net/smc: propagate file from SMC to TCP socket

fcntl(fd, F_SETOWN, getpid()) selects the recipient of SIGURG signals
that are delivered when out-of-band data arrives on socket fd.
If an SMC socket program makes use of such an fcntl() call, it fails
in case of fallback to TCP-mode. In case of fallback the traffic is
processed with the internal TCP socket. Propagating field "file" from the
SMC socket to the internal TCP socket fixes the issue.

Reviewed-by: Karsten Graul <kgraul@linux.ibm.com>
Signed-off-by: Ursula Braun <ubraun@linux.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/net/sock.h b/include/net/sock.h
index 8de5ee2..341f8ba 100644 (file)
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -2084,12 +2084,6 @@ static inline bool skwq_has_sleeper(struct socket_wq *wq)
  * @p:              poll_table
  *
  * See the comments in the wq_has_sleeper function.
- *
- * Do not derive sock from filp->private_data here. An SMC socket establishes
- * an internal TCP socket that is used in the fallback case. All socket
- * operations on the SMC socket are then forwarded to the TCP socket. In case of
- * poll, the filp->private_data pointer references the SMC socket because the
- * TCP socket has no file assigned.
  */
 static inline void sock_poll_wait(struct file *filp, struct socket *sock,
                                  poll_table *p)

diff --git a/net/smc/af_smc.c b/net/smc/af_smc.c
index 9bdaed2..d2a0d15 100644 (file)
--- a/net/smc/af_smc.c
+++ b/net/smc/af_smc.c
@@ -445,10 +445,19 @@ static void smc_link_save_peer_info(struct smc_link *link,
        link->peer_mtu = clc->qp_mtu;
 }
 
+static void smc_switch_to_fallback(struct smc_sock *smc)
+{
+       smc->use_fallback = true;
+       if (smc->sk.sk_socket && smc->sk.sk_socket->file) {
+               smc->clcsock->file = smc->sk.sk_socket->file;
+               smc->clcsock->file->private_data = smc->clcsock;
+       }
+}
+
 /* fall back during connect */
 static int smc_connect_fallback(struct smc_sock *smc, int reason_code)
 {
-       smc->use_fallback = true;
+       smc_switch_to_fallback(smc);
        smc->fallback_rsn = reason_code;
        smc_copy_sock_settings_to_clc(smc);
        if (smc->sk.sk_state == SMC_INIT)
@@ -774,10 +783,14 @@ static void smc_connect_work(struct work_struct *work)
                smc->sk.sk_err = -rc;
 
 out:
-       if (smc->sk.sk_err)
-               smc->sk.sk_state_change(&smc->sk);
-       else
-               smc->sk.sk_write_space(&smc->sk);
+       if (!sock_flag(&smc->sk, SOCK_DEAD)) {
+               if (smc->sk.sk_err) {
+                       smc->sk.sk_state_change(&smc->sk);
+               } else { /* allow polling before and after fallback decision */
+                       smc->clcsock->sk->sk_write_space(smc->clcsock->sk);
+                       smc->sk.sk_write_space(&smc->sk);
+               }
+       }
        kfree(smc->connect_info);
        smc->connect_info = NULL;
        release_sock(&smc->sk);
@@ -934,8 +947,13 @@ struct sock *smc_accept_dequeue(struct sock *parent,
                        sock_put(new_sk); /* final */
                        continue;
                }
-               if (new_sock)
+               if (new_sock) {
                        sock_graft(new_sk, new_sock);
+                       if (isk->use_fallback) {
+                               smc_sk(new_sk)->clcsock->file = new_sock->file;
+                               isk->clcsock->file->private_data = isk->clcsock;
+                       }
+               }
                return new_sk;
        }
        return NULL;
@@ -1086,7 +1104,7 @@ static void smc_listen_decline(struct smc_sock *new_smc, int reason_code,
                return;
        }
        smc_conn_free(&new_smc->conn);
-       new_smc->use_fallback = true;
+       smc_switch_to_fallback(new_smc);
        new_smc->fallback_rsn = reason_code;
        if (reason_code && reason_code != SMC_CLC_DECL_PEERDECL) {
                if (smc_clc_send_decline(new_smc, reason_code) < 0) {
@@ -1246,7 +1264,7 @@ static void smc_listen_work(struct work_struct *work)
 
        /* check if peer is smc capable */
        if (!tcp_sk(newclcsock->sk)->syn_smc) {
-               new_smc->use_fallback = true;
+               smc_switch_to_fallback(new_smc);
                new_smc->fallback_rsn = SMC_CLC_DECL_PEERNOSMC;
                smc_listen_out_connected(new_smc);
                return;
@@ -1503,7 +1521,7 @@ static int smc_sendmsg(struct socket *sock, struct msghdr *msg, size_t len)
 
        if (msg->msg_flags & MSG_FASTOPEN) {
                if (sk->sk_state == SMC_INIT) {
-                       smc->use_fallback = true;
+                       smc_switch_to_fallback(smc);
                        smc->fallback_rsn = SMC_CLC_DECL_OPTUNSUPP;
                } else {
                        rc = -EINVAL;
@@ -1705,7 +1723,7 @@ static int smc_setsockopt(struct socket *sock, int level, int optname,
        case TCP_FASTOPEN_NO_COOKIE:
                /* option not supported by SMC */
                if (sk->sk_state == SMC_INIT) {
-                       smc->use_fallback = true;
+                       smc_switch_to_fallback(smc);
                        smc->fallback_rsn = SMC_CLC_DECL_OPTUNSUPP;
                } else {
                        if (!smc->use_fallback)