diff options
Diffstat (limited to 'net/rxrpc/conn_client.c')
| -rw-r--r-- | net/rxrpc/conn_client.c | 910 |
1 files changed, 795 insertions, 115 deletions
diff --git a/net/rxrpc/conn_client.c b/net/rxrpc/conn_client.c index 6e1099ed1dbd..349402b08e5a 100644 --- a/net/rxrpc/conn_client.c +++ b/net/rxrpc/conn_client.c @@ -7,6 +7,68 @@ * 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 @@ -16,22 +78,37 @@ #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. - * - * 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. */ static int rxrpc_get_client_connection_id(struct rxrpc_connection *conn, gfp_t gfp) @@ -114,8 +191,7 @@ void rxrpc_destroy_client_conn_ids(void) } /* - * Allocate a client connection. The caller must take care to clear any - * padding bytes in *cp. + * Allocate a client connection. */ static struct rxrpc_connection * rxrpc_alloc_client_connection(struct rxrpc_conn_parameters *cp, gfp_t gfp) @@ -131,6 +207,10 @@ rxrpc_alloc_client_connection(struct rxrpc_conn_parameters *cp, gfp_t gfp) 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; @@ -148,7 +228,6 @@ rxrpc_alloc_client_connection(struct rxrpc_conn_parameters *cp, gfp_t gfp) goto error_2; write_lock(&rxrpc_connection_lock); - list_add_tail(&conn->link, &rxrpc_connections); list_add_tail(&conn->proc_link, &rxrpc_connection_proc_list); write_unlock(&rxrpc_connection_lock); @@ -171,32 +250,68 @@ error_0: } /* - * find a connection for a call - * - called in process context with IRQs enabled + * Determine if a connection may be reused. */ -int rxrpc_connect_call(struct rxrpc_call *call, - struct rxrpc_conn_parameters *cp, - struct sockaddr_rxrpc *srx, - gfp_t gfp) +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 chan; - - DECLARE_WAITQUEUE(myself, current); + 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) - return -ENOMEM; + 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) { - /* 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; @@ -207,39 +322,55 @@ int rxrpc_connect_call(struct rxrpc_call *call, diff = (cmp(peer) ?: cmp(key) ?: cmp(security_level)); - if (diff < 0) +#undef cmp + if (diff < 0) { p = p->rb_left; - else if (diff > 0) + } else if (diff > 0) { p = p->rb_right; - else - goto found_extant_conn; + } 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); } - /* We didn't find a connection or we want an exclusive one. */ - _debug("get new conn"); + /* 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 (!candidate) { - _leave(" = -ENOMEM"); - return -ENOMEM; + 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) { - /* 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; + call->conn = candidate; + _leave(" = 0 [exclusive %d]", candidate->debug_id); + return 0; } - /* We need to redo the search before attempting to add a new connection - * lest we race with someone else adding a conflicting instance. + /* 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); @@ -250,123 +381,672 @@ int rxrpc_connect_call(struct rxrpc_call *call, 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)); - if (diff < 0) +#undef cmp + if (diff < 0) { pp = &(*pp)->rb_left; - else if (diff > 0) + } else if (diff > 0) { pp = &(*pp)->rb_right; - else - goto found_extant_conn; + } 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; + } } - /* 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"); - 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: - conn = candidate; - candidate = NULL; - atomic_set(&conn->avail_chans, RXRPC_MAXCALLS - 1); - spin_lock(&conn->channel_lock); +candidate_published: + set_bit(RXRPC_CONN_IN_CLIENT_CONNS, &candidate->flags); + call->conn = candidate; spin_unlock(&local->client_conns_lock); - chan = 0; + _leave(" = 0 [new %d]", candidate->debug_id); + return 0; -found_channel: - _debug("found chan"); - call->conn = conn; - call->peer = rxrpc_get_peer(conn->params.peer); - 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); + /* 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); - _net("CONNECT call %d on conn %d", call->debug_id, conn->debug_id); + 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; - _leave(" = %p {u=%d}", conn, atomic_read(&conn->usage)); - return 0; +error: + _leave(" = %d", ret); + return ret; +} - /* 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. - */ -found_extant_conn: - _debug("found conn"); - 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; +/* + * 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(); } - spin_unlock(&local->client_conns_lock); +out_unlock: + spin_unlock(&rxrpc_client_conn_cache_lock); +out: + _leave(" [%d]", conn->cache_state); + return; - rxrpc_put_connection(candidate); +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; + + 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 (!atomic_add_unless(&conn->avail_chans, -1, 0)) { if (!gfpflags_allow_blocking(gfp)) { - rxrpc_put_connection(conn); - _leave(" = -EAGAIN"); - return -EAGAIN; + ret = -EAGAIN; + goto out; } - add_wait_queue(&conn->channel_wq, &myself); + add_wait_queue_exclusive(&call->waitq, &myself); for (;;) { set_current_state(TASK_INTERRUPTIBLE); - if (atomic_add_unless(&conn->avail_chans, -1, 0)) + if (call->call_id) + break; + if (signal_pending(current)) { + ret = -ERESTARTSYS; break; - if (signal_pending(current)) - goto interrupted; + } schedule(); } - remove_wait_queue(&conn->channel_wq, &myself); + remove_wait_queue(&call->waitq, &myself); __set_current_state(TASK_RUNNING); } - /* The connection allegedly now has a free channel and we can now - * attach the call to it. - */ + /* 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); - for (chan = 0; chan < RXRPC_MAXCALLS; chan++) - if (!conn->channels[chan].call) - goto found_channel; - BUG(); + /* 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->local_abort); + __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(); + } -interrupted: - remove_wait_queue(&conn->channel_wq, &myself); - __set_current_state(TASK_RUNNING); +out: + spin_unlock(&rxrpc_client_conn_cache_lock); +out_2: + spin_unlock(&conn->channel_lock); rxrpc_put_connection(conn); - rxrpc_put_peer(cp->peer); - cp->peer = NULL; - _leave(" = -ERESTARTSYS"); - return -ERESTARTSYS; + _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; } /* - * Remove a client connection from the local endpoint's tree, thereby removing - * it as a target for reuse for new client calls. + * Clean up a dead client connection. */ -void rxrpc_unpublish_client_conn(struct rxrpc_connection *conn) +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; - 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); + 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(""); } |