1 files changed, 444 insertions, 0 deletions

diff --git a/net/smc/smc_rx.c b/net/smc/smc_rx.c
new file mode 100644
index 000000000..3757aff6c
--- /dev/null
+++ b/net/smc/smc_rx.c
@@ -0,0 +1,444 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Shared Memory Communications over RDMA (SMC-R) and RoCE
+ *
+ * Manage RMBE
+ * copy new RMBE data into user space
+ *
+ * Copyright IBM Corp. 2016
+ *
+ * Author(s):  Ursula Braun <ubraun@linux.vnet.ibm.com>
+ */
+
+#include <linux/net.h>
+#include <linux/rcupdate.h>
+#include <linux/sched/signal.h>
+
+#include <net/sock.h>
+
+#include "smc.h"
+#include "smc_core.h"
+#include "smc_cdc.h"
+#include "smc_tx.h" /* smc_tx_consumer_update() */
+#include "smc_rx.h"
+
+/* callback implementation to wakeup consumers blocked with smc_rx_wait().
+ * indirectly called by smc_cdc_msg_recv_action().
+ */
+static void smc_rx_wake_up(struct sock *sk)
+{
+	struct socket_wq *wq;
+
+	/* derived from sock_def_readable() */
+	/* called already in smc_listen_work() */
+	rcu_read_lock();
+	wq = rcu_dereference(sk->sk_wq);
+	if (skwq_has_sleeper(wq))
+		wake_up_interruptible_sync_poll(&wq->wait, EPOLLIN | EPOLLPRI |
+						EPOLLRDNORM | EPOLLRDBAND);
+	sk_wake_async(sk, SOCK_WAKE_WAITD, POLL_IN);
+	if ((sk->sk_shutdown == SHUTDOWN_MASK) ||
+	    (sk->sk_state == SMC_CLOSED))
+		sk_wake_async(sk, SOCK_WAKE_WAITD, POLL_HUP);
+	rcu_read_unlock();
+}
+
+/* Update consumer cursor
+ *   @conn   connection to update
+ *   @cons   consumer cursor
+ *   @len    number of Bytes consumed
+ *   Returns:
+ *   1 if we should end our receive, 0 otherwise
+ */
+static int smc_rx_update_consumer(struct smc_sock *smc,
+				  union smc_host_cursor cons, size_t len)
+{
+	struct smc_connection *conn = &smc->conn;
+	struct sock *sk = &smc->sk;
+	bool force = false;
+	int diff, rc = 0;
+
+	smc_curs_add(conn->rmb_desc->len, &cons, len);
+
+	/* did we process urgent data? */
+	if (conn->urg_state == SMC_URG_VALID || conn->urg_rx_skip_pend) {
+		diff = smc_curs_comp(conn->rmb_desc->len, &cons,
+				     &conn->urg_curs);
+		if (sock_flag(sk, SOCK_URGINLINE)) {
+			if (diff == 0) {
+				force = true;
+				rc = 1;
+				conn->urg_state = SMC_URG_READ;
+			}
+		} else {
+			if (diff == 1) {
+				/* skip urgent byte */
+				force = true;
+				smc_curs_add(conn->rmb_desc->len, &cons, 1);
+				conn->urg_rx_skip_pend = false;
+			} else if (diff < -1)
+				/* we read past urgent byte */
+				conn->urg_state = SMC_URG_READ;
+		}
+	}
+
+	smc_curs_copy(&conn->local_tx_ctrl.cons, &cons, conn);
+
+	/* send consumer cursor update if required */
+	/* similar to advertising new TCP rcv_wnd if required */
+	smc_tx_consumer_update(conn, force);
+
+	return rc;
+}
+
+static void smc_rx_update_cons(struct smc_sock *smc, size_t len)
+{
+	struct smc_connection *conn = &smc->conn;
+	union smc_host_cursor cons;
+
+	smc_curs_copy(&cons, &conn->local_tx_ctrl.cons, conn);
+	smc_rx_update_consumer(smc, cons, len);
+}
+
+struct smc_spd_priv {
+	struct smc_sock *smc;
+	size_t		 len;
+};
+
+static void smc_rx_pipe_buf_release(struct pipe_inode_info *pipe,
+				    struct pipe_buffer *buf)
+{
+	struct smc_spd_priv *priv = (struct smc_spd_priv *)buf->private;
+	struct smc_sock *smc = priv->smc;
+	struct smc_connection *conn;
+	struct sock *sk = &smc->sk;
+
+	if (sk->sk_state == SMC_CLOSED ||
+	    sk->sk_state == SMC_PEERFINCLOSEWAIT ||
+	    sk->sk_state == SMC_APPFINCLOSEWAIT)
+		goto out;
+	conn = &smc->conn;
+	lock_sock(sk);
+	smc_rx_update_cons(smc, priv->len);
+	release_sock(sk);
+	if (atomic_sub_and_test(priv->len, &conn->splice_pending))
+		smc_rx_wake_up(sk);
+out:
+	kfree(priv);
+	put_page(buf->page);
+	sock_put(sk);
+}
+
+static const struct pipe_buf_operations smc_pipe_ops = {
+	.release = smc_rx_pipe_buf_release,
+	.get = generic_pipe_buf_get
+};
+
+static void smc_rx_spd_release(struct splice_pipe_desc *spd,
+			       unsigned int i)
+{
+	put_page(spd->pages[i]);
+}
+
+static int smc_rx_splice(struct pipe_inode_info *pipe, char *src, size_t len,
+			 struct smc_sock *smc)
+{
+	struct splice_pipe_desc spd;
+	struct partial_page partial;
+	struct smc_spd_priv *priv;
+	int bytes;
+
+	priv = kzalloc(sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+	priv->len = len;
+	priv->smc = smc;
+	partial.offset = src - (char *)smc->conn.rmb_desc->cpu_addr;
+	partial.len = len;
+	partial.private = (unsigned long)priv;
+
+	spd.nr_pages_max = 1;
+	spd.nr_pages = 1;
+	spd.pages = &smc->conn.rmb_desc->pages;
+	spd.partial = &partial;
+	spd.ops = &smc_pipe_ops;
+	spd.spd_release = smc_rx_spd_release;
+
+	bytes = splice_to_pipe(pipe, &spd);
+	if (bytes > 0) {
+		sock_hold(&smc->sk);
+		get_page(smc->conn.rmb_desc->pages);
+		atomic_add(bytes, &smc->conn.splice_pending);
+	}
+
+	return bytes;
+}
+
+static int smc_rx_data_available_and_no_splice_pend(struct smc_connection *conn)
+{
+	return atomic_read(&conn->bytes_to_rcv) &&
+	       !atomic_read(&conn->splice_pending);
+}
+
+/* blocks rcvbuf consumer until >=len bytes available or timeout or interrupted
+ *   @smc    smc socket
+ *   @timeo  pointer to max seconds to wait, pointer to value 0 for no timeout
+ *   @fcrit  add'l criterion to evaluate as function pointer
+ * Returns:
+ * 1 if at least 1 byte available in rcvbuf or if socket error/shutdown.
+ * 0 otherwise (nothing in rcvbuf nor timeout, e.g. interrupted).
+ */
+int smc_rx_wait(struct smc_sock *smc, long *timeo,
+		int (*fcrit)(struct smc_connection *conn))
+{
+	DEFINE_WAIT_FUNC(wait, woken_wake_function);
+	struct smc_connection *conn = &smc->conn;
+	struct smc_cdc_conn_state_flags *cflags =
+					&conn->local_tx_ctrl.conn_state_flags;
+	struct sock *sk = &smc->sk;
+	int rc;
+
+	if (fcrit(conn))
+		return 1;
+	sk_set_bit(SOCKWQ_ASYNC_WAITDATA, sk);
+	add_wait_queue(sk_sleep(sk), &wait);
+	rc = sk_wait_event(sk, timeo,
+			   READ_ONCE(sk->sk_err) ||
+			   cflags->peer_conn_abort ||
+			   READ_ONCE(sk->sk_shutdown) & RCV_SHUTDOWN ||
+			   conn->killed ||
+			   fcrit(conn),
+			   &wait);
+	remove_wait_queue(sk_sleep(sk), &wait);
+	sk_clear_bit(SOCKWQ_ASYNC_WAITDATA, sk);
+	return rc;
+}
+
+static int smc_rx_recv_urg(struct smc_sock *smc, struct msghdr *msg, int len,
+			   int flags)
+{
+	struct smc_connection *conn = &smc->conn;
+	union smc_host_cursor cons;
+	struct sock *sk = &smc->sk;
+	int rc = 0;
+
+	if (sock_flag(sk, SOCK_URGINLINE) ||
+	    !(conn->urg_state == SMC_URG_VALID) ||
+	    conn->urg_state == SMC_URG_READ)
+		return -EINVAL;
+
+	if (conn->urg_state == SMC_URG_VALID) {
+		if (!(flags & MSG_PEEK))
+			smc->conn.urg_state = SMC_URG_READ;
+		msg->msg_flags |= MSG_OOB;
+		if (len > 0) {
+			if (!(flags & MSG_TRUNC))
+				rc = memcpy_to_msg(msg, &conn->urg_rx_byte, 1);
+			len = 1;
+			smc_curs_copy(&cons, &conn->local_tx_ctrl.cons, conn);
+			if (smc_curs_diff(conn->rmb_desc->len, &cons,
+					  &conn->urg_curs) > 1)
+				conn->urg_rx_skip_pend = true;
+			/* Urgent Byte was already accounted for, but trigger
+			 * skipping the urgent byte in non-inline case
+			 */
+			if (!(flags & MSG_PEEK))
+				smc_rx_update_consumer(smc, cons, 0);
+		} else {
+			msg->msg_flags |= MSG_TRUNC;
+		}
+
+		return rc ? -EFAULT : len;
+	}
+
+	if (sk->sk_state == SMC_CLOSED || sk->sk_shutdown & RCV_SHUTDOWN)
+		return 0;
+
+	return -EAGAIN;
+}
+
+static bool smc_rx_recvmsg_data_available(struct smc_sock *smc)
+{
+	struct smc_connection *conn = &smc->conn;
+
+	if (smc_rx_data_available(conn))
+		return true;
+	else if (conn->urg_state == SMC_URG_VALID)
+		/* we received a single urgent Byte - skip */
+		smc_rx_update_cons(smc, 0);
+	return false;
+}
+
+/* smc_rx_recvmsg - receive data from RMBE
+ * @msg:	copy data to receive buffer
+ * @pipe:	copy data to pipe if set - indicates splice() call
+ *
+ * rcvbuf consumer: main API called by socket layer.
+ * Called under sk lock.
+ */
+int smc_rx_recvmsg(struct smc_sock *smc, struct msghdr *msg,
+		   struct pipe_inode_info *pipe, size_t len, int flags)
+{
+	size_t copylen, read_done = 0, read_remaining = len;
+	size_t chunk_len, chunk_off, chunk_len_sum;
+	struct smc_connection *conn = &smc->conn;
+	int (*func)(struct smc_connection *conn);
+	union smc_host_cursor cons;
+	int readable, chunk;
+	char *rcvbuf_base;
+	struct sock *sk;
+	int splbytes;
+	long timeo;
+	int target;		/* Read at least these many bytes */
+	int rc;
+
+	if (unlikely(flags & MSG_ERRQUEUE))
+		return -EINVAL; /* future work for sk.sk_family == AF_SMC */
+
+	sk = &smc->sk;
+	if (sk->sk_state == SMC_LISTEN)
+		return -ENOTCONN;
+	if (flags & MSG_OOB)
+		return smc_rx_recv_urg(smc, msg, len, flags);
+	timeo = sock_rcvtimeo(sk, flags & MSG_DONTWAIT);
+	target = sock_rcvlowat(sk, flags & MSG_WAITALL, len);
+
+	/* we currently use 1 RMBE per RMB, so RMBE == RMB base addr */
+	rcvbuf_base = conn->rx_off + conn->rmb_desc->cpu_addr;
+
+	do { /* while (read_remaining) */
+		if (read_done >= target || (pipe && read_done))
+			break;
+
+		if (conn->killed)
+			break;
+
+		if (smc_rx_recvmsg_data_available(smc))
+			goto copy;
+
+		if (sk->sk_shutdown & RCV_SHUTDOWN) {
+			/* smc_cdc_msg_recv_action() could have run after
+			 * above smc_rx_recvmsg_data_available()
+			 */
+			if (smc_rx_recvmsg_data_available(smc))
+				goto copy;
+			break;
+		}
+
+		if (read_done) {
+			if (sk->sk_err ||
+			    sk->sk_state == SMC_CLOSED ||
+			    !timeo ||
+			    signal_pending(current))
+				break;
+		} else {
+			if (sk->sk_err) {
+				read_done = sock_error(sk);
+				break;
+			}
+			if (sk->sk_state == SMC_CLOSED) {
+				if (!sock_flag(sk, SOCK_DONE)) {
+					/* This occurs when user tries to read
+					 * from never connected socket.
+					 */
+					read_done = -ENOTCONN;
+					break;
+				}
+				break;
+			}
+			if (!timeo)
+				return -EAGAIN;
+			if (signal_pending(current)) {
+				read_done = sock_intr_errno(timeo);
+				break;
+			}
+		}
+
+		if (!smc_rx_data_available(conn)) {
+			smc_rx_wait(smc, &timeo, smc_rx_data_available);
+			continue;
+		}
+
+copy:
+		/* initialize variables for 1st iteration of subsequent loop */
+		/* could be just 1 byte, even after waiting on data above */
+		readable = atomic_read(&conn->bytes_to_rcv);
+		splbytes = atomic_read(&conn->splice_pending);
+		if (!readable || (msg && splbytes)) {
+			if (splbytes)
+				func = smc_rx_data_available_and_no_splice_pend;
+			else
+				func = smc_rx_data_available;
+			smc_rx_wait(smc, &timeo, func);
+			continue;
+		}
+
+		smc_curs_copy(&cons, &conn->local_tx_ctrl.cons, conn);
+		/* subsequent splice() calls pick up where previous left */
+		if (splbytes)
+			smc_curs_add(conn->rmb_desc->len, &cons, splbytes);
+		if (conn->urg_state == SMC_URG_VALID &&
+		    sock_flag(&smc->sk, SOCK_URGINLINE) &&
+		    readable > 1)
+			readable--;	/* always stop at urgent Byte */
+		/* not more than what user space asked for */
+		copylen = min_t(size_t, read_remaining, readable);
+		/* determine chunks where to read from rcvbuf */
+		/* either unwrapped case, or 1st chunk of wrapped case */
+		chunk_len = min_t(size_t, copylen, conn->rmb_desc->len -
+				  cons.count);
+		chunk_len_sum = chunk_len;
+		chunk_off = cons.count;
+		smc_rmb_sync_sg_for_cpu(conn);
+		for (chunk = 0; chunk < 2; chunk++) {
+			if (!(flags & MSG_TRUNC)) {
+				if (msg) {
+					rc = memcpy_to_msg(msg, rcvbuf_base +
+							   chunk_off,
+							   chunk_len);
+				} else {
+					rc = smc_rx_splice(pipe, rcvbuf_base +
+							chunk_off, chunk_len,
+							smc);
+				}
+				if (rc < 0) {
+					if (!read_done)
+						read_done = -EFAULT;
+					smc_rmb_sync_sg_for_device(conn);
+					goto out;
+				}
+			}
+			read_remaining -= chunk_len;
+			read_done += chunk_len;
+
+			if (chunk_len_sum == copylen)
+				break; /* either on 1st or 2nd iteration */
+			/* prepare next (== 2nd) iteration */
+			chunk_len = copylen - chunk_len; /* remainder */
+			chunk_len_sum += chunk_len;
+			chunk_off = 0; /* modulo offset in recv ring buffer */
+		}
+		smc_rmb_sync_sg_for_device(conn);
+
+		/* update cursors */
+		if (!(flags & MSG_PEEK)) {
+			/* increased in recv tasklet smc_cdc_msg_rcv() */
+			smp_mb__before_atomic();
+			atomic_sub(copylen, &conn->bytes_to_rcv);
+			/* guarantee 0 <= bytes_to_rcv <= rmb_desc->len */
+			smp_mb__after_atomic();
+			if (msg && smc_rx_update_consumer(smc, cons, copylen))
+				goto out;
+		}
+	} while (read_remaining);
+out:
+	return read_done;
+}
+
+/* Initialize receive properties on connection establishment. NB: not __init! */
+void smc_rx_init(struct smc_sock *smc)
+{
+	smc->sk.sk_data_ready = smc_rx_wake_up;
+	atomic_set(&smc->conn.splice_pending, 0);
+	smc->conn.urg_state = SMC_URG_READ;
+}