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Diffstat (limited to '')
| -rw-r--r-- | net/smc/smc_tx.c | 779 |
1 files changed, 779 insertions, 0 deletions
diff --git a/net/smc/smc_tx.c b/net/smc/smc_tx.c new file mode 100644 index 000000000..45128443f --- /dev/null +++ b/net/smc/smc_tx.c @@ -0,0 +1,779 @@ +// 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 <net/tcp.h> + +#include "smc.h" +#include "smc_wr.h" +#include "smc_cdc.h" +#include "smc_close.h" +#include "smc_ism.h" +#include "smc_tx.h" +#include "smc_stats.h" +#include "smc_tracepoint.h" + +#define SMC_TX_WORK_DELAY 0 + +/***************************** sndbuf producer *******************************/ + +/* callback implementation for sk.sk_write_space() + * to wakeup sndbuf producers that blocked with smc_tx_wait(). + * 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) { + if (test_bit(SOCK_NOSPACE, &sock->flags)) + SMC_STAT_RMB_TX_FULL(smc, !smc->conn.lnk); + 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, + EPOLLOUT | EPOLLWRNORM | + EPOLLWRBAND); + 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(). + * 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 + * or urgent Byte was consumed + */ +static int smc_tx_wait(struct smc_sock *smc, int flags) +{ + DEFINE_WAIT_FUNC(wait, woken_wake_function); + struct smc_connection *conn = &smc->conn; + struct sock *sk = &smc->sk; + long timeo; + int rc = 0; + + /* similar to sk_stream_wait_memory */ + timeo = sock_sndtimeo(sk, flags & MSG_DONTWAIT); + 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->killed || + conn->local_tx_ctrl.conn_state_flags.peer_done_writing) { + rc = -EPIPE; + break; + } + if (smc_cdc_rxed_any_close(conn)) { + rc = -ECONNRESET; + break; + } + if (!timeo) { + /* ensure EPOLLOUT is subsequently generated */ + 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) && !conn->urg_tx_pend) + break; /* at least 1 byte of free & no urgent data */ + set_bit(SOCK_NOSPACE, &sk->sk_socket->flags); + sk_wait_event(sk, &timeo, + READ_ONCE(sk->sk_err) || + (READ_ONCE(sk->sk_shutdown) & SEND_SHUTDOWN) || + smc_cdc_rxed_any_close(conn) || + (atomic_read(&conn->sndbuf_space) && + !conn->urg_tx_pend), + &wait); + } + remove_wait_queue(sk_sleep(sk), &wait); + return rc; +} + +static bool smc_tx_is_corked(struct smc_sock *smc) +{ + struct tcp_sock *tp = tcp_sk(smc->clcsock->sk); + + return (tp->nonagle & TCP_NAGLE_CORK) ? true : false; +} + +/* If we have pending CDC messages, do not send: + * Because CQE of this CDC message will happen shortly, it gives + * a chance to coalesce future sendmsg() payload in to one RDMA Write, + * without need for a timer, and with no latency trade off. + * Algorithm here: + * 1. First message should never cork + * 2. If we have pending Tx CDC messages, wait for the first CDC + * message's completion + * 3. Don't cork to much data in a single RDMA Write to prevent burst + * traffic, total corked message should not exceed sendbuf/2 + */ +static bool smc_should_autocork(struct smc_sock *smc) +{ + struct smc_connection *conn = &smc->conn; + int corking_size; + + corking_size = min_t(unsigned int, conn->sndbuf_desc->len >> 1, + sock_net(&smc->sk)->smc.sysctl_autocorking_size); + + if (atomic_read(&conn->cdc_pend_tx_wr) == 0 || + smc_tx_prepared_sends(conn) > corking_size) + return false; + return true; +} + +static bool smc_tx_should_cork(struct smc_sock *smc, struct msghdr *msg) +{ + struct smc_connection *conn = &smc->conn; + + if (smc_should_autocork(smc)) + return true; + + /* for a corked socket defer the RDMA writes if + * sndbuf_space is still available. The applications + * should known how/when to uncork it. + */ + if ((msg->msg_flags & MSG_MORE || + smc_tx_is_corked(smc) || + msg->msg_flags & MSG_SENDPAGE_NOTLAST) && + atomic_read(&conn->sndbuf_space)) + return true; + + return false; +} + +/* 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; + } + + if (sk->sk_state == SMC_INIT) + return -ENOTCONN; + + if (len > conn->sndbuf_desc->len) + SMC_STAT_RMB_TX_SIZE_SMALL(smc, !conn->lnk); + + if (len > conn->peer_rmbe_size) + SMC_STAT_RMB_TX_PEER_SIZE_SMALL(smc, !conn->lnk); + + if (msg->msg_flags & MSG_OOB) + SMC_STAT_INC(smc, urg_data_cnt); + + while (msg_data_left(msg)) { + if (smc->sk.sk_shutdown & SEND_SHUTDOWN || + (smc->sk.sk_err == ECONNABORTED) || + conn->killed) + return -EPIPE; + if (smc_cdc_rxed_any_close(conn)) + return send_done ?: -ECONNRESET; + + if (msg->msg_flags & MSG_OOB) + conn->local_tx_ctrl.prod_flags.urg_data_pending = 1; + + if (!atomic_read(&conn->sndbuf_space) || conn->urg_tx_pend) { + if (send_done) + return send_done; + rc = smc_tx_wait(smc, msg->msg_flags); + if (rc) + goto out_err; + continue; + } + + /* initialize variables for 1st iteration of subsequent loop */ + /* could be just 1 byte, even after smc_tx_wait 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_copy(&prep, &conn->tx_curs_prep, 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_desc->len - + 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) { + 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_desc->len, &prep, copylen); + smc_curs_copy(&conn->tx_curs_prep, &prep, conn); + /* increased in send tasklet smc_cdc_tx_handler() */ + smp_mb__before_atomic(); + atomic_sub(copylen, &conn->sndbuf_space); + /* guarantee 0 <= sndbuf_space <= sndbuf_desc->len */ + smp_mb__after_atomic(); + /* since we just produced more new data into sndbuf, + * trigger sndbuf consumer: RDMA write into peer RMBE and CDC + */ + if ((msg->msg_flags & MSG_OOB) && !send_remaining) + conn->urg_tx_pend = true; + /* If we need to cork, do nothing and wait for the next + * sendmsg() call or push on tx completion + */ + if (!smc_tx_should_cork(smc, msg)) + smc_tx_sndbuf_nonempty(conn); + + trace_smc_tx_sendmsg(smc, copylen); + } /* 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; +} + +int smc_tx_sendpage(struct smc_sock *smc, struct page *page, int offset, + size_t size, int flags) +{ + struct msghdr msg = {.msg_flags = flags}; + char *kaddr = kmap(page); + struct kvec iov; + int rc; + + iov.iov_base = kaddr + offset; + iov.iov_len = size; + iov_iter_kvec(&msg.msg_iter, ITER_SOURCE, &iov, 1, size); + rc = smc_tx_sendmsg(smc, &msg, size); + kunmap(page); + return rc; +} + +/***************************** sndbuf consumer *******************************/ + +/* sndbuf consumer: actual data transfer of one target chunk with ISM write */ +int smcd_tx_ism_write(struct smc_connection *conn, void *data, size_t len, + u32 offset, int signal) +{ + int rc; + + rc = smc_ism_write(conn->lgr->smcd, conn->peer_token, + conn->peer_rmbe_idx, signal, conn->tx_off + offset, + data, len); + if (rc) + conn->local_tx_ctrl.conn_state_flags.peer_conn_abort = 1; + return rc; +} + +/* 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_rdma_wr *rdma_wr) +{ + struct smc_link_group *lgr = conn->lgr; + struct smc_link *link = conn->lnk; + int rc; + + rdma_wr->wr.wr_id = smc_wr_tx_get_next_wr_id(link); + rdma_wr->wr.num_sge = num_sges; + rdma_wr->remote_addr = + lgr->rtokens[conn->rtoken_idx][link->link_idx].dma_addr + + /* RMBE within RMB */ + conn->tx_off + + /* offset within RMBE */ + peer_rmbe_offset; + rdma_wr->rkey = lgr->rtokens[conn->rtoken_idx][link->link_idx].rkey; + rc = ib_post_send(link->roce_qp, &rdma_wr->wr, NULL); + if (rc) + smcr_link_down_cond_sched(link); + 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_desc->len, sent, len); +} + +/* SMC-R helper for smc_tx_rdma_writes() */ +static int smcr_tx_rdma_writes(struct smc_connection *conn, size_t len, + size_t src_off, size_t src_len, + size_t dst_off, size_t dst_len, + struct smc_rdma_wr *wr_rdma_buf) +{ + struct smc_link *link = conn->lnk; + + dma_addr_t dma_addr = + sg_dma_address(conn->sndbuf_desc->sgt[link->link_idx].sgl); + u64 virt_addr = (uintptr_t)conn->sndbuf_desc->cpu_addr; + int src_len_sum = src_len, dst_len_sum = dst_len; + int sent_count = src_off; + int srcchunk, dstchunk; + int num_sges; + int rc; + + for (dstchunk = 0; dstchunk < 2; dstchunk++) { + struct ib_rdma_wr *wr = &wr_rdma_buf->wr_tx_rdma[dstchunk]; + struct ib_sge *sge = wr->wr.sg_list; + u64 base_addr = dma_addr; + + if (dst_len < link->qp_attr.cap.max_inline_data) { + base_addr = virt_addr; + wr->wr.send_flags |= IB_SEND_INLINE; + } else { + wr->wr.send_flags &= ~IB_SEND_INLINE; + } + + num_sges = 0; + for (srcchunk = 0; srcchunk < 2; srcchunk++) { + sge[srcchunk].addr = conn->sndbuf_desc->is_vm ? + (virt_addr + src_off) : (base_addr + src_off); + sge[srcchunk].length = src_len; + if (conn->sndbuf_desc->is_vm) + sge[srcchunk].lkey = + conn->sndbuf_desc->mr[link->link_idx]->lkey; + num_sges++; + + src_off += src_len; + if (src_off >= conn->sndbuf_desc->len) + src_off -= conn->sndbuf_desc->len; + /* 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, wr); + 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_desc->len - + sent_count); + src_len_sum = src_len; + } + return 0; +} + +/* SMC-D helper for smc_tx_rdma_writes() */ +static int smcd_tx_rdma_writes(struct smc_connection *conn, size_t len, + size_t src_off, size_t src_len, + size_t dst_off, size_t dst_len) +{ + int src_len_sum = src_len, dst_len_sum = dst_len; + int srcchunk, dstchunk; + int rc; + + for (dstchunk = 0; dstchunk < 2; dstchunk++) { + for (srcchunk = 0; srcchunk < 2; srcchunk++) { + void *data = conn->sndbuf_desc->cpu_addr + src_off; + + rc = smcd_tx_ism_write(conn, data, src_len, dst_off + + sizeof(struct smcd_cdc_msg), 0); + if (rc) + return rc; + dst_off += src_len; + src_off += src_len; + if (src_off >= conn->sndbuf_desc->len) + src_off -= conn->sndbuf_desc->len; + /* 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; + } + 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_desc->len - src_off); + src_len_sum = src_len; + } + return 0; +} + +/* 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, + struct smc_rdma_wr *wr_rdma_buf) +{ + size_t len, src_len, dst_off, dst_len; /* current chunk values */ + union smc_host_cursor sent, prep, prod, cons; + struct smc_cdc_producer_flags *pflags; + int to_send, rmbespace; + int rc; + + /* source: sndbuf */ + smc_curs_copy(&sent, &conn->tx_curs_sent, conn); + smc_curs_copy(&prep, &conn->tx_curs_prep, conn); + /* cf. wmem_alloc - (snd_max - snd_una) */ + to_send = smc_curs_diff(conn->sndbuf_desc->len, &sent, &prep); + if (to_send <= 0) + return 0; + + /* destination: RMBE */ + /* cf. snd_wnd */ + rmbespace = atomic_read(&conn->peer_rmbe_space); + if (rmbespace <= 0) { + struct smc_sock *smc = container_of(conn, struct smc_sock, + conn); + SMC_STAT_RMB_TX_PEER_FULL(smc, !conn->lnk); + return 0; + } + smc_curs_copy(&prod, &conn->local_tx_ctrl.prod, conn); + smc_curs_copy(&cons, &conn->local_rx_ctrl.cons, conn); + + /* if usable snd_wnd closes ask peer to advertise once it opens again */ + pflags = &conn->local_tx_ctrl.prod_flags; + pflags->write_blocked = (to_send >= rmbespace); + /* cf. usable snd_wnd */ + len = min(to_send, rmbespace); + + /* initialize variables for first iteration of subsequent nested loop */ + 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 determines the maximum src_len */ + if (sent.count + dst_len <= conn->sndbuf_desc->len) { + /* 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_desc->len - sent.count; + } + + if (conn->lgr->is_smcd) + rc = smcd_tx_rdma_writes(conn, len, sent.count, src_len, + dst_off, dst_len); + else + rc = smcr_tx_rdma_writes(conn, len, sent.count, src_len, + dst_off, dst_len, wr_rdma_buf); + if (rc) + return rc; + + if (conn->urg_tx_pend && len == to_send) + pflags->urg_data_present = 1; + smc_tx_advance_cursors(conn, &prod, &sent, len); + /* update connection's cursors with advanced local cursors */ + smc_curs_copy(&conn->local_tx_ctrl.prod, &prod, conn); + /* dst: peer RMBE */ + smc_curs_copy(&conn->tx_curs_sent, &sent, 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 + */ +static int smcr_tx_sndbuf_nonempty(struct smc_connection *conn) +{ + struct smc_cdc_producer_flags *pflags = &conn->local_tx_ctrl.prod_flags; + struct smc_link *link = conn->lnk; + struct smc_rdma_wr *wr_rdma_buf; + struct smc_cdc_tx_pend *pend; + struct smc_wr_buf *wr_buf; + int rc; + + if (!link || !smc_wr_tx_link_hold(link)) + return -ENOLINK; + rc = smc_cdc_get_free_slot(conn, link, &wr_buf, &wr_rdma_buf, &pend); + if (rc < 0) { + smc_wr_tx_link_put(link); + if (rc == -EBUSY) { + struct smc_sock *smc = + container_of(conn, struct smc_sock, conn); + + if (smc->sk.sk_err == ECONNABORTED) + return sock_error(&smc->sk); + if (conn->killed) + return -EPIPE; + rc = 0; + mod_delayed_work(conn->lgr->tx_wq, &conn->tx_work, + SMC_TX_WORK_DELAY); + } + return rc; + } + + spin_lock_bh(&conn->send_lock); + if (link != conn->lnk) { + /* link of connection changed, tx_work will restart */ + smc_wr_tx_put_slot(link, + (struct smc_wr_tx_pend_priv *)pend); + rc = -ENOLINK; + goto out_unlock; + } + if (!pflags->urg_data_present) { + rc = smc_tx_rdma_writes(conn, wr_rdma_buf); + if (rc) { + smc_wr_tx_put_slot(link, + (struct smc_wr_tx_pend_priv *)pend); + goto out_unlock; + } + } + + rc = smc_cdc_msg_send(conn, wr_buf, pend); + if (!rc && pflags->urg_data_present) { + pflags->urg_data_pending = 0; + pflags->urg_data_present = 0; + } + +out_unlock: + spin_unlock_bh(&conn->send_lock); + smc_wr_tx_link_put(link); + return rc; +} + +static int smcd_tx_sndbuf_nonempty(struct smc_connection *conn) +{ + struct smc_cdc_producer_flags *pflags = &conn->local_tx_ctrl.prod_flags; + int rc = 0; + + spin_lock_bh(&conn->send_lock); + if (!pflags->urg_data_present) + rc = smc_tx_rdma_writes(conn, NULL); + if (!rc) + rc = smcd_cdc_msg_send(conn); + + if (!rc && pflags->urg_data_present) { + pflags->urg_data_pending = 0; + pflags->urg_data_present = 0; + } + spin_unlock_bh(&conn->send_lock); + return rc; +} + +static int __smc_tx_sndbuf_nonempty(struct smc_connection *conn) +{ + struct smc_sock *smc = container_of(conn, struct smc_sock, conn); + int rc = 0; + + /* No data in the send queue */ + if (unlikely(smc_tx_prepared_sends(conn) <= 0)) + goto out; + + /* Peer don't have RMBE space */ + if (unlikely(atomic_read(&conn->peer_rmbe_space) <= 0)) { + SMC_STAT_RMB_TX_PEER_FULL(smc, !conn->lnk); + goto out; + } + + if (conn->killed || + conn->local_rx_ctrl.conn_state_flags.peer_conn_abort) { + rc = -EPIPE; /* connection being aborted */ + goto out; + } + if (conn->lgr->is_smcd) + rc = smcd_tx_sndbuf_nonempty(conn); + else + rc = smcr_tx_sndbuf_nonempty(conn); + + if (!rc) { + /* trigger socket release if connection is closing */ + smc_close_wake_tx_prepared(smc); + } + +out: + return rc; +} + +int smc_tx_sndbuf_nonempty(struct smc_connection *conn) +{ + int rc; + + /* This make sure only one can send simultaneously to prevent wasting + * of CPU and CDC slot. + * Record whether someone has tried to push while we are pushing. + */ + if (atomic_inc_return(&conn->tx_pushing) > 1) + return 0; + +again: + atomic_set(&conn->tx_pushing, 1); + smp_wmb(); /* Make sure tx_pushing is 1 before real send */ + rc = __smc_tx_sndbuf_nonempty(conn); + + /* We need to check whether someone else have added some data into + * the send queue and tried to push but failed after the atomic_set() + * when we are pushing. + * If so, we need to push again to prevent those data hang in the send + * queue. + */ + if (unlikely(!atomic_dec_and_test(&conn->tx_pushing))) + goto again; + + return rc; +} + +/* Wakeup sndbuf consumers from process context + * since there is more data to transmit. The caller + * must hold sock lock. + */ +void smc_tx_pending(struct smc_connection *conn) +{ + struct smc_sock *smc = container_of(conn, struct smc_sock, conn); + int rc; + + if (smc->sk.sk_err) + return; + + 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; +} + +/* Wakeup sndbuf consumers from process context + * since there is more data to transmit in locked + * sock. + */ +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); + + lock_sock(&smc->sk); + smc_tx_pending(conn); + release_sock(&smc->sk); +} + +void smc_tx_consumer_update(struct smc_connection *conn, bool force) +{ + union smc_host_cursor cfed, cons, prod; + int sender_free = conn->rmb_desc->len; + int to_confirm; + + smc_curs_copy(&cons, &conn->local_tx_ctrl.cons, conn); + smc_curs_copy(&cfed, &conn->rx_curs_confirmed, conn); + to_confirm = smc_curs_diff(conn->rmb_desc->len, &cfed, &cons); + if (to_confirm > conn->rmbe_update_limit) { + smc_curs_copy(&prod, &conn->local_rx_ctrl.prod, conn); + sender_free = conn->rmb_desc->len - + smc_curs_diff_large(conn->rmb_desc->len, + &cfed, &prod); + } + + if (conn->local_rx_ctrl.prod_flags.cons_curs_upd_req || + force || + ((to_confirm > conn->rmbe_update_limit) && + ((sender_free <= (conn->rmb_desc->len / 2)) || + conn->local_rx_ctrl.prod_flags.write_blocked))) { + if (conn->killed || + conn->local_rx_ctrl.conn_state_flags.peer_conn_abort) + return; + if ((smc_cdc_get_slot_and_msg_send(conn) < 0) && + !conn->killed) { + queue_delayed_work(conn->lgr->tx_wq, &conn->tx_work, + SMC_TX_WORK_DELAY); + return; + } + } + 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! */ +void smc_tx_init(struct smc_sock *smc) +{ + smc->sk.sk_write_space = smc_tx_write_space; +} |