[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>

3 files changed, 175 insertions, 20 deletions

diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 4e067d25a63c..ff6ccda9ff46 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -263,7 +263,7 @@
 #include <net/tcp.h>
 #include <net/xfrm.h>
 #include <net/ip.h>
-
+#include <net/netdma.h>
 
 #include <asm/uaccess.h>
 #include <asm/ioctls.h>
@@ -1110,6 +1110,7 @@ int tcp_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
         int target;             /* Read at least this many bytes */
         long timeo;
         struct task_struct *user_recv = NULL;
+        int copied_early = 0;
 
         lock_sock(sk);
 
@@ -1133,6 +1134,17 @@ int tcp_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
 
         target = sock_rcvlowat(sk, flags & MSG_WAITALL, len);
 
+#ifdef CONFIG_NET_DMA
+        tp->ucopy.dma_chan = NULL;
+        preempt_disable();
+        if ((len > sysctl_tcp_dma_copybreak) && !(flags & MSG_PEEK) &&
+            !sysctl_tcp_low_latency && __get_cpu_var(softnet_data.net_dma)) {
+                preempt_enable_no_resched();
+                tp->ucopy.pinned_list = dma_pin_iovec_pages(msg->msg_iov, len);
+        } else
+                preempt_enable_no_resched();
+#endif
+
         do {
                 struct sk_buff *skb;
                 u32 offset;
@@ -1274,6 +1286,10 @@ int tcp_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
                 } else
                         sk_wait_data(sk, &timeo);
 
+#ifdef CONFIG_NET_DMA
+                tp->ucopy.wakeup = 0;
+#endif
+
                 if (user_recv) {
                         int chunk;
 
@@ -1329,13 +1345,39 @@ do_prequeue:
                 }
 
                 if (!(flags & MSG_TRUNC)) {
-                        err = skb_copy_datagram_iovec(skb, offset,
-                                                      msg->msg_iov, used);
-                        if (err) {
-                                /* Exception. Bailout! */
-                                if (!copied)
-                                        copied = -EFAULT;
-                                break;
+#ifdef CONFIG_NET_DMA
+                        if (!tp->ucopy.dma_chan && tp->ucopy.pinned_list)
+                                tp->ucopy.dma_chan = get_softnet_dma();
+
+                        if (tp->ucopy.dma_chan) {
+                                tp->ucopy.dma_cookie = dma_skb_copy_datagram_iovec(
+                                        tp->ucopy.dma_chan, skb, offset,
+                                        msg->msg_iov, used,
+                                        tp->ucopy.pinned_list);
+
+                                if (tp->ucopy.dma_cookie < 0) {
+
+                                        printk(KERN_ALERT "dma_cookie < 0\n");
+
+                                        /* Exception. Bailout! */
+                                        if (!copied)
+                                                copied = -EFAULT;
+                                        break;
+                                }
+                                if ((offset + used) == skb->len)
+                                        copied_early = 1;
+
+                        } else
+#endif
+                        {
+                                err = skb_copy_datagram_iovec(skb, offset,
+                                                msg->msg_iov, used);
+                                if (err) {
+                                        /* Exception. Bailout! */
+                                        if (!copied)
+                                                copied = -EFAULT;
+                                        break;
+                                }
                         }
                 }
 
@@ -1355,15 +1397,19 @@ skip_copy:
 
                 if (skb->h.th->fin)
                         goto found_fin_ok;
-                if (!(flags & MSG_PEEK))
-                        sk_eat_skb(sk, skb, 0);
+                if (!(flags & MSG_PEEK)) {
+                        sk_eat_skb(sk, skb, copied_early);
+                        copied_early = 0;
+                }
                 continue;
 
         found_fin_ok:
                 /* Process the FIN. */
                 ++*seq;
-                if (!(flags & MSG_PEEK))
-                        sk_eat_skb(sk, skb, 0);
+                if (!(flags & MSG_PEEK)) {
+                        sk_eat_skb(sk, skb, copied_early);
+                        copied_early = 0;
+                }
                 break;
         } while (len > 0);
 
@@ -1386,6 +1432,36 @@ skip_copy:
                 tp->ucopy.len = 0;
         }
 
+#ifdef CONFIG_NET_DMA
+        if (tp->ucopy.dma_chan) {
+                struct sk_buff *skb;
+                dma_cookie_t done, used;
+
+                dma_async_memcpy_issue_pending(tp->ucopy.dma_chan);
+
+                while (dma_async_memcpy_complete(tp->ucopy.dma_chan,
+                                                 tp->ucopy.dma_cookie, &done,
+                                                 &used) == DMA_IN_PROGRESS) {
+                        /* do partial cleanup of sk_async_wait_queue */
+                        while ((skb = skb_peek(&sk->sk_async_wait_queue)) &&
+                               (dma_async_is_complete(skb->dma_cookie, done,
+                                                      used) == DMA_SUCCESS)) {
+                                __skb_dequeue(&sk->sk_async_wait_queue);
+                                kfree_skb(skb);
+                        }
+                }
+
+                /* Safe to free early-copied skbs now */
+                __skb_queue_purge(&sk->sk_async_wait_queue);
+                dma_chan_put(tp->ucopy.dma_chan);
+                tp->ucopy.dma_chan = NULL;
+        }
+        if (tp->ucopy.pinned_list) {
+                dma_unpin_iovec_pages(tp->ucopy.pinned_list);
+                tp->ucopy.pinned_list = NULL;
+        }
+#endif
+
         /* According to UNIX98, msg_name/msg_namelen are ignored
          * on connected socket. I was just happy when found this 8) --ANK
          */
@@ -1658,6 +1734,9 @@ int tcp_disconnect(struct sock *sk, int flags)
         __skb_queue_purge(&sk->sk_receive_queue);
         sk_stream_writequeue_purge(sk);
         __skb_queue_purge(&tp->out_of_order_queue);
+#ifdef CONFIG_NET_DMA
+        __skb_queue_purge(&sk->sk_async_wait_queue);
+#endif
 
         inet->dport = 0;
 
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
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 672950e54c49..25ecc6e2478b 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -71,6 +71,7 @@
 #include <net/inet_common.h>
 #include <net/timewait_sock.h>
 #include <net/xfrm.h>
+#include <net/netdma.h>
 
 #include <linux/inet.h>
 #include <linux/ipv6.h>
@@ -1091,8 +1092,18 @@ process:
         bh_lock_sock(sk);
         ret = 0;
         if (!sock_owned_by_user(sk)) {
-                if (!tcp_prequeue(sk, skb))
+#ifdef CONFIG_NET_DMA
+                struct tcp_sock *tp = tcp_sk(sk);
+                if (!tp->ucopy.dma_chan && tp->ucopy.pinned_list)
+                        tp->ucopy.dma_chan = get_softnet_dma();
+                if (tp->ucopy.dma_chan)
                         ret = tcp_v4_do_rcv(sk, skb);
+                else
+#endif
+                {
+                        if (!tcp_prequeue(sk, skb))
+                        ret = tcp_v4_do_rcv(sk, skb);
+                }
         } else
                 sk_add_backlog(sk, skb);
         bh_unlock_sock(sk);
@@ -1296,6 +1307,11 @@ int tcp_v4_destroy_sock(struct sock *sk)
         /* Cleans up our, hopefully empty, out_of_order_queue. */
         __skb_queue_purge(&tp->out_of_order_queue);
 
+#ifdef CONFIG_NET_DMA
+        /* Cleans up our sk_async_wait_queue */
+        __skb_queue_purge(&sk->sk_async_wait_queue);
+#endif
+
         /* Clean prequeue, it must be empty really */
         __skb_queue_purge(&tp->ucopy.prequeue);