Merge branch 'tipc-refactor-socket-receive-functions'

Jon Maloy says:

====================
tipc: refactor socket receive functions

We try to make the functions tipc_sk_recvmsg() and
tipc_sk_recvstream() more readable.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 122 insertions, 144 deletions

diff --git a/net/tipc/socket.c b/net/tipc/socket.c
index 8a4e9fe5f9eb..7e45ef938c18 100644
--- a/net/tipc/socket.c
+++ b/net/tipc/socket.c
@@ -51,6 +51,7 @@
 #define TIPC_FWD_MSG            1
 #define TIPC_MAX_PORT           0xffffffff
 #define TIPC_MIN_PORT           1
+#define TIPC_ACK_RATE           4       /* ACK at 1/4 of of rcv window size */
 
 enum {
         TIPC_LISTEN = TCP_LISTEN,
@@ -1290,7 +1291,7 @@ static int tipc_wait_for_rcvmsg(struct socket *sock, long *timeop)
 /**
  * tipc_recvmsg - receive packet-oriented message
  * @m: descriptor for message info
- * @buf_len: total size of user buffer area
+ * @buflen: length of user buffer area
  * @flags: receive flags
  *
  * Used for SOCK_DGRAM, SOCK_RDM, and SOCK_SEQPACKET messages.
@@ -1298,95 +1299,85 @@ static int tipc_wait_for_rcvmsg(struct socket *sock, long *timeop)
  *
  * Returns size of returned message data, errno otherwise
  */
-static int tipc_recvmsg(struct socket *sock, struct msghdr *m, size_t buf_len,
-                        int flags)
+static int tipc_recvmsg(struct socket *sock, struct msghdr *m,
+                        size_t buflen,  int flags)
 {
         struct sock *sk = sock->sk;
         struct tipc_sock *tsk = tipc_sk(sk);
-        struct sk_buff *buf;
-        struct tipc_msg *msg;
-        bool is_connectionless = tipc_sk_type_connectionless(sk);
-        long timeo;
-        unsigned int sz;
-        u32 err;
-        int res, hlen;
+        struct sk_buff *skb;
+        struct tipc_msg *hdr;
+        bool connected = !tipc_sk_type_connectionless(sk);
+        int rc, err, hlen, dlen, copy;
+        long timeout;
 
         /* Catch invalid receive requests */
-        if (unlikely(!buf_len))
+        if (unlikely(!buflen))
                 return -EINVAL;
 
         lock_sock(sk);
-
-        if (!is_connectionless && unlikely(sk->sk_state == TIPC_OPEN)) {
-                res = -ENOTCONN;
+        if (unlikely(connected && sk->sk_state == TIPC_OPEN)) {
+                rc = -ENOTCONN;
                 goto exit;
         }
+        timeout = sock_rcvtimeo(sk, flags & MSG_DONTWAIT);
 
-        timeo = sock_rcvtimeo(sk, flags & MSG_DONTWAIT);
-restart:
-
-        /* Look for a message in receive queue; wait if necessary */
-        res = tipc_wait_for_rcvmsg(sock, &timeo);
-        if (res)
-                goto exit;
-
-        /* Look at first message in receive queue */
-        buf = skb_peek(&sk->sk_receive_queue);
-        msg = buf_msg(buf);
-        sz = msg_data_sz(msg);
-        hlen = msg_hdr_sz(msg);
-        err = msg_errcode(msg);
-
-        /* Discard an empty non-errored message & try again */
-        if ((!sz) && (!err)) {
+        do {
+                /* Look at first msg in receive queue; wait if necessary */
+                rc = tipc_wait_for_rcvmsg(sock, &timeout);
+                if (unlikely(rc))
+                        goto exit;
+                skb = skb_peek(&sk->sk_receive_queue);
+                hdr = buf_msg(skb);
+                dlen = msg_data_sz(hdr);
+                hlen = msg_hdr_sz(hdr);
+                err = msg_errcode(hdr);
+                if (likely(dlen || err))
+                        break;
                 tsk_advance_rx_queue(sk);
-                goto restart;
-        }
-
-        /* Capture sender's address (optional) */
-        set_orig_addr(m, msg);
+        } while (1);
 
-        /* Capture ancillary data (optional) */
-        res = tipc_sk_anc_data_recv(m, msg, tsk);
-        if (res)
+        /* Collect msg meta data, including error code and rejected data */
+        set_orig_addr(m, hdr);
+        rc = tipc_sk_anc_data_recv(m, hdr, tsk);
+        if (unlikely(rc))
                 goto exit;
 
-        /* Capture message data (if valid) & compute return value (always) */
-        if (!err) {
-                if (unlikely(buf_len < sz)) {
-                        sz = buf_len;
+        /* Capture data if non-error msg, otherwise just set return value */
+        if (likely(!err)) {
+                copy = min_t(int, dlen, buflen);
+                if (unlikely(copy != dlen))
                         m->msg_flags |= MSG_TRUNC;
-                }
-                res = skb_copy_datagram_msg(buf, hlen, m, sz);
-                if (res)
-                        goto exit;
-                res = sz;
+                rc = skb_copy_datagram_msg(skb, hlen, m, copy);
         } else {
-                if (is_connectionless || err == TIPC_CONN_SHUTDOWN ||
-                    m->msg_control)
-                        res = 0;
-                else
-                        res = -ECONNRESET;
+                copy = 0;
+                rc = 0;
+                if (err != TIPC_CONN_SHUTDOWN && connected && !m->msg_control)
+                        rc = -ECONNRESET;
         }
+        if (unlikely(rc))
+                goto exit;
 
+        /* Caption of data or error code/rejected data was successful */
         if (unlikely(flags & MSG_PEEK))
                 goto exit;
 
-        if (likely(!is_connectionless)) {
-                tsk->rcv_unacked += tsk_inc(tsk, hlen + sz);
-                if (unlikely(tsk->rcv_unacked >= (tsk->rcv_win / 4)))
-                        tipc_sk_send_ack(tsk);
-        }
         tsk_advance_rx_queue(sk);
+        if (likely(!connected))
+                goto exit;
+
+        /* Send connection flow control ack when applicable */
+        tsk->rcv_unacked += tsk_inc(tsk, hlen + dlen);
+        if (tsk->rcv_unacked >= tsk->rcv_win / TIPC_ACK_RATE)
+                tipc_sk_send_ack(tsk);
 exit:
         release_sock(sk);
-        return res;
+        return rc ? rc : copy;
 }
 
 /**
- * tipc_recv_stream - receive stream-oriented data
+ * tipc_recvstream - receive stream-oriented data
  * @m: descriptor for message info
- * @buf_len: total size of user buffer area
+ * @buflen: total size of user buffer area
  * @flags: receive flags
  *
  * Used for SOCK_STREAM messages only.  If not enough data is available
@@ -1394,111 +1385,98 @@ exit:
  *
  * Returns size of returned message data, errno otherwise
  */
-static int tipc_recv_stream(struct socket *sock, struct msghdr *m,
-                            size_t buf_len, int flags)
+static int tipc_recvstream(struct socket *sock, struct msghdr *m,
+                           size_t buflen, int flags)
 {
         struct sock *sk = sock->sk;
         struct tipc_sock *tsk = tipc_sk(sk);
-        struct sk_buff *buf;
-        struct tipc_msg *msg;
-        long timeo;
-        unsigned int sz;
-        int target;
-        int sz_copied = 0;
-        u32 err;
-        int res = 0, hlen;
+        struct sk_buff *skb;
+        struct tipc_msg *hdr;
+        struct tipc_skb_cb *skb_cb;
+        bool peek = flags & MSG_PEEK;
+        int offset, required, copy, copied = 0;
+        int hlen, dlen, err, rc;
+        long timeout;
 
         /* Catch invalid receive attempts */
-        if (unlikely(!buf_len))
+        if (unlikely(!buflen))
                 return -EINVAL;
 
         lock_sock(sk);
 
         if (unlikely(sk->sk_state == TIPC_OPEN)) {
-                res = -ENOTCONN;
-                goto exit;
-        }
-
-        target = sock_rcvlowat(sk, flags & MSG_WAITALL, buf_len);
-        timeo = sock_rcvtimeo(sk, flags & MSG_DONTWAIT);
-
-restart:
-        /* Look for a message in receive queue; wait if necessary */
-        res = tipc_wait_for_rcvmsg(sock, &timeo);
-        if (res)
+                rc = -ENOTCONN;
                 goto exit;
-
-        /* Look at first message in receive queue */
-        buf = skb_peek(&sk->sk_receive_queue);
-        msg = buf_msg(buf);
-        sz = msg_data_sz(msg);
-        hlen = msg_hdr_sz(msg);
-        err = msg_errcode(msg);
-
-        /* Discard an empty non-errored message & try again */
-        if ((!sz) && (!err)) {
-                tsk_advance_rx_queue(sk);
-                goto restart;
-        }
-
-        /* Optionally capture sender's address & ancillary data of first msg */
-        if (sz_copied == 0) {
-                set_orig_addr(m, msg);
-                res = tipc_sk_anc_data_recv(m, msg, tsk);
-                if (res)
-                        goto exit;
         }
+        required = sock_rcvlowat(sk, flags & MSG_WAITALL, buflen);
+        timeout = sock_rcvtimeo(sk, flags & MSG_DONTWAIT);
 
-        /* Capture message data (if valid) & compute return value (always) */
-        if (!err) {
-                u32 offset = TIPC_SKB_CB(buf)->bytes_read;
-                u32 needed;
-                int sz_to_copy;
-
-                sz -= offset;
-                needed = (buf_len - sz_copied);
-                sz_to_copy = min(sz, needed);
-
-                res = skb_copy_datagram_msg(buf, hlen + offset, m, sz_to_copy);
-                if (res)
-                        goto exit;
+        do {
+                /* Look at first msg in receive queue; wait if necessary */
+                rc = tipc_wait_for_rcvmsg(sock, &timeout);
+                if (unlikely(rc))
+                        break;
+                skb = skb_peek(&sk->sk_receive_queue);
+                skb_cb = TIPC_SKB_CB(skb);
+                hdr = buf_msg(skb);
+                dlen = msg_data_sz(hdr);
+                hlen = msg_hdr_sz(hdr);
+                err = msg_errcode(hdr);
+
+                /* Discard any empty non-errored (SYN-) message */
+                if (unlikely(!dlen && !err)) {
+                        tsk_advance_rx_queue(sk);
+                        continue;
+                }
 
-                sz_copied += sz_to_copy;
+                /* Collect msg meta data, incl. error code and rejected data */
+                if (!copied) {
+                        set_orig_addr(m, hdr);
+                        rc = tipc_sk_anc_data_recv(m, hdr, tsk);
+                        if (rc)
+                                break;
+                }
 
-                if (sz_to_copy < sz) {
-                        if (!(flags & MSG_PEEK))
-                                TIPC_SKB_CB(buf)->bytes_read =
-                                        offset + sz_to_copy;
-                        goto exit;
+                /* Copy data if msg ok, otherwise return error/partial data */
+                if (likely(!err)) {
+                        offset = skb_cb->bytes_read;
+                        copy = min_t(int, dlen - offset, buflen - copied);
+                        rc = skb_copy_datagram_msg(skb, hlen + offset, m, copy);
+                        if (unlikely(rc))
+                                break;
+                        copied += copy;
+                        offset += copy;
+                        if (unlikely(offset < dlen)) {
+                                if (!peek)
+                                        skb_cb->bytes_read = offset;
+                                break;
+                        }
+                } else {
+                        rc = 0;
+                        if ((err != TIPC_CONN_SHUTDOWN) && !m->msg_control)
+                                rc = -ECONNRESET;
+                        if (copied || rc)
+                                break;
                 }
-        } else {
-                if (sz_copied != 0)
-                        goto exit; /* can't add error msg to valid data */
 
-                if ((err == TIPC_CONN_SHUTDOWN) || m->msg_control)
-                        res = 0;
-                else
-                        res = -ECONNRESET;
-        }
+                if (unlikely(peek))
+                        break;
 
-        if (unlikely(flags & MSG_PEEK))
-                goto exit;
+                tsk_advance_rx_queue(sk);
 
-        tsk->rcv_unacked += tsk_inc(tsk, hlen + msg_data_sz(msg));
-        if (unlikely(tsk->rcv_unacked >= (tsk->rcv_win / 4)))
-                tipc_sk_send_ack(tsk);
-        tsk_advance_rx_queue(sk);
+                /* Send connection flow control advertisement when applicable */
+                tsk->rcv_unacked += tsk_inc(tsk, hlen + dlen);
+                if (unlikely(tsk->rcv_unacked >= tsk->rcv_win / TIPC_ACK_RATE))
+                        tipc_sk_send_ack(tsk);
 
-        /* Loop around if more data is required */
-        if ((sz_copied < buf_len) &&    /* didn't get all requested data */
-            (!skb_queue_empty(&sk->sk_receive_queue) ||
-            (sz_copied < target)) &&    /* and more is ready or required */
-            (!err))                     /* and haven't reached a FIN */
-                goto restart;
+                /* Exit if all requested data or FIN/error received */
+                if (copied == buflen || err)
+                        break;
 
+        } while (!skb_queue_empty(&sk->sk_receive_queue) || copied < required);
 exit:
         release_sock(sk);
-        return sz_copied ? sz_copied : res;
+        return copied ? copied : rc;
 }
 
 /**
@@ -2593,7 +2571,7 @@ static const struct proto_ops stream_ops = {
         .setsockopt     = tipc_setsockopt,
         .getsockopt     = tipc_getsockopt,
         .sendmsg        = tipc_sendstream,
-        .recvmsg        = tipc_recv_stream,
+        .recvmsg        = tipc_recvstream,
         .mmap           = sock_no_mmap,
         .sendpage       = sock_no_sendpage
 };