[linux.git] / net / smc / smc_rx.c

// 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 <[email protected]>
 */

#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 int smc_rx_pipe_buf_nosteal(struct pipe_inode_info *pipe,
				   struct pipe_buffer *buf)
{
	return 1;
}

static const struct pipe_buf_operations smc_pipe_ops = {
	.can_merge = 0,
	.confirm = generic_pipe_buf_confirm,
	.release = smc_rx_pipe_buf_release,
	.steal = smc_rx_pipe_buf_nosteal,
	.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 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,
			   sk->sk_err ||
			   sk->sk_shutdown & RCV_SHUTDOWN ||
			   fcrit(conn) ||
			   smc_cdc_rxed_any_close_or_senddone(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;
}

/* 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 (atomic_read(&conn->bytes_to_rcv))
			goto copy;
		else if (conn->urg_state == SMC_URG_VALID)
			/* we received a single urgent Byte - skip */
			smc_rx_update_cons(smc, 0);

		if (sk->sk_shutdown & RCV_SHUTDOWN ||
		    smc_cdc_rxed_any_close_or_senddone(conn) ||
		    conn->local_tx_ctrl.conn_state_flags.peer_conn_abort)
			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 (signal_pending(current)) {
				read_done = sock_intr_errno(timeo);
				break;
			}
			if (!timeo)
				return -EAGAIN;
		}

		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;
}
Commit	Line	Data
b2441318	1	// SPDX-License-Identifier: GPL-2.0
952310cc UB	2	/*
	3	* Shared Memory Communications over RDMA (SMC-R) and RoCE
	4	*
	5	* Manage RMBE
	6	* copy new RMBE data into user space
	7	*
	8	* Copyright IBM Corp. 2016
	9	*
	10	* Author(s): Ursula Braun <[email protected]>
	11	*/
	12
	13	#include <linux/net.h>
	14	#include <linux/rcupdate.h>
c3edc401 IM	15	#include <linux/sched/signal.h>
c3edc401 IM	16
952310cc UB	17	#include <net/sock.h>
	18
	19	#include "smc.h"
	20	#include "smc_core.h"
	21	#include "smc_cdc.h"
	22	#include "smc_tx.h" /* smc_tx_consumer_update() */
	23	#include "smc_rx.h"
	24
b51fa1b1	25	/* callback implementation to wakeup consumers blocked with smc_rx_wait().
952310cc UB	26	* indirectly called by smc_cdc_msg_recv_action().
952310cc UB	27	*/
b51fa1b1	28	static void smc_rx_wake_up(struct sock *sk)
952310cc UB	29	{
	30	struct socket_wq *wq;
	31
	32	/* derived from sock_def_readable() */
	33	/* called already in smc_listen_work() */
	34	rcu_read_lock();
	35	wq = rcu_dereference(sk->sk_wq);
	36	if (skwq_has_sleeper(wq))
a9a08845 LT	37	wake_up_interruptible_sync_poll(&wq->wait, EPOLLIN \| EPOLLPRI \|
a9a08845 LT	38	EPOLLRDNORM \| EPOLLRDBAND);
90e9517e	39	sk_wake_async(sk, SOCK_WAKE_WAITD, POLL_IN);
952310cc UB	40	if ((sk->sk_shutdown == SHUTDOWN_MASK) \|\|
	41	(sk->sk_state == SMC_CLOSED))
	42	sk_wake_async(sk, SOCK_WAKE_WAITD, POLL_HUP);
952310cc UB	43	rcu_read_unlock();
	44	}
	45
9014db20 SR	46	/* Update consumer cursor
	47	* @conn connection to update
	48	* @cons consumer cursor
	49	* @len number of Bytes consumed
de8474eb SR	50	* Returns:
de8474eb SR	51	* 1 if we should end our receive, 0 otherwise
9014db20	52	*/
de8474eb SR	53	static int smc_rx_update_consumer(struct smc_sock *smc,
de8474eb SR	54	union smc_host_cursor cons, size_t len)
9014db20	55	{
de8474eb SR	56	struct smc_connection *conn = &smc->conn;
	57	struct sock *sk = &smc->sk;
	58	bool force = false;
	59	int diff, rc = 0;
	60
69cb7dc0	61	smc_curs_add(conn->rmb_desc->len, &cons, len);
de8474eb SR	62
	63	/* did we process urgent data? */
	64	if (conn->urg_state == SMC_URG_VALID \|\| conn->urg_rx_skip_pend) {
	65	diff = smc_curs_comp(conn->rmb_desc->len, &cons,
	66	&conn->urg_curs);
	67	if (sock_flag(sk, SOCK_URGINLINE)) {
	68	if (diff == 0) {
	69	force = true;
	70	rc = 1;
	71	conn->urg_state = SMC_URG_READ;
	72	}
	73	} else {
	74	if (diff == 1) {
	75	/* skip urgent byte */
	76	force = true;
	77	smc_curs_add(conn->rmb_desc->len, &cons, 1);
	78	conn->urg_rx_skip_pend = false;
	79	} else if (diff < -1)
	80	/* we read past urgent byte */
	81	conn->urg_state = SMC_URG_READ;
	82	}
	83	}
	84
bac6de7b	85	smc_curs_copy(&conn->local_tx_ctrl.cons, &cons, conn);
de8474eb	86
9014db20 SR	87	/* send consumer cursor update if required */
9014db20 SR	88	/* similar to advertising new TCP rcv_wnd if required */
de8474eb SR	89	smc_tx_consumer_update(conn, force);
	90
	91	return rc;
	92	}
	93
	94	static void smc_rx_update_cons(struct smc_sock *smc, size_t len)
	95	{
	96	struct smc_connection *conn = &smc->conn;
	97	union smc_host_cursor cons;
	98
bac6de7b	99	smc_curs_copy(&cons, &conn->local_tx_ctrl.cons, conn);
de8474eb	100	smc_rx_update_consumer(smc, cons, len);
9014db20 SR	101	}
	102
	103	struct smc_spd_priv {
	104	struct smc_sock *smc;
	105	size_t len;
	106	};
	107
	108	static void smc_rx_pipe_buf_release(struct pipe_inode_info *pipe,
	109	struct pipe_buffer *buf)
	110	{
	111	struct smc_spd_priv priv = (struct smc_spd_priv )buf->private;
	112	struct smc_sock *smc = priv->smc;
	113	struct smc_connection *conn;
9014db20 SR	114	struct sock *sk = &smc->sk;
	115
	116	if (sk->sk_state == SMC_CLOSED \|\|
	117	sk->sk_state == SMC_PEERFINCLOSEWAIT \|\|
	118	sk->sk_state == SMC_APPFINCLOSEWAIT)
	119	goto out;
	120	conn = &smc->conn;
	121	lock_sock(sk);
de8474eb	122	smc_rx_update_cons(smc, priv->len);
9014db20 SR	123	release_sock(sk);
	124	if (atomic_sub_and_test(priv->len, &conn->splice_pending))
	125	smc_rx_wake_up(sk);
	126	out:
	127	kfree(priv);
	128	put_page(buf->page);
	129	sock_put(sk);
	130	}
	131
	132	static int smc_rx_pipe_buf_nosteal(struct pipe_inode_info *pipe,
	133	struct pipe_buffer *buf)
	134	{
	135	return 1;
	136	}
	137
	138	static const struct pipe_buf_operations smc_pipe_ops = {
	139	.can_merge = 0,
	140	.confirm = generic_pipe_buf_confirm,
	141	.release = smc_rx_pipe_buf_release,
	142	.steal = smc_rx_pipe_buf_nosteal,
	143	.get = generic_pipe_buf_get
	144	};
	145
	146	static void smc_rx_spd_release(struct splice_pipe_desc *spd,
	147	unsigned int i)
	148	{
	149	put_page(spd->pages[i]);
	150	}
	151
	152	static int smc_rx_splice(struct pipe_inode_info pipe, char src, size_t len,
	153	struct smc_sock *smc)
	154	{
	155	struct splice_pipe_desc spd;
	156	struct partial_page partial;
	157	struct smc_spd_priv *priv;
9014db20 SR	158	int bytes;
9014db20 SR	159
9014db20 SR	160	priv = kzalloc(sizeof(*priv), GFP_KERNEL);
	161	if (!priv)
	162	return -ENOMEM;
	163	priv->len = len;
	164	priv->smc = smc;
	165	partial.offset = src - (char *)smc->conn.rmb_desc->cpu_addr;
	166	partial.len = len;
	167	partial.private = (unsigned long)priv;
	168
	169	spd.nr_pages_max = 1;
	170	spd.nr_pages = 1;
48bf5231	171	spd.pages = &smc->conn.rmb_desc->pages;
9014db20 SR	172	spd.partial = &partial;
	173	spd.ops = &smc_pipe_ops;
	174	spd.spd_release = smc_rx_spd_release;
	175
	176	bytes = splice_to_pipe(pipe, &spd);
	177	if (bytes > 0) {
	178	sock_hold(&smc->sk);
	179	get_page(smc->conn.rmb_desc->pages);
	180	atomic_add(bytes, &smc->conn.splice_pending);
	181	}
	182
	183	return bytes;
	184	}
	185
	186	static int smc_rx_data_available_and_no_splice_pend(struct smc_connection *conn)
	187	{
	188	return atomic_read(&conn->bytes_to_rcv) &&
	189	!atomic_read(&conn->splice_pending);
	190	}
	191
952310cc UB	192	/* blocks rcvbuf consumer until >=len bytes available or timeout or interrupted
	193	* @smc smc socket
	194	* @timeo pointer to max seconds to wait, pointer to value 0 for no timeout
b51fa1b1	195	* @fcrit add'l criterion to evaluate as function pointer
952310cc UB	196	* Returns:
	197	* 1 if at least 1 byte available in rcvbuf or if socket error/shutdown.
	198	* 0 otherwise (nothing in rcvbuf nor timeout, e.g. interrupted).
	199	*/
b51fa1b1 SR	200	int smc_rx_wait(struct smc_sock smc, long timeo,
b51fa1b1 SR	201	int (fcrit)(struct smc_connection conn))
952310cc UB	202	{
	203	DEFINE_WAIT_FUNC(wait, woken_wake_function);
	204	struct smc_connection *conn = &smc->conn;
	205	struct sock *sk = &smc->sk;
	206	int rc;
	207
b51fa1b1	208	if (fcrit(conn))
952310cc UB	209	return 1;
	210	sk_set_bit(SOCKWQ_ASYNC_WAITDATA, sk);
	211	add_wait_queue(sk_sleep(sk), &wait);
	212	rc = sk_wait_event(sk, timeo,
	213	sk->sk_err \|\|
	214	sk->sk_shutdown & RCV_SHUTDOWN \|\|
b51fa1b1	215	fcrit(conn) \|\|
952310cc UB	216	smc_cdc_rxed_any_close_or_senddone(conn),
	217	&wait);
	218	remove_wait_queue(sk_sleep(sk), &wait);
	219	sk_clear_bit(SOCKWQ_ASYNC_WAITDATA, sk);
	220	return rc;
	221	}
	222
de8474eb SR	223	static int smc_rx_recv_urg(struct smc_sock smc, struct msghdr msg, int len,
	224	int flags)
	225	{
	226	struct smc_connection *conn = &smc->conn;
	227	union smc_host_cursor cons;
	228	struct sock *sk = &smc->sk;
	229	int rc = 0;
	230
	231	if (sock_flag(sk, SOCK_URGINLINE) \|\|
	232	!(conn->urg_state == SMC_URG_VALID) \|\|
	233	conn->urg_state == SMC_URG_READ)
	234	return -EINVAL;
	235
	236	if (conn->urg_state == SMC_URG_VALID) {
	237	if (!(flags & MSG_PEEK))
	238	smc->conn.urg_state = SMC_URG_READ;
	239	msg->msg_flags \|= MSG_OOB;
	240	if (len > 0) {
	241	if (!(flags & MSG_TRUNC))
	242	rc = memcpy_to_msg(msg, &conn->urg_rx_byte, 1);
	243	len = 1;
bac6de7b	244	smc_curs_copy(&cons, &conn->local_tx_ctrl.cons, conn);
de8474eb SR	245	if (smc_curs_diff(conn->rmb_desc->len, &cons,
	246	&conn->urg_curs) > 1)
	247	conn->urg_rx_skip_pend = true;
	248	/* Urgent Byte was already accounted for, but trigger
	249	* skipping the urgent byte in non-inline case
	250	*/
	251	if (!(flags & MSG_PEEK))
	252	smc_rx_update_consumer(smc, cons, 0);
	253	} else {
	254	msg->msg_flags \|= MSG_TRUNC;
	255	}
	256
	257	return rc ? -EFAULT : len;
	258	}
	259
	260	if (sk->sk_state == SMC_CLOSED \|\| sk->sk_shutdown & RCV_SHUTDOWN)
	261	return 0;
	262
	263	return -EAGAIN;
	264	}
	265
9014db20 SR	266	/* smc_rx_recvmsg - receive data from RMBE
	267	* @msg: copy data to receive buffer
	268	* @pipe: copy data to pipe if set - indicates splice() call
	269	*
	270	* rcvbuf consumer: main API called by socket layer.
	271	* Called under sk lock.
952310cc	272	*/
9014db20 SR	273	int smc_rx_recvmsg(struct smc_sock smc, struct msghdr msg,
9014db20 SR	274	struct pipe_inode_info *pipe, size_t len, int flags)
952310cc UB	275	{
	276	size_t copylen, read_done = 0, read_remaining = len;
	277	size_t chunk_len, chunk_off, chunk_len_sum;
	278	struct smc_connection *conn = &smc->conn;
9014db20	279	int (func)(struct smc_connection conn);
952310cc UB	280	union smc_host_cursor cons;
	281	int readable, chunk;
	282	char *rcvbuf_base;
	283	struct sock *sk;
9014db20	284	int splbytes;
952310cc UB	285	long timeo;
	286	int target; /* Read at least these many bytes */
	287	int rc;
	288
	289	if (unlikely(flags & MSG_ERRQUEUE))
	290	return -EINVAL; /* future work for sk.sk_family == AF_SMC */
952310cc UB	291
	292	sk = &smc->sk;
	293	if (sk->sk_state == SMC_LISTEN)
	294	return -ENOTCONN;
de8474eb SR	295	if (flags & MSG_OOB)
de8474eb SR	296	return smc_rx_recv_urg(smc, msg, len, flags);
952310cc UB	297	timeo = sock_rcvtimeo(sk, flags & MSG_DONTWAIT);
	298	target = sock_rcvlowat(sk, flags & MSG_WAITALL, len);
	299
952310cc	300	/* we currently use 1 RMBE per RMB, so RMBE == RMB base addr */
be244f28	301	rcvbuf_base = conn->rx_off + conn->rmb_desc->cpu_addr;
952310cc UB	302
952310cc UB	303	do { /* while (read_remaining) */
9014db20	304	if (read_done >= target \|\| (pipe && read_done))
952310cc UB	305	break;
	306
	307	if (atomic_read(&conn->bytes_to_rcv))
	308	goto copy;
de8474eb SR	309	else if (conn->urg_state == SMC_URG_VALID)
	310	/* we received a single urgent Byte - skip */
	311	smc_rx_update_cons(smc, 0);
952310cc	312
c8b8ec8e SR	313	if (sk->sk_shutdown & RCV_SHUTDOWN \|\|
	314	smc_cdc_rxed_any_close_or_senddone(conn) \|\|
	315	conn->local_tx_ctrl.conn_state_flags.peer_conn_abort)
	316	break;
	317
952310cc UB	318	if (read_done) {
	319	if (sk->sk_err \|\|
	320	sk->sk_state == SMC_CLOSED \|\|
952310cc	321	!timeo \|\|
c8b8ec8e	322	signal_pending(current))
952310cc UB	323	break;
952310cc UB	324	} else {
952310cc UB	325	if (sk->sk_err) {
	326	read_done = sock_error(sk);
	327	break;
	328	}
952310cc UB	329	if (sk->sk_state == SMC_CLOSED) {
	330	if (!sock_flag(sk, SOCK_DONE)) {
	331	/* This occurs when user tries to read
	332	* from never connected socket.
	333	*/
	334	read_done = -ENOTCONN;
	335	break;
	336	}
	337	break;
	338	}
	339	if (signal_pending(current)) {
	340	read_done = sock_intr_errno(timeo);
	341	break;
	342	}
846e344e HW	343	if (!timeo)
846e344e HW	344	return -EAGAIN;
952310cc UB	345	}
952310cc UB	346
b51fa1b1 SR	347	if (!smc_rx_data_available(conn)) {
b51fa1b1 SR	348	smc_rx_wait(smc, &timeo, smc_rx_data_available);
952310cc UB	349	continue;
	350	}
	351
	352	copy:
	353	/* initialize variables for 1st iteration of subsequent loop */
b51fa1b1	354	/* could be just 1 byte, even after waiting on data above */
952310cc	355	readable = atomic_read(&conn->bytes_to_rcv);
9014db20 SR	356	splbytes = atomic_read(&conn->splice_pending);
	357	if (!readable \|\| (msg && splbytes)) {
	358	if (splbytes)
	359	func = smc_rx_data_available_and_no_splice_pend;
	360	else
	361	func = smc_rx_data_available;
	362	smc_rx_wait(smc, &timeo, func);
	363	continue;
	364	}
	365
bac6de7b	366	smc_curs_copy(&cons, &conn->local_tx_ctrl.cons, conn);
9014db20 SR	367	/* subsequent splice() calls pick up where previous left */
9014db20 SR	368	if (splbytes)
69cb7dc0	369	smc_curs_add(conn->rmb_desc->len, &cons, splbytes);
de8474eb SR	370	if (conn->urg_state == SMC_URG_VALID &&
	371	sock_flag(&smc->sk, SOCK_URGINLINE) &&
	372	readable > 1)
	373	readable--; /* always stop at urgent Byte */
	374	/* not more than what user space asked for */
	375	copylen = min_t(size_t, read_remaining, readable);
952310cc UB	376	/* determine chunks where to read from rcvbuf */
952310cc UB	377	/* either unwrapped case, or 1st chunk of wrapped case */
69cb7dc0 HW	378	chunk_len = min_t(size_t, copylen, conn->rmb_desc->len -
69cb7dc0 HW	379	cons.count);
952310cc UB	380	chunk_len_sum = chunk_len;
952310cc UB	381	chunk_off = cons.count;
10428dd8	382	smc_rmb_sync_sg_for_cpu(conn);
952310cc UB	383	for (chunk = 0; chunk < 2; chunk++) {
952310cc UB	384	if (!(flags & MSG_TRUNC)) {
9014db20 SR	385	if (msg) {
	386	rc = memcpy_to_msg(msg, rcvbuf_base +
	387	chunk_off,
	388	chunk_len);
	389	} else {
	390	rc = smc_rx_splice(pipe, rcvbuf_base +
	391	chunk_off, chunk_len,
	392	smc);
	393	}
	394	if (rc < 0) {
952310cc UB	395	if (!read_done)
952310cc UB	396	read_done = -EFAULT;
10428dd8	397	smc_rmb_sync_sg_for_device(conn);
952310cc UB	398	goto out;
	399	}
	400	}
	401	read_remaining -= chunk_len;
	402	read_done += chunk_len;
	403
	404	if (chunk_len_sum == copylen)
	405	break; /* either on 1st or 2nd iteration */
	406	/* prepare next (== 2nd) iteration */
	407	chunk_len = copylen - chunk_len; /* remainder */
	408	chunk_len_sum += chunk_len;
	409	chunk_off = 0; /* modulo offset in recv ring buffer */
	410	}
10428dd8	411	smc_rmb_sync_sg_for_device(conn);
952310cc UB	412
	413	/* update cursors */
	414	if (!(flags & MSG_PEEK)) {
952310cc UB	415	/* increased in recv tasklet smc_cdc_msg_rcv() */
	416	smp_mb__before_atomic();
	417	atomic_sub(copylen, &conn->bytes_to_rcv);
69cb7dc0	418	/* guarantee 0 <= bytes_to_rcv <= rmb_desc->len */
952310cc	419	smp_mb__after_atomic();
de8474eb SR	420	if (msg && smc_rx_update_consumer(smc, cons, copylen))
de8474eb SR	421	goto out;
952310cc UB	422	}
	423	} while (read_remaining);
	424	out:
	425	return read_done;
	426	}
	427
	428	/* Initialize receive properties on connection establishment. NB: not __init! */
	429	void smc_rx_init(struct smc_sock *smc)
	430	{
b51fa1b1	431	smc->sk.sk_data_ready = smc_rx_wake_up;
9014db20	432	atomic_set(&smc->conn.splice_pending, 0);
de8474eb	433	smc->conn.urg_state = SMC_URG_READ;
952310cc	434	}