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linux_dsm_epyc7002/net/sunrpc/xprt.c
Trond Myklebust 2275cde4cc SUNRPC: Queue latency-sensitive socket tasks to xprtiod 
The response to a write_space notification is very latency sensitive,
so we should queue it to the lower latency xprtiod_workqueue. This
is something we already do for the other cases where an rpc task
holds the transport XPRT_LOCKED bitlock.

Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
2018-02-07 09:25:52 -05:00

1529 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, if a reply is expected,
* 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/ktime.h>
#include <linux/sunrpc/clnt.h>
#include <linux/sunrpc/metrics.h>
#include <linux/sunrpc/bc_xprt.h>
#include <linux/rcupdate.h>
#include <trace/events/sunrpc.h>
#include "sunrpc.h"
/*
* Local variables
*/
#if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
# define RPCDBG_FACILITY RPCDBG_XPRT
#endif
/*
* Local functions
*/
static void xprt_init(struct rpc_xprt *xprt, struct net *net);
static void xprt_request_init(struct rpc_task *, struct rpc_xprt *);
static void xprt_connect_status(struct rpc_task *task);
static int __xprt_get_cong(struct rpc_xprt *, struct rpc_task *);
static void __xprt_put_cong(struct rpc_xprt *, struct rpc_rqst *);
static void xprt_destroy(struct rpc_xprt *xprt);
static DEFINE_SPINLOCK(xprt_list_lock);
static LIST_HEAD(xprt_list);
/**
* 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;
}
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);
goto out;
}
}
result = -ENOENT;
out:
spin_unlock(&xprt_list_lock);
return result;
}
EXPORT_SYMBOL_GPL(xprt_unregister_transport);
/**
* xprt_load_transport - load a transport implementation
* @transport_name: transport to load
*
* Returns:
* 0: transport successfully loaded
* -ENOENT: transport module not available
*/
int xprt_load_transport(const char *transport_name)
{
struct xprt_class *t;
int result;
result = 0;
spin_lock(&xprt_list_lock);
list_for_each_entry(t, &xprt_list, list) {
if (strcmp(t->name, transport_name) == 0) {
spin_unlock(&xprt_list_lock);
goto out;
}
}
spin_unlock(&xprt_list_lock);
result = request_module("xprt%s", transport_name);
out:
return result;
}
EXPORT_SYMBOL_GPL(xprt_load_transport);
/**
* xprt_reserve_xprt - serialize write access to transports
* @task: task that is requesting access to the transport
* @xprt: pointer to the target 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_xprt *xprt, struct rpc_task *task)
{
struct rpc_rqst *req = task->tk_rqstp;
int priority;
if (test_and_set_bit(XPRT_LOCKED, &xprt->state)) {
if (task == xprt->snd_task)
return 1;
goto out_sleep;
}
xprt->snd_task = task;
if (req != NULL)
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 == NULL)
priority = RPC_PRIORITY_LOW;
else if (!req->rq_ntrans)
priority = RPC_PRIORITY_NORMAL;
else
priority = RPC_PRIORITY_HIGH;
rpc_sleep_on_priority(&xprt->sending, task, NULL, priority);
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)) {
smp_mb__before_atomic();
clear_bit(XPRT_LOCKED, &xprt->state);
smp_mb__after_atomic();
} else
queue_work(xprtiod_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_xprt *xprt, struct rpc_task *task)
{
struct rpc_rqst *req = task->tk_rqstp;
int priority;
if (test_and_set_bit(XPRT_LOCKED, &xprt->state)) {
if (task == xprt->snd_task)
return 1;
goto out_sleep;
}
if (req == NULL) {
xprt->snd_task = task;
return 1;
}
if (__xprt_get_cong(xprt, task)) {
xprt->snd_task = task;
req->rq_ntrans++;
return 1;
}
xprt_clear_locked(xprt);
out_sleep:
if (req)
__xprt_put_cong(xprt, req);
dprintk("RPC: %5u failed to lock transport %p\n", task->tk_pid, xprt);
task->tk_timeout = 0;
task->tk_status = -EAGAIN;
if (req == NULL)
priority = RPC_PRIORITY_LOW;
else if (!req->rq_ntrans)
priority = RPC_PRIORITY_NORMAL;
else
priority = RPC_PRIORITY_HIGH;
rpc_sleep_on_priority(&xprt->sending, task, NULL, priority);
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(xprt, task);
spin_unlock_bh(&xprt->transport_lock);
return retval;
}
static bool __xprt_lock_write_func(struct rpc_task *task, void *data)
{
struct rpc_xprt *xprt = data;
struct rpc_rqst *req;
req = task->tk_rqstp;
xprt->snd_task = task;
if (req)
req->rq_ntrans++;
return true;
}
static void __xprt_lock_write_next(struct rpc_xprt *xprt)
{
if (test_and_set_bit(XPRT_LOCKED, &xprt->state))
return;
if (rpc_wake_up_first_on_wq(xprtiod_workqueue, &xprt->sending,
__xprt_lock_write_func, xprt))
return;
xprt_clear_locked(xprt);
}
static bool __xprt_lock_write_cong_func(struct rpc_task *task, void *data)
{
struct rpc_xprt *xprt = data;
struct rpc_rqst *req;
req = task->tk_rqstp;
if (req == NULL) {
xprt->snd_task = task;
return true;
}
if (__xprt_get_cong(xprt, task)) {
xprt->snd_task = task;
req->rq_ntrans++;
return true;
}
return false;
}
static void __xprt_lock_write_next_cong(struct rpc_xprt *xprt)
{
if (test_and_set_bit(XPRT_LOCKED, &xprt->state))
return;
if (RPCXPRT_CONGESTED(xprt))
goto out_unlock;
if (rpc_wake_up_first_on_wq(xprtiod_workqueue, &xprt->sending,
__xprt_lock_write_cong_func, xprt))
return;
out_unlock:
xprt_clear_locked(xprt);
}
static void xprt_task_clear_bytes_sent(struct rpc_task *task)
{
if (task != NULL) {
struct rpc_rqst *req = task->tk_rqstp;
if (req != NULL)
req->rq_bytes_sent = 0;
}
}
/**
* 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_task_clear_bytes_sent(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_task_clear_bytes_sent(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)
{
struct rpc_rqst *req = task->tk_rqstp;
__xprt_put_cong(req->rq_xprt, req);
}
EXPORT_SYMBOL_GPL(xprt_release_rqst_cong);
/**
* xprt_adjust_cwnd - adjust transport congestion window
* @xprt: pointer to xprt
* @task: recently completed RPC request used to adjust window
* @result: result code of completed RPC request
*
* 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.
*/
void xprt_adjust_cwnd(struct rpc_xprt *xprt, struct rpc_task *task, int result)
{
struct rpc_rqst *req = task->tk_rqstp;
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
*
* Note that we only set the timer for the case of RPC_IS_SOFT(), since
* we don't in general want to force a socket disconnection due to
* an incomplete RPC call transmission.
*/
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 = RPC_IS_SOFT(task) ? req->rq_timeout : 0;
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)
{
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_on_wq(xprtiod_workqueue,
&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);
clear_bit(XPRT_CLOSE_WAIT, &xprt->state);
xprt->ops->close(xprt);
xprt_release_write(xprt, NULL);
wake_up_bit(&xprt->state, XPRT_LOCKED);
}
/**
* 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, -EAGAIN);
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(xprtiod_workqueue, &xprt->task_cleanup);
xprt_wake_pending_tasks(xprt, -EAGAIN);
spin_unlock_bh(&xprt->transport_lock);
}
EXPORT_SYMBOL_GPL(xprt_force_disconnect);
/**
* 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))
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(xprtiod_workqueue, &xprt->task_cleanup);
xprt_wake_pending_tasks(xprt, -EAGAIN);
out:
spin_unlock_bh(&xprt->transport_lock);
}
static bool
xprt_has_timer(const struct rpc_xprt *xprt)
{
return xprt->idle_timeout != 0;
}
static void
xprt_schedule_autodisconnect(struct rpc_xprt *xprt)
__must_hold(&xprt->transport_lock)
{
if (list_empty(&xprt->recv) && xprt_has_timer(xprt))
mod_timer(&xprt->timer, xprt->last_used + xprt->idle_timeout);
}
static void
xprt_init_autodisconnect(struct timer_list *t)
{
struct rpc_xprt *xprt = from_timer(xprt, t, timer);
spin_lock(&xprt->transport_lock);
if (!list_empty(&xprt->recv))
goto out_abort;
/* Reset xprt->last_used to avoid connect/autodisconnect cycling */
xprt->last_used = jiffies;
if (test_and_set_bit(XPRT_LOCKED, &xprt->state))
goto out_abort;
spin_unlock(&xprt->transport_lock);
queue_work(xprtiod_workqueue, &xprt->task_cleanup);
return;
out_abort:
spin_unlock(&xprt->transport_lock);
}
bool xprt_lock_connect(struct rpc_xprt *xprt,
struct rpc_task *task,
void *cookie)
{
bool ret = false;
spin_lock_bh(&xprt->transport_lock);
if (!test_bit(XPRT_LOCKED, &xprt->state))
goto out;
if (xprt->snd_task != task)
goto out;
xprt_task_clear_bytes_sent(task);
xprt->snd_task = cookie;
ret = true;
out:
spin_unlock_bh(&xprt->transport_lock);
return ret;
}
void xprt_unlock_connect(struct rpc_xprt *xprt, void *cookie)
{
spin_lock_bh(&xprt->transport_lock);
if (xprt->snd_task != cookie)
goto out;
if (!test_bit(XPRT_LOCKED, &xprt->state))
goto out;
xprt->snd_task =NULL;
xprt->ops->release_xprt(xprt, NULL);
xprt_schedule_autodisconnect(xprt);
out:
spin_unlock_bh(&xprt->transport_lock);
wake_up_bit(&xprt->state, XPRT_LOCKED);
}
/**
* 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_rqstp->rq_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 = -EAGAIN;
return;
}
if (!xprt_lock_write(xprt, task))
return;
if (test_and_clear_bit(XPRT_CLOSE_WAIT, &xprt->state))
xprt->ops->close(xprt);
if (!xprt_connected(xprt)) {
task->tk_rqstp->rq_bytes_sent = 0;
task->tk_timeout = task->tk_rqstp->rq_timeout;
task->tk_rqstp->rq_connect_cookie = xprt->connect_cookie;
rpc_sleep_on(&xprt->pending, task, xprt_connect_status);
if (test_bit(XPRT_CLOSING, &xprt->state))
return;
if (xprt_test_and_set_connecting(xprt))
return;
xprt->stat.connect_start = jiffies;
xprt->ops->connect(xprt, task);
}
xprt_release_write(xprt, task);
}
static void xprt_connect_status(struct rpc_task *task)
{
struct rpc_xprt *xprt = task->tk_rqstp->rq_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 -ECONNREFUSED:
case -ECONNRESET:
case -ECONNABORTED:
case -ENETUNREACH:
case -EHOSTUNREACH:
case -EPIPE:
case -EAGAIN:
dprintk("RPC: %5u xprt_connect_status: retrying\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,
xprt->servername);
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 rpc_rqst *entry;
list_for_each_entry(entry, &xprt->recv, rq_list)
if (entry->rq_xid == xid) {
trace_xprt_lookup_rqst(xprt, xid, 0);
return entry;
}
dprintk("RPC: xprt_lookup_rqst did not find xid %08x\n",
ntohl(xid));
trace_xprt_lookup_rqst(xprt, xid, -ENOENT);
xprt->stat.bad_xids++;
return NULL;
}
EXPORT_SYMBOL_GPL(xprt_lookup_rqst);
/**
* xprt_pin_rqst - Pin a request on the transport receive list
* @req: Request to pin
*
* Caller must ensure this is atomic with the call to xprt_lookup_rqst()
* so should be holding the xprt transport lock.
*/
void xprt_pin_rqst(struct rpc_rqst *req)
{
set_bit(RPC_TASK_MSG_RECV, &req->rq_task->tk_runstate);
}
EXPORT_SYMBOL_GPL(xprt_pin_rqst);
/**
* xprt_unpin_rqst - Unpin a request on the transport receive list
* @req: Request to pin
*
* Caller should be holding the xprt transport lock.
*/
void xprt_unpin_rqst(struct rpc_rqst *req)
{
struct rpc_task *task = req->rq_task;
clear_bit(RPC_TASK_MSG_RECV, &task->tk_runstate);
if (test_bit(RPC_TASK_MSG_RECV_WAIT, &task->tk_runstate))
wake_up_bit(&task->tk_runstate, RPC_TASK_MSG_RECV);
}
EXPORT_SYMBOL_GPL(xprt_unpin_rqst);
static void xprt_wait_on_pinned_rqst(struct rpc_rqst *req)
__must_hold(&req->rq_xprt->recv_lock)
{
struct rpc_task *task = req->rq_task;
if (task && test_bit(RPC_TASK_MSG_RECV, &task->tk_runstate)) {
spin_unlock(&req->rq_xprt->recv_lock);
set_bit(RPC_TASK_MSG_RECV_WAIT, &task->tk_runstate);
wait_on_bit(&task->tk_runstate, RPC_TASK_MSG_RECV,
TASK_UNINTERRUPTIBLE);
clear_bit(RPC_TASK_MSG_RECV_WAIT, &task->tk_runstate);
spin_lock(&req->rq_xprt->recv_lock);
}
}
static 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 int timer = task->tk_msg.rpc_proc->p_timer;
long m = usecs_to_jiffies(ktime_to_us(req->rq_rtt));
if (timer) {
if (req->rq_ntrans == 1)
rpc_update_rtt(rtt, timer, m);
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;
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);
trace_xprt_complete_rqst(xprt, req->rq_xid, copied);
xprt->stat.recvs++;
req->rq_rtt = ktime_sub(ktime_get(), req->rq_xtime);
if (xprt->ops->timer != NULL)
xprt_update_rtt(task);
list_del_init(&req->rq_list);
req->rq_private_buf.len = copied;
/* Ensure all writes are done before we update */
/* req->rq_reply_bytes_recvd */
smp_wmb();
req->rq_reply_bytes_recvd = 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;
trace_xprt_timer(xprt, req->rq_xid, task->tk_status);
if (!req->rq_reply_bytes_recvd) {
if (xprt->ops->timer)
xprt->ops->timer(xprt, task);
} else
task->tk_status = 0;
}
/**
* xprt_prepare_transmit - reserve the transport before sending a request
* @task: RPC task about to send a request
*
*/
bool xprt_prepare_transmit(struct rpc_task *task)
{
struct rpc_rqst *req = task->tk_rqstp;
struct rpc_xprt *xprt = req->rq_xprt;
bool ret = false;
dprintk("RPC: %5u xprt_prepare_transmit\n", task->tk_pid);
spin_lock_bh(&xprt->transport_lock);
if (!req->rq_bytes_sent) {
if (req->rq_reply_bytes_recvd) {
task->tk_status = req->rq_reply_bytes_recvd;
goto out_unlock;
}
if ((task->tk_flags & RPC_TASK_NO_RETRANS_TIMEOUT)
&& xprt_connected(xprt)
&& req->rq_connect_cookie == xprt->connect_cookie) {
xprt->ops->set_retrans_timeout(task);
rpc_sleep_on(&xprt->pending, task, xprt_timer);
goto out_unlock;
}
}
if (!xprt->ops->reserve_xprt(xprt, task)) {
task->tk_status = -EAGAIN;
goto out_unlock;
}
ret = true;
out_unlock:
spin_unlock_bh(&xprt->transport_lock);
return ret;
}
void xprt_end_transmit(struct rpc_task *task)
{
xprt_release_write(task->tk_rqstp->rq_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;
unsigned int connect_cookie;
int status, numreqs;
dprintk("RPC: %5u xprt_transmit(%u)\n", task->tk_pid, req->rq_slen);
if (!req->rq_reply_bytes_recvd) {
if (list_empty(&req->rq_list) && rpc_reply_expected(task)) {
/*
* Add to the list only if we're expecting a reply
*/
/* 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 */
spin_lock(&xprt->recv_lock);
list_add_tail(&req->rq_list, &xprt->recv);
spin_unlock(&xprt->recv_lock);
xprt_reset_majortimeo(req);
/* Turn off autodisconnect */
del_singleshot_timer_sync(&xprt->timer);
}
} else if (!req->rq_bytes_sent)
return;
connect_cookie = xprt->connect_cookie;
req->rq_xtime = ktime_get();
status = xprt->ops->send_request(task);
trace_xprt_transmit(xprt, req->rq_xid, status);
if (status != 0) {
task->tk_status = status;
return;
}
xprt_inject_disconnect(xprt);
dprintk("RPC: %5u xmit complete\n", task->tk_pid);
task->tk_flags |= RPC_TASK_SENT;
spin_lock_bh(&xprt->transport_lock);
xprt->ops->set_retrans_timeout(task);
numreqs = atomic_read(&xprt->num_reqs);
if (numreqs > xprt->stat.max_slots)
xprt->stat.max_slots = numreqs;
xprt->stat.sends++;
xprt->stat.req_u += xprt->stat.sends - xprt->stat.recvs;
xprt->stat.bklog_u += xprt->backlog.qlen;
xprt->stat.sending_u += xprt->sending.qlen;
xprt->stat.pending_u += xprt->pending.qlen;
spin_unlock_bh(&xprt->transport_lock);
req->rq_connect_cookie = connect_cookie;
if (rpc_reply_expected(task) && !READ_ONCE(req->rq_reply_bytes_recvd)) {
/*
* Sleep on the pending queue if we're expecting a reply.
* The spinlock ensures atomicity between the test of
* req->rq_reply_bytes_recvd, and the call to rpc_sleep_on().
*/
spin_lock(&xprt->recv_lock);
if (!req->rq_reply_bytes_recvd) {
rpc_sleep_on(&xprt->pending, task, xprt_timer);
/*
* Send an extra queue wakeup call if the
* connection was dropped in case the call to
* rpc_sleep_on() raced.
*/
if (!xprt_connected(xprt))
xprt_wake_pending_tasks(xprt, -ENOTCONN);
}
spin_unlock(&xprt->recv_lock);
}
}
static void xprt_add_backlog(struct rpc_xprt *xprt, struct rpc_task *task)
{
set_bit(XPRT_CONGESTED, &xprt->state);
rpc_sleep_on(&xprt->backlog, task, NULL);
}
static void xprt_wake_up_backlog(struct rpc_xprt *xprt)
{
if (rpc_wake_up_next(&xprt->backlog) == NULL)
clear_bit(XPRT_CONGESTED, &xprt->state);
}
static bool xprt_throttle_congested(struct rpc_xprt *xprt, struct rpc_task *task)
{
bool ret = false;
if (!test_bit(XPRT_CONGESTED, &xprt->state))
goto out;
spin_lock(&xprt->reserve_lock);
if (test_bit(XPRT_CONGESTED, &xprt->state)) {
rpc_sleep_on(&xprt->backlog, task, NULL);
ret = true;
}
spin_unlock(&xprt->reserve_lock);
out:
return ret;
}
static struct rpc_rqst *xprt_dynamic_alloc_slot(struct rpc_xprt *xprt)
{
struct rpc_rqst *req = ERR_PTR(-EAGAIN);
if (!atomic_add_unless(&xprt->num_reqs, 1, xprt->max_reqs))
goto out;
spin_unlock(&xprt->reserve_lock);
req = kzalloc(sizeof(struct rpc_rqst), GFP_NOFS);
spin_lock(&xprt->reserve_lock);
if (req != NULL)
goto out;
atomic_dec(&xprt->num_reqs);
req = ERR_PTR(-ENOMEM);
out:
return req;
}
static bool xprt_dynamic_free_slot(struct rpc_xprt *xprt, struct rpc_rqst *req)
{
if (atomic_add_unless(&xprt->num_reqs, -1, xprt->min_reqs)) {
kfree(req);
return true;
}
return false;
}
void xprt_alloc_slot(struct rpc_xprt *xprt, struct rpc_task *task)
{
struct rpc_rqst *req;
spin_lock(&xprt->reserve_lock);
if (!list_empty(&xprt->free)) {
req = list_entry(xprt->free.next, struct rpc_rqst, rq_list);
list_del(&req->rq_list);
goto out_init_req;
}
req = xprt_dynamic_alloc_slot(xprt);
if (!IS_ERR(req))
goto out_init_req;
switch (PTR_ERR(req)) {
case -ENOMEM:
dprintk("RPC: dynamic allocation of request slot "
"failed! Retrying\n");
task->tk_status = -ENOMEM;
break;
case -EAGAIN:
xprt_add_backlog(xprt, task);
dprintk("RPC: waiting for request slot\n");
/* fall through */
default:
task->tk_status = -EAGAIN;
}
spin_unlock(&xprt->reserve_lock);
return;
out_init_req:
task->tk_status = 0;
task->tk_rqstp = req;
xprt_request_init(task, xprt);
spin_unlock(&xprt->reserve_lock);
}
EXPORT_SYMBOL_GPL(xprt_alloc_slot);
void xprt_lock_and_alloc_slot(struct rpc_xprt *xprt, struct rpc_task *task)
{
/* Note: grabbing the xprt_lock_write() ensures that we throttle
* new slot allocation if the transport is congested (i.e. when
* reconnecting a stream transport or when out of socket write
* buffer space).
*/
if (xprt_lock_write(xprt, task)) {
xprt_alloc_slot(xprt, task);
xprt_release_write(xprt, task);
}
}
EXPORT_SYMBOL_GPL(xprt_lock_and_alloc_slot);
static void xprt_free_slot(struct rpc_xprt *xprt, struct rpc_rqst *req)
{
spin_lock(&xprt->reserve_lock);
if (!xprt_dynamic_free_slot(xprt, req)) {
memset(req, 0, sizeof(*req)); /* mark unused */
list_add(&req->rq_list, &xprt->free);
}
xprt_wake_up_backlog(xprt);
spin_unlock(&xprt->reserve_lock);
}
static void xprt_free_all_slots(struct rpc_xprt *xprt)
{
struct rpc_rqst *req;
while (!list_empty(&xprt->free)) {
req = list_first_entry(&xprt->free, struct rpc_rqst, rq_list);
list_del(&req->rq_list);
kfree(req);
}
}
struct rpc_xprt *xprt_alloc(struct net *net, size_t size,
unsigned int num_prealloc,
unsigned int max_alloc)
{
struct rpc_xprt *xprt;
struct rpc_rqst *req;
int i;
xprt = kzalloc(size, GFP_KERNEL);
if (xprt == NULL)
goto out;
xprt_init(xprt, net);
for (i = 0; i < num_prealloc; i++) {
req = kzalloc(sizeof(struct rpc_rqst), GFP_KERNEL);
if (!req)
goto out_free;
list_add(&req->rq_list, &xprt->free);
}
if (max_alloc > num_prealloc)
xprt->max_reqs = max_alloc;
else
xprt->max_reqs = num_prealloc;
xprt->min_reqs = num_prealloc;
atomic_set(&xprt->num_reqs, num_prealloc);
return xprt;
out_free:
xprt_free(xprt);
out:
return NULL;
}
EXPORT_SYMBOL_GPL(xprt_alloc);
void xprt_free(struct rpc_xprt *xprt)
{
put_net(xprt->xprt_net);
xprt_free_all_slots(xprt);
kfree_rcu(xprt, rcu);
}
EXPORT_SYMBOL_GPL(xprt_free);
/**
* xprt_reserve - allocate an RPC request slot
* @task: RPC task requesting a slot allocation
*
* If the transport is marked as being congested, or 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 = 0;
if (task->tk_rqstp != NULL)
return;
task->tk_timeout = 0;
task->tk_status = -EAGAIN;
if (!xprt_throttle_congested(xprt, task))
xprt->ops->alloc_slot(xprt, task);
}
/**
* xprt_retry_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.
* Note that the only difference with xprt_reserve is that we now
* ignore the value of the XPRT_CONGESTED flag.
*/
void xprt_retry_reserve(struct rpc_task *task)
{
struct rpc_xprt *xprt = task->tk_xprt;
task->tk_status = 0;
if (task->tk_rqstp != NULL)
return;
task->tk_timeout = 0;
task->tk_status = -EAGAIN;
xprt->ops->alloc_slot(xprt, task);
}
static inline __be32 xprt_alloc_xid(struct rpc_xprt *xprt)
{
return (__force __be32)xprt->xid++;
}
static inline void xprt_init_xid(struct rpc_xprt *xprt)
{
xprt->xid = prandom_u32();
}
static void xprt_request_init(struct rpc_task *task, struct rpc_xprt *xprt)
{
struct rpc_rqst *req = task->tk_rqstp;
INIT_LIST_HEAD(&req->rq_list);
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_connect_cookie = xprt->connect_cookie - 1;
req->rq_bytes_sent = 0;
req->rq_snd_buf.len = 0;
req->rq_snd_buf.buflen = 0;
req->rq_rcv_buf.len = 0;
req->rq_rcv_buf.buflen = 0;
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;
struct rpc_rqst *req = task->tk_rqstp;
if (req == NULL) {
if (task->tk_client) {
xprt = task->tk_xprt;
if (xprt->snd_task == task)
xprt_release_write(xprt, task);
}
return;
}
xprt = req->rq_xprt;
if (task->tk_ops->rpc_count_stats != NULL)
task->tk_ops->rpc_count_stats(task, task->tk_calldata);
else if (task->tk_client)
rpc_count_iostats(task, task->tk_client->cl_metrics);
spin_lock(&xprt->recv_lock);
if (!list_empty(&req->rq_list)) {
list_del_init(&req->rq_list);
xprt_wait_on_pinned_rqst(req);
}
spin_unlock(&xprt->recv_lock);
spin_lock_bh(&xprt->transport_lock);
xprt->ops->release_xprt(xprt, task);
if (xprt->ops->release_request)
xprt->ops->release_request(task);
xprt->last_used = jiffies;
xprt_schedule_autodisconnect(xprt);
spin_unlock_bh(&xprt->transport_lock);
if (req->rq_buffer)
xprt->ops->buf_free(task);
xprt_inject_disconnect(xprt);
if (req->rq_cred != NULL)
put_rpccred(req->rq_cred);
task->tk_rqstp = NULL;
if (req->rq_release_snd_buf)
req->rq_release_snd_buf(req);
dprintk("RPC: %5u release request %p\n", task->tk_pid, req);
if (likely(!bc_prealloc(req)))
xprt_free_slot(xprt, req);
else
xprt_free_bc_request(req);
}
static void xprt_init(struct rpc_xprt *xprt, struct net *net)
{
kref_init(&xprt->kref);
spin_lock_init(&xprt->transport_lock);
spin_lock_init(&xprt->reserve_lock);
spin_lock_init(&xprt->recv_lock);
INIT_LIST_HEAD(&xprt->free);
INIT_LIST_HEAD(&xprt->recv);
#if defined(CONFIG_SUNRPC_BACKCHANNEL)
spin_lock_init(&xprt->bc_pa_lock);
INIT_LIST_HEAD(&xprt->bc_pa_list);
#endif /* CONFIG_SUNRPC_BACKCHANNEL */
INIT_LIST_HEAD(&xprt->xprt_switch);
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_priority_wait_queue(&xprt->sending, "xprt_sending");
rpc_init_priority_wait_queue(&xprt->backlog, "xprt_backlog");
xprt_init_xid(xprt);
xprt->xprt_net = get_net(net);
}
/**
* 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 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);
dprintk("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));
goto out;
}
if (args->flags & XPRT_CREATE_NO_IDLE_TIMEOUT)
xprt->idle_timeout = 0;
INIT_WORK(&xprt->task_cleanup, xprt_autoclose);
if (xprt_has_timer(xprt))
timer_setup(&xprt->timer, xprt_init_autodisconnect, 0);
else
timer_setup(&xprt->timer, NULL, 0);
if (strlen(args->servername) > RPC_MAXNETNAMELEN) {
xprt_destroy(xprt);
return ERR_PTR(-EINVAL);
}
xprt->servername = kstrdup(args->servername, GFP_KERNEL);
if (xprt->servername == NULL) {
xprt_destroy(xprt);
return ERR_PTR(-ENOMEM);
}
rpc_xprt_debugfs_register(xprt);
dprintk("RPC: created transport %p with %u slots\n", xprt,
xprt->max_reqs);
out:
return xprt;
}
static void xprt_destroy_cb(struct work_struct *work)
{
struct rpc_xprt *xprt =
container_of(work, struct rpc_xprt, task_cleanup);
rpc_xprt_debugfs_unregister(xprt);
rpc_destroy_wait_queue(&xprt->binding);
rpc_destroy_wait_queue(&xprt->pending);
rpc_destroy_wait_queue(&xprt->sending);
rpc_destroy_wait_queue(&xprt->backlog);
kfree(xprt->servername);
/*
* Tear down transport state and free the rpc_xprt
*/
xprt->ops->destroy(xprt);
}
/**
* xprt_destroy - destroy an RPC transport, killing off all requests.
* @xprt: transport to destroy
*
*/
static void xprt_destroy(struct rpc_xprt *xprt)
{
dprintk("RPC: destroying transport %p\n", xprt);
/*
* Exclude transport connect/disconnect handlers and autoclose
*/
wait_on_bit_lock(&xprt->state, XPRT_LOCKED, TASK_UNINTERRUPTIBLE);
del_timer_sync(&xprt->timer);
/*
* Destroy sockets etc from the system workqueue so they can
* safely flush receive work running on rpciod.
*/
INIT_WORK(&xprt->task_cleanup, xprt_destroy_cb);
schedule_work(&xprt->task_cleanup);
}
static void xprt_destroy_kref(struct kref *kref)
{
xprt_destroy(container_of(kref, struct rpc_xprt, kref));
}
/**
* xprt_get - return a reference to an RPC transport.
* @xprt: pointer to the transport
*
*/
struct rpc_xprt *xprt_get(struct rpc_xprt *xprt)
{
if (xprt != NULL && kref_get_unless_zero(&xprt->kref))
return xprt;
return NULL;
}
EXPORT_SYMBOL_GPL(xprt_get);
/**
* xprt_put - release a reference to an RPC transport.
* @xprt: pointer to the transport
*
*/
void xprt_put(struct rpc_xprt *xprt)
{
if (xprt != NULL)
kref_put(&xprt->kref, xprt_destroy_kref);
}
EXPORT_SYMBOL_GPL(xprt_put);
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