iv/linux
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity
248f219cb8
linux/net/rxrpc/call_object.c
David Howells 248f219cb8 rxrpc: Rewrite the data and ack handling code 
Rewrite the data and ack handling code such that:

 (1) Parsing of received ACK and ABORT packets and the distribution and the
     filing of DATA packets happens entirely within the data_ready context
     called from the UDP socket.  This allows us to process and discard ACK
     and ABORT packets much more quickly (they're no longer stashed on a
     queue for a background thread to process).

 (2) We avoid calling skb_clone(), pskb_pull() and pskb_trim().  We instead
     keep track of the offset and length of the content of each packet in
     the sk_buff metadata.  This means we don't do any allocation in the
     receive path.

 (3) Jumbo DATA packet parsing is now done in data_ready context.  Rather
     than cloning the packet once for each subpacket and pulling/trimming
     it, we file the packet multiple times with an annotation for each
     indicating which subpacket is there.  From that we can directly
     calculate the offset and length.

 (4) A call's receive queue can be accessed without taking locks (memory
     barriers do have to be used, though).

 (5) Incoming calls are set up from preallocated resources and immediately
     made live.  They can than have packets queued upon them and ACKs
     generated.  If insufficient resources exist, DATA packet #1 is given a
     BUSY reply and other DATA packets are discarded).

 (6) sk_buffs no longer take a ref on their parent call.

To make this work, the following changes are made:

 (1) Each call's receive buffer is now a circular buffer of sk_buff
     pointers (rxtx_buffer) rather than a number of sk_buff_heads spread
     between the call and the socket.  This permits each sk_buff to be in
     the buffer multiple times.  The receive buffer is reused for the
     transmit buffer.

 (2) A circular buffer of annotations (rxtx_annotations) is kept parallel
     to the data buffer.  Transmission phase annotations indicate whether a
     buffered packet has been ACK'd or not and whether it needs
     retransmission.

     Receive phase annotations indicate whether a slot holds a whole packet
     or a jumbo subpacket and, if the latter, which subpacket.  They also
     note whether the packet has been decrypted in place.

 (3) DATA packet window tracking is much simplified.  Each phase has just
     two numbers representing the window (rx_hard_ack/rx_top and
     tx_hard_ack/tx_top).

     The hard_ack number is the sequence number before base of the window,
     representing the last packet the other side says it has consumed.
     hard_ack starts from 0 and the first packet is sequence number 1.

     The top number is the sequence number of the highest-numbered packet
     residing in the buffer.  Packets between hard_ack+1 and top are
     soft-ACK'd to indicate they've been received, but not yet consumed.

     Four macros, before(), before_eq(), after() and after_eq() are added
     to compare sequence numbers within the window.  This allows for the
     top of the window to wrap when the hard-ack sequence number gets close
     to the limit.

     Two flags, RXRPC_CALL_RX_LAST and RXRPC_CALL_TX_LAST, are added also
     to indicate when rx_top and tx_top point at the packets with the
     LAST_PACKET bit set, indicating the end of the phase.

 (4) Calls are queued on the socket 'receive queue' rather than packets.
     This means that we don't need have to invent dummy packets to queue to
     indicate abnormal/terminal states and we don't have to keep metadata
     packets (such as ABORTs) around

 (5) The offset and length of a (sub)packet's content are now passed to
     the verify_packet security op.  This is currently expected to decrypt
     the packet in place and validate it.

     However, there's now nowhere to store the revised offset and length of
     the actual data within the decrypted blob (there may be a header and
     padding to skip) because an sk_buff may represent multiple packets, so
     a locate_data security op is added to retrieve these details from the
     sk_buff content when needed.

 (6) recvmsg() now has to handle jumbo subpackets, where each subpacket is
     individually secured and needs to be individually decrypted.  The code
     to do this is broken out into rxrpc_recvmsg_data() and shared with the
     kernel API.  It now iterates over the call's receive buffer rather
     than walking the socket receive queue.

Additional changes:

 (1) The timers are condensed to a single timer that is set for the soonest
     of three timeouts (delayed ACK generation, DATA retransmission and
     call lifespan).

 (2) Transmission of ACK and ABORT packets is effected immediately from
     process-context socket ops/kernel API calls that cause them instead of
     them being punted off to a background work item.  The data_ready
     handler still has to defer to the background, though.

 (3) A shutdown op is added to the AF_RXRPC socket so that the AFS
     filesystem can shut down the socket and flush its own work items
     before closing the socket to deal with any in-progress service calls.

Future additional changes that will need to be considered:

 (1) Make sure that a call doesn't hog the front of the queue by receiving
     data from the network as fast as userspace is consuming it to the
     exclusion of other calls.

 (2) Transmit delayed ACKs from within recvmsg() when we've consumed
     sufficiently more packets to avoid the background work item needing to
     run.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-08 11:10:12 +01:00

590 lines
15 KiB
C
Raw Blame History

/* RxRPC individual remote procedure call handling
*
* Copyright (C) 2007 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 License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/circ_buf.h>
#include <linux/spinlock_types.h>
#include <net/sock.h>
#include <net/af_rxrpc.h>
#include "ar-internal.h"
/*
* Maximum lifetime of a call (in jiffies).
*/
unsigned int rxrpc_max_call_lifetime = 60 * HZ;
const char *const rxrpc_call_states[NR__RXRPC_CALL_STATES] = {
[RXRPC_CALL_UNINITIALISED] = "Uninit ",
[RXRPC_CALL_CLIENT_AWAIT_CONN] = "ClWtConn",
[RXRPC_CALL_CLIENT_SEND_REQUEST] = "ClSndReq",
[RXRPC_CALL_CLIENT_AWAIT_REPLY] = "ClAwtRpl",
[RXRPC_CALL_CLIENT_RECV_REPLY] = "ClRcvRpl",
[RXRPC_CALL_SERVER_PREALLOC] = "SvPrealc",
[RXRPC_CALL_SERVER_SECURING] = "SvSecure",
[RXRPC_CALL_SERVER_ACCEPTING] = "SvAccept",
[RXRPC_CALL_SERVER_RECV_REQUEST] = "SvRcvReq",
[RXRPC_CALL_SERVER_ACK_REQUEST] = "SvAckReq",
[RXRPC_CALL_SERVER_SEND_REPLY] = "SvSndRpl",
[RXRPC_CALL_SERVER_AWAIT_ACK] = "SvAwtACK",
[RXRPC_CALL_COMPLETE] = "Complete",
};
const char *const rxrpc_call_completions[NR__RXRPC_CALL_COMPLETIONS] = {
[RXRPC_CALL_SUCCEEDED] = "Complete",
[RXRPC_CALL_REMOTELY_ABORTED] = "RmtAbort",
[RXRPC_CALL_LOCALLY_ABORTED] = "LocAbort",
[RXRPC_CALL_LOCAL_ERROR] = "LocError",
[RXRPC_CALL_NETWORK_ERROR] = "NetError",
};
const char rxrpc_call_traces[rxrpc_call__nr_trace][4] = {
[rxrpc_call_new_client] = "NWc",
[rxrpc_call_new_service] = "NWs",
[rxrpc_call_queued] = "QUE",
[rxrpc_call_queued_ref] = "QUR",
[rxrpc_call_seen] = "SEE",
[rxrpc_call_got] = "GOT",
[rxrpc_call_got_userid] = "Gus",
[rxrpc_call_put] = "PUT",
[rxrpc_call_put_userid] = "Pus",
[rxrpc_call_put_noqueue] = "PNQ",
};
struct kmem_cache *rxrpc_call_jar;
LIST_HEAD(rxrpc_calls);
DEFINE_RWLOCK(rxrpc_call_lock);
static void rxrpc_call_timer_expired(unsigned long _call)
{
struct rxrpc_call *call = (struct rxrpc_call *)_call;
_enter("%d", call->debug_id);
if (call->state < RXRPC_CALL_COMPLETE)
rxrpc_queue_call(call);
}
/*
* find an extant server call
* - called in process context with IRQs enabled
*/
struct rxrpc_call *rxrpc_find_call_by_user_ID(struct rxrpc_sock *rx,
unsigned long user_call_ID)
{
struct rxrpc_call *call;
struct rb_node *p;
_enter("%p,%lx", rx, user_call_ID);
read_lock(&rx->call_lock);
p = rx->calls.rb_node;
while (p) {
call = rb_entry(p, struct rxrpc_call, sock_node);
if (user_call_ID < call->user_call_ID)
p = p->rb_left;
else if (user_call_ID > call->user_call_ID)
p = p->rb_right;
else
goto found_extant_call;
}
read_unlock(&rx->call_lock);
_leave(" = NULL");
return NULL;
found_extant_call:
rxrpc_get_call(call, rxrpc_call_got);
read_unlock(&rx->call_lock);
_leave(" = %p [%d]", call, atomic_read(&call->usage));
return call;
}
/*
* allocate a new call
*/
struct rxrpc_call *rxrpc_alloc_call(gfp_t gfp)
{
struct rxrpc_call *call;
call = kmem_cache_zalloc(rxrpc_call_jar, gfp);
if (!call)
return NULL;
call->rxtx_buffer = kcalloc(RXRPC_RXTX_BUFF_SIZE,
sizeof(struct sk_buff *),
gfp);
if (!call->rxtx_buffer)
goto nomem;
call->rxtx_annotations = kcalloc(RXRPC_RXTX_BUFF_SIZE, sizeof(u8), gfp);
if (!call->rxtx_annotations)
goto nomem_2;
setup_timer(&call->timer, rxrpc_call_timer_expired,
(unsigned long)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);
INIT_LIST_HEAD(&call->recvmsg_link);
INIT_LIST_HEAD(&call->sock_link);
init_waitqueue_head(&call->waitq);
spin_lock_init(&call->lock);
rwlock_init(&call->state_lock);
atomic_set(&call->usage, 1);
call->debug_id = atomic_inc_return(&rxrpc_debug_id);
memset(&call->sock_node, 0xed, sizeof(call->sock_node));
/* Leave space in the ring to handle a maxed-out jumbo packet */
call->rx_winsize = RXRPC_RXTX_BUFF_SIZE - 1 - 46;
call->tx_winsize = 16;
call->rx_expect_next = 1;
return call;
nomem_2:
kfree(call->rxtx_buffer);
nomem:
kmem_cache_free(rxrpc_call_jar, call);
return NULL;
}
/*
* Allocate a new client call.
*/
static struct rxrpc_call *rxrpc_alloc_client_call(struct sockaddr_rxrpc *srx,
gfp_t gfp)
{
struct rxrpc_call *call;
_enter("");
call = rxrpc_alloc_call(gfp);
if (!call)
return ERR_PTR(-ENOMEM);
call->state = RXRPC_CALL_CLIENT_AWAIT_CONN;
call->service_id = srx->srx_service;
_leave(" = %p", call);
return call;
}
/*
* Initiate the call ack/resend/expiry timer.
*/
static void rxrpc_start_call_timer(struct rxrpc_call *call)
{
unsigned long expire_at;
expire_at = jiffies + rxrpc_max_call_lifetime;
call->expire_at = expire_at;
call->ack_at = expire_at;
call->resend_at = expire_at;
call->timer.expires = expire_at;
add_timer(&call->timer);
}
/*
* set up a call for the given data
* - called in process context with IRQs enabled
*/
struct rxrpc_call *rxrpc_new_client_call(struct rxrpc_sock *rx,
struct rxrpc_conn_parameters *cp,
struct sockaddr_rxrpc *srx,
unsigned long user_call_ID,
gfp_t gfp)
{
struct rxrpc_call *call, *xcall;
struct rb_node *parent, **pp;
const void *here = __builtin_return_address(0);
int ret;
_enter("%p,%lx", rx, user_call_ID);
call = rxrpc_alloc_client_call(srx, gfp);
if (IS_ERR(call)) {
_leave(" = %ld", PTR_ERR(call));
return call;
}
trace_rxrpc_call(call, 0, atomic_read(&call->usage), here,
(const void *)user_call_ID);
/* Publish the call, even though it is incompletely set up as yet */
call->user_call_ID = user_call_ID;
__set_bit(RXRPC_CALL_HAS_USERID, &call->flags);
write_lock(&rx->call_lock);
pp = &rx->calls.rb_node;
parent = NULL;
while (*pp) {
parent = *pp;
xcall = rb_entry(parent, struct rxrpc_call, sock_node);
if (user_call_ID < xcall->user_call_ID)
pp = &(*pp)->rb_left;
else if (user_call_ID > xcall->user_call_ID)
pp = &(*pp)->rb_right;
else
goto found_user_ID_now_present;
}
rcu_assign_pointer(call->socket, rx);
rxrpc_get_call(call, rxrpc_call_got_userid);
rb_link_node(&call->sock_node, parent, pp);
rb_insert_color(&call->sock_node, &rx->calls);
list_add(&call->sock_link, &rx->sock_calls);
write_unlock(&rx->call_lock);
write_lock(&rxrpc_call_lock);
list_add_tail(&call->link, &rxrpc_calls);
write_unlock(&rxrpc_call_lock);
/* Set up or get a connection record and set the protocol parameters,
* including channel number and call ID.
*/
ret = rxrpc_connect_call(call, cp, srx, gfp);
if (ret < 0)
goto error;
spin_lock_bh(&call->conn->params.peer->lock);
hlist_add_head(&call->error_link,
&call->conn->params.peer->error_targets);
spin_unlock_bh(&call->conn->params.peer->lock);
rxrpc_start_call_timer(call);
_net("CALL new %d on CONN %d", call->debug_id, call->conn->debug_id);
_leave(" = %p [new]", call);
return call;
error:
write_lock(&rx->call_lock);
rb_erase(&call->sock_node, &rx->calls);
write_unlock(&rx->call_lock);
rxrpc_put_call(call, rxrpc_call_put_userid);
write_lock(&rxrpc_call_lock);
list_del_init(&call->link);
write_unlock(&rxrpc_call_lock);
error_out:
__rxrpc_set_call_completion(call, RXRPC_CALL_LOCAL_ERROR,
RX_CALL_DEAD, ret);
set_bit(RXRPC_CALL_RELEASED, &call->flags);
rxrpc_put_call(call, rxrpc_call_put);
_leave(" = %d", ret);
return ERR_PTR(ret);
/* We unexpectedly found the user ID in the list after taking
* the call_lock. This shouldn't happen unless the user races
* with itself and tries to add the same user ID twice at the
* same time in different threads.
*/
found_user_ID_now_present:
write_unlock(&rx->call_lock);
ret = -EEXIST;
goto error_out;
}
/*
* Set up an incoming call. call->conn points to the connection.
* This is called in BH context and isn't allowed to fail.
*/
void rxrpc_incoming_call(struct rxrpc_sock *rx,
struct rxrpc_call *call,
struct sk_buff *skb)
{
struct rxrpc_connection *conn = call->conn;
struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
u32 chan;
_enter(",%d", call->conn->debug_id);
rcu_assign_pointer(call->socket, rx);
call->call_id = sp->hdr.callNumber;
call->service_id = sp->hdr.serviceId;
call->cid = sp->hdr.cid;
call->state = RXRPC_CALL_SERVER_ACCEPTING;
if (sp->hdr.securityIndex > 0)
call->state = RXRPC_CALL_SERVER_SECURING;
/* Set the channel for this call. We don't get channel_lock as we're
* only defending against the data_ready handler (which we're called
* from) and the RESPONSE packet parser (which is only really
* interested in call_counter and can cope with a disagreement with the
* call pointer).
*/
chan = sp->hdr.cid & RXRPC_CHANNELMASK;
conn->channels[chan].call_counter = call->call_id;
conn->channels[chan].call_id = call->call_id;
rcu_assign_pointer(conn->channels[chan].call, call);
spin_lock(&conn->params.peer->lock);
hlist_add_head(&call->error_link, &conn->params.peer->error_targets);
spin_unlock(&conn->params.peer->lock);
_net("CALL incoming %d on CONN %d", call->debug_id, call->conn->debug_id);
rxrpc_start_call_timer(call);
_leave("");
}
/*
* Queue a call's work processor, getting a ref to pass to the work queue.
*/
bool rxrpc_queue_call(struct rxrpc_call *call)
{
const void *here = __builtin_return_address(0);
int n = __atomic_add_unless(&call->usage, 1, 0);
if (n == 0)
return false;
if (rxrpc_queue_work(&call->processor))
trace_rxrpc_call(call, rxrpc_call_queued, n + 1, here, NULL);
else
rxrpc_put_call(call, rxrpc_call_put_noqueue);
return true;
}
/*
* Queue a call's work processor, passing the callers ref to the work queue.
*/
bool __rxrpc_queue_call(struct rxrpc_call *call)
{
const void *here = __builtin_return_address(0);
int n = atomic_read(&call->usage);
ASSERTCMP(n, >=, 1);
if (rxrpc_queue_work(&call->processor))
trace_rxrpc_call(call, rxrpc_call_queued_ref, n, here, NULL);
else
rxrpc_put_call(call, rxrpc_call_put_noqueue);
return true;
}
/*
* Note the re-emergence of a call.
*/
void rxrpc_see_call(struct rxrpc_call *call)
{
const void *here = __builtin_return_address(0);
if (call) {
int n = atomic_read(&call->usage);
trace_rxrpc_call(call, rxrpc_call_seen, n, here, NULL);
}
}
/*
* Note the addition of a ref on a call.
*/
void rxrpc_get_call(struct rxrpc_call *call, enum rxrpc_call_trace op)
{
const void *here = __builtin_return_address(0);
int n = atomic_inc_return(&call->usage);
trace_rxrpc_call(call, op, n, here, NULL);
}
/*
* Detach a call from its owning socket.
*/
void rxrpc_release_call(struct rxrpc_sock *rx, struct rxrpc_call *call)
{
struct rxrpc_connection *conn = call->conn;
bool put = false;
int i;
_enter("{%d,%d}", call->debug_id, atomic_read(&call->usage));
ASSERTCMP(call->state, ==, RXRPC_CALL_COMPLETE);
rxrpc_see_call(call);
spin_lock_bh(&call->lock);
if (test_and_set_bit(RXRPC_CALL_RELEASED, &call->flags))
BUG();
spin_unlock_bh(&call->lock);
del_timer_sync(&call->timer);
/* Make sure we don't get any more notifications */
write_lock_bh(&rx->recvmsg_lock);
if (!list_empty(&call->recvmsg_link)) {
_debug("unlinking once-pending call %p { e=%lx f=%lx }",
call, call->events, call->flags);
list_del(&call->recvmsg_link);
put = true;
}
/* list_empty() must return false in rxrpc_notify_socket() */
call->recvmsg_link.next = NULL;
call->recvmsg_link.prev = NULL;
write_unlock_bh(&rx->recvmsg_lock);
if (put)
rxrpc_put_call(call, rxrpc_call_put);
write_lock(&rx->call_lock);
if (test_and_clear_bit(RXRPC_CALL_HAS_USERID, &call->flags)) {
rb_erase(&call->sock_node, &rx->calls);
memset(&call->sock_node, 0xdd, sizeof(call->sock_node));
rxrpc_put_call(call, rxrpc_call_put_userid);
}
list_del(&call->sock_link);
write_unlock(&rx->call_lock);
_debug("RELEASE CALL %p (%d CONN %p)", call, call->debug_id, conn);
if (conn)
rxrpc_disconnect_call(call);
for (i = 0; i < RXRPC_RXTX_BUFF_SIZE; i++) {
rxrpc_free_skb(call->rxtx_buffer[i]);
call->rxtx_buffer[i] = NULL;
}
/* We have to release the prealloc backlog ref */
if (rxrpc_is_service_call(call))
rxrpc_put_call(call, rxrpc_call_put);
_leave("");
}
/*
* release all the calls associated with a socket
*/
void rxrpc_release_calls_on_socket(struct rxrpc_sock *rx)
{
struct rxrpc_call *call;
_enter("%p", rx);
while (!list_empty(&rx->sock_calls)) {
call = list_entry(rx->sock_calls.next,
struct rxrpc_call, sock_link);
rxrpc_get_call(call, rxrpc_call_got);
rxrpc_abort_call("SKT", call, 0, RX_CALL_DEAD, ECONNRESET);
rxrpc_send_call_packet(call, RXRPC_PACKET_TYPE_ABORT);
rxrpc_release_call(rx, call);
rxrpc_put_call(call, rxrpc_call_put);
}
_leave("");
}
/*
* release a call
*/
void rxrpc_put_call(struct rxrpc_call *call, enum rxrpc_call_trace op)
{
const void *here = __builtin_return_address(0);
int n;
ASSERT(call != NULL);
n = atomic_dec_return(&call->usage);
trace_rxrpc_call(call, op, n, here, NULL);
ASSERTCMP(n, >=, 0);
if (n == 0) {
_debug("call %d dead", call->debug_id);
ASSERTCMP(call->state, ==, RXRPC_CALL_COMPLETE);
write_lock(&rxrpc_call_lock);
list_del_init(&call->link);
write_unlock(&rxrpc_call_lock);
rxrpc_cleanup_call(call);
}
}
/*
* Final call destruction under RCU.
*/
static void rxrpc_rcu_destroy_call(struct rcu_head *rcu)
{
struct rxrpc_call *call = container_of(rcu, struct rxrpc_call, rcu);
rxrpc_put_peer(call->peer);
kfree(call->rxtx_buffer);
kfree(call->rxtx_annotations);
kmem_cache_free(rxrpc_call_jar, call);
}
/*
* clean up a call
*/
void rxrpc_cleanup_call(struct rxrpc_call *call)
{
int i;
_net("DESTROY CALL %d", call->debug_id);
memset(&call->sock_node, 0xcd, sizeof(call->sock_node));
del_timer_sync(&call->timer);
ASSERTCMP(call->state, ==, RXRPC_CALL_COMPLETE);
ASSERT(test_bit(RXRPC_CALL_RELEASED, &call->flags));
ASSERTCMP(call->conn, ==, NULL);
/* Clean up the Rx/Tx buffer */
for (i = 0; i < RXRPC_RXTX_BUFF_SIZE; i++)
rxrpc_free_skb(call->rxtx_buffer[i]);
rxrpc_free_skb(call->tx_pending);
call_rcu(&call->rcu, rxrpc_rcu_destroy_call);
}
/*
* Make sure that all calls are gone.
*/
void __exit rxrpc_destroy_all_calls(void)
{
struct rxrpc_call *call;
_enter("");
if (list_empty(&rxrpc_calls))
return;
write_lock(&rxrpc_call_lock);
while (!list_empty(&rxrpc_calls)) {
call = list_entry(rxrpc_calls.next, struct rxrpc_call, link);
_debug("Zapping call %p", call);
rxrpc_see_call(call);
list_del_init(&call->link);
pr_err("Call %p still in use (%d,%s,%lx,%lx)!\n",
call, atomic_read(&call->usage),
rxrpc_call_states[call->state],
call->flags, call->events);
write_unlock(&rxrpc_call_lock);
cond_resched();
write_lock(&rxrpc_call_lock);
}
write_unlock(&rxrpc_call_lock);
}
Reference in New Issue View Git Blame Copy Permalink