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Release 4.15 net/smc/smc_tx.c

Directory: net/smc
// SPDX-License-Identifier: GPL-2.0
/*
 * 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 <linux/sched/signal.h>

#include <net/sock.h>

#include "smc.h"
#include "smc_wr.h"
#include "smc_cdc.h"
#include "smc_tx.h"


#define SMC_TX_WORK_DELAY	HZ

/***************************** 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(); } }

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/* 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); }

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/* 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; }

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/* 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 || (smc->sk.sk_err == ECONNABORTED) || 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; smc_sndbuf_sync_sg_for_cpu(conn); for (chunk = 0; chunk < 2; chunk++) { rc = memcpy_from_msg(sndbuf_base + chunk_off, msg, chunk_len); if (rc) { smc_sndbuf_sync_sg_for_device(conn); 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 */ } smc_sndbuf_sync_sg_for_device(conn); /* 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; }

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/***************************** 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; }

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/* 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); }

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/* 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; dma_addr_t dma_addr; 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; dma_addr = sg_dma_address(conn->sndbuf_desc->sgt[SMC_SINGLE_LINK].sgl); for (dstchunk = 0; dstchunk < 2; dstchunk++) { num_sges = 0; for (srcchunk = 0; srcchunk < 2; srcchunk++) { sges[srcchunk].addr = dma_addr + 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; }

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/* 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, &wr_buf, &pend); if (rc < 0) { if (rc == -EBUSY) { struct smc_sock *smc = container_of(conn, struct smc_sock, conn); if (smc->sk.sk_err == ECONNABORTED) { rc = sock_error(&smc->sk); goto out_unlock; } rc = 0; schedule_delayed_work(&conn->tx_work, SMC_TX_WORK_DELAY); } 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; }

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/* 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(to_delayed_work(work), struct smc_connection, tx_work); struct smc_sock *smc = container_of(conn, struct smc_sock, conn); int rc; lock_sock(&smc->sk); rc = smc_tx_sndbuf_nonempty(conn); if (!rc && conn->local_rx_ctrl.prod_flags.write_blocked && !atomic_read(&conn->bytes_to_rcv)) conn->local_rx_ctrl.prod_flags.write_blocked = 0; release_sock(&smc->sk); }

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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, &wr_buf, &pend); if (!rc) rc = smc_cdc_msg_send(conn, wr_buf, pend); if (rc < 0) { schedule_delayed_work(&conn->tx_work, SMC_TX_WORK_DELAY); 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; }

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/***************************** 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_DELAYED_WORK(&smc->conn.tx_work, smc_tx_work); spin_lock_init(&smc->conn.send_lock); }

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Directory: net/smc
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