[I/OAT]: TCP recv offload to I/OAT

Locks down user pages and sets up for DMA in tcp_recvmsg, then calls
dma_async_try_early_copy in tcp_v4_do_rcv

Signed-off-by: Chris Leech <christopher.leech@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 67 insertions, 7 deletions

diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index b5521a9d3dc1..c6d62f0a9966 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -71,6 +71,7 @@
 #include <net/inet_common.h>
 #include <linux/ipsec.h>
 #include <asm/unaligned.h>
+#include <net/netdma.h>
 
 int sysctl_tcp_timestamps = 1;
 int sysctl_tcp_window_scaling = 1;
@@ -3785,6 +3786,50 @@ static inline int tcp_checksum_complete_user(struct sock *sk, struct sk_buff *sk
                 __tcp_checksum_complete_user(sk, skb);
 }
 
+#ifdef CONFIG_NET_DMA
+static int tcp_dma_try_early_copy(struct sock *sk, struct sk_buff *skb, int hlen)
+{
+        struct tcp_sock *tp = tcp_sk(sk);
+        int chunk = skb->len - hlen;
+        int dma_cookie;
+        int copied_early = 0;
+
+        if (tp->ucopy.wakeup)
+                return 0;
+
+        if (!tp->ucopy.dma_chan && tp->ucopy.pinned_list)
+                tp->ucopy.dma_chan = get_softnet_dma();
+
+        if (tp->ucopy.dma_chan && skb->ip_summed == CHECKSUM_UNNECESSARY) {
+
+                dma_cookie = dma_skb_copy_datagram_iovec(tp->ucopy.dma_chan,
+                        skb, hlen, tp->ucopy.iov, chunk, tp->ucopy.pinned_list);
+
+                if (dma_cookie < 0)
+                        goto out;
+
+                tp->ucopy.dma_cookie = dma_cookie;
+                copied_early = 1;
+
+                tp->ucopy.len -= chunk;
+                tp->copied_seq += chunk;
+                tcp_rcv_space_adjust(sk);
+
+                if ((tp->ucopy.len == 0) ||
+                    (tcp_flag_word(skb->h.th) & TCP_FLAG_PSH) ||
+                    (atomic_read(&sk->sk_rmem_alloc) > (sk->sk_rcvbuf >> 1))) {
+                        tp->ucopy.wakeup = 1;
+                        sk->sk_data_ready(sk, 0);
+                }
+        } else if (chunk > 0) {
+                tp->ucopy.wakeup = 1;
+                sk->sk_data_ready(sk, 0);
+        }
+out:
+        return copied_early;
+}
+#endif /* CONFIG_NET_DMA */
+
 /*
  *      TCP receive function for the ESTABLISHED state. 
  *
@@ -3901,14 +3946,23 @@ int tcp_rcv_established(struct sock *sk, struct sk_buff *skb,
                         }
                 } else {
                         int eaten = 0;
+                        int copied_early = 0;
 
-                        if (tp->ucopy.task == current &&
-                            tp->copied_seq == tp->rcv_nxt &&
-                            len - tcp_header_len <= tp->ucopy.len &&
-                            sock_owned_by_user(sk)) {
-                                __set_current_state(TASK_RUNNING);
+                        if (tp->copied_seq == tp->rcv_nxt &&
+                            len - tcp_header_len <= tp->ucopy.len) {
+#ifdef CONFIG_NET_DMA
+                                if (tcp_dma_try_early_copy(sk, skb, tcp_header_len)) {
+                                        copied_early = 1;
+                                        eaten = 1;
+                                }
+#endif
+                                if (tp->ucopy.task == current && sock_owned_by_user(sk) && !copied_early) {
+                                        __set_current_state(TASK_RUNNING);
 
-                                if (!tcp_copy_to_iovec(sk, skb, tcp_header_len)) {
+                                        if (!tcp_copy_to_iovec(sk, skb, tcp_header_len))
+                                                eaten = 1;
+                                }
+                                if (eaten) {
                                         /* Predicted packet is in window by definition.
                                          * seq == rcv_nxt and rcv_wup <= rcv_nxt.
                                          * Hence, check seq<=rcv_wup reduces to:
@@ -3924,8 +3978,9 @@ int tcp_rcv_established(struct sock *sk, struct sk_buff *skb,
                                         __skb_pull(skb, tcp_header_len);
                                         tp->rcv_nxt = TCP_SKB_CB(skb)->end_seq;
                                         NET_INC_STATS_BH(LINUX_MIB_TCPHPHITSTOUSER);
-                                        eaten = 1;
                                 }
+                                if (copied_early)
+                                        tcp_cleanup_rbuf(sk, skb->len);
                         }
                         if (!eaten) {
                                 if (tcp_checksum_complete_user(sk, skb))
@@ -3966,6 +4021,11 @@ int tcp_rcv_established(struct sock *sk, struct sk_buff *skb,
 
                         __tcp_ack_snd_check(sk, 0);
 no_ack:
+#ifdef CONFIG_NET_DMA
+                        if (copied_early)
+                                __skb_queue_tail(&sk->sk_async_wait_queue, skb);
+                        else
+#endif
                         if (eaten)
                                 __kfree_skb(skb);
                         else