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kernel-aes67/net/sunrpc/xprt.c
Chuck Lever 03bf4b707e [PATCH] RPC: parametrize various transport connect timeouts 
Each transport implementation can now set unique bind, connect,
 reestablishment, and idle timeout values.  These are variables,
 allowing the values to be modified dynamically.  This permits
 exponential backoff of any of these values, for instance.

 As an example, we implement exponential backoff for the connection
 reestablishment timeout.

 Test-plan:
 Destructive testing (unplugging the network temporarily).  Connectathon
 with UDP and TCP.

 Signed-off-by: Chuck Lever <cel@netapp.com>
 Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2005-09-23 12:38:53 -04:00

990 lines
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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/random.h>
#include <linux/sunrpc/clnt.h>
/*
* Local variables
*/
#ifdef RPC_DEBUG
# undef RPC_DEBUG_DATA
# 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 *);
/*
* 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_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: %4d 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, NULL);
else
rpc_sleep_on(&xprt->sending, task, NULL, NULL);
return 0;
}
/*
* 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;
}
smp_mb__before_clear_bit();
clear_bit(XPRT_LOCKED, &xprt->state);
smp_mb__after_clear_bit();
out_sleep:
dprintk("RPC: %4d 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, NULL);
else
rpc_sleep_on(&xprt->sending, task, NULL, NULL);
return 0;
}
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:
smp_mb__before_clear_bit();
clear_bit(XPRT_LOCKED, &xprt->state);
smp_mb__after_clear_bit();
}
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:
smp_mb__before_clear_bit();
clear_bit(XPRT_LOCKED, &xprt->state);
smp_mb__after_clear_bit();
}
/**
* 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->snd_task = NULL;
smp_mb__before_clear_bit();
clear_bit(XPRT_LOCKED, &xprt->state);
smp_mb__after_clear_bit();
__xprt_lock_write_next(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->snd_task = NULL;
smp_mb__before_clear_bit();
clear_bit(XPRT_LOCKED, &xprt->state);
smp_mb__after_clear_bit();
__xprt_lock_write_next_cong(xprt);
}
}
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: %4d xprt_cwnd_limited cong = %ld cwnd = %ld\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);
}
/**
* 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);
}
/**
* 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);
}
/**
* xprt_wait_for_buffer_space - wait for transport output buffer to clear
* @task: task to be put to sleep
*
*/
void xprt_wait_for_buffer_space(struct rpc_task *task)
{
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, NULL, NULL);
}
/**
* 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_task(xprt->snd_task);
}
spin_unlock_bh(&xprt->transport_lock);
}
/**
* 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;
}
/*
* 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_rtt *rtt = task->tk_client->cl_rtt;
struct rpc_rqst *req = task->tk_rqstp;
unsigned long max_timeout = req->rq_xprt->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;
}
static void xprt_reset_majortimeo(struct rpc_rqst *req)
{
struct rpc_timeout *to = &req->rq_xprt->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;
struct rpc_timeout *to = &xprt->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++;
pprintk("RPC: %lu retrans\n", jiffies);
} 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);
pprintk("RPC: %lu timeout\n", jiffies);
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(void *args)
{
struct rpc_xprt *xprt = (struct rpc_xprt *)args;
xprt_disconnect(xprt);
xprt->ops->close(xprt);
xprt_release_write(xprt, NULL);
}
/**
* xprt_disconnect - mark a transport as disconnected
* @xprt: transport to flag for disconnect
*
*/
void xprt_disconnect(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);
}
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
schedule_work(&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: %4d xprt_connect xprt %p %s connected\n", task->tk_pid,
xprt, (xprt_connected(xprt) ? "is" : "is not"));
if (xprt->shutdown) {
task->tk_status = -EIO;
return;
}
if (!xprt->addr.sin_port) {
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, NULL);
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) {
dprintk("RPC: %4d xprt_connect_status: connection established\n",
task->tk_pid);
return;
}
switch (task->tk_status) {
case -ECONNREFUSED:
case -ECONNRESET:
dprintk("RPC: %4d xprt_connect_status: server %s refused connection\n",
task->tk_pid, task->tk_client->cl_server);
break;
case -ENOTCONN:
dprintk("RPC: %4d xprt_connect_status: connection broken\n",
task->tk_pid);
break;
case -ETIMEDOUT:
dprintk("RPC: %4d xprt_connect_status: connect attempt timed out\n",
task->tk_pid);
break;
default:
dprintk("RPC: %4d 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;
return;
}
/* if soft mounted, just cause this RPC to fail */
if (RPC_IS_SOFT(task)) {
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, u32 xid)
{
struct list_head *pos;
struct rpc_rqst *req = NULL;
list_for_each(pos, &xprt->recv) {
struct rpc_rqst *entry = list_entry(pos, struct rpc_rqst, rq_list);
if (entry->rq_xid == xid) {
req = entry;
break;
}
}
return req;
}
/**
* 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);
}
}
/**
* 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;
dprintk("RPC: %5u xid %08x complete (%d bytes received)\n",
task->tk_pid, ntohl(req->rq_xid), copied);
list_del_init(&req->rq_list);
req->rq_received = req->rq_private_buf.len = copied;
rpc_wake_up_task(task);
}
static void xprt_timer(struct rpc_task *task)
{
struct rpc_rqst *req = task->tk_rqstp;
struct rpc_xprt *xprt = req->rq_xprt;
dprintk("RPC: %4d xprt_timer\n", task->tk_pid);
spin_lock(&xprt->transport_lock);
if (!req->rq_received) {
if (xprt->ops->timer)
xprt->ops->timer(task);
task->tk_status = -ETIMEDOUT;
}
task->tk_timeout = 0;
rpc_wake_up_task(task);
spin_unlock(&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: %4d xprt_prepare_transmit\n", task->tk_pid);
if (xprt->shutdown)
return -EIO;
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;
}
/**
* 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: %4d xprt_transmit(%u)\n", task->tk_pid, req->rq_slen);
smp_rmb();
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;
status = xprt->ops->send_request(task);
if (status == 0) {
dprintk("RPC: %4d xmit complete\n", task->tk_pid);
spin_lock_bh(&xprt->transport_lock);
xprt->ops->set_retrans_timeout(task);
/* Don't race with disconnect */
if (!xprt_connected(xprt))
task->tk_status = -ENOTCONN;
else if (!req->rq_received)
rpc_sleep_on(&xprt->pending, task, NULL, xprt_timer);
xprt->ops->release_xprt(xprt, task);
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;
switch (status) {
case -ECONNREFUSED:
rpc_sleep_on(&xprt->sending, task, NULL, NULL);
case -EAGAIN:
case -ENOTCONN:
return;
default:
break;
}
xprt_release_write(xprt, task);
return;
}
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, 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;
if (!xprt->shutdown) {
spin_lock(&xprt->reserve_lock);
do_xprt_reserve(task);
spin_unlock(&xprt->reserve_lock);
}
}
static inline u32 xprt_alloc_xid(struct rpc_xprt *xprt)
{
return xprt->xid++;
}
static inline void xprt_init_xid(struct rpc_xprt *xprt)
{
get_random_bytes(&xprt->xid, sizeof(xprt->xid));
}
static void xprt_request_init(struct rpc_task *task, struct rpc_xprt *xprt)
{
struct rpc_rqst *req = task->tk_rqstp;
req->rq_timeout = xprt->timeout.to_initval;
req->rq_task = task;
req->rq_xprt = xprt;
req->rq_xid = xprt_alloc_xid(xprt);
dprintk("RPC: %4d 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;
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) && !xprt->shutdown)
mod_timer(&xprt->timer,
xprt->last_used + xprt->idle_timeout);
spin_unlock_bh(&xprt->transport_lock);
task->tk_rqstp = NULL;
memset(req, 0, sizeof(*req)); /* mark unused */
dprintk("RPC: %4d 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_set_timeout - set constant RPC timeout
* @to: RPC timeout parameters to set up
* @retr: number of retries
* @incr: amount of increase after each retry
*
*/
void xprt_set_timeout(struct rpc_timeout *to, unsigned int retr, unsigned long incr)
{
to->to_initval =
to->to_increment = incr;
to->to_maxval = to->to_initval + (incr * retr);
to->to_retries = retr;
to->to_exponential = 0;
}
static struct rpc_xprt *xprt_setup(int proto, struct sockaddr_in *ap, struct rpc_timeout *to)
{
int result;
struct rpc_xprt *xprt;
struct rpc_rqst *req;
if ((xprt = kmalloc(sizeof(struct rpc_xprt), GFP_KERNEL)) == NULL)
return ERR_PTR(-ENOMEM);
memset(xprt, 0, sizeof(*xprt)); /* Nnnngh! */
xprt->addr = *ap;
switch (proto) {
case IPPROTO_UDP:
result = xs_setup_udp(xprt, to);
break;
case IPPROTO_TCP:
result = xs_setup_tcp(xprt, to);
break;
default:
printk(KERN_ERR "RPC: unrecognized transport protocol: %d\n",
proto);
result = -EIO;
break;
}
if (result) {
kfree(xprt);
return ERR_PTR(result);
}
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, xprt);
init_timer(&xprt->timer);
xprt->timer.function = xprt_init_autodisconnect;
xprt->timer.data = (unsigned long) xprt;
xprt->last_used = jiffies;
xprt->cwnd = RPC_INITCWND;
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_create_proto - create an RPC client transport
* @proto: requested transport protocol
* @sap: remote peer's address
* @to: timeout parameters for new transport
*
*/
struct rpc_xprt *xprt_create_proto(int proto, struct sockaddr_in *sap, struct rpc_timeout *to)
{
struct rpc_xprt *xprt;
xprt = xprt_setup(proto, sap, to);
if (IS_ERR(xprt))
dprintk("RPC: xprt_create_proto failed\n");
else
dprintk("RPC: xprt_create_proto created xprt %p\n", xprt);
return xprt;
}
static void xprt_shutdown(struct rpc_xprt *xprt)
{
xprt->shutdown = 1;
rpc_wake_up(&xprt->sending);
rpc_wake_up(&xprt->resend);
xprt_wake_pending_tasks(xprt, -EIO);
rpc_wake_up(&xprt->backlog);
del_timer_sync(&xprt->timer);
}
/**
* xprt_destroy - destroy an RPC transport, killing off all requests.
* @xprt: transport to destroy
*
*/
int xprt_destroy(struct rpc_xprt *xprt)
{
dprintk("RPC: destroying transport %p\n", xprt);
xprt_shutdown(xprt);
xprt->ops->destroy(xprt);
kfree(xprt);
return 0;
}
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