcp.h.fin = tcph->fin;
+ eddp->th.tcp.h.psh = tcph->psh;
+ }
+ if (eddp->skb->protocol == ETH_P_IP)
+ hcsum = qeth_eddp_check_tcp4_hdr(eddp, data_len);
+ else
+ hcsum = qeth_eddp_check_tcp6_hdr(eddp, data_len);
+ /* fill the next segment into the context */
+ qeth_eddp_create_segment_hdrs(ctx, eddp);
+ qeth_eddp_create_segment_data_tcp(ctx, eddp, data_len, hcsum);
+ if (eddp->skb_offset >= eddp->skb->len)
+ break;
+ /* prepare headers for next round */
+ if (eddp->skb->protocol == ETH_P_IP)
+ eddp->nh.ip4.h.id++;
+ eddp->th.tcp.h.seq += data_len;
+ }
+}
+
+static inline int
+qeth_eddp_fill_context_tcp(struct qeth_eddp_context *ctx,
+ struct sk_buff *skb, struct qeth_hdr *qhdr)
+{
+ struct qeth_eddp_data *eddp = NULL;
+
+ QETH_DBF_TEXT(trace, 5, "eddpficx");
+ /* create our segmentation headers and copy original headers */
+ if (skb->protocol == ETH_P_IP)
+ eddp = qeth_eddp_create_eddp_data(qhdr, (u8 *)skb->nh.iph,
+ skb->nh.iph->ihl*4,
+ (u8 *)skb->h.th, skb->h.th->doff*4);
+ else
+ eddp = qeth_eddp_create_eddp_data(qhdr, (u8 *)skb->nh.ipv6h,
+ sizeof(struct ipv6hdr),
+ (u8 *)skb->h.th, skb->h.th->doff*4);
+
+ if (eddp == NULL) {
+ QETH_DBF_TEXT(trace, 2, "eddpfcnm");
+ return -ENOMEM;
+ }
+ if (qhdr->hdr.l2.id == QETH_HEADER_TYPE_LAYER2) {
+ memcpy(&eddp->mac, eth_hdr(skb), ETH_HLEN);
+#ifdef CONFIG_QETH_VLAN
+ if (eddp->mac.h_proto == __constant_htons(ETH_P_8021Q)) {
+ eddp->vlan[0] = __constant_htons(skb->protocol);
+ eddp->vlan[1] = htons(vlan_tx_tag_get(skb));
+ }
+#endif /* CONFIG_QETH_VLAN */
+ }
+ /* the next flags will only be set on the last segment */
+ eddp->th.tcp.h.fin = 0;
+ eddp->th.tcp.h.psh = 0;
+ eddp->skb = skb;
+ /* begin segmentation and fill context */
+ __qeth_eddp_fill_context_tcp(ctx, eddp);
+ kfree(eddp);
+ return 0;
+}
+
+static inline void
+qeth_eddp_calc_num_pages(struct qeth_eddp_context *ctx, struct sk_buff *skb,
+ int hdr_len)
+{
+ int skbs_per_page;
+
+ QETH_DBF_TEXT(trace, 5, "eddpcanp");
+ /* can we put multiple skbs in one page? */
+ skbs_per_page = PAGE_SIZE / (skb_shinfo(skb)->tso_size + hdr_len);
+ if (skbs_per_page > 1){
+ ctx->num_pages = (skb_shinfo(skb)->tso_segs + 1) /
+ skbs_per_page + 1;
+ ctx->elements_per_skb = 1;
+ } else {
+ /* no -> how many elements per skb? */
+ ctx->elements_per_skb = (skb_shinfo(skb)->tso_size + hdr_len +
+ PAGE_SIZE) >> PAGE_SHIFT;
+ ctx->num_pages = ctx->elements_per_skb *
+ (skb_shinfo(skb)->tso_segs + 1);
+ }
+ ctx->num_elements = ctx->elements_per_skb *
+ (skb_shinfo(skb)->tso_segs + 1);
+}
+
+static inline struct qeth_eddp_context *
+qeth_eddp_create_context_generic(struct qeth_card *card, struct sk_buff *skb,
+ int hdr_len)
+{
+ struct qeth_eddp_context *ctx = NULL;
+ u8 *addr;
+ int i;
+
+ QETH_DBF_TEXT(trace, 5, "creddpcg");
+ /* create the context and allocate pages */
+ ctx = kmalloc(sizeof(struct qeth_eddp_context), GFP_ATOMIC);
+ if (ctx == NULL){
+ QETH_DBF_TEXT(trace, 2, "ceddpcn1");
+ return NULL;
+ }
+ memset(ctx, 0, sizeof(struct qeth_eddp_context));
+ ctx->type = QETH_LARGE_SEND_EDDP;
+ qeth_eddp_calc_num_pages(ctx, skb, hdr_len);
+ if (ctx->elements_per_skb > QETH_MAX_BUFFER_ELEMENTS(card)){
+ QETH_DBF_TEXT(trace, 2, "ceddpcis");
+ kfree(ctx);
+ return NULL;
+ }
+ ctx->pages = kmalloc(ctx->num_pages * sizeof(u8 *), GFP_ATOMIC);
+ if (ctx->pages == NULL){
+ QETH_DBF_TEXT(trace, 2, "ceddpcn2");
+ kfree(ctx);
+ return NULL;
+ }
+ memset(ctx->pages, 0, ctx->num_pages * sizeof(u8 *));
+ for (i = 0; i < ctx->num_pages; ++i){
+ addr = (u8 *)__get_free_page(GFP_ATOMIC);
+ if (addr == NULL){
+ QETH_DBF_TEXT(trace, 2, "ceddpcn3");
+ ctx->num_pages = i;
+ qeth_eddp_free_context(ctx);
+ return NULL;
+ }
+ memset(addr, 0, PAGE_SIZE);
+ ctx->pages[i] = addr;
+ }
+ ctx->elements = kmalloc(ctx->num_elements *
+ sizeof(struct qeth_eddp_element), GFP_ATOMIC);
+ if (ctx->elements == NULL){
+ QETH_DBF_TEXT(trace, 2, "ceddpcn4");
+ qeth_eddp_free_context(ctx);
+ return NULL;
+ }
+ memset(ctx->elements, 0,
+ ctx->num_elements * sizeof(struct qeth_eddp_element));
+ /* reset num_elements; will be incremented again in fill_buffer to
+ * reflect number of actually used elements */
+ ctx->num_elements = 0;
+ return ctx;
+}
+
+static inline struct qeth_eddp_context *
+qeth_eddp_create_context_tcp(struct qeth_card *card, struct sk_buff *skb,
+ struct qeth_hdr *qhdr)
+{
+ struct qeth_eddp_context *ctx = NULL;
+
+ QETH_DBF_TEXT(trace, 5, "creddpct");
+ if (skb->protocol == ETH_P_IP)
+ ctx = qeth_eddp_create_context_generic(card, skb,
+ sizeof(struct qeth_hdr) + skb->nh.iph->ihl*4 +
+ skb->h.th->doff*4);
+ else if (skb->protocol == ETH_P_IPV6)
+ ctx = qeth_eddp_create_context_generic(card, skb,
+ sizeof(struct qeth_hdr) + sizeof(struct ipv6hdr) +
+ skb->h.th->doff*4);
+ else
+ QETH_DBF_TEXT(trace, 2, "cetcpinv");
+
+ if (ctx == NULL) {
+ QETH_DBF_TEXT(trace, 2, "creddpnl");
+ return NULL;
+ }
+ if (qeth_eddp_fill_context_tcp(ctx, skb, qhdr)){
+ QETH_DBF_TEXT(trace, 2, "ceddptfe");
+ qeth_eddp_free_context(ctx);
+ return NULL;
+ }
+ atomic_set(&ctx->refcnt, 1);
+ return ctx;
+}
+
+struct qeth_eddp_context *
+qeth_eddp_create_context(struct qeth_card *card, struct sk_buff *skb,
+ struct qeth_hdr *qhdr)
+{
+ QETH_DBF_TEXT(trace, 5, "creddpc");
+ switch (skb->sk->sk_protocol){
+ case IPPROTO_TCP:
+ return qeth_eddp_create_context_tcp(card, skb, qhdr);
+ default:
+ QETH_DBF_TEXT(trace, 2, "eddpinvp");
+ }
+ return NULL;
+}
+
+
diff -Nru a/drivers/s390/net/qeth_eddp.h b/drivers/s390/net/qeth_eddp.h
--- /dev/null Wed Dec 31 16:00:00 196900
+++ b/drivers/s390/net/qeth_eddp.h 2005-03-28 21:33:12 -08:00
@@ -0,0 +1,85 @@
+/*
+ * linux/drivers/s390/net/qeth_eddp.c ($Revision: 1.5 $)
+ *
+ * Header file for qeth enhanced device driver pakcing.
+ *
+ * Copyright 2004 IBM Corporation
+ *
+ * Author(s): Thomas Spatzier <tspat@xxxxxxxxxx>
+ *
+ * $Revision: 1.5 $ $Date: 2005/03/24 09:04:18 $
+ *
+ */
+#ifndef __QETH_EDDP_H__
+#define __QETH_EDDP_H__
+
+struct qeth_eddp_element {
+ u32 flags;
+ u32 length;
+ void *addr;
+};
+
+struct qeth_eddp_context {
+ atomic_t refcnt;
+ enum qeth_large_send_types type;
+ int num_pages; /* # of allocated pages */
+ u8 **pages; /* pointers to pages */
+ int offset; /* offset in ctx during creation */
+ int num_elements; /* # of required 'SBALEs' */
+ struct qeth_eddp_element *elements; /* array of 'SBALEs' */
+ int elements_per_skb; /* # of 'SBALEs' per skb **/
+};
+
+struct qeth_eddp_context_reference {
+ struct list_head list;
+ struct qeth_eddp_context *ctx;
+};
+
+extern struct qeth_eddp_context *
+qeth_eddp_create_context(struct qeth_card *,struct sk_buff *,struct qeth_hdr *);
+
+extern void
+qeth_eddp_put_context(struct qeth_eddp_context *);
+
+extern int
+qeth_eddp_fill_buffer(struct qeth_qdio_out_q *,struct qeth_eddp_context *,int);
+
+extern void
+qeth_eddp_buf_release_contexts(struct qeth_qdio_out_buffer *);
+
+extern int
+qeth_eddp_check_buffers_for_context(struct qeth_qdio_out_q *,
+ struct qeth_eddp_context *);
+/*
+ * Data used for fragmenting a IP packet.
+ */
+struct qeth_eddp_data {
+ struct qeth_hdr qh;
+ struct ethhdr mac;
+ u16 vlan[2];
+ union {
+ struct {
+ struct iphdr h;
+ u8 options[40];
+ } ip4;
+ struct {
+ struct ipv6hdr h;
+ } ip6;
+ } nh;
+ u8 nhl;
+ void *nh_in_ctx; /* address of nh within the ctx */
+ union {
+ struct {
+ struct tcphdr h;
+ u8 options[40];
+ } tcp;
+ } th;
+ u8 thl;
+ void *th_in_ctx; /* address of th within the ctx */
+ struct sk_buff *skb;
+ int skb_offset;
+ int frag;
+ int frag_offset;
+} __attribute__ ((packed));
+
+#endif /* __QETH_EDDP_H__ */
diff -Nru a/drivers/s390/net/qeth_main.c b/drivers/s390/net/qeth_main.c
--- a/drivers/s390/net/qeth_main.c 2005-03-28 21:33:12 -08:00
+++ b/drivers/s390/net/qeth_main.c 2005-03-28 21:33:12 -08:00
@@ -61,6 +61,7 @@
-
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