/* 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.
*
*
* Client connections need to be cached for a little while after they've made a
* call so as to handle retransmitted DATA packets in case the server didn't
* receive the final ACK or terminating ABORT we sent it.
*
* Client connections can be in one of a number of cache states:
*
* (1) INACTIVE - The connection is not held in any list and may not have been
* exposed to the world. If it has been previously exposed, it was
* discarded from the idle list after expiring.
*
* (2) WAITING - The connection is waiting for the number of client conns to
* drop below the maximum capacity. Calls may be in progress upon it from
* when it was active and got culled.
*
* The connection is on the rxrpc_waiting_client_conns list which is kept
* in to-be-granted order. Culled conns with waiters go to the back of
* the queue just like new conns.
*
* (3) ACTIVE - The connection has at least one call in progress upon it, it
* may freely grant available channels to new calls and calls may be
* waiting on it for channels to become available.
*
* The connection is on the rxrpc_active_client_conns list which is kept
* in activation order for culling purposes.
*
* rxrpc_nr_active_client_conns is held incremented also.
*
* (4) CULLED - The connection got summarily culled to try and free up
* capacity. Calls currently in progress on the connection are allowed to
* continue, but new calls will have to wait. There can be no waiters in
* this state - the conn would have to go to the WAITING state instead.
*
* (5) IDLE - The connection has no calls in progress upon it and must have
* been exposed to the world (ie. the EXPOSED flag must be set). When it
* expires, the EXPOSED flag is cleared and the connection transitions to
* the INACTIVE state.
*
* The connection is on the rxrpc_idle_client_conns list which is kept in
* order of how soon they'll expire.
*
* There are flags of relevance to the cache:
*
* (1) EXPOSED - The connection ID got exposed to the world. If this flag is
* set, an extra ref is added to the connection preventing it from being
* reaped when it has no calls outstanding. This flag is cleared and the
* ref dropped when a conn is discarded from the idle list.
*
* This allows us to move terminal call state retransmission to the
* connection and to discard the call immediately we think it is done
* with. It also give us a chance to reuse the connection.
*
* (2) DONT_REUSE - The connection should be discarded as soon as possible and
* should not be reused. This is set when an exclusive connection is used
* or a call ID counter overflows.
*
* The caching state may only be changed if the cache lock is held.
*
* There are two idle client connection expiry durations. If the total number
* of connections is below the reap threshold, we use the normal duration; if
* it's above, we use the fast duration.
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/slab.h>
#include <linux/idr.h>
#include <linux/timer.h>
#include "ar-internal.h"
__read_mostly unsigned int rxrpc_max_client_connections = 1000;
__read_mostly unsigned int rxrpc_reap_client_connections = 900;
__read_mostly unsigned int rxrpc_conn_idle_client_expiry = 2 * 60 * HZ;
__read_mostly unsigned int rxrpc_conn_idle_client_fast_expiry = 2 * HZ;
static unsigned int rxrpc_nr_client_conns;
static unsigned int rxrpc_nr_active_client_conns;
static __read_mostly bool rxrpc_kill_all_client_conns;
static DEFINE_SPINLOCK(rxrpc_client_conn_cache_lock);
static DEFINE_SPINLOCK(rxrpc_client_conn_discard_mutex);
static LIST_HEAD(rxrpc_waiting_client_conns);
static LIST_HEAD(rxrpc_active_client_conns);
static LIST_HEAD(rxrpc_idle_client_conns);
/*
* We use machine-unique IDs for our client connections.
*/
DEFINE_IDR(rxrpc_client_conn_ids);
static DEFINE_SPINLOCK(rxrpc_conn_id_lock);
static void rxrpc_cull_active_client_conns(void);
static void rxrpc_discard_expired_client_conns(struct work_struct *);
static DECLARE_DELAYED_WORK(rxrpc_client_conn_reap,
rxrpc_discard_expired_client_conns);
/*
* 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.
*/
static int rxrpc_get_client_connection_id(struct rxrpc_connection *conn,
gfp_t gfp)
{
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.
*/
static void rxrpc_put_client_connection_id(struct rxrpc_connection *conn)
{
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);
}
}
/*
* 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);
}
/*
* Allocate a client connection.
*/
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);
}
atomic_set(&conn->usage, 1);
if (conn->params.exclusive)
__set_bit(RXRPC_CONN_DONT_REUSE, &conn->flags);
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->proc_link, &rxrpc_connection_proc_list);
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);
}
/*
* Determine if a connection may be reused.
*/
static bool rxrpc_may_reuse_conn(struct rxrpc_connection *conn)
{
int id_cursor, id, distance, limit;
if (test_bit(RXRPC_CONN_DONT_REUSE, &conn->flags))
goto dont_reuse;
if (conn->proto.epoch != rxrpc_epoch)
goto mark_dont_reuse;
/* The IDR tree gets very expensive on memory if the connection IDs are
* widely scattered throughout the number space, so we shall want to
* kill off connections that, say, have an ID more than about four
* times the maximum number of client conns away from the current
* allocation point to try and keep the IDs concentrated.
*/
id_cursor = READ_ONCE(rxrpc_client_conn_ids.cur);
id = conn->proto.cid >> RXRPC_CIDSHIFT;
distance = id - id_cursor;
if (distance < 0)
distance = -distance;
limit = round_up(rxrpc_max_client_connections, IDR_SIZE) * 4;
if (distance > limit)
goto mark_dont_reuse;
return true;
mark_dont_reuse:
set_bit(RXRPC_CONN_DONT_REUSE, &conn->flags);
dont_reuse:
return false;
}
/*
* Create or find a client connection to use for a call.
*
* If we return with a connection, the call will be on its waiting list. It's
* left to the caller to assign a channel and wake up the call.
*/
static int rxrpc_get_client_conn(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 ret = -ENOMEM;
_enter("{%d,%lx},", call->debug_id, call->user_call_ID);
cp->peer = rxrpc_lookup_peer(cp->local, srx, gfp);
if (!cp->peer)
goto error;
/* If the connection is not meant to be exclusive, search the available
* connections to see if the connection we want to use already exists.
*/
if (!cp->exclusive) {
_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));
#undef cmp
if (diff < 0) {
p = p->rb_left;
} else if (diff > 0) {
p = p->rb_right;
} else {
if (rxrpc_may_reuse_conn(conn) &&
rxrpc_get_connection_maybe(conn))
goto found_extant_conn;
/* The connection needs replacing. It's better
* to effect that when we have something to
* replace it with so that we don't have to
* rebalance the tree twice.
*/
break;
}
}
spin_unlock(&local->client_conns_lock);
}
/* There wasn't a connection yet or we need an exclusive connection.
* We need to create a candidate and then potentially redo the search
* in case we're racing with another thread also trying to connect on a
* shareable connection.
*/
_debug("new conn");
candidate = rxrpc_alloc_client_connection(cp, gfp);
if (IS_ERR(candidate)) {
ret = PTR_ERR(candidate);
goto error_peer;
}
/* Add the call to the new connection's waiting list in case we're
* going to have to wait for the connection to come live. It's our
* connection, so we want first dibs on the channel slots. We would
* normally have to take channel_lock but we do this before anyone else
* can see the connection.
*/
list_add_tail(&call->chan_wait_link, &candidate->waiting_calls);
if (cp->exclusive) {
call->conn = candidate;
_leave(" = 0 [exclusive %d]", candidate->debug_id);
return 0;
}
/* Publish the new connection for userspace to find. We need to redo
* the search before doing this 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);
#define cmp(X) ((long)conn->params.X - (long)candidate->params.X)
diff = (cmp(peer) ?:
cmp(key) ?:
cmp(security_level));
#undef cmp
if (diff < 0) {
pp = &(*pp)->rb_left;
} else if (diff > 0) {
pp = &(*pp)->rb_right;
} else {
if (rxrpc_may_reuse_conn(conn) &&
rxrpc_get_connection_maybe(conn))
goto found_extant_conn;
/* The old connection is from an outdated epoch. */
_debug("replace conn");
clear_bit(RXRPC_CONN_IN_CLIENT_CONNS, &conn->flags);
rb_replace_node(&conn->client_node,
&candidate->client_node,
&local->client_conns);
goto candidate_published;
}
}
_debug("new conn");
rb_link_node(&candidate->client_node, parent, pp);
rb_insert_color(&candidate->client_node, &local->client_conns);
candidate_published:
set_bit(RXRPC_CONN_IN_CLIENT_CONNS, &candidate->flags);
call->conn = candidate;
spin_unlock(&local->client_conns_lock);
_leave(" = 0 [new %d]", candidate->debug_id);
return 0;
/* We come here if we found a suitable connection already in existence.
* Discard any candidate we may have allocated, and try to get a
* channel on this one.
*/
found_extant_conn:
_debug("found conn");
spin_unlock(&local->client_conns_lock);
rxrpc_put_connection(candidate);
candidate = NULL;
spin_lock(&conn->channel_lock);
call->conn = conn;
list_add(&call->chan_wait_link, &conn->waiting_calls);
spin_unlock(&conn->channel_lock);
_leave(" = 0 [extant %d]", conn->debug_id);
return 0;
error_peer:
rxrpc_put_peer(cp->peer);
cp->peer = NULL;
error:
_leave(" = %d", ret);
return ret;
}
/*
* Activate a connection.
*/
static void rxrpc_activate_conn(struct rxrpc_connection *conn)
{
conn->cache_state = RXRPC_CONN_CLIENT_ACTIVE;
rxrpc_nr_active_client_conns++;
list_move_tail(&conn->cache_link, &rxrpc_active_client_conns);
}
/*
* Attempt to animate a connection for a new call.
*
* If it's not exclusive, the connection is in the endpoint tree, and we're in
* the conn's list of those waiting to grab a channel. There is, however, a
* limit on the number of live connections allowed at any one time, so we may
* have to wait for capacity to become available.
*
* Note that a connection on the waiting queue might *also* have active
* channels if it has been culled to make space and then re-requested by a new
* call.
*/
static void rxrpc_animate_client_conn(struct rxrpc_connection *conn)
{
unsigned int nr_conns;
_enter("%d,%d", conn->debug_id, conn->cache_state);
if (conn->cache_state == RXRPC_CONN_CLIENT_ACTIVE)
goto out;
spin_lock(&rxrpc_client_conn_cache_lock);
nr_conns = rxrpc_nr_client_conns;
if (!test_and_set_bit(RXRPC_CONN_COUNTED, &conn->flags))
rxrpc_nr_client_conns = nr_conns + 1;
switch (conn->cache_state) {
case RXRPC_CONN_CLIENT_ACTIVE:
case RXRPC_CONN_CLIENT_WAITING:
break;
case RXRPC_CONN_CLIENT_INACTIVE:
case RXRPC_CONN_CLIENT_CULLED:
case RXRPC_CONN_CLIENT_IDLE:
if (nr_conns >= rxrpc_max_client_connections)
goto wait_for_capacity;
goto activate_conn;
default:
BUG();
}
out_unlock:
spin_unlock(&rxrpc_client_conn_cache_lock);
out:
_leave(" [%d]", conn->cache_state);
return;
activate_conn:
_debug("activate");
rxrpc_activate_conn(conn);
goto out_unlock;
wait_for_capacity:
_debug("wait");
conn->cache_state = RXRPC_CONN_CLIENT_WAITING;
list_move_tail(&conn->cache_link, &rxrpc_waiting_client_conns);
goto out_unlock;
}
/*
* Deactivate a channel.
*/
static void rxrpc_deactivate_one_channel(struct rxrpc_connection *conn,
unsigned int channel)
{
struct rxrpc_channel *chan = &conn->channels[channel];
rcu_assign_pointer(chan->call, NULL);
conn->active_chans &= ~(1 << channel);
}
/*
* Assign a channel to the call at the front of the queue and wake the call up.
* We don't increment the callNumber counter until this number has been exposed
* to the world.
*/
static void rxrpc_activate_one_channel(struct rxrpc_connection *conn,
unsigned int channel)
{
struct rxrpc_channel *chan = &conn->channels[channel];
struct rxrpc_call *call = list_entry(conn->waiting_calls.next,
struct rxrpc_call, chan_wait_link);
u32 call_id = chan->call_counter + 1;
rxrpc_see_call(call);
list_del_init(&call->chan_wait_link);
conn->active_chans |= 1 << channel;
call->peer = rxrpc_get_peer(conn->params.peer);
call->cid = conn->proto.cid | channel;
call->call_id = call_id;
_net("CONNECT call %08x:%08x as call %d on conn %d",
call->cid, call->call_id, call->debug_id, conn->debug_id);
/* Paired with the read barrier in rxrpc_wait_for_channel(). This
* orders cid and epoch in the connection wrt to call_id without the
* need to take the channel_lock.
*
* We provisionally assign a callNumber at this point, but we don't
* confirm it until the call is about to be exposed.
*
* TODO: Pair with a barrier in the data_ready handler when that looks
* at the call ID through a connection channel.
*/
smp_wmb();
chan->call_id = call_id;
rcu_assign_pointer(chan->call, call);
wake_up(&call->waitq);
}
/*
* Assign channels and callNumbers to waiting calls.
*/
static void rxrpc_activate_channels(struct rxrpc_connection *conn)
{
unsigned char mask;
_enter("%d", conn->debug_id);
if (conn->cache_state != RXRPC_CONN_CLIENT_ACTIVE ||
conn->active_chans == RXRPC_ACTIVE_CHANS_MASK)
return;
spin_lock(&conn->channel_lock);
while (!list_empty(&conn->waiting_calls) &&
(mask = ~conn->active_chans,
mask &= RXRPC_ACTIVE_CHANS_MASK,
mask != 0))
rxrpc_activate_one_channel(conn, __ffs(mask));
spin_unlock(&conn->channel_lock);
_leave("");
}
/*
* Wait for a callNumber and a channel to be granted to a call.
*/
static int rxrpc_wait_for_channel(struct rxrpc_call *call, gfp_t gfp)
{
int ret = 0;
_enter("%d", call->debug_id);
if (!call->call_id) {
DECLARE_WAITQUEUE(myself, current);
if (!gfpflags_allow_blocking(gfp)) {
ret = -EAGAIN;
goto out;
}
add_wait_queue_exclusive(&call->waitq, &myself);
for (;;) {
set_current_state(TASK_INTERRUPTIBLE);
if (call->call_id)
break;
if (signal_pending(current)) {
ret = -ERESTARTSYS;
break;
}
schedule();
}
remove_wait_queue(&call->waitq, &myself);
__set_current_state(TASK_RUNNING);
}
/* Paired with the write barrier in rxrpc_activate_one_channel(). */
smp_rmb();
out:
_leave(" = %d", ret);
return 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)
{
int ret;
_enter("{%d,%lx},", call->debug_id, call->user_call_ID);
rxrpc_discard_expired_client_conns(NULL);
rxrpc_cull_active_client_conns();
ret = rxrpc_get_client_conn(call, cp, srx, gfp);
if (ret < 0)
return ret;
rxrpc_animate_client_conn(call->conn);
rxrpc_activate_channels(call->conn);
ret = rxrpc_wait_for_channel(call, gfp);
if (ret < 0)
rxrpc_disconnect_client_call(call);
_leave(" = %d", ret);
return ret;
}
/*
* Note that a connection is about to be exposed to the world. Once it is
* exposed, we maintain an extra ref on it that stops it from being summarily
* discarded before it's (a) had a chance to deal with retransmission and (b)
* had a chance at re-use (the per-connection security negotiation is
* expensive).
*/
static void rxrpc_expose_client_conn(struct rxrpc_connection *conn)
{
if (!test_and_set_bit(RXRPC_CONN_EXPOSED, &conn->flags))
rxrpc_get_connection(conn);
}
/*
* Note that a call, and thus a connection, is about to be exposed to the
* world.
*/
void rxrpc_expose_client_call(struct rxrpc_call *call)
{
struct rxrpc_connection *conn = call->conn;
struct rxrpc_channel *chan =
&conn->channels[call->cid & RXRPC_CHANNELMASK];
if (!test_and_set_bit(RXRPC_CALL_EXPOSED, &call->flags)) {
/* Mark the call ID as being used. If the callNumber counter
* exceeds ~2 billion, we kill the connection after its
* outstanding calls have finished so that the counter doesn't
* wrap.
*/
chan->call_counter++;
if (chan->call_counter >= INT_MAX)
set_bit(RXRPC_CONN_DONT_REUSE, &conn->flags);
rxrpc_expose_client_conn(conn);
}
}
/*
* Disconnect a client call.
*/
void rxrpc_disconnect_client_call(struct rxrpc_call *call)
{
unsigned int channel = call->cid & RXRPC_CHANNELMASK;
struct rxrpc_connection *conn = call->conn;
struct rxrpc_channel *chan = &conn->channels[channel];
call->conn = NULL;
spin_lock(&conn->channel_lock);
/* Calls that have never actually been assigned a channel can simply be
* discarded. If the conn didn't get used either, it will follow
* immediately unless someone else grabs it in the meantime.
*/
if (!list_empty(&call->chan_wait_link)) {
_debug("call is waiting");
ASSERTCMP(call->call_id, ==, 0);
ASSERT(!test_bit(RXRPC_CALL_EXPOSED, &call->flags));
list_del_init(&call->chan_wait_link);
/* We must deactivate or idle the connection if it's now
* waiting for nothing.
*/
spin_lock(&rxrpc_client_conn_cache_lock);
if (conn->cache_state == RXRPC_CONN_CLIENT_WAITING &&
list_empty(&conn->waiting_calls) &&
!conn->active_chans)
goto idle_connection;
goto out;
}
ASSERTCMP(rcu_access_pointer(chan->call), ==, call);
ASSERTCMP(atomic_read(&conn->usage), >=, 2);
/* If a client call was exposed to the world, we save the result for
* retransmission.
*
* We use a barrier here so that the call number and abort code can be
* read without needing to take a lock.
*
* TODO: Make the incoming packet handler check this and handle
* terminal retransmission without requiring access to the call.
*/
if (test_bit(RXRPC_CALL_EXPOSED, &call->flags)) {
_debug("exposed %u,%u", call->call_id, call->abort_code);
__rxrpc_disconnect_call(conn, call);
}
/* See if we can pass the channel directly to another call. */
if (conn->cache_state == RXRPC_CONN_CLIENT_ACTIVE &&
!list_empty(&conn->waiting_calls)) {
_debug("pass chan");
rxrpc_activate_one_channel(conn, channel);
goto out_2;
}
/* Things are more complex and we need the cache lock. We might be
* able to simply idle the conn or it might now be lurking on the wait
* list. It might even get moved back to the active list whilst we're
* waiting for the lock.
*/
spin_lock(&rxrpc_client_conn_cache_lock);
switch (conn->cache_state) {
case RXRPC_CONN_CLIENT_ACTIVE:
if (list_empty(&conn->waiting_calls)) {
rxrpc_deactivate_one_channel(conn, channel);
if (!conn->active_chans) {
rxrpc_nr_active_client_conns--;
goto idle_connection;
}
goto out;
}
_debug("pass chan 2");
rxrpc_activate_one_channel(conn, channel);
goto out;
case RXRPC_CONN_CLIENT_CULLED:
rxrpc_deactivate_one_channel(conn, channel);
ASSERT(list_empty(&conn->waiting_calls));
if (!conn->active_chans)
goto idle_connection;
goto out;
case RXRPC_CONN_CLIENT_WAITING:
rxrpc_deactivate_one_channel(conn, channel);
goto out;
default:
BUG();
}
out:
spin_unlock(&rxrpc_client_conn_cache_lock);
out_2:
spin_unlock(&conn->channel_lock);
rxrpc_put_connection(conn);
_leave("");
return;
idle_connection:
/* As no channels remain active, the connection gets deactivated
* immediately or moved to the idle list for a short while.
*/
if (test_bit(RXRPC_CONN_EXPOSED, &conn->flags)) {
_debug("make idle");
conn->idle_timestamp = jiffies;
conn->cache_state = RXRPC_CONN_CLIENT_IDLE;
list_move_tail(&conn->cache_link, &rxrpc_idle_client_conns);
if (rxrpc_idle_client_conns.next == &conn->cache_link &&
!rxrpc_kill_all_client_conns)
queue_delayed_work(rxrpc_workqueue,
&rxrpc_client_conn_reap,
rxrpc_conn_idle_client_expiry);
} else {
_debug("make inactive");
conn->cache_state = RXRPC_CONN_CLIENT_INACTIVE;
list_del_init(&conn->cache_link);
}
goto out;
}
/*
* Clean up a dead client connection.
*/
static struct rxrpc_connection *
rxrpc_put_one_client_conn(struct rxrpc_connection *conn)
{
struct rxrpc_connection *next;
struct rxrpc_local *local = conn->params.local;
unsigned int nr_conns;
if (test_bit(RXRPC_CONN_IN_CLIENT_CONNS, &conn->flags)) {
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);
ASSERTCMP(conn->cache_state, ==, RXRPC_CONN_CLIENT_INACTIVE);
if (!test_bit(RXRPC_CONN_COUNTED, &conn->flags))
return NULL;
spin_lock(&rxrpc_client_conn_cache_lock);
nr_conns = --rxrpc_nr_client_conns;
next = NULL;
if (nr_conns < rxrpc_max_client_connections &&
!list_empty(&rxrpc_waiting_client_conns)) {
next = list_entry(rxrpc_waiting_client_conns.next,
struct rxrpc_connection, cache_link);
rxrpc_get_connection(next);
rxrpc_activate_conn(next);
}
spin_unlock(&rxrpc_client_conn_cache_lock);
rxrpc_kill_connection(conn);
if (next)
rxrpc_activate_channels(next);
/* We need to get rid of the temporary ref we took upon next, but we
* can't call rxrpc_put_connection() recursively.
*/
return next;
}
/*
* Clean up a dead client connections.
*/
void rxrpc_put_client_conn(struct rxrpc_connection *conn)
{
struct rxrpc_connection *next;
do {
_enter("%p{u=%d,d=%d}",
conn, atomic_read(&conn->usage), conn->debug_id);
next = rxrpc_put_one_client_conn(conn);
if (!next)
break;
conn = next;
} while (atomic_dec_and_test(&conn->usage));
_leave("");
}
/*
* Kill the longest-active client connections to make room for new ones.
*/
static void rxrpc_cull_active_client_conns(void)
{
struct rxrpc_connection *conn;
unsigned int nr_conns = rxrpc_nr_client_conns;
unsigned int nr_active, limit;
_enter("");
ASSERTCMP(nr_conns, >=, 0);
if (nr_conns < rxrpc_max_client_connections) {
_leave(" [ok]");
return;
}
limit = rxrpc_reap_client_connections;
spin_lock(&rxrpc_client_conn_cache_lock);
nr_active = rxrpc_nr_active_client_conns;
while (nr_active > limit) {
ASSERT(!list_empty(&rxrpc_active_client_conns));
conn = list_entry(rxrpc_active_client_conns.next,
struct rxrpc_connection, cache_link);
ASSERTCMP(conn->cache_state, ==, RXRPC_CONN_CLIENT_ACTIVE);
if (list_empty(&conn->waiting_calls)) {
conn->cache_state = RXRPC_CONN_CLIENT_CULLED;
list_del_init(&conn->cache_link);
} else {
conn->cache_state = RXRPC_CONN_CLIENT_WAITING;
list_move_tail(&conn->cache_link,
&rxrpc_waiting_client_conns);
}
nr_active--;
}
rxrpc_nr_active_client_conns = nr_active;
spin_unlock(&rxrpc_client_conn_cache_lock);
ASSERTCMP(nr_active, >=, 0);
_leave(" [culled]");
}
/*
* Discard expired client connections from the idle list. Each conn in the
* idle list has been exposed and holds an extra ref because of that.
*
* This may be called from conn setup or from a work item so cannot be
* considered non-reentrant.
*/
static void rxrpc_discard_expired_client_conns(struct work_struct *work)
{
struct rxrpc_connection *conn;
unsigned long expiry, conn_expires_at, now;
unsigned int nr_conns;
bool did_discard = false;
_enter("%c", work ? 'w' : 'n');
if (list_empty(&rxrpc_idle_client_conns)) {
_leave(" [empty]");
return;
}
/* Don't double up on the discarding */
if (!spin_trylock(&rxrpc_client_conn_discard_mutex)) {
_leave(" [already]");
return;
}
/* We keep an estimate of what the number of conns ought to be after
* we've discarded some so that we don't overdo the discarding.
*/
nr_conns = rxrpc_nr_client_conns;
next:
spin_lock(&rxrpc_client_conn_cache_lock);
if (list_empty(&rxrpc_idle_client_conns))
goto out;
conn = list_entry(rxrpc_idle_client_conns.next,
struct rxrpc_connection, cache_link);
ASSERT(test_bit(RXRPC_CONN_EXPOSED, &conn->flags));
if (!rxrpc_kill_all_client_conns) {
/* If the number of connections is over the reap limit, we
* expedite discard by reducing the expiry timeout. We must,
* however, have at least a short grace period to be able to do
* final-ACK or ABORT retransmission.
*/
expiry = rxrpc_conn_idle_client_expiry;
if (nr_conns > rxrpc_reap_client_connections)
expiry = rxrpc_conn_idle_client_fast_expiry;
conn_expires_at = conn->idle_timestamp + expiry;
now = READ_ONCE(jiffies);
if (time_after(conn_expires_at, now))
goto not_yet_expired;
}
_debug("discard conn %d", conn->debug_id);
if (!test_and_clear_bit(RXRPC_CONN_EXPOSED, &conn->flags))
BUG();
conn->cache_state = RXRPC_CONN_CLIENT_INACTIVE;
list_del_init(&conn->cache_link);
spin_unlock(&rxrpc_client_conn_cache_lock);
/* When we cleared the EXPOSED flag, we took on responsibility for the
* reference that that had on the usage count. We deal with that here.
* If someone re-sets the flag and re-gets the ref, that's fine.
*/
rxrpc_put_connection(conn);
did_discard = true;
nr_conns--;
goto next;
not_yet_expired:
/* The connection at the front of the queue hasn't yet expired, so
* schedule the work item for that point if we discarded something.
*
* We don't worry if the work item is already scheduled - it can look
* after rescheduling itself at a later time. We could cancel it, but
* then things get messier.
*/
_debug("not yet");
if (!rxrpc_kill_all_client_conns)
queue_delayed_work(rxrpc_workqueue,
&rxrpc_client_conn_reap,
conn_expires_at - now);
out:
spin_unlock(&rxrpc_client_conn_cache_lock);
spin_unlock(&rxrpc_client_conn_discard_mutex);
_leave("");
}
/*
* Preemptively destroy all the client connection records rather than waiting
* for them to time out
*/
void __exit rxrpc_destroy_all_client_connections(void)
{
_enter("");
spin_lock(&rxrpc_client_conn_cache_lock);
rxrpc_kill_all_client_conns = true;
spin_unlock(&rxrpc_client_conn_cache_lock);
cancel_delayed_work(&rxrpc_client_conn_reap);
if (!queue_delayed_work(rxrpc_workqueue, &rxrpc_client_conn_reap, 0))
_debug("destroy: queue failed");
_leave("");
}
