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// 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_ism.h"
#include "smc_tx.h"
#define SMC_TX_WORK_DELAY HZ
#define SMC_TX_CORK_DELAY (HZ >> 2) /* 250 ms */
/***************************** 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) {
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;
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 (smc_cdc_rxed_any_close(conn)) {
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) && !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,
sk->sk_err ||
(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;
}
/* 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 (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) {
rc = smc_tx_wait(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 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;
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<
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