diff options
| -rw-r--r-- | net/rxrpc/ar-internal.h | 56 | ||||
| -rw-r--r-- | net/rxrpc/call_event.c | 4 | ||||
| -rw-r--r-- | net/rxrpc/call_object.c | 5 | ||||
| -rw-r--r-- | net/rxrpc/conn_client.c | 910 | ||||
| -rw-r--r-- | net/rxrpc/conn_object.c | 71 | ||||
| -rw-r--r-- | net/rxrpc/conn_service.c | 5 | ||||
| -rw-r--r-- | net/rxrpc/output.c | 6 | ||||
| -rw-r--r-- | net/rxrpc/sysctl.c | 33 |
8 files changed, 933 insertions, 157 deletions
diff --git a/net/rxrpc/ar-internal.h b/net/rxrpc/ar-internal.h index 2efbfba87cbe..c761124961cc 100644 --- a/net/rxrpc/ar-internal.h +++ b/net/rxrpc/ar-internal.h @@ -255,6 +255,9 @@ enum rxrpc_conn_flag { RXRPC_CONN_HAS_IDR, /* Has a client conn ID assigned */ RXRPC_CONN_IN_SERVICE_CONNS, /* Conn is in peer->service_conns */ RXRPC_CONN_IN_CLIENT_CONNS, /* Conn is in local->client_conns */ + RXRPC_CONN_EXPOSED, /* Conn has extra ref for exposure */ + RXRPC_CONN_DONT_REUSE, /* Don't reuse this connection */ + RXRPC_CONN_COUNTED, /* Counted by rxrpc_nr_client_conns */ }; /* @@ -265,6 +268,17 @@ enum rxrpc_conn_event { }; /* + * The connection cache state. + */ +enum rxrpc_conn_cache_state { + RXRPC_CONN_CLIENT_INACTIVE, /* Conn is not yet listed */ + RXRPC_CONN_CLIENT_WAITING, /* Conn is on wait list, waiting for capacity */ + RXRPC_CONN_CLIENT_ACTIVE, /* Conn is on active list, doing calls */ + RXRPC_CONN_CLIENT_CULLED, /* Conn is culled and delisted, doing calls */ + RXRPC_CONN_CLIENT_IDLE, /* Conn is on idle list, doing mostly nothing */ +}; + +/* * The connection protocol state. */ enum rxrpc_conn_proto_state { @@ -276,6 +290,7 @@ enum rxrpc_conn_proto_state { RXRPC_CONN_REMOTELY_ABORTED, /* Conn aborted by peer */ RXRPC_CONN_LOCALLY_ABORTED, /* Conn aborted locally */ RXRPC_CONN_NETWORK_ERROR, /* Conn terminated by network error */ + RXRPC_CONN_LOCAL_ERROR, /* Conn terminated by local error */ RXRPC_CONN__NR_STATES }; @@ -288,8 +303,14 @@ struct rxrpc_connection { struct rxrpc_conn_proto proto; struct rxrpc_conn_parameters params; - spinlock_t channel_lock; + atomic_t usage; + struct rcu_head rcu; + struct list_head cache_link; + spinlock_t channel_lock; + unsigned char active_chans; /* Mask of active channels */ +#define RXRPC_ACTIVE_CHANS_MASK ((1 << RXRPC_MAXCALLS) - 1) + struct list_head waiting_calls; /* Calls waiting for channels */ struct rxrpc_channel { struct rxrpc_call __rcu *call; /* Active call */ u32 call_id; /* ID of current call */ @@ -302,9 +323,7 @@ struct rxrpc_connection { u32 last_abort; }; } channels[RXRPC_MAXCALLS]; - wait_queue_head_t channel_wq; /* queue to wait for channel to become available */ - struct rcu_head rcu; struct work_struct processor; /* connection event processor */ union { struct rb_node client_node; /* Node in local->client_conns */ @@ -321,7 +340,7 @@ struct rxrpc_connection { unsigned long events; unsigned long idle_timestamp; /* Time at which last became idle */ spinlock_t state_lock; /* state-change lock */ - atomic_t usage; + enum rxrpc_conn_cache_state cache_state : 8; enum rxrpc_conn_proto_state state : 8; /* current state of connection */ u32 local_abort; /* local abort code */ u32 remote_abort; /* remote abort code */ @@ -329,7 +348,6 @@ struct rxrpc_connection { int debug_id; /* debug ID for printks */ atomic_t serial; /* packet serial number counter */ unsigned int hi_serial; /* highest serial number received */ - atomic_t avail_chans; /* number of channels available */ u8 size_align; /* data size alignment (for security) */ u8 header_size; /* rxrpc + security header size */ u8 security_size; /* security header size */ @@ -351,6 +369,7 @@ enum rxrpc_call_flag { RXRPC_CALL_HAS_USERID, /* has a user ID attached */ RXRPC_CALL_EXPECT_OOS, /* expect out of sequence packets */ RXRPC_CALL_IS_SERVICE, /* Call is service call */ + RXRPC_CALL_EXPOSED, /* The call was exposed to the world */ }; /* @@ -417,13 +436,14 @@ struct rxrpc_call { struct work_struct destroyer; /* call destroyer */ struct work_struct processor; /* packet processor and ACK generator */ struct list_head link; /* link in master call list */ + struct list_head chan_wait_link; /* Link in conn->waiting_calls */ struct hlist_node error_link; /* link in error distribution list */ struct list_head accept_link; /* calls awaiting acceptance */ struct rb_node sock_node; /* node in socket call tree */ struct sk_buff_head rx_queue; /* received packets */ struct sk_buff_head rx_oos_queue; /* packets received out of sequence */ struct sk_buff *tx_pending; /* Tx socket buffer being filled */ - wait_queue_head_t tx_waitq; /* wait for Tx window space to become available */ + wait_queue_head_t waitq; /* Wait queue for channel or Tx */ __be32 crypto_buf[2]; /* Temporary packet crypto buffer */ unsigned long user_call_ID; /* user-defined call ID */ unsigned long creation_jif; /* time of call creation */ @@ -546,12 +566,19 @@ static inline bool rxrpc_is_client_call(const struct rxrpc_call *call) /* * conn_client.c */ +extern unsigned int rxrpc_max_client_connections; +extern unsigned int rxrpc_reap_client_connections; +extern unsigned int rxrpc_conn_idle_client_expiry; +extern unsigned int rxrpc_conn_idle_client_fast_expiry; extern struct idr rxrpc_client_conn_ids; void rxrpc_destroy_client_conn_ids(void); int rxrpc_connect_call(struct rxrpc_call *, struct rxrpc_conn_parameters *, struct sockaddr_rxrpc *, gfp_t); -void rxrpc_unpublish_client_conn(struct rxrpc_connection *); +void rxrpc_expose_client_call(struct rxrpc_call *); +void rxrpc_disconnect_client_call(struct rxrpc_call *); +void rxrpc_put_client_conn(struct rxrpc_connection *); +void __exit rxrpc_destroy_all_client_connections(void); /* * conn_event.c @@ -572,8 +599,9 @@ int rxrpc_extract_addr_from_skb(struct sockaddr_rxrpc *, struct sk_buff *); struct rxrpc_connection *rxrpc_alloc_connection(gfp_t); struct rxrpc_connection *rxrpc_find_connection_rcu(struct rxrpc_local *, struct sk_buff *); -void __rxrpc_disconnect_call(struct rxrpc_call *); +void __rxrpc_disconnect_call(struct rxrpc_connection *, struct rxrpc_call *); void rxrpc_disconnect_call(struct rxrpc_call *); +void rxrpc_kill_connection(struct rxrpc_connection *); void __rxrpc_put_connection(struct rxrpc_connection *); void __exit rxrpc_destroy_all_connections(void); @@ -600,8 +628,16 @@ struct rxrpc_connection *rxrpc_get_connection_maybe(struct rxrpc_connection *con static inline void rxrpc_put_connection(struct rxrpc_connection *conn) { - if (conn && atomic_dec_return(&conn->usage) == 1) - __rxrpc_put_connection(conn); + if (!conn) + return; + + if (rxrpc_conn_is_client(conn)) { + if (atomic_dec_and_test(&conn->usage)) + rxrpc_put_client_conn(conn); + } else { + if (atomic_dec_return(&conn->usage) == 1) + __rxrpc_put_connection(conn); + } } diff --git a/net/rxrpc/call_event.c b/net/rxrpc/call_event.c index 3d1961d82325..5292bcfd8816 100644 --- a/net/rxrpc/call_event.c +++ b/net/rxrpc/call_event.c @@ -193,6 +193,8 @@ static void rxrpc_resend(struct rxrpc_call *call) stop = true; sp->resend_at = jiffies + 3; } else { + if (rxrpc_is_client_call(call)) + rxrpc_expose_client_call(call); sp->resend_at = jiffies + rxrpc_resend_timeout; } @@ -378,7 +380,7 @@ static void rxrpc_rotate_tx_window(struct rxrpc_call *call, u32 hard) call->acks_hard++; } - wake_up(&call->tx_waitq); + wake_up(&call->waitq); } /* diff --git a/net/rxrpc/call_object.c b/net/rxrpc/call_object.c index f23432591a0f..e7cbcc4a87cf 100644 --- a/net/rxrpc/call_object.c +++ b/net/rxrpc/call_object.c @@ -127,10 +127,11 @@ static struct rxrpc_call *rxrpc_alloc_call(gfp_t gfp) INIT_WORK(&call->destroyer, &rxrpc_destroy_call); INIT_WORK(&call->processor, &rxrpc_process_call); INIT_LIST_HEAD(&call->link); + INIT_LIST_HEAD(&call->chan_wait_link); INIT_LIST_HEAD(&call->accept_link); skb_queue_head_init(&call->rx_queue); skb_queue_head_init(&call->rx_oos_queue); - init_waitqueue_head(&call->tx_waitq); + init_waitqueue_head(&call->waitq); spin_lock_init(&call->lock); rwlock_init(&call->state_lock); atomic_set(&call->usage, 1); @@ -358,7 +359,7 @@ struct rxrpc_call *rxrpc_incoming_call(struct rxrpc_sock *rx, call->debug_id, rxrpc_call_states[call->state]); if (call->state >= RXRPC_CALL_COMPLETE) { - __rxrpc_disconnect_call(call); + __rxrpc_disconnect_call(conn, call); } else { spin_unlock(&conn->channel_lock); kmem_cache_free(rxrpc_call_jar, candidate); 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, |