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linux-sg2042/net/rxrpc/conn_client.c

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rxrpc: Use IDR to allocate client conn IDs on a machine-wide basis Use the IDR facility to allocate client connection IDs on a machine-wide basis so that each client connection has a unique identifier. When the connection ID space wraps, we advance the epoch by 1, thereby effectively having a 62-bit ID space. The IDR facility is then used to look up client connections during incoming packet routing instead of using an rbtree rooted on the transport. This change allows for the removal of the transport in the future and also means that client connections can be looked up directly in the data-ready handler by connection ID. The ID management code is placed in a new file, conn-client.c, to which all the client connection-specific code will eventually move. Note that the IDR tree gets very expensive on memory if the connection IDs are widely scattered throughout the number space, so we shall need to retire connections that have, say, an ID more than four times the maximum number of client conns away from the current allocation point to try and keep the IDs concentrated. We will also need to retire connections from an old epoch. Also note that, for the moment, a pointer to the transport has to be passed through into the ID allocation function so that we can take a BH lock to prevent a locking issue against in-BH lookup of client connections. This will go away later when RCU is used for server connections also. Signed-off-by: David Howells <dhowells@redhat.com>
2016-04-04 21:00:37 +08:00
/* Client connection-specific management code.
*
* Copyright (C) 2016 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public Licence
* as published by the Free Software Foundation; either version
* 2 of the Licence, or (at your option) any later version.
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/slab.h>
#include <linux/idr.h>
#include <linux/timer.h>
#include "ar-internal.h"
/*
* We use machine-unique IDs for our client connections.
*/
DEFINE_IDR(rxrpc_client_conn_ids);
static DEFINE_SPINLOCK(rxrpc_conn_id_lock);
/*
* Get a connection ID and epoch for a client connection from the global pool.
* The connection struct pointer is then recorded in the idr radix tree. The
* epoch is changed if this wraps.
*
* TODO: The IDR tree gets very expensive on memory if the connection IDs are
* widely scattered throughout the number space, so we shall need to retire
* connections that have, say, an ID more than four times the maximum number of
* client conns away from the current allocation point to try and keep the IDs
* concentrated. We will also need to retire connections from an old epoch.
*/
rxrpc: Split client connection code out into its own file Split the client-specific connection code out into its own file. It will behave somewhat differently from the service-specific connection code, so it makes sense to separate them. Signed-off-by: David Howells <dhowells@redhat.com>
2016-04-04 21:00:40 +08:00
static int rxrpc_get_client_connection_id(struct rxrpc_connection *conn,
gfp_t gfp)
rxrpc: Use IDR to allocate client conn IDs on a machine-wide basis Use the IDR facility to allocate client connection IDs on a machine-wide basis so that each client connection has a unique identifier. When the connection ID space wraps, we advance the epoch by 1, thereby effectively having a 62-bit ID space. The IDR facility is then used to look up client connections during incoming packet routing instead of using an rbtree rooted on the transport. This change allows for the removal of the transport in the future and also means that client connections can be looked up directly in the data-ready handler by connection ID. The ID management code is placed in a new file, conn-client.c, to which all the client connection-specific code will eventually move. Note that the IDR tree gets very expensive on memory if the connection IDs are widely scattered throughout the number space, so we shall need to retire connections that have, say, an ID more than four times the maximum number of client conns away from the current allocation point to try and keep the IDs concentrated. We will also need to retire connections from an old epoch. Also note that, for the moment, a pointer to the transport has to be passed through into the ID allocation function so that we can take a BH lock to prevent a locking issue against in-BH lookup of client connections. This will go away later when RCU is used for server connections also. Signed-off-by: David Howells <dhowells@redhat.com>
2016-04-04 21:00:37 +08:00
{
u32 epoch;
int id;
_enter("");
idr_preload(gfp);
spin_lock(&rxrpc_conn_id_lock);
epoch = rxrpc_epoch;
/* We could use idr_alloc_cyclic() here, but we really need to know
* when the thing wraps so that we can advance the epoch.
*/
if (rxrpc_client_conn_ids.cur == 0)
rxrpc_client_conn_ids.cur = 1;
id = idr_alloc(&rxrpc_client_conn_ids, conn,
rxrpc_client_conn_ids.cur, 0x40000000, GFP_NOWAIT);
if (id < 0) {
if (id != -ENOSPC)
goto error;
id = idr_alloc(&rxrpc_client_conn_ids, conn,
1, 0x40000000, GFP_NOWAIT);
if (id < 0)
goto error;
epoch++;
rxrpc_epoch = epoch;
}
rxrpc_client_conn_ids.cur = id + 1;
spin_unlock(&rxrpc_conn_id_lock);
idr_preload_end();
conn->proto.epoch = epoch;
conn->proto.cid = id << RXRPC_CIDSHIFT;
set_bit(RXRPC_CONN_HAS_IDR, &conn->flags);
_leave(" [CID %x:%x]", epoch, conn->proto.cid);
return 0;
error:
spin_unlock(&rxrpc_conn_id_lock);
idr_preload_end();
_leave(" = %d", id);
return id;
}
/*
* Release a connection ID for a client connection from the global pool.
*/
rxrpc: Maintain an extra ref on a conn for the cache list Overhaul the usage count accounting for the rxrpc_connection struct to make it easier to implement RCU access from the data_ready handler. The problem is that currently we're using a lock to prevent the garbage collector from trying to clean up a connection that we're contemplating unidling. We could just stick incoming packets on the connection we find, but we've then got a problem that we may race when dispatching a work item to process it as we need to give that a ref to prevent the rxrpc_connection struct from disappearing in the meantime. Further, incoming packets may get discarded if attached to an rxrpc_connection struct that is going away. Whilst this is not a total disaster - the client will presumably resend - it would delay processing of the call. This would affect the AFS client filesystem's service manager operation. To this end: (1) We now maintain an extra count on the connection usage count whilst it is on the connection list. This mean it is not in use when its refcount is 1. (2) When trying to reuse an old connection, we only increment the refcount if it is greater than 0. If it is 0, we replace it in the tree with a new candidate connection. (3) Two connection flags are added to indicate whether or not a connection is in the local's client connection tree (used by sendmsg) or the peer's service connection tree (used by data_ready). This makes sure that we don't try and remove a connection if it got replaced. The flags are tested under lock with the removal operation to prevent the reaper from killing the rxrpc_connection struct whilst someone else is trying to effect a replacement. This could probably be alleviated by using memory barriers between the flag set/test and the rb_tree ops. The rb_tree op would still need to be under the lock, however. (4) When trying to reap an old connection, we try to flip the usage count from 1 to 0. If it's not 1 at that point, then it must've come back to life temporarily and we ignore it. Signed-off-by: David Howells <dhowells@redhat.com>
2016-06-30 17:45:22 +08:00
static void rxrpc_put_client_connection_id(struct rxrpc_connection *conn)
rxrpc: Use IDR to allocate client conn IDs on a machine-wide basis Use the IDR facility to allocate client connection IDs on a machine-wide basis so that each client connection has a unique identifier. When the connection ID space wraps, we advance the epoch by 1, thereby effectively having a 62-bit ID space. The IDR facility is then used to look up client connections during incoming packet routing instead of using an rbtree rooted on the transport. This change allows for the removal of the transport in the future and also means that client connections can be looked up directly in the data-ready handler by connection ID. The ID management code is placed in a new file, conn-client.c, to which all the client connection-specific code will eventually move. Note that the IDR tree gets very expensive on memory if the connection IDs are widely scattered throughout the number space, so we shall need to retire connections that have, say, an ID more than four times the maximum number of client conns away from the current allocation point to try and keep the IDs concentrated. We will also need to retire connections from an old epoch. Also note that, for the moment, a pointer to the transport has to be passed through into the ID allocation function so that we can take a BH lock to prevent a locking issue against in-BH lookup of client connections. This will go away later when RCU is used for server connections also. Signed-off-by: David Howells <dhowells@redhat.com>
2016-04-04 21:00:37 +08:00
{
if (test_bit(RXRPC_CONN_HAS_IDR, &conn->flags)) {
spin_lock(&rxrpc_conn_id_lock);
idr_remove(&rxrpc_client_conn_ids,
conn->proto.cid >> RXRPC_CIDSHIFT);
spin_unlock(&rxrpc_conn_id_lock);
}
}
rxrpc: Check that the client conns cache is empty before module removal Check that the client conns cache is empty before module removal and bug if not, listing any offending connections that are still present. Unfortunately, if there are connections still around, then the transport socket is still unexpectedly open and active, so we can't just unallocate the connections. Signed-off-by: David Howells <dhowells@redhat.com>
2016-06-27 17:32:02 +08:00
/*
* Destroy the client connection ID tree.
*/
void rxrpc_destroy_client_conn_ids(void)
{
struct rxrpc_connection *conn;
int id;
if (!idr_is_empty(&rxrpc_client_conn_ids)) {
idr_for_each_entry(&rxrpc_client_conn_ids, conn, id) {
pr_err("AF_RXRPC: Leaked client conn %p {%d}\n",
conn, atomic_read(&conn->usage));
}
BUG();
}
idr_destroy(&rxrpc_client_conn_ids);
}
rxrpc: Split client connection code out into its own file Split the client-specific connection code out into its own file. It will behave somewhat differently from the service-specific connection code, so it makes sense to separate them. Signed-off-by: David Howells <dhowells@redhat.com>
2016-04-04 21:00:40 +08:00
/*
* Allocate a client connection. The caller must take care to clear any
* padding bytes in *cp.
*/
static struct rxrpc_connection *
rxrpc_alloc_client_connection(struct rxrpc_conn_parameters *cp, gfp_t gfp)
{
struct rxrpc_connection *conn;
int ret;
_enter("");
conn = rxrpc_alloc_connection(gfp);
if (!conn) {
_leave(" = -ENOMEM");
return ERR_PTR(-ENOMEM);
}
conn->params = *cp;
conn->out_clientflag = RXRPC_CLIENT_INITIATED;
conn->state = RXRPC_CONN_CLIENT;
ret = rxrpc_get_client_connection_id(conn, gfp);
if (ret < 0)
goto error_0;
ret = rxrpc_init_client_conn_security(conn);
if (ret < 0)
goto error_1;
ret = conn->security->prime_packet_security(conn);
if (ret < 0)
goto error_2;
write_lock(&rxrpc_connection_lock);
list_add_tail(&conn->link, &rxrpc_connections);
write_unlock(&rxrpc_connection_lock);
/* We steal the caller's peer ref. */
cp->peer = NULL;
rxrpc_get_local(conn->params.local);
key_get(conn->params.key);
_leave(" = %p", conn);
return conn;
error_2:
conn->security->clear(conn);
error_1:
rxrpc_put_client_connection_id(conn);
error_0:
kfree(conn);
_leave(" = %d", ret);
return ERR_PTR(ret);
}
/*
* find a connection for a call
* - called in process context with IRQs enabled
*/
int rxrpc_connect_call(struct rxrpc_call *call,
struct rxrpc_conn_parameters *cp,
struct sockaddr_rxrpc *srx,
gfp_t gfp)
{
struct rxrpc_connection *conn, *candidate = NULL;
struct rxrpc_local *local = cp->local;
struct rb_node *p, **pp, *parent;
long diff;
int chan;
DECLARE_WAITQUEUE(myself, current);
_enter("{%d,%lx},", call->debug_id, call->user_call_ID);
cp->peer = rxrpc_lookup_peer(cp->local, srx, gfp);
if (!cp->peer)
return -ENOMEM;
if (!cp->exclusive) {
/* Search for a existing client connection unless this is going
* to be a connection that's used exclusively for a single call.
*/
_debug("search 1");
spin_lock(&local->client_conns_lock);
p = local->client_conns.rb_node;
while (p) {
conn = rb_entry(p, struct rxrpc_connection, client_node);
#define cmp(X) ((long)conn->params.X - (long)cp->X)
diff = (cmp(peer) ?:
cmp(key) ?:
cmp(security_level));
if (diff < 0)
p = p->rb_left;
else if (diff > 0)
p = p->rb_right;
else
goto found_extant_conn;
}
spin_unlock(&local->client_conns_lock);
}
/* We didn't find a connection or we want an exclusive one. */
_debug("get new conn");
candidate = rxrpc_alloc_client_connection(cp, gfp);
if (!candidate) {
_leave(" = -ENOMEM");
return -ENOMEM;
}
if (cp->exclusive) {
/* Assign the call on an exclusive connection to channel 0 and
* don't add the connection to the endpoint's shareable conn
* lookup tree.
*/
_debug("exclusive chan 0");
conn = candidate;
atomic_set(&conn->avail_chans, RXRPC_MAXCALLS - 1);
spin_lock(&conn->channel_lock);
chan = 0;
goto found_channel;
}
/* We need to redo the search before attempting to add a new connection
* lest we race with someone else adding a conflicting instance.
*/
_debug("search 2");
spin_lock(&local->client_conns_lock);
pp = &local->client_conns.rb_node;
parent = NULL;
while (*pp) {
parent = *pp;
conn = rb_entry(parent, struct rxrpc_connection, client_node);
diff = (cmp(peer) ?:
cmp(key) ?:
cmp(security_level));
if (diff < 0)
pp = &(*pp)->rb_left;
else if (diff > 0)
pp = &(*pp)->rb_right;
else
goto found_extant_conn;
}
/* The second search also failed; simply add the new connection with
* the new call in channel 0. Note that we need to take the channel
* lock before dropping the client conn lock.
*/
_debug("new conn");
rxrpc: Maintain an extra ref on a conn for the cache list Overhaul the usage count accounting for the rxrpc_connection struct to make it easier to implement RCU access from the data_ready handler. The problem is that currently we're using a lock to prevent the garbage collector from trying to clean up a connection that we're contemplating unidling. We could just stick incoming packets on the connection we find, but we've then got a problem that we may race when dispatching a work item to process it as we need to give that a ref to prevent the rxrpc_connection struct from disappearing in the meantime. Further, incoming packets may get discarded if attached to an rxrpc_connection struct that is going away. Whilst this is not a total disaster - the client will presumably resend - it would delay processing of the call. This would affect the AFS client filesystem's service manager operation. To this end: (1) We now maintain an extra count on the connection usage count whilst it is on the connection list. This mean it is not in use when its refcount is 1. (2) When trying to reuse an old connection, we only increment the refcount if it is greater than 0. If it is 0, we replace it in the tree with a new candidate connection. (3) Two connection flags are added to indicate whether or not a connection is in the local's client connection tree (used by sendmsg) or the peer's service connection tree (used by data_ready). This makes sure that we don't try and remove a connection if it got replaced. The flags are tested under lock with the removal operation to prevent the reaper from killing the rxrpc_connection struct whilst someone else is trying to effect a replacement. This could probably be alleviated by using memory barriers between the flag set/test and the rb_tree ops. The rb_tree op would still need to be under the lock, however. (4) When trying to reap an old connection, we try to flip the usage count from 1 to 0. If it's not 1 at that point, then it must've come back to life temporarily and we ignore it. Signed-off-by: David Howells <dhowells@redhat.com>
2016-06-30 17:45:22 +08:00
set_bit(RXRPC_CONN_IN_CLIENT_CONNS, &candidate->flags);
rb_link_node(&candidate->client_node, parent, pp);
rb_insert_color(&candidate->client_node, &local->client_conns);
attached:
rxrpc: Split client connection code out into its own file Split the client-specific connection code out into its own file. It will behave somewhat differently from the service-specific connection code, so it makes sense to separate them. Signed-off-by: David Howells <dhowells@redhat.com>
2016-04-04 21:00:40 +08:00
conn = candidate;
candidate = NULL;
atomic_set(&conn->avail_chans, RXRPC_MAXCALLS - 1);
spin_lock(&conn->channel_lock);
spin_unlock(&local->client_conns_lock);
chan = 0;
found_channel:
_debug("found chan");
call->conn = conn;
call->channel = chan;
call->epoch = conn->proto.epoch;
call->cid = conn->proto.cid | chan;
call->call_id = ++conn->channels[chan].call_counter;
conn->channels[chan].call_id = call->call_id;
rcu_assign_pointer(conn->channels[chan].call, call);
_net("CONNECT call %d on conn %d", call->debug_id, conn->debug_id);
spin_unlock(&conn->channel_lock);
rxrpc_put_peer(cp->peer);
cp->peer = NULL;
_leave(" = %p {u=%d}", conn, atomic_read(&conn->usage));
return 0;
rxrpc: Maintain an extra ref on a conn for the cache list Overhaul the usage count accounting for the rxrpc_connection struct to make it easier to implement RCU access from the data_ready handler. The problem is that currently we're using a lock to prevent the garbage collector from trying to clean up a connection that we're contemplating unidling. We could just stick incoming packets on the connection we find, but we've then got a problem that we may race when dispatching a work item to process it as we need to give that a ref to prevent the rxrpc_connection struct from disappearing in the meantime. Further, incoming packets may get discarded if attached to an rxrpc_connection struct that is going away. Whilst this is not a total disaster - the client will presumably resend - it would delay processing of the call. This would affect the AFS client filesystem's service manager operation. To this end: (1) We now maintain an extra count on the connection usage count whilst it is on the connection list. This mean it is not in use when its refcount is 1. (2) When trying to reuse an old connection, we only increment the refcount if it is greater than 0. If it is 0, we replace it in the tree with a new candidate connection. (3) Two connection flags are added to indicate whether or not a connection is in the local's client connection tree (used by sendmsg) or the peer's service connection tree (used by data_ready). This makes sure that we don't try and remove a connection if it got replaced. The flags are tested under lock with the removal operation to prevent the reaper from killing the rxrpc_connection struct whilst someone else is trying to effect a replacement. This could probably be alleviated by using memory barriers between the flag set/test and the rb_tree ops. The rb_tree op would still need to be under the lock, however. (4) When trying to reap an old connection, we try to flip the usage count from 1 to 0. If it's not 1 at that point, then it must've come back to life temporarily and we ignore it. Signed-off-by: David Howells <dhowells@redhat.com>
2016-06-30 17:45:22 +08:00
/* We found a potentially suitable connection already in existence. If
* we can reuse it (ie. its usage count hasn't been reduced to 0 by the
* reaper), discard any candidate we may have allocated, and try to get
* a channel on this one, otherwise we have to replace it.
rxrpc: Split client connection code out into its own file Split the client-specific connection code out into its own file. It will behave somewhat differently from the service-specific connection code, so it makes sense to separate them. Signed-off-by: David Howells <dhowells@redhat.com>
2016-04-04 21:00:40 +08:00
*/
found_extant_conn:
_debug("found conn");
rxrpc: Maintain an extra ref on a conn for the cache list Overhaul the usage count accounting for the rxrpc_connection struct to make it easier to implement RCU access from the data_ready handler. The problem is that currently we're using a lock to prevent the garbage collector from trying to clean up a connection that we're contemplating unidling. We could just stick incoming packets on the connection we find, but we've then got a problem that we may race when dispatching a work item to process it as we need to give that a ref to prevent the rxrpc_connection struct from disappearing in the meantime. Further, incoming packets may get discarded if attached to an rxrpc_connection struct that is going away. Whilst this is not a total disaster - the client will presumably resend - it would delay processing of the call. This would affect the AFS client filesystem's service manager operation. To this end: (1) We now maintain an extra count on the connection usage count whilst it is on the connection list. This mean it is not in use when its refcount is 1. (2) When trying to reuse an old connection, we only increment the refcount if it is greater than 0. If it is 0, we replace it in the tree with a new candidate connection. (3) Two connection flags are added to indicate whether or not a connection is in the local's client connection tree (used by sendmsg) or the peer's service connection tree (used by data_ready). This makes sure that we don't try and remove a connection if it got replaced. The flags are tested under lock with the removal operation to prevent the reaper from killing the rxrpc_connection struct whilst someone else is trying to effect a replacement. This could probably be alleviated by using memory barriers between the flag set/test and the rb_tree ops. The rb_tree op would still need to be under the lock, however. (4) When trying to reap an old connection, we try to flip the usage count from 1 to 0. If it's not 1 at that point, then it must've come back to life temporarily and we ignore it. Signed-off-by: David Howells <dhowells@redhat.com>
2016-06-30 17:45:22 +08:00
if (!rxrpc_get_connection_maybe(conn)) {
set_bit(RXRPC_CONN_IN_CLIENT_CONNS, &candidate->flags);
rb_replace_node(&conn->client_node,
&candidate->client_node,
&local->client_conns);
clear_bit(RXRPC_CONN_IN_CLIENT_CONNS, &conn->flags);
goto attached;
}
rxrpc: Split client connection code out into its own file Split the client-specific connection code out into its own file. It will behave somewhat differently from the service-specific connection code, so it makes sense to separate them. Signed-off-by: David Howells <dhowells@redhat.com>
2016-04-04 21:00:40 +08:00
spin_unlock(&local->client_conns_lock);
rxrpc_put_connection(candidate);
if (!atomic_add_unless(&conn->avail_chans, -1, 0)) {
if (!gfpflags_allow_blocking(gfp)) {
rxrpc_put_connection(conn);
_leave(" = -EAGAIN");
return -EAGAIN;
}
add_wait_queue(&conn->channel_wq, &myself);
for (;;) {
set_current_state(TASK_INTERRUPTIBLE);
if (atomic_add_unless(&conn->avail_chans, -1, 0))
break;
if (signal_pending(current))
goto interrupted;
schedule();
}
remove_wait_queue(&conn->channel_wq, &myself);
__set_current_state(TASK_RUNNING);
}
/* The connection allegedly now has a free channel and we can now
* attach the call to it.
*/
spin_lock(&conn->channel_lock);
for (chan = 0; chan < RXRPC_MAXCALLS; chan++)
if (!conn->channels[chan].call)
goto found_channel;
BUG();
interrupted:
remove_wait_queue(&conn->channel_wq, &myself);
__set_current_state(TASK_RUNNING);
rxrpc_put_connection(conn);
rxrpc_put_peer(cp->peer);
cp->peer = NULL;
_leave(" = -ERESTARTSYS");
return -ERESTARTSYS;
}
rxrpc: Maintain an extra ref on a conn for the cache list Overhaul the usage count accounting for the rxrpc_connection struct to make it easier to implement RCU access from the data_ready handler. The problem is that currently we're using a lock to prevent the garbage collector from trying to clean up a connection that we're contemplating unidling. We could just stick incoming packets on the connection we find, but we've then got a problem that we may race when dispatching a work item to process it as we need to give that a ref to prevent the rxrpc_connection struct from disappearing in the meantime. Further, incoming packets may get discarded if attached to an rxrpc_connection struct that is going away. Whilst this is not a total disaster - the client will presumably resend - it would delay processing of the call. This would affect the AFS client filesystem's service manager operation. To this end: (1) We now maintain an extra count on the connection usage count whilst it is on the connection list. This mean it is not in use when its refcount is 1. (2) When trying to reuse an old connection, we only increment the refcount if it is greater than 0. If it is 0, we replace it in the tree with a new candidate connection. (3) Two connection flags are added to indicate whether or not a connection is in the local's client connection tree (used by sendmsg) or the peer's service connection tree (used by data_ready). This makes sure that we don't try and remove a connection if it got replaced. The flags are tested under lock with the removal operation to prevent the reaper from killing the rxrpc_connection struct whilst someone else is trying to effect a replacement. This could probably be alleviated by using memory barriers between the flag set/test and the rb_tree ops. The rb_tree op would still need to be under the lock, however. (4) When trying to reap an old connection, we try to flip the usage count from 1 to 0. If it's not 1 at that point, then it must've come back to life temporarily and we ignore it. Signed-off-by: David Howells <dhowells@redhat.com>
2016-06-30 17:45:22 +08:00
/*
* Remove a client connection from the local endpoint's tree, thereby removing
* it as a target for reuse for new client calls.
*/
void rxrpc_unpublish_client_conn(struct rxrpc_connection *conn)
{
struct rxrpc_local *local = conn->params.local;
spin_lock(&local->client_conns_lock);
if (test_and_clear_bit(RXRPC_CONN_IN_CLIENT_CONNS, &conn->flags))
rb_erase(&conn->client_node, &local->client_conns);
spin_unlock(&local->client_conns_lock);
rxrpc_put_client_connection_id(conn);
}