linux/net/smc/smc_tx.c
Karsten Graul 8f3d65c166 net/smc: fix wait on already cleared link
There can be a race between the waiters for a tx work request buffer
and the link down processing that finally clears the link. Although
all waiters are woken up before the link is cleared there might be
waiters which did not yet get back control and are still waiting.
This results in an access to a cleared wait queue head.

Fix this by introducing atomic reference counting around the wait calls,
and wait with the link clear processing until all waiters have finished.
Move the work request layer related calls into smc_wr.c and set the
link state to INACTIVE before calling smcr_link_clear() in
smc_llc_srv_add_link().

Fixes: 15e1b99aad ("net/smc: no WR buffer wait for terminating link group")
Signed-off-by: Karsten Graul <kgraul@linux.ibm.com>
Signed-off-by: Guvenc Gulce <guvenc@linux.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2021-08-09 10:46:59 +01:00

676 lines
19 KiB
C

// 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"
#define SMC_TX_WORK_DELAY 0
#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) {
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,
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;
}
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;
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_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 ((msg->msg_flags & MSG_MORE || smc_tx_is_corked(smc)) &&
(atomic_read(&conn->sndbuf_space) >
(conn->sndbuf_desc->len >> 1)))
/* for a corked socket defer the RDMA writes if there
* is still sufficient sndbuf_space available
*/
queue_delayed_work(conn->lgr->tx_wq, &conn->tx_work,
SMC_TX_CORK_DELAY);
else
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 ISM write */
int smcd_tx_ism_write(struct smc_connection *conn, void *data, size_t len,
u32 offset, int signal)
{
struct smc_ism_position pos;
int rc;
memset(&pos, 0, sizeof(pos));
pos.token = conn->peer_token;
pos.index = conn->peer_rmbe_idx;
pos.offset = conn->tx_off + offset;
pos.signal = signal;
rc = smc_ism_write(conn->lgr->smcd, &pos, 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);
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_sge *sge =
wr_rdma_buf->wr_tx_rdma[dstchunk].wr.sg_list;
num_sges = 0;
for (srcchunk = 0; srcchunk < 2; srcchunk++) {
sge[srcchunk].addr = dma_addr + src_off;
sge[srcchunk].length = src_len;
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_rdma_buf->wr_tx_rdma[dstchunk]);
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;
rc = smc_cdc_get_free_slot(conn, link, &wr_buf, &wr_rdma_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)
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);
return rc;
}
static int smcr_tx_sndbuf_nonempty(struct smc_connection *conn)
{
struct smc_link *link = conn->lnk;
int rc = -ENOLINK;
if (!link)
return rc;
atomic_inc(&link->wr_tx_refcnt);
if (smc_link_usable(link))
rc = _smcr_tx_sndbuf_nonempty(conn);
if (atomic_dec_and_test(&link->wr_tx_refcnt))
wake_up_all(&link->wr_tx_wait);
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;
}
int smc_tx_sndbuf_nonempty(struct smc_connection *conn)
{
int rc;
if (conn->killed ||
conn->local_rx_ctrl.conn_state_flags.peer_conn_abort)
return -EPIPE; /* connection being aborted */
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 */
struct smc_sock *smc = container_of(conn, struct smc_sock,
conn);
smc_close_wake_tx_prepared(smc);
}
return rc;
}
/* Wakeup sndbuf consumers from process context
* since there is more data to transmit
*/
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);
if (smc->sk.sk_err)
goto out;
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;
out:
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;
}