linux/net/rds/loop.c
Andy Grover 2e7b3b9945 RDS: Fix congestion issues for loopback
We have two kinds of loopback: software (via loop transport)
and hardware (via IB). sw is used for 127.0.0.1, and doesn't
support rdma ops. hw is used for sends to local device IPs,
and supports rdma. Both are used in different cases.

For both of these, when there is a congestion map update, we
want to call rds_cong_map_updated() but not actually send
anything -- since loopback local and foreign congestion maps
point to the same spot, they're already in sync.

The old code never called sw loop's xmit_cong_map(),so
rds_cong_map_updated() wasn't being called for it. sw loop
ports would not work right with the congestion monitor.

Fixing that meant that hw loopback now would send congestion maps
to itself. This is also undesirable (racy), so we check for this
case in the ib-specific xmit code.

Signed-off-by: Andy Grover <andy.grover@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2010-03-16 21:16:55 -07:00

181 lines
5.4 KiB
C

/*
* Copyright (c) 2006 Oracle. All rights reserved.
*
* This software is available to you under a choice of one of two
* licenses. You may choose to be licensed under the terms of the GNU
* General Public License (GPL) Version 2, available from the file
* COPYING in the main directory of this source tree, or the
* OpenIB.org BSD license below:
*
* Redistribution and use in source and binary forms, with or
* without modification, are permitted provided that the following
* conditions are met:
*
* - Redistributions of source code must retain the above
* copyright notice, this list of conditions and the following
* disclaimer.
*
* - Redistributions in binary form must reproduce the above
* copyright notice, this list of conditions and the following
* disclaimer in the documentation and/or other materials
* provided with the distribution.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
* BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
* ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*
*/
#include <linux/kernel.h>
#include <linux/in.h>
#include "rds.h"
#include "loop.h"
static DEFINE_SPINLOCK(loop_conns_lock);
static LIST_HEAD(loop_conns);
/*
* This 'loopback' transport is a special case for flows that originate
* and terminate on the same machine.
*
* Connection build-up notices if the destination address is thought of
* as a local address by a transport. At that time it decides to use the
* loopback transport instead of the bound transport of the sending socket.
*
* The loopback transport's sending path just hands the sent rds_message
* straight to the receiving path via an embedded rds_incoming.
*/
/*
* Usually a message transits both the sender and receiver's conns as it
* flows to the receiver. In the loopback case, though, the receive path
* is handed the sending conn so the sense of the addresses is reversed.
*/
static int rds_loop_xmit(struct rds_connection *conn, struct rds_message *rm,
unsigned int hdr_off, unsigned int sg,
unsigned int off)
{
BUG_ON(hdr_off || sg || off);
rds_inc_init(&rm->m_inc, conn, conn->c_laddr);
rds_message_addref(rm); /* for the inc */
rds_recv_incoming(conn, conn->c_laddr, conn->c_faddr, &rm->m_inc,
GFP_KERNEL, KM_USER0);
rds_send_drop_acked(conn, be64_to_cpu(rm->m_inc.i_hdr.h_sequence),
NULL);
rds_inc_put(&rm->m_inc);
return sizeof(struct rds_header) + be32_to_cpu(rm->m_inc.i_hdr.h_len);
}
static int rds_loop_xmit_cong_map(struct rds_connection *conn,
struct rds_cong_map *map,
unsigned long offset)
{
BUG_ON(offset);
BUG_ON(map != conn->c_lcong);
rds_cong_map_updated(conn->c_fcong, ~(u64) 0);
return sizeof(struct rds_header) + RDS_CONG_MAP_BYTES;
}
/* we need to at least give the thread something to succeed */
static int rds_loop_recv(struct rds_connection *conn)
{
return 0;
}
struct rds_loop_connection {
struct list_head loop_node;
struct rds_connection *conn;
};
/*
* Even the loopback transport needs to keep track of its connections,
* so it can call rds_conn_destroy() on them on exit. N.B. there are
* 1+ loopback addresses (127.*.*.*) so it's not a bug to have
* multiple loopback conns allocated, although rather useless.
*/
static int rds_loop_conn_alloc(struct rds_connection *conn, gfp_t gfp)
{
struct rds_loop_connection *lc;
unsigned long flags;
lc = kzalloc(sizeof(struct rds_loop_connection), GFP_KERNEL);
if (lc == NULL)
return -ENOMEM;
INIT_LIST_HEAD(&lc->loop_node);
lc->conn = conn;
conn->c_transport_data = lc;
spin_lock_irqsave(&loop_conns_lock, flags);
list_add_tail(&lc->loop_node, &loop_conns);
spin_unlock_irqrestore(&loop_conns_lock, flags);
return 0;
}
static void rds_loop_conn_free(void *arg)
{
struct rds_loop_connection *lc = arg;
rdsdebug("lc %p\n", lc);
list_del(&lc->loop_node);
kfree(lc);
}
static int rds_loop_conn_connect(struct rds_connection *conn)
{
rds_connect_complete(conn);
return 0;
}
static void rds_loop_conn_shutdown(struct rds_connection *conn)
{
}
void rds_loop_exit(void)
{
struct rds_loop_connection *lc, *_lc;
LIST_HEAD(tmp_list);
/* avoid calling conn_destroy with irqs off */
spin_lock_irq(&loop_conns_lock);
list_splice(&loop_conns, &tmp_list);
INIT_LIST_HEAD(&loop_conns);
spin_unlock_irq(&loop_conns_lock);
list_for_each_entry_safe(lc, _lc, &tmp_list, loop_node) {
WARN_ON(lc->conn->c_passive);
rds_conn_destroy(lc->conn);
}
}
/*
* This is missing .xmit_* because loop doesn't go through generic
* rds_send_xmit() and doesn't call rds_recv_incoming(). .listen_stop and
* .laddr_check are missing because transport.c doesn't iterate over
* rds_loop_transport.
*/
struct rds_transport rds_loop_transport = {
.xmit = rds_loop_xmit,
.xmit_cong_map = rds_loop_xmit_cong_map,
.recv = rds_loop_recv,
.conn_alloc = rds_loop_conn_alloc,
.conn_free = rds_loop_conn_free,
.conn_connect = rds_loop_conn_connect,
.conn_shutdown = rds_loop_conn_shutdown,
.inc_copy_to_user = rds_message_inc_copy_to_user,
.inc_purge = rds_message_inc_purge,
.inc_free = rds_message_inc_free,
.t_name = "loopback",
};