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linux-hardened/net/sunrpc/xprt.c
Chuck Lever b22602a673 SUNRPC: Ensure all transports set rq_xtime consistently 
The RPC client uses the rq_xtime field in each RPC request to determine the
round-trip time of the request.  Currently, the rq_xtime field is
initialized by each transport just before it starts enqueing a request to
be sent.  However, transports do not handle initializing this value
consistently; sometimes they don't initialize it at all.

To make the measurement of request round-trip time consistent for all
RPC client transport capabilities, pull rq_xtime initialization into the
RPC client's generic transport logic.  Now all transports will get a
standardized RTT measure automatically, from:

  xprt_transmit()

to

  xprt_complete_rqst()

This makes round-trip time calculation more accurate for the TCP transport.
The socket ->sendmsg() method can return "-EAGAIN" if the socket's output
buffer is full, so the TCP transport's ->send_request() method may call
the ->sendmsg() method repeatedly until it gets all of the request's bytes
queued in the socket's buffer.

Currently, the TCP transport sets the rq_xtime field every time through
that loop so the final value is the timestamp just before the *last* call
to the underlying socket's ->sendmsg() method.  After this patch, the
rq_xtime field contains a timestamp that reflects the time just before the
*first* call to ->sendmsg().

This is consequential under heavy workloads because large requests often
take multiple ->sendmsg() calls to get all the bytes of a request queued.
The TCP transport causes the request to sleep until the remote end of the
socket has received enough bytes to clear space in the socket's local
output buffer.  This delay can be quite significant.

The method introduced by this patch is a more accurate measure of RTT
for stream transports, since the server can cause enough back pressure
to delay (ie increase the latency of) requests from the client.

Additionally, this patch corrects the behavior of the RDMA transport, which
entirely neglected to initialize the rq_xtime field.  RPC performance
metrics for RDMA transports now display correct RPC request round trip
times.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Acked-by: Tom Talpey <thomas.talpey@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2008-07-09 12:09:15 -04:00

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/*
* linux/net/sunrpc/xprt.c
*
* This is a generic RPC call interface supporting congestion avoidance,
* and asynchronous calls.
*
* The interface works like this:
*
* - When a process places a call, it allocates a request slot if
* one is available. Otherwise, it sleeps on the backlog queue
* (xprt_reserve).
* - Next, the caller puts together the RPC message, stuffs it into
* the request struct, and calls xprt_transmit().
* - xprt_transmit sends the message and installs the caller on the
* transport's wait list. At the same time, it installs a timer that
* is run after the packet's timeout has expired.
* - When a packet arrives, the data_ready handler walks the list of
* pending requests for that transport. If a matching XID is found, the
* caller is woken up, and the timer removed.
* - When no reply arrives within the timeout interval, the timer is
* fired by the kernel and runs xprt_timer(). It either adjusts the
* timeout values (minor timeout) or wakes up the caller with a status
* of -ETIMEDOUT.
* - When the caller receives a notification from RPC that a reply arrived,
* it should release the RPC slot, and process the reply.
* If the call timed out, it may choose to retry the operation by
* adjusting the initial timeout value, and simply calling rpc_call
* again.
*
* Support for async RPC is done through a set of RPC-specific scheduling
* primitives that `transparently' work for processes as well as async
* tasks that rely on callbacks.
*
* Copyright (C) 1995-1997, Olaf Kirch <okir@monad.swb.de>
*
* Transport switch API copyright (C) 2005, Chuck Lever <cel@netapp.com>
*/
#include <linux/module.h>
#include <linux/types.h>
#include <linux/interrupt.h>
#include <linux/workqueue.h>
#include <linux/net.h>
#include <linux/sunrpc/clnt.h>
#include <linux/sunrpc/metrics.h>
/*
* Local variables
*/
#ifdef RPC_DEBUG
# define RPCDBG_FACILITY RPCDBG_XPRT
#endif
/*
* Local functions
*/
static void xprt_request_init(struct rpc_task *, struct rpc_xprt *);
static inline void do_xprt_reserve(struct rpc_task *);
static void xprt_connect_status(struct rpc_task *task);
static int __xprt_get_cong(struct rpc_xprt *, struct rpc_task *);
static DEFINE_SPINLOCK(xprt_list_lock);
static LIST_HEAD(xprt_list);
/*
* The transport code maintains an estimate on the maximum number of out-
* standing RPC requests, using a smoothed version of the congestion
* avoidance implemented in 44BSD. This is basically the Van Jacobson
* congestion algorithm: If a retransmit occurs, the congestion window is
* halved; otherwise, it is incremented by 1/cwnd when
*
* - a reply is received and
* - a full number of requests are outstanding and
* - the congestion window hasn't been updated recently.
*/
#define RPC_CWNDSHIFT (8U)
#define RPC_CWNDSCALE (1U << RPC_CWNDSHIFT)
#define RPC_INITCWND RPC_CWNDSCALE
#define RPC_MAXCWND(xprt) ((xprt)->max_reqs << RPC_CWNDSHIFT)
#define RPCXPRT_CONGESTED(xprt) ((xprt)->cong >= (xprt)->cwnd)
/**
* xprt_register_transport - register a transport implementation
* @transport: transport to register
*
* If a transport implementation is loaded as a kernel module, it can
* call this interface to make itself known to the RPC client.
*
* Returns:
* 0: transport successfully registered
* -EEXIST: transport already registered
* -EINVAL: transport module being unloaded
*/
int xprt_register_transport(struct xprt_class *transport)
{
struct xprt_class *t;
int result;
result = -EEXIST;
spin_lock(&xprt_list_lock);
list_for_each_entry(t, &xprt_list, list) {
/* don't register the same transport class twice */
if (t->ident == transport->ident)
goto out;
}
result = -EINVAL;
if (try_module_get(THIS_MODULE)) {
list_add_tail(&transport->list, &xprt_list);
printk(KERN_INFO "RPC: Registered %s transport module.\n",
transport->name);
result = 0;
}
out:
spin_unlock(&xprt_list_lock);
return result;
}
EXPORT_SYMBOL_GPL(xprt_register_transport);
/**
* xprt_unregister_transport - unregister a transport implementation
* @transport: transport to unregister
*
* Returns:
* 0: transport successfully unregistered
* -ENOENT: transport never registered
*/
int xprt_unregister_transport(struct xprt_class *transport)
{
struct xprt_class *t;
int result;
result = 0;
spin_lock(&xprt_list_lock);
list_for_each_entry(t, &xprt_list, list) {
if (t == transport) {
printk(KERN_INFO
"RPC: Unregistered %s transport module.\n",
transport->name);
list_del_init(&transport->list);
module_put(THIS_MODULE);
goto out;
}
}
result = -ENOENT;
out:
spin_unlock(&xprt_list_lock);
return result;
}
EXPORT_SYMBOL_GPL(xprt_unregister_transport);
/**
* xprt_reserve_xprt - serialize write access to transports
* @task: task that is requesting access to the transport
*
* This prevents mixing the payload of separate requests, and prevents
* transport connects from colliding with writes. No congestion control
* is provided.
*/
int xprt_reserve_xprt(struct rpc_task *task)
{
struct rpc_xprt *xprt = task->tk_xprt;
struct rpc_rqst *req = task->tk_rqstp;
if (test_and_set_bit(XPRT_LOCKED, &xprt->state)) {
if (task == xprt->snd_task)
return 1;
if (task == NULL)
return 0;
goto out_sleep;
}
xprt->snd_task = task;
if (req) {
req->rq_bytes_sent = 0;
req->rq_ntrans++;
}
return 1;
out_sleep:
dprintk("RPC: %5u failed to lock transport %p\n",
task->tk_pid, xprt);
task->tk_timeout = 0;
task->tk_status = -EAGAIN;
if (req && req->rq_ntrans)
rpc_sleep_on(&xprt->resend, task, NULL);
else
rpc_sleep_on(&xprt->sending, task, NULL);
return 0;
}
EXPORT_SYMBOL_GPL(xprt_reserve_xprt);
static void xprt_clear_locked(struct rpc_xprt *xprt)
{
xprt->snd_task = NULL;
if (!test_bit(XPRT_CLOSE_WAIT, &xprt->state) || xprt->shutdown) {
smp_mb__before_clear_bit();
clear_bit(XPRT_LOCKED, &xprt->state);
smp_mb__after_clear_bit();
} else
queue_work(rpciod_workqueue, &xprt->task_cleanup);
}
/*
* xprt_reserve_xprt_cong - serialize write access to transports
* @task: task that is requesting access to the transport
*
* Same as xprt_reserve_xprt, but Van Jacobson congestion control is
* integrated into the decision of whether a request is allowed to be
* woken up and given access to the transport.
*/
int xprt_reserve_xprt_cong(struct rpc_task *task)
{
struct rpc_xprt *xprt = task->tk_xprt;
struct rpc_rqst *req = task->tk_rqstp;
if (test_and_set_bit(XPRT_LOCKED, &xprt->state)) {
if (task == xprt->snd_task)
return 1;
goto out_sleep;
}
if (__xprt_get_cong(xprt, task)) {
xprt->snd_task = task;
if (req) {
req->rq_bytes_sent = 0;
req->rq_ntrans++;
}
return 1;
}
xprt_clear_locked(xprt);
out_sleep:
dprintk("RPC: %5u failed to lock transport %p\n", task->tk_pid, xprt);
task->tk_timeout = 0;
task->tk_status = -EAGAIN;
if (req && req->rq_ntrans)
rpc_sleep_on(&xprt->resend, task, NULL);
else
rpc_sleep_on(&xprt->sending, task, NULL);
return 0;
}
EXPORT_SYMBOL_GPL(xprt_reserve_xprt_cong);
static inline int xprt_lock_write(struct rpc_xprt *xprt, struct rpc_task *task)
{
int retval;
spin_lock_bh(&xprt->transport_lock);
retval = xprt->ops->reserve_xprt(task);
spin_unlock_bh(&xprt->transport_lock);
return retval;
}
static void __xprt_lock_write_next(struct rpc_xprt *xprt)
{
struct rpc_task *task;
struct rpc_rqst *req;
if (test_and_set_bit(XPRT_LOCKED, &xprt->state))
return;
task = rpc_wake_up_next(&xprt->resend);
if (!task) {
task = rpc_wake_up_next(&xprt->sending);
if (!task)
goto out_unlock;
}
req = task->tk_rqstp;
xprt->snd_task = task;
if (req) {
req->rq_bytes_sent = 0;
req->rq_ntrans++;
}
return;
out_unlock:
xprt_clear_locked(xprt);
}
static void __xprt_lock_write_next_cong(struct rpc_xprt *xprt)
{
struct rpc_task *task;
if (test_and_set_bit(XPRT_LOCKED, &xprt->state))
return;
if (RPCXPRT_CONGESTED(xprt))
goto out_unlock;
task = rpc_wake_up_next(&xprt->resend);
if (!task) {
task = rpc_wake_up_next(&xprt->sending);
if (!task)
goto out_unlock;
}
if (__xprt_get_cong(xprt, task)) {
struct rpc_rqst *req = task->tk_rqstp;
xprt->snd_task = task;
if (req) {
req->rq_bytes_sent = 0;
req->rq_ntrans++;
}
return;
}
out_unlock:
xprt_clear_locked(xprt);
}
/**
* xprt_release_xprt - allow other requests to use a transport
* @xprt: transport with other tasks potentially waiting
* @task: task that is releasing access to the transport
*
* Note that "task" can be NULL. No congestion control is provided.
*/
void xprt_release_xprt(struct rpc_xprt *xprt, struct rpc_task *task)
{
if (xprt->snd_task == task) {
xprt_clear_locked(xprt);
__xprt_lock_write_next(xprt);
}
}
EXPORT_SYMBOL_GPL(xprt_release_xprt);
/**
* xprt_release_xprt_cong - allow other requests to use a transport
* @xprt: transport with other tasks potentially waiting
* @task: task that is releasing access to the transport
*
* Note that "task" can be NULL. Another task is awoken to use the
* transport if the transport's congestion window allows it.
*/
void xprt_release_xprt_cong(struct rpc_xprt *xprt, struct rpc_task *task)
{
if (xprt->snd_task == task) {
xprt_clear_locked(xprt);
__xprt_lock_write_next_cong(xprt);
}
}
EXPORT_SYMBOL_GPL(xprt_release_xprt_cong);
static inline void xprt_release_write(struct rpc_xprt *xprt, struct rpc_task *task)
{
spin_lock_bh(&xprt->transport_lock);
xprt->ops->release_xprt(xprt, task);
spin_unlock_bh(&xprt->transport_lock);
}
/*
* Van Jacobson congestion avoidance. Check if the congestion window
* overflowed. Put the task to sleep if this is the case.
*/
static int
__xprt_get_cong(struct rpc_xprt *xprt, struct rpc_task *task)
{
struct rpc_rqst *req = task->tk_rqstp;
if (req->rq_cong)
return 1;
dprintk("RPC: %5u xprt_cwnd_limited cong = %lu cwnd = %lu\n",
task->tk_pid, xprt->cong, xprt->cwnd);
if (RPCXPRT_CONGESTED(xprt))
return 0;
req->rq_cong = 1;
xprt->cong += RPC_CWNDSCALE;
return 1;
}
/*
* Adjust the congestion window, and wake up the next task
* that has been sleeping due to congestion
*/
static void
__xprt_put_cong(struct rpc_xprt *xprt, struct rpc_rqst *req)
{
if (!req->rq_cong)
return;
req->rq_cong = 0;
xprt->cong -= RPC_CWNDSCALE;
__xprt_lock_write_next_cong(xprt);
}
/**
* xprt_release_rqst_cong - housekeeping when request is complete
* @task: RPC request that recently completed
*
* Useful for transports that require congestion control.
*/
void xprt_release_rqst_cong(struct rpc_task *task)
{
__xprt_put_cong(task->tk_xprt, task->tk_rqstp);
}
EXPORT_SYMBOL_GPL(xprt_release_rqst_cong);
/**
* xprt_adjust_cwnd - adjust transport congestion window
* @task: recently completed RPC request used to adjust window
* @result: result code of completed RPC request
*
* We use a time-smoothed congestion estimator to avoid heavy oscillation.
*/
void xprt_adjust_cwnd(struct rpc_task *task, int result)
{
struct rpc_rqst *req = task->tk_rqstp;
struct rpc_xprt *xprt = task->tk_xprt;
unsigned long cwnd = xprt->cwnd;
if (result >= 0 && cwnd <= xprt->cong) {
/* The (cwnd >> 1) term makes sure
* the result gets rounded properly. */
cwnd += (RPC_CWNDSCALE * RPC_CWNDSCALE + (cwnd >> 1)) / cwnd;
if (cwnd > RPC_MAXCWND(xprt))
cwnd = RPC_MAXCWND(xprt);
__xprt_lock_write_next_cong(xprt);
} else if (result == -ETIMEDOUT) {
cwnd >>= 1;
if (cwnd < RPC_CWNDSCALE)
cwnd = RPC_CWNDSCALE;
}
dprintk("RPC: cong %ld, cwnd was %ld, now %ld\n",
xprt->cong, xprt->cwnd, cwnd);
xprt->cwnd = cwnd;
__xprt_put_cong(xprt, req);
}
EXPORT_SYMBOL_GPL(xprt_adjust_cwnd);
/**
* xprt_wake_pending_tasks - wake all tasks on a transport's pending queue
* @xprt: transport with waiting tasks
* @status: result code to plant in each task before waking it
*
*/
void xprt_wake_pending_tasks(struct rpc_xprt *xprt, int status)
{
if (status < 0)
rpc_wake_up_status(&xprt->pending, status);
else
rpc_wake_up(&xprt->pending);
}
EXPORT_SYMBOL_GPL(xprt_wake_pending_tasks);
/**
* xprt_wait_for_buffer_space - wait for transport output buffer to clear
* @task: task to be put to sleep
* @action: function pointer to be executed after wait
*/
void xprt_wait_for_buffer_space(struct rpc_task *task, rpc_action action)
{
struct rpc_rqst *req = task->tk_rqstp;
struct rpc_xprt *xprt = req->rq_xprt;
task->tk_timeout = req->rq_timeout;
rpc_sleep_on(&xprt->pending, task, action);
}
EXPORT_SYMBOL_GPL(xprt_wait_for_buffer_space);
/**
* xprt_write_space - wake the task waiting for transport output buffer space
* @xprt: transport with waiting tasks
*
* Can be called in a soft IRQ context, so xprt_write_space never sleeps.
*/
void xprt_write_space(struct rpc_xprt *xprt)
{
if (unlikely(xprt->shutdown))
return;
spin_lock_bh(&xprt->transport_lock);
if (xprt->snd_task) {
dprintk("RPC: write space: waking waiting task on "
"xprt %p\n", xprt);
rpc_wake_up_queued_task(&xprt->pending, xprt->snd_task);
}
spin_unlock_bh(&xprt->transport_lock);
}
EXPORT_SYMBOL_GPL(xprt_write_space);
/**
* xprt_set_retrans_timeout_def - set a request's retransmit timeout
* @task: task whose timeout is to be set
*
* Set a request's retransmit timeout based on the transport's
* default timeout parameters. Used by transports that don't adjust
* the retransmit timeout based on round-trip time estimation.
*/
void xprt_set_retrans_timeout_def(struct rpc_task *task)
{
task->tk_timeout = task->tk_rqstp->rq_timeout;
}
EXPORT_SYMBOL_GPL(xprt_set_retrans_timeout_def);
/*
* xprt_set_retrans_timeout_rtt - set a request's retransmit timeout
* @task: task whose timeout is to be set
*
* Set a request's retransmit timeout using the RTT estimator.
*/
void xprt_set_retrans_timeout_rtt(struct rpc_task *task)
{
int timer = task->tk_msg.rpc_proc->p_timer;
struct rpc_clnt *clnt = task->tk_client;
struct rpc_rtt *rtt = clnt->cl_rtt;
struct rpc_rqst *req = task->tk_rqstp;
unsigned long max_timeout = clnt->cl_timeout->to_maxval;
task->tk_timeout = rpc_calc_rto(rtt, timer);
task->tk_timeout <<= rpc_ntimeo(rtt, timer) + req->rq_retries;
if (task->tk_timeout > max_timeout || task->tk_timeout == 0)
task->tk_timeout = max_timeout;
}
EXPORT_SYMBOL_GPL(xprt_set_retrans_timeout_rtt);
static void xprt_reset_majortimeo(struct rpc_rqst *req)
{
const struct rpc_timeout *to = req->rq_task->tk_client->cl_timeout;
req->rq_majortimeo = req->rq_timeout;
if (to->to_exponential)
req->rq_majortimeo <<= to->to_retries;
else
req->rq_majortimeo += to->to_increment * to->to_retries;
if (req->rq_majortimeo > to->to_maxval || req->rq_majortimeo == 0)
req->rq_majortimeo = to->to_maxval;
req->rq_majortimeo += jiffies;
}
/**
* xprt_adjust_timeout - adjust timeout values for next retransmit
* @req: RPC request containing parameters to use for the adjustment
*
*/
int xprt_adjust_timeout(struct rpc_rqst *req)
{
struct rpc_xprt *xprt = req->rq_xprt;
const struct rpc_timeout *to = req->rq_task->tk_client->cl_timeout;
int status = 0;
if (time_before(jiffies, req->rq_majortimeo)) {
if (to->to_exponential)
req->rq_timeout <<= 1;
else
req->rq_timeout += to->to_increment;
if (to->to_maxval && req->rq_timeout >= to->to_maxval)
req->rq_timeout = to->to_maxval;
req->rq_retries++;
} else {
req->rq_timeout = to->to_initval;
req->rq_retries = 0;
xprt_reset_majortimeo(req);
/* Reset the RTT counters == "slow start" */
spin_lock_bh(&xprt->transport_lock);
rpc_init_rtt(req->rq_task->tk_client->cl_rtt, to->to_initval);
spin_unlock_bh(&xprt->transport_lock);
status = -ETIMEDOUT;
}
if (req->rq_timeout == 0) {
printk(KERN_WARNING "xprt_adjust_timeout: rq_timeout = 0!\n");
req->rq_timeout = 5 * HZ;
}
return status;
}
static void xprt_autoclose(struct work_struct *work)
{
struct rpc_xprt *xprt =
container_of(work, struct rpc_xprt, task_cleanup);
xprt->ops->close(xprt);
clear_bit(XPRT_CLOSE_WAIT, &xprt->state);
xprt_release_write(xprt, NULL);
}
/**
* xprt_disconnect_done - mark a transport as disconnected
* @xprt: transport to flag for disconnect
*
*/
void xprt_disconnect_done(struct rpc_xprt *xprt)
{
dprintk("RPC: disconnected transport %p\n", xprt);
spin_lock_bh(&xprt->transport_lock);
xprt_clear_connected(xprt);
xprt_wake_pending_tasks(xprt, -ENOTCONN);
spin_unlock_bh(&xprt->transport_lock);
}
EXPORT_SYMBOL_GPL(xprt_disconnect_done);
/**
* xprt_force_disconnect - force a transport to disconnect
* @xprt: transport to disconnect
*
*/
void xprt_force_disconnect(struct rpc_xprt *xprt)
{
/* Don't race with the test_bit() in xprt_clear_locked() */
spin_lock_bh(&xprt->transport_lock);
set_bit(XPRT_CLOSE_WAIT, &xprt->state);
/* Try to schedule an autoclose RPC call */
if (test_and_set_bit(XPRT_LOCKED, &xprt->state) == 0)
queue_work(rpciod_workqueue, &xprt->task_cleanup);
xprt_wake_pending_tasks(xprt, -ENOTCONN);
spin_unlock_bh(&xprt->transport_lock);
}
/**
* xprt_conditional_disconnect - force a transport to disconnect
* @xprt: transport to disconnect
* @cookie: 'connection cookie'
*
* This attempts to break the connection if and only if 'cookie' matches
* the current transport 'connection cookie'. It ensures that we don't
* try to break the connection more than once when we need to retransmit
* a batch of RPC requests.
*
*/
void xprt_conditional_disconnect(struct rpc_xprt *xprt, unsigned int cookie)
{
/* Don't race with the test_bit() in xprt_clear_locked() */
spin_lock_bh(&xprt->transport_lock);
if (cookie != xprt->connect_cookie)
goto out;
if (test_bit(XPRT_CLOSING, &xprt->state) || !xprt_connected(xprt))
goto out;
set_bit(XPRT_CLOSE_WAIT, &xprt->state);
/* Try to schedule an autoclose RPC call */
if (test_and_set_bit(XPRT_LOCKED, &xprt->state) == 0)
queue_work(rpciod_workqueue, &xprt->task_cleanup);
xprt_wake_pending_tasks(xprt, -ENOTCONN);
out:
spin_unlock_bh(&xprt->transport_lock);
}
static void
xprt_init_autodisconnect(unsigned long data)
{
struct rpc_xprt *xprt = (struct rpc_xprt *)data;
spin_lock(&xprt->transport_lock);
if (!list_empty(&xprt->recv) || xprt->shutdown)
goto out_abort;
if (test_and_set_bit(XPRT_LOCKED, &xprt->state))
goto out_abort;
spin_unlock(&xprt->transport_lock);
if (xprt_connecting(xprt))
xprt_release_write(xprt, NULL);
else
queue_work(rpciod_workqueue, &xprt->task_cleanup);
return;
out_abort:
spin_unlock(&xprt->transport_lock);
}
/**
* xprt_connect - schedule a transport connect operation
* @task: RPC task that is requesting the connect
*
*/
void xprt_connect(struct rpc_task *task)
{
struct rpc_xprt *xprt = task->tk_xprt;
dprintk("RPC: %5u xprt_connect xprt %p %s connected\n", task->tk_pid,
xprt, (xprt_connected(xprt) ? "is" : "is not"));
if (!xprt_bound(xprt)) {
task->tk_status = -EIO;
return;
}
if (!xprt_lock_write(xprt, task))
return;
if (xprt_connected(xprt))
xprt_release_write(xprt, task);
else {
if (task->tk_rqstp)
task->tk_rqstp->rq_bytes_sent = 0;
task->tk_timeout = xprt->connect_timeout;
rpc_sleep_on(&xprt->pending, task, xprt_connect_status);
xprt->stat.connect_start = jiffies;
xprt->ops->connect(task);
}
return;
}
static void xprt_connect_status(struct rpc_task *task)
{
struct rpc_xprt *xprt = task->tk_xprt;
if (task->tk_status == 0) {
xprt->stat.connect_count++;
xprt->stat.connect_time += (long)jiffies - xprt->stat.connect_start;
dprintk("RPC: %5u xprt_connect_status: connection established\n",
task->tk_pid);
return;
}
switch (task->tk_status) {
case -ENOTCONN:
dprintk("RPC: %5u xprt_connect_status: connection broken\n",
task->tk_pid);
break;
case -ETIMEDOUT:
dprintk("RPC: %5u xprt_connect_status: connect attempt timed "
"out\n", task->tk_pid);
break;
default:
dprintk("RPC: %5u xprt_connect_status: error %d connecting to "
"server %s\n", task->tk_pid, -task->tk_status,
task->tk_client->cl_server);
xprt_release_write(xprt, task);
task->tk_status = -EIO;
}
}
/**
* xprt_lookup_rqst - find an RPC request corresponding to an XID
* @xprt: transport on which the original request was transmitted
* @xid: RPC XID of incoming reply
*
*/
struct rpc_rqst *xprt_lookup_rqst(struct rpc_xprt *xprt, __be32 xid)
{
struct list_head *pos;
list_for_each(pos, &xprt->recv) {
struct rpc_rqst *entry = list_entry(pos, struct rpc_rqst, rq_list);
if (entry->rq_xid == xid)
return entry;
}
dprintk("RPC: xprt_lookup_rqst did not find xid %08x\n",
ntohl(xid));
xprt->stat.bad_xids++;
return NULL;
}
EXPORT_SYMBOL_GPL(xprt_lookup_rqst);
/**
* xprt_update_rtt - update an RPC client's RTT state after receiving a reply
* @task: RPC request that recently completed
*
*/
void xprt_update_rtt(struct rpc_task *task)
{
struct rpc_rqst *req = task->tk_rqstp;
struct rpc_rtt *rtt = task->tk_client->cl_rtt;
unsigned timer = task->tk_msg.rpc_proc->p_timer;
if (timer) {
if (req->rq_ntrans == 1)
rpc_update_rtt(rtt, timer,
(long)jiffies - req->rq_xtime);
rpc_set_timeo(rtt, timer, req->rq_ntrans - 1);
}
}
EXPORT_SYMBOL_GPL(xprt_update_rtt);
/**
* xprt_complete_rqst - called when reply processing is complete
* @task: RPC request that recently completed
* @copied: actual number of bytes received from the transport
*
* Caller holds transport lock.
*/
void xprt_complete_rqst(struct rpc_task *task, int copied)
{
struct rpc_rqst *req = task->tk_rqstp;
struct rpc_xprt *xprt = req->rq_xprt;
dprintk("RPC: %5u xid %08x complete (%d bytes received)\n",
task->tk_pid, ntohl(req->rq_xid), copied);
xprt->stat.recvs++;
task->tk_rtt = (long)jiffies - req->rq_xtime;
list_del_init(&req->rq_list);
req->rq_private_buf.len = copied;
/* Ensure all writes are done before we update req->rq_received */
smp_wmb();
req->rq_received = copied;
rpc_wake_up_queued_task(&xprt->pending, task);
}
EXPORT_SYMBOL_GPL(xprt_complete_rqst);
static void xprt_timer(struct rpc_task *task)
{
struct rpc_rqst *req = task->tk_rqstp;
struct rpc_xprt *xprt = req->rq_xprt;
if (task->tk_status != -ETIMEDOUT)
return;
dprintk("RPC: %5u xprt_timer\n", task->tk_pid);
spin_lock_bh(&xprt->transport_lock);
if (!req->rq_received) {
if (xprt->ops->timer)
xprt->ops->timer(task);
} else
task->tk_status = 0;
spin_unlock_bh(&xprt->transport_lock);
}
/**
* xprt_prepare_transmit - reserve the transport before sending a request
* @task: RPC task about to send a request
*
*/
int xprt_prepare_transmit(struct rpc_task *task)
{
struct rpc_rqst *req = task->tk_rqstp;
struct rpc_xprt *xprt = req->rq_xprt;
int err = 0;
dprintk("RPC: %5u xprt_prepare_transmit\n", task->tk_pid);
spin_lock_bh(&xprt->transport_lock);
if (req->rq_received && !req->rq_bytes_sent) {
err = req->rq_received;
goto out_unlock;
}
if (!xprt->ops->reserve_xprt(task)) {
err = -EAGAIN;
goto out_unlock;
}
if (!xprt_connected(xprt)) {
err = -ENOTCONN;
goto out_unlock;
}
out_unlock:
spin_unlock_bh(&xprt->transport_lock);
return err;
}
void xprt_end_transmit(struct rpc_task *task)
{
xprt_release_write(task->tk_xprt, task);
}
/**
* xprt_transmit - send an RPC request on a transport
* @task: controlling RPC task
*
* We have to copy the iovec because sendmsg fiddles with its contents.
*/
void xprt_transmit(struct rpc_task *task)
{
struct rpc_rqst *req = task->tk_rqstp;
struct rpc_xprt *xprt = req->rq_xprt;
int status;
dprintk("RPC: %5u xprt_transmit(%u)\n", task->tk_pid, req->rq_slen);
if (!req->rq_received) {
if (list_empty(&req->rq_list)) {
spin_lock_bh(&xprt->transport_lock);
/* Update the softirq receive buffer */
memcpy(&req->rq_private_buf, &req->rq_rcv_buf,
sizeof(req->rq_private_buf));
/* Add request to the receive list */
list_add_tail(&req->rq_list, &xprt->recv);
spin_unlock_bh(&xprt->transport_lock);
xprt_reset_majortimeo(req);
/* Turn off autodisconnect */
del_singleshot_timer_sync(&xprt->timer);
}
} else if (!req->rq_bytes_sent)
return;
req->rq_connect_cookie = xprt->connect_cookie;
req->rq_xtime = jiffies;
status = xprt->ops->send_request(task);
if (status == 0) {
dprintk("RPC: %5u xmit complete\n", task->tk_pid);
spin_lock_bh(&xprt->transport_lock);
xprt->ops->set_retrans_timeout(task);
xprt->stat.sends++;
xprt->stat.req_u += xprt->stat.sends - xprt->stat.recvs;
xprt->stat.bklog_u += xprt->backlog.qlen;
/* Don't race with disconnect */
if (!xprt_connected(xprt))
task->tk_status = -ENOTCONN;
else if (!req->rq_received)
rpc_sleep_on(&xprt->pending, task, xprt_timer);
spin_unlock_bh(&xprt->transport_lock);
return;
}
/* Note: at this point, task->tk_sleeping has not yet been set,
* hence there is no danger of the waking up task being put on
* schedq, and being picked up by a parallel run of rpciod().
*/
task->tk_status = status;
if (status == -ECONNREFUSED)
rpc_sleep_on(&xprt->sending, task, NULL);
}
static inline void do_xprt_reserve(struct rpc_task *task)
{
struct rpc_xprt *xprt = task->tk_xprt;
task->tk_status = 0;
if (task->tk_rqstp)
return;
if (!list_empty(&xprt->free)) {
struct rpc_rqst *req = list_entry(xprt->free.next, struct rpc_rqst, rq_list);
list_del_init(&req->rq_list);
task->tk_rqstp = req;
xprt_request_init(task, xprt);
return;
}
dprintk("RPC: waiting for request slot\n");
task->tk_status = -EAGAIN;
task->tk_timeout = 0;
rpc_sleep_on(&xprt->backlog, task, NULL);
}
/**
* xprt_reserve - allocate an RPC request slot
* @task: RPC task requesting a slot allocation
*
* If no more slots are available, place the task on the transport's
* backlog queue.
*/
void xprt_reserve(struct rpc_task *task)
{
struct rpc_xprt *xprt = task->tk_xprt;
task->tk_status = -EIO;
spin_lock(&xprt->reserve_lock);
do_xprt_reserve(task);
spin_unlock(&xprt->reserve_lock);
}
static inline __be32 xprt_alloc_xid(struct rpc_xprt *xprt)
{
return xprt->xid++;
}
static inline void xprt_init_xid(struct rpc_xprt *xprt)
{
xprt->xid = net_random();
}
static void xprt_request_init(struct rpc_task *task, struct rpc_xprt *xprt)
{
struct rpc_rqst *req = task->tk_rqstp;
req->rq_timeout = task->tk_client->cl_timeout->to_initval;
req->rq_task = task;
req->rq_xprt = xprt;
req->rq_buffer = NULL;
req->rq_xid = xprt_alloc_xid(xprt);
req->rq_release_snd_buf = NULL;
xprt_reset_majortimeo(req);
dprintk("RPC: %5u reserved req %p xid %08x\n", task->tk_pid,
req, ntohl(req->rq_xid));
}
/**
* xprt_release - release an RPC request slot
* @task: task which is finished with the slot
*
*/
void xprt_release(struct rpc_task *task)
{
struct rpc_xprt *xprt = task->tk_xprt;
struct rpc_rqst *req;
if (!(req = task->tk_rqstp))
return;
rpc_count_iostats(task);
spin_lock_bh(&xprt->transport_lock);
xprt->ops->release_xprt(xprt, task);
if (xprt->ops->release_request)
xprt->ops->release_request(task);
if (!list_empty(&req->rq_list))
list_del(&req->rq_list);
xprt->last_used = jiffies;
if (list_empty(&xprt->recv))
mod_timer(&xprt->timer,
xprt->last_used + xprt->idle_timeout);
spin_unlock_bh(&xprt->transport_lock);
xprt->ops->buf_free(req->rq_buffer);
task->tk_rqstp = NULL;
if (req->rq_release_snd_buf)
req->rq_release_snd_buf(req);
memset(req, 0, sizeof(*req)); /* mark unused */
dprintk("RPC: %5u release request %p\n", task->tk_pid, req);
spin_lock(&xprt->reserve_lock);
list_add(&req->rq_list, &xprt->free);
rpc_wake_up_next(&xprt->backlog);
spin_unlock(&xprt->reserve_lock);
}
/**
* xprt_create_transport - create an RPC transport
* @args: rpc transport creation arguments
*
*/
struct rpc_xprt *xprt_create_transport(struct xprt_create *args)
{
struct rpc_xprt *xprt;
struct rpc_rqst *req;
struct xprt_class *t;
spin_lock(&xprt_list_lock);
list_for_each_entry(t, &xprt_list, list) {
if (t->ident == args->ident) {
spin_unlock(&xprt_list_lock);
goto found;
}
}
spin_unlock(&xprt_list_lock);
printk(KERN_ERR "RPC: transport (%d) not supported\n", args->ident);
return ERR_PTR(-EIO);
found:
xprt = t->setup(args);
if (IS_ERR(xprt)) {
dprintk("RPC: xprt_create_transport: failed, %ld\n",
-PTR_ERR(xprt));
return xprt;
}
kref_init(&xprt->kref);
spin_lock_init(&xprt->transport_lock);
spin_lock_init(&xprt->reserve_lock);
INIT_LIST_HEAD(&xprt->free);
INIT_LIST_HEAD(&xprt->recv);
INIT_WORK(&xprt->task_cleanup, xprt_autoclose);
setup_timer(&xprt->timer, xprt_init_autodisconnect,
(unsigned long)xprt);
xprt->last_used = jiffies;
xprt->cwnd = RPC_INITCWND;
xprt->bind_index = 0;
rpc_init_wait_queue(&xprt->binding, "xprt_binding");
rpc_init_wait_queue(&xprt->pending, "xprt_pending");
rpc_init_wait_queue(&xprt->sending, "xprt_sending");
rpc_init_wait_queue(&xprt->resend, "xprt_resend");
rpc_init_priority_wait_queue(&xprt->backlog, "xprt_backlog");
/* initialize free list */
for (req = &xprt->slot[xprt->max_reqs-1]; req >= &xprt->slot[0]; req--)
list_add(&req->rq_list, &xprt->free);
xprt_init_xid(xprt);
dprintk("RPC: created transport %p with %u slots\n", xprt,
xprt->max_reqs);
return xprt;
}
/**
* xprt_destroy - destroy an RPC transport, killing off all requests.
* @kref: kref for the transport to destroy
*
*/
static void xprt_destroy(struct kref *kref)
{
struct rpc_xprt *xprt = container_of(kref, struct rpc_xprt, kref);
dprintk("RPC: destroying transport %p\n", xprt);
xprt->shutdown = 1;
del_timer_sync(&xprt->timer);
rpc_destroy_wait_queue(&xprt->binding);
rpc_destroy_wait_queue(&xprt->pending);
rpc_destroy_wait_queue(&xprt->sending);
rpc_destroy_wait_queue(&xprt->resend);
rpc_destroy_wait_queue(&xprt->backlog);
/*
* Tear down transport state and free the rpc_xprt
*/
xprt->ops->destroy(xprt);
}
/**
* xprt_put - release a reference to an RPC transport.
* @xprt: pointer to the transport
*
*/
void xprt_put(struct rpc_xprt *xprt)
{
kref_put(&xprt->kref, xprt_destroy);
}
/**
* xprt_get - return a reference to an RPC transport.
* @xprt: pointer to the transport
*
*/
struct rpc_xprt *xprt_get(struct rpc_xprt *xprt)
{
kref_get(&xprt->kref);
return xprt;
}
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