linux/net/smc/smc_rx.c
Ursula Braun 71c125c3f2 smc: cleanup close checking during data receival
When waiting for data to be received it must be checked if the
peer signals shutdown. The SMC code uses two different checks
for this purpose, even though just one check is sufficient.
This patch removes the superfluous test for SOCK_DONE.

Signed-off-by: Ursula Braun <ubraun@linux.vnet.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2017-12-07 15:03:12 -05:00

222 lines
6.1 KiB
C

// SPDX-License-Identifier: GPL-2.0
/*
* Shared Memory Communications over RDMA (SMC-R) and RoCE
*
* Manage RMBE
* copy new RMBE data into user space
*
* Copyright IBM Corp. 2016
*
* Author(s): Ursula Braun <ubraun@linux.vnet.ibm.com>
*/
#include <linux/net.h>
#include <linux/rcupdate.h>
#include <linux/sched/signal.h>
#include <net/sock.h>
#include "smc.h"
#include "smc_core.h"
#include "smc_cdc.h"
#include "smc_tx.h" /* smc_tx_consumer_update() */
#include "smc_rx.h"
/* callback implementation for sk.sk_data_ready()
* to wakeup rcvbuf consumers that blocked with smc_rx_wait_data().
* indirectly called by smc_cdc_msg_recv_action().
*/
static void smc_rx_data_ready(struct sock *sk)
{
struct socket_wq *wq;
/* derived from sock_def_readable() */
/* called already in smc_listen_work() */
rcu_read_lock();
wq = rcu_dereference(sk->sk_wq);
if (skwq_has_sleeper(wq))
wake_up_interruptible_sync_poll(&wq->wait, POLLIN | POLLPRI |
POLLRDNORM | POLLRDBAND);
sk_wake_async(sk, SOCK_WAKE_WAITD, POLL_IN);
if ((sk->sk_shutdown == SHUTDOWN_MASK) ||
(sk->sk_state == SMC_CLOSED))
sk_wake_async(sk, SOCK_WAKE_WAITD, POLL_HUP);
rcu_read_unlock();
}
/* blocks rcvbuf consumer until >=len bytes available or timeout or interrupted
* @smc smc socket
* @timeo pointer to max seconds to wait, pointer to value 0 for no timeout
* Returns:
* 1 if at least 1 byte available in rcvbuf or if socket error/shutdown.
* 0 otherwise (nothing in rcvbuf nor timeout, e.g. interrupted).
*/
static int smc_rx_wait_data(struct smc_sock *smc, long *timeo)
{
DEFINE_WAIT_FUNC(wait, woken_wake_function);
struct smc_connection *conn = &smc->conn;
struct sock *sk = &smc->sk;
int rc;
if (atomic_read(&conn->bytes_to_rcv))
return 1;
sk_set_bit(SOCKWQ_ASYNC_WAITDATA, sk);
add_wait_queue(sk_sleep(sk), &wait);
rc = sk_wait_event(sk, timeo,
sk->sk_err ||
sk->sk_shutdown & RCV_SHUTDOWN ||
atomic_read(&conn->bytes_to_rcv) ||
smc_cdc_rxed_any_close_or_senddone(conn),
&wait);
remove_wait_queue(sk_sleep(sk), &wait);
sk_clear_bit(SOCKWQ_ASYNC_WAITDATA, sk);
return rc;
}
/* rcvbuf consumer: main API called by socket layer.
* called under sk lock.
*/
int smc_rx_recvmsg(struct smc_sock *smc, struct msghdr *msg, size_t len,
int flags)
{
size_t copylen, read_done = 0, read_remaining = len;
size_t chunk_len, chunk_off, chunk_len_sum;
struct smc_connection *conn = &smc->conn;
union smc_host_cursor cons;
int readable, chunk;
char *rcvbuf_base;
struct sock *sk;
long timeo;
int target; /* Read at least these many bytes */
int rc;
if (unlikely(flags & MSG_ERRQUEUE))
return -EINVAL; /* future work for sk.sk_family == AF_SMC */
if (flags & MSG_OOB)
return -EINVAL; /* future work */
sk = &smc->sk;
if (sk->sk_state == SMC_LISTEN)
return -ENOTCONN;
timeo = sock_rcvtimeo(sk, flags & MSG_DONTWAIT);
target = sock_rcvlowat(sk, flags & MSG_WAITALL, len);
msg->msg_namelen = 0;
/* we currently use 1 RMBE per RMB, so RMBE == RMB base addr */
rcvbuf_base = conn->rmb_desc->cpu_addr;
do { /* while (read_remaining) */
if (read_done >= target)
break;
if (atomic_read(&conn->bytes_to_rcv))
goto copy;
if (read_done) {
if (sk->sk_err ||
sk->sk_state == SMC_CLOSED ||
sk->sk_shutdown & RCV_SHUTDOWN ||
!timeo ||
signal_pending(current) ||
smc_cdc_rxed_any_close_or_senddone(conn) ||
conn->local_tx_ctrl.conn_state_flags.
peer_conn_abort)
break;
} else {
if (sk->sk_err) {
read_done = sock_error(sk);
break;
}
if (sk->sk_shutdown & RCV_SHUTDOWN ||
smc_cdc_rxed_any_close_or_senddone(conn) ||
conn->local_tx_ctrl.conn_state_flags.
peer_conn_abort)
break;
if (sk->sk_state == SMC_CLOSED) {
if (!sock_flag(sk, SOCK_DONE)) {
/* This occurs when user tries to read
* from never connected socket.
*/
read_done = -ENOTCONN;
break;
}
break;
}
if (signal_pending(current)) {
read_done = sock_intr_errno(timeo);
break;
}
if (!timeo)
return -EAGAIN;
}
if (!atomic_read(&conn->bytes_to_rcv)) {
smc_rx_wait_data(smc, &timeo);
continue;
}
copy:
/* initialize variables for 1st iteration of subsequent loop */
/* could be just 1 byte, even after smc_rx_wait_data above */
readable = atomic_read(&conn->bytes_to_rcv);
/* not more than what user space asked for */
copylen = min_t(size_t, read_remaining, readable);
smc_curs_write(&cons,
smc_curs_read(&conn->local_tx_ctrl.cons, conn),
conn);
/* determine chunks where to read from rcvbuf */
/* either unwrapped case, or 1st chunk of wrapped case */
chunk_len = min_t(size_t,
copylen, conn->rmbe_size - cons.count);
chunk_len_sum = chunk_len;
chunk_off = cons.count;
smc_rmb_sync_sg_for_cpu(conn);
for (chunk = 0; chunk < 2; chunk++) {
if (!(flags & MSG_TRUNC)) {
rc = memcpy_to_msg(msg, rcvbuf_base + chunk_off,
chunk_len);
if (rc) {
if (!read_done)
read_done = -EFAULT;
smc_rmb_sync_sg_for_device(conn);
goto out;
}
}
read_remaining -= chunk_len;
read_done += 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 recv ring buffer */
}
smc_rmb_sync_sg_for_device(conn);
/* update cursors */
if (!(flags & MSG_PEEK)) {
smc_curs_add(conn->rmbe_size, &cons, copylen);
/* increased in recv tasklet smc_cdc_msg_rcv() */
smp_mb__before_atomic();
atomic_sub(copylen, &conn->bytes_to_rcv);
/* guarantee 0 <= bytes_to_rcv <= rmbe_size */
smp_mb__after_atomic();
smc_curs_write(&conn->local_tx_ctrl.cons,
smc_curs_read(&cons, conn),
conn);
/* send consumer cursor update if required */
/* similar to advertising new TCP rcv_wnd if required */
smc_tx_consumer_update(conn);
}
} while (read_remaining);
out:
return read_done;
}
/* Initialize receive properties on connection establishment. NB: not __init! */
void smc_rx_init(struct smc_sock *smc)
{
smc->sk.sk_data_ready = smc_rx_data_ready;
}