svc: Add xpo_accept transport function

Previously, the accept logic looked into the socket state to determine
whether to call accept or recv when data-ready was indicated on an endpoint.
Since some transports don't use sockets, this logic now uses a flag
bit (SK_LISTENER) to identify listening endpoints. A transport function
(xpo_accept) allows each transport to define its own accept processing.
A transport's initialization logic is reponsible for setting the
SK_LISTENER bit. I didn't see any way to do this in transport independent
logic since the passive side of a UDP connection doesn't listen and
always recv's.

In the svc_recv function, if the SK_LISTENER bit is set, the transport
xpo_accept function is called to handle accept processing.

Note that all functions are defined even if they don't make sense
for a given transport. For example, accept doesn't mean anything for
UDP. The function is defined anyway and bug checks if called. The
UDP transport should never set the SK_LISTENER bit.

Signed-off-by: Tom Tucker <tom@opengridcomputing.com>
Acked-by: Neil Brown <neilb@suse.de>
Reviewed-by: Chuck Lever <chuck.lever@oracle.com>
Reviewed-by: Greg Banks <gnb@sgi.com>
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>

3 files changed, 21 insertions, 12 deletions

diff --git a/include/linux/sunrpc/svc_xprt.h b/include/linux/sunrpc/svc_xprt.h
index 85df97acc2d0..31a44f441fd1 100644
--- a/include/linux/sunrpc/svc_xprt.h
+++ b/include/linux/sunrpc/svc_xprt.h
@@ -10,6 +10,7 @@
 #include <linux/sunrpc/svc.h>
 
 struct svc_xprt_ops {
+        struct svc_xprt *(*xpo_accept)(struct svc_xprt *);
         int             (*xpo_has_wspace)(struct svc_xprt *);
         int             (*xpo_recvfrom)(struct svc_rqst *);
         void            (*xpo_prep_reply_hdr)(struct svc_rqst *);
diff --git a/include/linux/sunrpc/svcsock.h b/include/linux/sunrpc/svcsock.h
index 08e78d0a364f..9882ce0ee33c 100644
--- a/include/linux/sunrpc/svcsock.h
+++ b/include/linux/sunrpc/svcsock.h
@@ -36,6 +36,7 @@ struct svc_sock {
 #define SK_DEFERRED     8                       /* request on sk_deferred */
 #define SK_OLD          9                       /* used for temp socket aging mark+sweep */
 #define SK_DETACHED     10                      /* detached from tempsocks list */
+#define SK_LISTENER     11                      /* listening endpoint */
 
         atomic_t                sk_reserved;    /* space on outq that is reserved */
 
diff --git a/net/sunrpc/svcsock.c b/net/sunrpc/svcsock.c
index 603db98b8fca..41d1f815fbbd 100644
--- a/net/sunrpc/svcsock.c
+++ b/net/sunrpc/svcsock.c
@@ -896,6 +896,12 @@ static int svc_udp_has_wspace(struct svc_xprt *xprt)
         return 1;
 }
 
+static struct svc_xprt *svc_udp_accept(struct svc_xprt *xprt)
+{
+        BUG();
+        return NULL;
+}
+
 static struct svc_xprt_ops svc_udp_ops = {
         .xpo_recvfrom = svc_udp_recvfrom,
         .xpo_sendto = svc_udp_sendto,
@@ -904,6 +910,7 @@ static struct svc_xprt_ops svc_udp_ops = {
         .xpo_free = svc_sock_free,
         .xpo_prep_reply_hdr = svc_udp_prep_reply_hdr,
         .xpo_has_wspace = svc_udp_has_wspace,
+        .xpo_accept = svc_udp_accept,
 };
 
 static struct svc_xprt_class svc_udp_class = {
@@ -1028,9 +1035,9 @@ static inline int svc_port_is_privileged(struct sockaddr *sin)
 /*
  * Accept a TCP connection
  */
-static void
-svc_tcp_accept(struct svc_sock *svsk)
+static struct svc_xprt *svc_tcp_accept(struct svc_xprt *xprt)
 {
+        struct svc_sock *svsk = container_of(xprt, struct svc_sock, sk_xprt);
         struct sockaddr_storage addr;
         struct sockaddr *sin = (struct sockaddr *) &addr;
         struct svc_serv *serv = svsk->sk_server;
@@ -1042,7 +1049,7 @@ svc_tcp_accept(struct svc_sock *svsk)
 
         dprintk("svc: tcp_accept %p sock %p\n", svsk, sock);
         if (!sock)
-                return;
+                return NULL;
 
         clear_bit(SK_CONN, &svsk->sk_flags);
         err = kernel_accept(sock, &newsock, O_NONBLOCK);
@@ -1053,7 +1060,7 @@ svc_tcp_accept(struct svc_sock *svsk)
                 else if (err != -EAGAIN && net_ratelimit())
                         printk(KERN_WARNING "%s: accept failed (err %d)!\n",
                                    serv->sv_name, -err);
-                return;
+                return NULL;
         }
 
         set_bit(SK_CONN, &svsk->sk_flags);
@@ -1147,11 +1154,11 @@ svc_tcp_accept(struct svc_sock *svsk)
         if (serv->sv_stats)
                 serv->sv_stats->nettcpconn++;
 
-        return;
+        return &newsvsk->sk_xprt;
 
 failed:
         sock_release(newsock);
-        return;
+        return NULL;
 }
 
 /*
@@ -1176,12 +1183,6 @@ svc_tcp_recvfrom(struct svc_rqst *rqstp)
                 return svc_deferred_recv(rqstp);
         }
 
-        if (svsk->sk_sk->sk_state == TCP_LISTEN) {
-                svc_tcp_accept(svsk);
-                svc_sock_received(svsk);
-                return 0;
-        }
-
         if (test_and_clear_bit(SK_CHNGBUF, &svsk->sk_flags))
                 /* sndbuf needs to have room for one request
                  * per thread, otherwise we can stall even when the
@@ -1393,6 +1394,7 @@ static struct svc_xprt_ops svc_tcp_ops = {
         .xpo_free = svc_sock_free,
         .xpo_prep_reply_hdr = svc_tcp_prep_reply_hdr,
         .xpo_has_wspace = svc_tcp_has_wspace,
+        .xpo_accept = svc_tcp_accept,
 };
 
 static struct svc_xprt_class svc_tcp_class = {
@@ -1423,6 +1425,7 @@ svc_tcp_init(struct svc_sock *svsk)
 
         if (sk->sk_state == TCP_LISTEN) {
                 dprintk("setting up TCP socket for listening\n");
+                set_bit(SK_LISTENER, &svsk->sk_flags);
                 sk->sk_data_ready = svc_tcp_listen_data_ready;
                 set_bit(SK_CONN, &svsk->sk_flags);
         } else {
@@ -1569,6 +1572,10 @@ svc_recv(struct svc_rqst *rqstp, long timeout)
         if (test_bit(SK_CLOSE, &svsk->sk_flags)) {
                 dprintk("svc_recv: found SK_CLOSE\n");
                 svc_delete_socket(svsk);
+        } else if (test_bit(SK_LISTENER, &svsk->sk_flags)) {
+                struct svc_xprt *newxpt;
+                newxpt = svsk->sk_xprt.xpt_ops->xpo_accept(&svsk->sk_xprt);
+                svc_sock_received(svsk);
         } else {
                 dprintk("svc: server %p, pool %u, socket %p, inuse=%d\n",
                         rqstp, pool->sp_id, svsk, atomic_read(&svsk->sk_inuse));