smc: send data (through RDMA)
authorUrsula Braun <ubraun@linux.vnet.ibm.com>
Mon, 9 Jan 2017 15:55:23 +0000 (16:55 +0100)
committerDavid S. Miller <davem@davemloft.net>
Mon, 9 Jan 2017 21:07:40 +0000 (16:07 -0500)
copy data to kernel send buffer, and trigger RDMA write

Signed-off-by: Ursula Braun <ubraun@linux.vnet.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
net/smc/Makefile
net/smc/af_smc.c
net/smc/smc.h
net/smc/smc_cdc.c
net/smc/smc_tx.c [new file with mode: 0644]
net/smc/smc_tx.h [new file with mode: 0644]

index ec0fd0338c6dea9b5c68994311623f117773ed19..fc28d79aec7d3952305f154f01836fc2d645ed9e 100644 (file)
@@ -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-y += smc_cdc.o smc_tx.o
index 4b1611d46ef79a44468eee78800477a9985b8d38..b62b69c6c718bdfff8e38d262991d3dc8dd403ae 100644 (file)
@@ -37,6 +37,7 @@
 #include "smc_core.h"
 #include "smc_ib.h"
 #include "smc_pnet.h"
+#include "smc_tx.h"
 
 static DEFINE_MUTEX(smc_create_lgr_pending);   /* serialize link group
                                                 * creation
@@ -410,6 +411,8 @@ static int smc_connect_rdma(struct smc_sock *smc)
        }
 
        mutex_unlock(&smc_create_lgr_pending);
+       smc_tx_init(smc);
+
 out_connected:
        smc_copy_sock_settings_to_clc(smc);
        smc->sk.sk_state = SMC_ACTIVE;
@@ -751,6 +754,8 @@ static void smc_listen_work(struct work_struct *work)
                        goto decline_rdma;
        }
 
+       smc_tx_init(new_smc);
+
 out_connected:
        sk_refcnt_debug_inc(newsmcsk);
        newsmcsk->sk_state = SMC_ACTIVE;
@@ -924,7 +929,7 @@ static int smc_sendmsg(struct socket *sock, struct msghdr *msg, size_t len)
        if (smc->use_fallback)
                rc = smc->clcsock->ops->sendmsg(smc->clcsock, msg, len);
        else
-               rc = sock_no_sendmsg(sock, msg, len);
+               rc = smc_tx_sendmsg(smc, msg, len);
 out:
        release_sock(sk);
        return rc;
@@ -1005,6 +1010,12 @@ static unsigned int smc_poll(struct file *file, struct socket *sock,
                        mask |= smc_accept_poll(sk);
                if (sk->sk_err)
                        mask |= POLLERR;
+               if (atomic_read(&smc->conn.sndbuf_space)) {
+                       mask |= POLLOUT | POLLWRNORM;
+               } else {
+                       sk_set_bit(SOCKWQ_ASYNC_NOSPACE, sk);
+                       set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
+               }
                /* for now - to be enhanced in follow-on patch */
        }
 
index a8d4a68aac30e462003e62d3035f85353a99dfc1..0c47d84c1db181cd461641887275d42d7ecdc059 100644 (file)
@@ -133,6 +133,7 @@ struct smc_connection {
        atomic_t                sndbuf_space;   /* remaining space in sndbuf */
        u16                     tx_cdc_seq;     /* sequence # for CDC send */
        spinlock_t              send_lock;      /* protect wr_sends */
+       struct work_struct      tx_work;        /* retry of smc_cdc_msg_send */
 
        struct smc_host_cdc_msg local_rx_ctrl;  /* filled during event_handl.
                                                 * .prod cf. TCP rcv_nxt
index 111d23ff9e174f0eaf7adb02efe8bd71b21e5208..77fe16967376612fb3e620208feff2dc235508fa 100644 (file)
@@ -14,6 +14,7 @@
 #include "smc.h"
 #include "smc_wr.h"
 #include "smc_cdc.h"
+#include "smc_tx.h"
 
 /********************************** send *************************************/
 
@@ -52,7 +53,7 @@ static void smc_cdc_tx_handler(struct smc_wr_tx_pend_priv *pnd_snd,
                               smc_curs_read(&cdcpend->cursor, cdcpend->conn),
                               cdcpend->conn);
        }
-       /* subsequent patch: wake if send buffer space available */
+       smc_tx_sndbuf_nonfull(smc);
        bh_unlock_sock(&smc->sk);
 }
 
@@ -204,7 +205,9 @@ static void smc_cdc_msg_recv_action(struct smc_sock *smc,
                /* subsequent patch: terminate connection */
 
        /* piggy backed tx info */
-       /* subsequent patch: wake receivers if receive buffer space available */
+       /* trigger sndbuf consumer: RDMA write into peer RMBE and CDC */
+       if (diff_cons && smc_tx_prepared_sends(conn))
+               smc_tx_sndbuf_nonempty(conn);
 
        /* subsequent patch: trigger socket release if connection closed */
 
diff --git a/net/smc/smc_tx.c b/net/smc/smc_tx.c
new file mode 100644 (file)
index 0000000..d86bef6
--- /dev/null
@@ -0,0 +1,438 @@
+/*
+ * Shared Memory Communications over RDMA (SMC-R) and RoCE
+ *
+ * Manage send buffer.
+ * Producer:
+ * Copy user space data into send buffer, if send buffer space available.
+ * Consumer:
+ * Trigger RDMA write into RMBE of peer and send CDC, if RMBE space available.
+ *
+ * Copyright IBM Corp. 2016
+ *
+ * Author(s):  Ursula Braun <ubraun@linux.vnet.ibm.com>
+ */
+
+#include <linux/net.h>
+#include <linux/rcupdate.h>
+#include <linux/workqueue.h>
+#include <net/sock.h>
+
+#include "smc.h"
+#include "smc_wr.h"
+#include "smc_cdc.h"
+#include "smc_tx.h"
+
+/***************************** sndbuf producer *******************************/
+
+/* callback implementation for sk.sk_write_space()
+ * to wakeup sndbuf producers that blocked with smc_tx_wait_memory().
+ * called under sk_socket lock.
+ */
+static void smc_tx_write_space(struct sock *sk)
+{
+       struct socket *sock = sk->sk_socket;
+       struct smc_sock *smc = smc_sk(sk);
+       struct socket_wq *wq;
+
+       /* similar to sk_stream_write_space */
+       if (atomic_read(&smc->conn.sndbuf_space) && sock) {
+               clear_bit(SOCK_NOSPACE, &sock->flags);
+               rcu_read_lock();
+               wq = rcu_dereference(sk->sk_wq);
+               if (skwq_has_sleeper(wq))
+                       wake_up_interruptible_poll(&wq->wait,
+                                                  POLLOUT | POLLWRNORM |
+                                                  POLLWRBAND);
+               if (wq && wq->fasync_list && !(sk->sk_shutdown & SEND_SHUTDOWN))
+                       sock_wake_async(wq, SOCK_WAKE_SPACE, POLL_OUT);
+               rcu_read_unlock();
+       }
+}
+
+/* Wakeup sndbuf producers that blocked with smc_tx_wait_memory().
+ * Cf. tcp_data_snd_check()=>tcp_check_space()=>tcp_new_space().
+ */
+void smc_tx_sndbuf_nonfull(struct smc_sock *smc)
+{
+       if (smc->sk.sk_socket &&
+           test_bit(SOCK_NOSPACE, &smc->sk.sk_socket->flags))
+               smc->sk.sk_write_space(&smc->sk);
+}
+
+/* blocks sndbuf producer until at least one byte of free space available */
+static int smc_tx_wait_memory(struct smc_sock *smc, int flags)
+{
+       DEFINE_WAIT_FUNC(wait, woken_wake_function);
+       struct smc_connection *conn = &smc->conn;
+       struct sock *sk = &smc->sk;
+       bool noblock;
+       long timeo;
+       int rc = 0;
+
+       /* similar to sk_stream_wait_memory */
+       timeo = sock_sndtimeo(sk, flags & MSG_DONTWAIT);
+       noblock = timeo ? false : true;
+       add_wait_queue(sk_sleep(sk), &wait);
+       while (1) {
+               sk_set_bit(SOCKWQ_ASYNC_NOSPACE, sk);
+               if (sk->sk_err ||
+                   (sk->sk_shutdown & SEND_SHUTDOWN) ||
+                   conn->local_tx_ctrl.conn_state_flags.peer_done_writing) {
+                       rc = -EPIPE;
+                       break;
+               }
+               if (conn->local_rx_ctrl.conn_state_flags.peer_conn_abort) {
+                       rc = -ECONNRESET;
+                       break;
+               }
+               if (!timeo) {
+                       if (noblock)
+                               set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
+                       rc = -EAGAIN;
+                       break;
+               }
+               if (signal_pending(current)) {
+                       rc = sock_intr_errno(timeo);
+                       break;
+               }
+               sk_clear_bit(SOCKWQ_ASYNC_NOSPACE, sk);
+               if (atomic_read(&conn->sndbuf_space))
+                       break; /* at least 1 byte of free space available */
+               set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
+               sk->sk_write_pending++;
+               sk_wait_event(sk, &timeo,
+                             sk->sk_err ||
+                             (sk->sk_shutdown & SEND_SHUTDOWN) ||
+                             smc_cdc_rxed_any_close_or_senddone(conn) ||
+                             atomic_read(&conn->sndbuf_space),
+                             &wait);
+               sk->sk_write_pending--;
+       }
+       remove_wait_queue(sk_sleep(sk), &wait);
+       return rc;
+}
+
+/* sndbuf producer: main API called by socket layer.
+ * called under sock lock.
+ */
+int smc_tx_sendmsg(struct smc_sock *smc, struct msghdr *msg, size_t len)
+{
+       size_t copylen, send_done = 0, send_remaining = len;
+       size_t chunk_len, chunk_off, chunk_len_sum;
+       struct smc_connection *conn = &smc->conn;
+       union smc_host_cursor prep;
+       struct sock *sk = &smc->sk;
+       char *sndbuf_base;
+       int tx_cnt_prep;
+       int writespace;
+       int rc, chunk;
+
+       /* This should be in poll */
+       sk_clear_bit(SOCKWQ_ASYNC_NOSPACE, sk);
+
+       if (sk->sk_err || (sk->sk_shutdown & SEND_SHUTDOWN)) {
+               rc = -EPIPE;
+               goto out_err;
+       }
+
+       while (msg_data_left(msg)) {
+               if (sk->sk_state == SMC_INIT)
+                       return -ENOTCONN;
+               if (smc->sk.sk_shutdown & SEND_SHUTDOWN ||
+                   conn->local_tx_ctrl.conn_state_flags.peer_conn_abort)
+                       return -EPIPE;
+               if (smc_cdc_rxed_any_close(conn))
+                       return send_done ?: -ECONNRESET;
+
+               if (!atomic_read(&conn->sndbuf_space)) {
+                       rc = smc_tx_wait_memory(smc, msg->msg_flags);
+                       if (rc) {
+                               if (send_done)
+                                       return send_done;
+                               goto out_err;
+                       }
+                       continue;
+               }
+
+               /* initialize variables for 1st iteration of subsequent loop */
+               /* could be just 1 byte, even after smc_tx_wait_memory above */
+               writespace = atomic_read(&conn->sndbuf_space);
+               /* not more than what user space asked for */
+               copylen = min_t(size_t, send_remaining, writespace);
+               /* determine start of sndbuf */
+               sndbuf_base = conn->sndbuf_desc->cpu_addr;
+               smc_curs_write(&prep,
+                              smc_curs_read(&conn->tx_curs_prep, conn),
+                              conn);
+               tx_cnt_prep = prep.count;
+               /* determine chunks where to write into sndbuf */
+               /* either unwrapped case, or 1st chunk of wrapped case */
+               chunk_len = min_t(size_t,
+                                 copylen, conn->sndbuf_size - tx_cnt_prep);
+               chunk_len_sum = chunk_len;
+               chunk_off = tx_cnt_prep;
+               for (chunk = 0; chunk < 2; chunk++) {
+                       rc = memcpy_from_msg(sndbuf_base + chunk_off,
+                                            msg, chunk_len);
+                       if (rc) {
+                               if (send_done)
+                                       return send_done;
+                               goto out_err;
+                       }
+                       send_done += chunk_len;
+                       send_remaining -= 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 send ring buffer */
+               }
+               /* update cursors */
+               smc_curs_add(conn->sndbuf_size, &prep, copylen);
+               smc_curs_write(&conn->tx_curs_prep,
+                              smc_curs_read(&prep, conn),
+                              conn);
+               /* increased in send tasklet smc_cdc_tx_handler() */
+               smp_mb__before_atomic();
+               atomic_sub(copylen, &conn->sndbuf_space);
+               /* guarantee 0 <= sndbuf_space <= sndbuf_size */
+               smp_mb__after_atomic();
+               /* since we just produced more new data into sndbuf,
+                * trigger sndbuf consumer: RDMA write into peer RMBE and CDC
+                */
+               smc_tx_sndbuf_nonempty(conn);
+       } /* while (msg_data_left(msg)) */
+
+       return send_done;
+
+out_err:
+       rc = sk_stream_error(sk, msg->msg_flags, rc);
+       /* make sure we wake any epoll edge trigger waiter */
+       if (unlikely(rc == -EAGAIN))
+               sk->sk_write_space(sk);
+       return rc;
+}
+
+/***************************** sndbuf consumer *******************************/
+
+/* sndbuf consumer: actual data transfer of one target chunk with RDMA write */
+static int smc_tx_rdma_write(struct smc_connection *conn, int peer_rmbe_offset,
+                            int num_sges, struct ib_sge sges[])
+{
+       struct smc_link_group *lgr = conn->lgr;
+       struct ib_send_wr *failed_wr = NULL;
+       struct ib_rdma_wr rdma_wr;
+       struct smc_link *link;
+       int rc;
+
+       memset(&rdma_wr, 0, sizeof(rdma_wr));
+       link = &lgr->lnk[SMC_SINGLE_LINK];
+       rdma_wr.wr.wr_id = smc_wr_tx_get_next_wr_id(link);
+       rdma_wr.wr.sg_list = sges;
+       rdma_wr.wr.num_sge = num_sges;
+       rdma_wr.wr.opcode = IB_WR_RDMA_WRITE;
+       rdma_wr.remote_addr =
+               lgr->rtokens[conn->rtoken_idx][SMC_SINGLE_LINK].dma_addr +
+               /* RMBE within RMB */
+               ((conn->peer_conn_idx - 1) * conn->peer_rmbe_size) +
+               /* offset within RMBE */
+               peer_rmbe_offset;
+       rdma_wr.rkey = lgr->rtokens[conn->rtoken_idx][SMC_SINGLE_LINK].rkey;
+       rc = ib_post_send(link->roce_qp, &rdma_wr.wr, &failed_wr);
+       if (rc)
+               conn->local_tx_ctrl.conn_state_flags.peer_conn_abort = 1;
+       return rc;
+}
+
+/* sndbuf consumer */
+static inline void smc_tx_advance_cursors(struct smc_connection *conn,
+                                         union smc_host_cursor *prod,
+                                         union smc_host_cursor *sent,
+                                         size_t len)
+{
+       smc_curs_add(conn->peer_rmbe_size, prod, len);
+       /* increased in recv tasklet smc_cdc_msg_rcv() */
+       smp_mb__before_atomic();
+       /* data in flight reduces usable snd_wnd */
+       atomic_sub(len, &conn->peer_rmbe_space);
+       /* guarantee 0 <= peer_rmbe_space <= peer_rmbe_size */
+       smp_mb__after_atomic();
+       smc_curs_add(conn->sndbuf_size, sent, len);
+}
+
+/* sndbuf consumer: prepare all necessary (src&dst) chunks of data transmit;
+ * usable snd_wnd as max transmit
+ */
+static int smc_tx_rdma_writes(struct smc_connection *conn)
+{
+       size_t src_off, src_len, dst_off, dst_len; /* current chunk values */
+       size_t len, dst_len_sum, src_len_sum, dstchunk, srcchunk;
+       union smc_host_cursor sent, prep, prod, cons;
+       struct ib_sge sges[SMC_IB_MAX_SEND_SGE];
+       struct smc_link_group *lgr = conn->lgr;
+       int to_send, rmbespace;
+       struct smc_link *link;
+       int num_sges;
+       int rc;
+
+       /* source: sndbuf */
+       smc_curs_write(&sent, smc_curs_read(&conn->tx_curs_sent, conn), conn);
+       smc_curs_write(&prep, smc_curs_read(&conn->tx_curs_prep, conn), conn);
+       /* cf. wmem_alloc - (snd_max - snd_una) */
+       to_send = smc_curs_diff(conn->sndbuf_size, &sent, &prep);
+       if (to_send <= 0)
+               return 0;
+
+       /* destination: RMBE */
+       /* cf. snd_wnd */
+       rmbespace = atomic_read(&conn->peer_rmbe_space);
+       if (rmbespace <= 0)
+               return 0;
+       smc_curs_write(&prod,
+                      smc_curs_read(&conn->local_tx_ctrl.prod, conn),
+                      conn);
+       smc_curs_write(&cons,
+                      smc_curs_read(&conn->local_rx_ctrl.cons, conn),
+                      conn);
+
+       /* if usable snd_wnd closes ask peer to advertise once it opens again */
+       conn->local_tx_ctrl.prod_flags.write_blocked = (to_send >= rmbespace);
+       /* cf. usable snd_wnd */
+       len = min(to_send, rmbespace);
+
+       /* initialize variables for first iteration of subsequent nested loop */
+       link = &lgr->lnk[SMC_SINGLE_LINK];
+       dst_off = prod.count;
+       if (prod.wrap == cons.wrap) {
+               /* the filled destination area is unwrapped,
+                * hence the available free destination space is wrapped
+                * and we need 2 destination chunks of sum len; start with 1st
+                * which is limited by what's available in sndbuf
+                */
+               dst_len = min_t(size_t,
+                               conn->peer_rmbe_size - prod.count, len);
+       } else {
+               /* the filled destination area is wrapped,
+                * hence the available free destination space is unwrapped
+                * and we need a single destination chunk of entire len
+                */
+               dst_len = len;
+       }
+       dst_len_sum = dst_len;
+       src_off = sent.count;
+       /* dst_len determines the maximum src_len */
+       if (sent.count + dst_len <= conn->sndbuf_size) {
+               /* unwrapped src case: single chunk of entire dst_len */
+               src_len = dst_len;
+       } else {
+               /* wrapped src case: 2 chunks of sum dst_len; start with 1st: */
+               src_len = conn->sndbuf_size - sent.count;
+       }
+       src_len_sum = src_len;
+       for (dstchunk = 0; dstchunk < 2; dstchunk++) {
+               num_sges = 0;
+               for (srcchunk = 0; srcchunk < 2; srcchunk++) {
+                       sges[srcchunk].addr =
+                               conn->sndbuf_desc->dma_addr[SMC_SINGLE_LINK] +
+                               src_off;
+                       sges[srcchunk].length = src_len;
+                       sges[srcchunk].lkey = link->roce_pd->local_dma_lkey;
+                       num_sges++;
+                       src_off += src_len;
+                       if (src_off >= conn->sndbuf_size)
+                               src_off -= conn->sndbuf_size;
+                                               /* modulo in send ring */
+                       if (src_len_sum == dst_len)
+                               break; /* either on 1st or 2nd iteration */
+                       /* prepare next (== 2nd) iteration */
+                       src_len = dst_len - src_len; /* remainder */
+                       src_len_sum += src_len;
+               }
+               rc = smc_tx_rdma_write(conn, dst_off, num_sges, sges);
+               if (rc)
+                       return rc;
+               if (dst_len_sum == len)
+                       break; /* either on 1st or 2nd iteration */
+               /* prepare next (== 2nd) iteration */
+               dst_off = 0; /* modulo offset in RMBE ring buffer */
+               dst_len = len - dst_len; /* remainder */
+               dst_len_sum += dst_len;
+               src_len = min_t(int,
+                               dst_len, conn->sndbuf_size - sent.count);
+               src_len_sum = src_len;
+       }
+
+       smc_tx_advance_cursors(conn, &prod, &sent, len);
+       /* update connection's cursors with advanced local cursors */
+       smc_curs_write(&conn->local_tx_ctrl.prod,
+                      smc_curs_read(&prod, conn),
+                      conn);
+                                                       /* dst: peer RMBE */
+       smc_curs_write(&conn->tx_curs_sent,
+                      smc_curs_read(&sent, conn),
+                      conn);
+                                                       /* src: local sndbuf */
+
+       return 0;
+}
+
+/* Wakeup sndbuf consumers from any context (IRQ or process)
+ * since there is more data to transmit; usable snd_wnd as max transmit
+ */
+int smc_tx_sndbuf_nonempty(struct smc_connection *conn)
+{
+       struct smc_cdc_tx_pend *pend;
+       struct smc_wr_buf *wr_buf;
+       int rc;
+
+       spin_lock_bh(&conn->send_lock);
+       rc = smc_cdc_get_free_slot(&conn->lgr->lnk[SMC_SINGLE_LINK], &wr_buf,
+                                  &pend);
+       if (rc < 0) {
+               if (rc == -EBUSY) {
+                       rc = 0;
+                       schedule_work(&conn->tx_work);
+               }
+               goto out_unlock;
+       }
+
+       rc = smc_tx_rdma_writes(conn);
+       if (rc) {
+               smc_wr_tx_put_slot(&conn->lgr->lnk[SMC_SINGLE_LINK],
+                                  (struct smc_wr_tx_pend_priv *)pend);
+               goto out_unlock;
+       }
+
+       rc = smc_cdc_msg_send(conn, wr_buf, pend);
+
+out_unlock:
+       spin_unlock_bh(&conn->send_lock);
+       return rc;
+}
+
+/* Wakeup sndbuf consumers from process context
+ * since there is more data to transmit
+ */
+static void smc_tx_work(struct work_struct *work)
+{
+       struct smc_connection *conn = container_of(work,
+                                                  struct smc_connection,
+                                                  tx_work);
+       struct smc_sock *smc = container_of(conn, struct smc_sock, conn);
+
+       lock_sock(&smc->sk);
+       smc_tx_sndbuf_nonempty(conn);
+       release_sock(&smc->sk);
+}
+
+/***************************** send initialize *******************************/
+
+/* Initialize send properties on connection establishment. NB: not __init! */
+void smc_tx_init(struct smc_sock *smc)
+{
+       smc->sk.sk_write_space = smc_tx_write_space;
+       INIT_WORK(&smc->conn.tx_work, smc_tx_work);
+       spin_lock_init(&smc->conn.send_lock);
+}
diff --git a/net/smc/smc_tx.h b/net/smc/smc_tx.h
new file mode 100644 (file)
index 0000000..931c666
--- /dev/null
@@ -0,0 +1,34 @@
+/*
+ * Shared Memory Communications over RDMA (SMC-R) and RoCE
+ *
+ * Manage send buffer
+ *
+ * Copyright IBM Corp. 2016
+ *
+ * Author(s):  Ursula Braun <ubraun@linux.vnet.ibm.com>
+ */
+
+#ifndef SMC_TX_H
+#define SMC_TX_H
+
+#include <linux/socket.h>
+#include <linux/types.h>
+
+#include "smc.h"
+#include "smc_cdc.h"
+
+static inline int smc_tx_prepared_sends(struct smc_connection *conn)
+{
+       union smc_host_cursor sent, prep;
+
+       smc_curs_write(&sent, smc_curs_read(&conn->tx_curs_sent, conn), conn);
+       smc_curs_write(&prep, smc_curs_read(&conn->tx_curs_prep, conn), conn);
+       return smc_curs_diff(conn->sndbuf_size, &sent, &prep);
+}
+
+void smc_tx_init(struct smc_sock *smc);
+int smc_tx_sendmsg(struct smc_sock *smc, struct msghdr *msg, size_t len);
+int smc_tx_sndbuf_nonempty(struct smc_connection *conn);
+void smc_tx_sndbuf_nonfull(struct smc_sock *smc);
+
+#endif /* SMC_TX_H */