[PATCH V2 net-next 13/15] smc: receive data from RMBE

Ursula Braun
2016-09-27T16:41:54Z

move RMBE data into user space buffer and update managing cursors

Signed-off-by: Ursula Braun <ubraun@linux.vnet.ibm.com>
---
net/smc/Makefile | 2 +-
net/smc/af_smc.c | 7 +-
net/smc/smc.h | 4 +
net/smc/smc_cdc.c | 6 +-
net/smc/smc_core.c | 10 +++
net/smc/smc_rx.c | 216 +++++++++++++++++++++++++++++++++++++++++++++++++++++
net/smc/smc_rx.h | 22 ++++++
net/smc/smc_tx.c | 37 +++++++++
net/smc/smc_tx.h | 1 +
9 files changed, 302 insertions(+), 3 deletions(-)
create mode 100644 net/smc/smc_rx.c
create mode 100644 net/smc/smc_rx.h

diff --git a/net/smc/Makefile b/net/smc/Makefile
index fc28d79..6255e29 100644
--- a/net/smc/Makefile
+++ b/net/smc/Makefile
@@ -1,3 +1,3 @@
obj-$(CONFIG_SMC) += smc.o
smc-y := af_smc.o smc_pnet.o smc_ib.o smc_clc.o smc_core.o smc_wr.o smc_llc.o
-smc-y += smc_cdc.o smc_tx.o
+smc-y += smc_cdc.o smc_tx.o smc_rx.o
diff --git a/net/smc/af_smc.c b/net/smc/af_smc.c
index c96a234..4652759 100644
--- a/net/smc/af_smc.c
+++ b/net/smc/af_smc.c
@@ -37,6 +37,7 @@
#include "smc_ib.h"
#include "smc_pnet.h"
#include "smc_tx.h"
+#include "smc_rx.h"

static DEFINE_MUTEX(smc_create_lgr_pending); /* serialize link group
* creation
@@ -422,6 +423,7 @@ static int smc_connect_rdma(struct smc_sock *smc)

mutex_unlock(&smc_create_lgr_pending);
smc_tx_init(smc);
+ smc_rx_init(smc);

out_connected:
smc_copy_sock_settings_to_clc(smc);
@@ -765,6 +767,7 @@ static void smc_listen_work(struct work_struct *work)
}

smc_tx_init(new_smc);
+ smc_rx_init(new_smc);

out_connected:
sk_refcnt_debug_inc(newsmcsk);
@@ -960,7 +963,7 @@ static int smc_recvmsg(struct socket *sock, struct msghdr *msg, size_t len,
if (smc->use_fallback)
rc = smc->clcsock->ops->recvmsg(smc->clcsock, msg, len, flags);
else
- rc = sock_no_recvmsg(sock, msg, len, flags);
+ rc = smc_rx_recvmsg(smc, msg, len, flags);
out:
release_sock(sk);
return rc;
@@ -1026,6 +1029,8 @@ static unsigned int smc_poll(struct file *file, struct socket *sock,
sk_set_bit(SOCKWQ_ASYNC_NOSPACE, sk);
set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
}
+ if (atomic_read(&smc->conn.bytes_to_rcv))
+ mask |= POLLIN | POLLRDNORM;
/* for now - to be enhanced in follow-on patch */
}

diff --git a/net/smc/smc.h b/net/smc/smc.h
index 191e913..13ceb9b 100644
--- a/net/smc/smc.h
+++ b/net/smc/smc.h
@@ -112,6 +112,10 @@ struct smc_connection {
struct smc_buf_desc *rmb_desc; /* RMBE descriptor */
int rmbe_size; /* RMBE size <== sock rmem */
int rmbe_size_short;/* compressed notation */
+ int rmbe_update_limit;
+ /* lower limit for consumer
+ * cursor update
+ */

struct smc_host_cdc_msg local_tx_ctrl; /* host byte order staging
* buffer for CDC msg send
diff --git a/net/smc/smc_cdc.c b/net/smc/smc_cdc.c
index d5e4a24..0a679c0 100644
--- a/net/smc/smc_cdc.c
+++ b/net/smc/smc_cdc.c
@@ -15,6 +15,7 @@
#include "smc_wr.h"
#include "smc_cdc.h"
#include "smc_tx.h"
+#include "smc_rx.h"

/********************************** send *************************************/

@@ -197,6 +198,7 @@ static void smc_cdc_msg_recv_action(struct smc_sock *smc,
atomic_add(diff_prod, &conn->bytes_to_rcv);
/* guarantee 0 <= bytes_to_rcv <= rmbe_size */
smp_mb__after_atomic();
+ smc->sk.sk_data_ready(&smc->sk);
}

if (conn->local_rx_ctrl.conn_state_flags.peer_conn_abort)
@@ -220,7 +222,9 @@ static void smc_cdc_msg_recv_action(struct smc_sock *smc,
return;

/* data available */
- /* subsequent patch: send delayed ack, wake receivers */
+ if ((conn->local_rx_ctrl.prod_flags.write_blocked) ||
+ (conn->local_rx_ctrl.prod_flags.cons_curs_upd_req))
+ smc_tx_consumer_update(conn);
}

/* called under tasklet context */
diff --git a/net/smc/smc_core.c b/net/smc/smc_core.c
index cb42d63..011093f 100644
--- a/net/smc/smc_core.c
+++ b/net/smc/smc_core.c
@@ -515,6 +515,15 @@ struct smc_buf_desc *smc_rmb_get_slot(struct smc_link_group *lgr,
return NULL;
}

+/* one of the conditions for announcing a receiver's current window size is
+ * that it "results in a minimum increase in the window size of 10% of the
+ * receive buffer space" [RFC7609]
+ */
+static inline int smc_rmb_wnd_update_limit(int rmbe_size)
+{
+ return min_t(int, rmbe_size / 10, SOCK_MIN_SNDBUF / 2);
+}
+
/* create the tx buffer for an SMC socket */
int smc_sndbuf_create(struct smc_sock *smc)
{
@@ -646,6 +655,7 @@ int smc_rmb_create(struct smc_sock *smc)
conn->rmbe_size_short = tmp_bufsize_short;
smc->sk.sk_rcvbuf = tmp_bufsize * 2;
atomic_set(&conn->bytes_to_rcv, 0);
+ conn->rmbe_update_limit = smc_rmb_wnd_update_limit(tmp_bufsize);
return 0;
} else {
return -ENOMEM;
diff --git a/net/smc/smc_rx.c b/net/smc/smc_rx.c
new file mode 100644
index 0000000..0807d1f
--- /dev/null
+++ b/net/smc/smc_rx.c
@@ -0,0 +1,216 @@
+/*
+ * 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 <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 for sk.sk_data_ready()
+ * to wakeup rcvbuf consumers that blocked with smc_rx_wait_data().
+ * indirectly called by smc_cdc_msg_recv_action().
+ */
+static void smc_rx_data_ready(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, POLLIN | POLLPRI |
+ POLLRDNORM | POLLRDBAND);
+ if ((sk->sk_shutdown == SHUTDOWN_MASK) ||
+ (sk->sk_state == SMC_CLOSED))
+ sk_wake_async(sk, SOCK_WAKE_WAITD, POLL_HUP);
+ else
+ sk_wake_async(sk, SOCK_WAKE_WAITD, POLL_IN);
+ rcu_read_unlock();
+}
+
+/* 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
+ * 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).
+ */
+static int smc_rx_wait_data(struct smc_sock *smc, long *timeo)
+{
+ struct smc_connection *conn = &smc->conn;
+ struct sock *sk = &smc->sk;
+ DEFINE_WAIT(wait);
+ int rc;
+
+ if (atomic_read(&conn->bytes_to_rcv))
+ return 1;
+ prepare_to_wait(sk_sleep(sk), &wait, TASK_INTERRUPTIBLE);
+ sk_set_bit(SOCKWQ_ASYNC_WAITDATA, sk);
+ rc = sk_wait_event(sk, timeo,
+ sk->sk_err ||
+ sk->sk_shutdown & RCV_SHUTDOWN ||
+ sock_flag(sk, SOCK_DONE) ||
+ atomic_read(&conn->bytes_to_rcv) ||
+ smc_cdc_rxed_any_close_or_senddone(conn));
+ sk_clear_bit(SOCKWQ_ASYNC_WAITDATA, sk);
+ finish_wait(sk_sleep(sk), &wait);
+ return rc;
+}
+
+/* rcvbuf consumer: main API called by socket layer.
+ * called under sk lock.
+ */
+int smc_rx_recvmsg(struct smc_sock *smc, struct msghdr *msg, 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;
+ union smc_host_cursor cons;
+ int readable, chunk;
+ char *rcvbuf_base;
+ struct sock *sk;
+ 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 */
+ if (flags & MSG_OOB)
+ return -EINVAL; /* future work */
+
+ sk = &smc->sk;
+ if (sk->sk_state == SMC_LISTEN)
+ return -ENOTCONN;
+ timeo = sock_rcvtimeo(sk, flags & MSG_DONTWAIT);
+ target = sock_rcvlowat(sk, flags & MSG_WAITALL, len);
+
+ msg->msg_namelen = 0;
+ /* we currently use 1 RMBE per RMB, so RMBE == RMB base addr */
+ rcvbuf_base = conn->rmb_desc->cpu_addr;
+
+ do { /* while (read_remaining) */
+ if (read_done >= target)
+ break;
+
+ if (atomic_read(&conn->bytes_to_rcv))
+ goto copy;
+
+ if (read_done) {
+ if (sk->sk_err ||
+ sk->sk_state == SMC_CLOSED ||
+ (sk->sk_shutdown & RCV_SHUTDOWN) ||
+ !timeo ||
+ signal_pending(current) ||
+ smc_cdc_rxed_any_close_or_senddone(conn) ||
+ conn->local_tx_ctrl.conn_state_flags.
+ peer_conn_abort)
+ break;
+ } else {
+ if (sock_flag(sk, SOCK_DONE))
+ break;
+ if (sk->sk_err) {
+ read_done = sock_error(sk);
+ break;
+ }
+ 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 (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 (!atomic_read(&conn->bytes_to_rcv)) {
+ smc_rx_wait_data(smc, &timeo);
+ continue;
+ }
+
+copy:
+ /* initialize variables for 1st iteration of subsequent loop */
+ /* could be just 1 byte, even after smc_rx_wait_data above */
+ readable = atomic_read(&conn->bytes_to_rcv);
+ /* not more than what user space asked for */
+ copylen = min_t(size_t, read_remaining, readable);
+ smc_curs_write(&cons,
+ smc_curs_read(&conn->local_tx_ctrl.cons, conn),
+ conn);
+ /* determine chunks where to read from rcvbuf */
+ /* either unwrapped case, or 1st chunk of wrapped case */
+ chunk_len = min_t(size_t,
+ copylen, conn->rmbe_size - cons.count);
+ chunk_len_sum = chunk_len;
+ chunk_off = cons.count;
+ for (chunk = 0; chunk < 2; chunk++) {
+ if (!(flags & MSG_TRUNC)) {
+ rc = memcpy_to_msg(msg, rcvbuf_base + chunk_off,
+ chunk_len);
+ if (rc) {
+ if (!read_done)
+ read_done = -EFAULT;
+ 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 */
+ }
+
+ /* update cursors */
+ if (!(flags & MSG_PEEK)) {
+ smc_curs_add(conn->rmbe_size, &cons, copylen);
+ /* increased in recv tasklet smc_cdc_msg_rcv() */
+ smp_mb__before_atomic();
+ atomic_sub(copylen, &conn->bytes_to_rcv);
+ /* guarantee 0 <= bytes_to_rcv <= rmbe_size */
+ smp_mb__after_atomic();
+ smc_curs_write(&conn->local_tx_ctrl.cons,
+ smc_curs_read(&cons, conn),
+ conn);
+ /* send consumer cursor update if required */
+ /* similar to advertising new TCP rcv_wnd if required */
+ smc_tx_consumer_update(conn);
+ }
+ } 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_data_ready;
+}
diff --git a/net/smc/smc_rx.h b/net/smc/smc_rx.h
new file mode 100644
index 0000000..08fcf8d
--- /dev/null
+++ b/net/smc/smc_rx.h
@@ -0,0 +1,22 @@
+/*
+ * Shared Memory Communications over RDMA (SMC-R) and RoCE
+ *
+ * Manage RMBE
+ *
+ * Copyright IBM Corp. 2016
+ *
+ * Author(s): Ursula Braun <ubraun@linux.vnet.ibm.com>
+ */
+
+#ifndef SMC_RX_H
+#define SMC_RX_H
+
+#include <linux/socket.h>
+#include <linux/types.h>
+
+#include "smc.h"
+
+void smc_rx_init(struct smc_sock *);
+int smc_rx_recvmsg(struct smc_sock *, struct msghdr *, size_t, int);
+
+#endif /* SMC_RX_H */
diff --git a/net/smc/smc_tx.c b/net/smc/smc_tx.c
index 368d27b..b8d779b 100644
--- a/net/smc/smc_tx.c
+++ b/net/smc/smc_tx.c
@@ -426,6 +426,43 @@ static void smc_tx_work(struct work_struct *work)
release_sock(&smc->sk);
}

+void smc_tx_consumer_update(struct smc_connection *conn)
+{
+ union smc_host_cursor cfed, cons;
+ struct smc_cdc_tx_pend *pend;
+ struct smc_wr_buf *wr_buf;
+ int to_confirm, rc;
+
+ smc_curs_write(&cons,
+ smc_curs_read(&conn->local_tx_ctrl.cons, conn),
+ conn);
+ smc_curs_write(&cfed,
+ smc_curs_read(&conn->rx_curs_confirmed, conn),
+ conn);
+ to_confirm = smc_curs_diff(conn->rmbe_size, &cfed, &cons);
+
+ if (conn->local_rx_ctrl.prod_flags.cons_curs_upd_req ||
+ ((to_confirm > conn->rmbe_update_limit) &&
+ ((to_confirm > (conn->rmbe_size / 2)) ||
+ conn->local_rx_ctrl.prod_flags.write_blocked))) {
+ rc = smc_cdc_get_free_slot(&conn->lgr->lnk[SMC_SINGLE_LINK],
+ &wr_buf, &pend);
+ if (!rc)
+ rc = smc_cdc_msg_send(conn, wr_buf, pend);
+ if (rc < 0) {
+ schedule_work(&conn->tx_work);
+ return;
+ }
+ smc_curs_write(&conn->rx_curs_confirmed,
+ smc_curs_read(&conn->local_tx_ctrl.cons, conn),
+ conn);
+ conn->local_rx_ctrl.prod_flags.cons_curs_upd_req = 0;
+ }
+ if (conn->local_rx_ctrl.prod_flags.write_blocked &&
+ !atomic_read(&conn->bytes_to_rcv))
+ conn->local_rx_ctrl.prod_flags.write_blocked = 0;
+}
+
/***************************** send initialize *******************************/

/* Initialize send properties on connection establishment. NB: not __init! */
diff --git a/net/smc/smc_tx.h b/net/smc/smc_tx.h
index 27db7b2..6760891 100644
--- a/net/smc/smc_tx.h
+++ b/net/smc/smc_tx.h
@@ -30,5 +30,6 @@ void smc_tx_init(struct smc_sock *);
int smc_tx_sendmsg(struct smc_sock *, struct msghdr *, size_t);
int smc_tx_sndbuf_nonempty(struct smc_connection *);
void smc_tx_sndbuf_nonfull(struct smc_sock *);
+void smc_tx_consumer_update(struct smc_connection *);

#endif /* SMC_TX_H */
--
2.8.4