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linux/net/sunrpc/xprt.c

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// SPDX-License-Identifier: GPL-2.0-only
/*
* 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 <linux/sched/mm.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 __be32 xprt_alloc_xid(struct rpc_xprt *xprt);
static void xprt_destroy(struct rpc_xprt *xprt);
static DEFINE_SPINLOCK(xprt_list_lock);
static LIST_HEAD(xprt_list);
static unsigned long xprt_request_timeout(const struct rpc_rqst *req)
{
unsigned long timeout = jiffies + req->rq_timeout;
if (time_before(timeout, req->rq_majortimeo))
return timeout;
return req->rq_majortimeo;
}
/**
* 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);
static void
xprt_class_release(const struct xprt_class *t)
{
module_put(t->owner);
}
static const struct xprt_class *
xprt_class_find_by_ident_locked(int ident)
{
const struct xprt_class *t;
list_for_each_entry(t, &xprt_list, list) {
if (t->ident != ident)
continue;
if (!try_module_get(t->owner))
continue;
return t;
}
return NULL;
}
static const struct xprt_class *
xprt_class_find_by_ident(int ident)
{
const struct xprt_class *t;
spin_lock(&xprt_list_lock);
t = xprt_class_find_by_ident_locked(ident);
spin_unlock(&xprt_list_lock);
return t;
}
static const struct xprt_class *
xprt_class_find_by_netid_locked(const char *netid)
{
const struct xprt_class *t;
unsigned int i;
list_for_each_entry(t, &xprt_list, list) {
for (i = 0; t->netid[i][0] != '\0'; i++) {
if (strcmp(t->netid[i], netid) != 0)
continue;
if (!try_module_get(t->owner))
continue;
return t;
}
}
return NULL;
}
static const struct xprt_class *
xprt_class_find_by_netid(const char *netid)
{
const struct xprt_class *t;
spin_lock(&xprt_list_lock);
t = xprt_class_find_by_netid_locked(netid);
if (!t) {
spin_unlock(&xprt_list_lock);
request_module("rpc%s", netid);
spin_lock(&xprt_list_lock);
t = xprt_class_find_by_netid_locked(netid);
}
spin_unlock(&xprt_list_lock);
return t;
}
/**
* xprt_find_transport_ident - convert a netid into a transport identifier
* @netid: transport to load
*
* Returns:
* > 0: transport identifier
* -ENOENT: transport module not available
*/
int xprt_find_transport_ident(const char *netid)
{
const struct xprt_class *t;
int ret;
t = xprt_class_find_by_netid(netid);
if (!t)
return -ENOENT;
ret = t->ident;
xprt_class_release(t);
return ret;
}
EXPORT_SYMBOL_GPL(xprt_find_transport_ident);
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 - 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;
if (test_and_set_bit(XPRT_LOCKED, &xprt->state)) {
if (task == xprt->snd_task)
goto out_locked;
goto out_sleep;
}
if (test_bit(XPRT_WRITE_SPACE, &xprt->state))
goto out_unlock;
xprt->snd_task = task;
out_locked:
trace_xprt_reserve_xprt(xprt, task);
return 1;
out_unlock:
xprt_clear_locked(xprt);
out_sleep:
task->tk_status = -EAGAIN;
if (RPC_IS_SOFT(task))
rpc_sleep_on_timeout(&xprt->sending, task, NULL,
xprt_request_timeout(req));
else
rpc_sleep_on(&xprt->sending, task, NULL);
return 0;
}
EXPORT_SYMBOL_GPL(xprt_reserve_xprt);
static bool
xprt_need_congestion_window_wait(struct rpc_xprt *xprt)
{
return test_bit(XPRT_CWND_WAIT, &xprt->state);
}
static void
xprt_set_congestion_window_wait(struct rpc_xprt *xprt)
{
if (!list_empty(&xprt->xmit_queue)) {
/* Peek at head of queue to see if it can make progress */
if (list_first_entry(&xprt->xmit_queue, struct rpc_rqst,
rq_xmit)->rq_cong)
return;
}
set_bit(XPRT_CWND_WAIT, &xprt->state);
}
static void
xprt_test_and_clear_congestion_window_wait(struct rpc_xprt *xprt)
{
if (!RPCXPRT_CONGESTED(xprt))
clear_bit(XPRT_CWND_WAIT, &xprt->state);
}
/*
* 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.
* Note that the lock is only granted if we know there are free slots.
*/
int xprt_reserve_xprt_cong(struct rpc_xprt *xprt, struct rpc_task *task)
{
struct rpc_rqst *req = task->tk_rqstp;
if (test_and_set_bit(XPRT_LOCKED, &xprt->state)) {
if (task == xprt->snd_task)
goto out_locked;
goto out_sleep;
}
if (req == NULL) {
xprt->snd_task = task;
goto out_locked;
}
if (test_bit(XPRT_WRITE_SPACE, &xprt->state))
goto out_unlock;
if (!xprt_need_congestion_window_wait(xprt)) {
xprt->snd_task = task;
goto out_locked;
}
out_unlock:
xprt_clear_locked(xprt);
out_sleep:
task->tk_status = -EAGAIN;
if (RPC_IS_SOFT(task))
rpc_sleep_on_timeout(&xprt->sending, task, NULL,
xprt_request_timeout(req));
else
rpc_sleep_on(&xprt->sending, task, NULL);
return 0;
out_locked:
trace_xprt_reserve_cong(xprt, task);
return 1;
}
EXPORT_SYMBOL_GPL(xprt_reserve_xprt_cong);
static inline int xprt_lock_write(struct rpc_xprt *xprt, struct rpc_task *task)
{
int retval;
if (test_bit(XPRT_LOCKED, &xprt->state) && xprt->snd_task == task)
return 1;
spin_lock(&xprt->transport_lock);
retval = xprt->ops->reserve_xprt(xprt, task);
spin_unlock(&xprt->transport_lock);
return retval;
}
static bool __xprt_lock_write_func(struct rpc_task *task, void *data)
{
struct rpc_xprt *xprt = data;
xprt->snd_task = task;
return true;
}
static void __xprt_lock_write_next(struct rpc_xprt *xprt)
{
if (test_and_set_bit(XPRT_LOCKED, &xprt->state))
return;
if (test_bit(XPRT_WRITE_SPACE, &xprt->state))
goto out_unlock;
if (rpc_wake_up_first_on_wq(xprtiod_workqueue, &xprt->sending,
__xprt_lock_write_func, xprt))
return;
out_unlock:
xprt_clear_locked(xprt);
}
static void __xprt_lock_write_next_cong(struct rpc_xprt *xprt)
{
if (test_and_set_bit(XPRT_LOCKED, &xprt->state))
return;
if (test_bit(XPRT_WRITE_SPACE, &xprt->state))
goto out_unlock;
if (xprt_need_congestion_window_wait(xprt))
goto out_unlock;
if (rpc_wake_up_first_on_wq(xprtiod_workqueue, &xprt->sending,
__xprt_lock_write_func, xprt))
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);
}
trace_xprt_release_xprt(xprt, task);
}
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);
}
trace_xprt_release_cong(xprt, task);
}
EXPORT_SYMBOL_GPL(xprt_release_xprt_cong);
static inline void xprt_release_write(struct rpc_xprt *xprt, struct rpc_task *task)
{
if (xprt->snd_task != task)
return;
spin_lock(&xprt->transport_lock);
xprt->ops->release_xprt(xprt, task);
spin_unlock(&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_rqst *req)
{
if (req->rq_cong)
return 1;
trace_xprt_get_cong(xprt, req->rq_task);
if (RPCXPRT_CONGESTED(xprt)) {
xprt_set_congestion_window_wait(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_test_and_clear_congestion_window_wait(xprt);
trace_xprt_put_cong(xprt, req->rq_task);
__xprt_lock_write_next_cong(xprt);
}
/**
* xprt_request_get_cong - Request congestion control credits
* @xprt: pointer to transport
* @req: pointer to RPC request
*
* Useful for transports that require congestion control.
*/
bool
xprt_request_get_cong(struct rpc_xprt *xprt, struct rpc_rqst *req)
{
bool ret = false;
if (req->rq_cong)
return true;
spin_lock(&xprt->transport_lock);
ret = __xprt_get_cong(xprt, req) != 0;
spin_unlock(&xprt->transport_lock);
return ret;
}
EXPORT_SYMBOL_GPL(xprt_request_get_cong);
/**
* 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);
static void xprt_clear_congestion_window_wait_locked(struct rpc_xprt *xprt)
{
if (test_and_clear_bit(XPRT_CWND_WAIT, &xprt->state))
__xprt_lock_write_next_cong(xprt);
}
/*
* Clear the congestion window wait flag and wake up the next
* entry on xprt->sending
*/
static void
xprt_clear_congestion_window_wait(struct rpc_xprt *xprt)
{
if (test_and_clear_bit(XPRT_CWND_WAIT, &xprt->state)) {
spin_lock(&xprt->transport_lock);
__xprt_lock_write_next_cong(xprt);
spin_unlock(&xprt->transport_lock);
}
}
/**
* 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
* @xprt: transport
*
* 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_xprt *xprt)
{
set_bit(XPRT_WRITE_SPACE, &xprt->state);
}
EXPORT_SYMBOL_GPL(xprt_wait_for_buffer_space);
static bool
xprt_clear_write_space_locked(struct rpc_xprt *xprt)
{
if (test_and_clear_bit(XPRT_WRITE_SPACE, &xprt->state)) {
__xprt_lock_write_next(xprt);
dprintk("RPC: write space: waking waiting task on "
"xprt %p\n", xprt);
return true;
}
return false;
}
/**
* 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.
*/
bool xprt_write_space(struct rpc_xprt *xprt)
{
bool ret;
if (!test_bit(XPRT_WRITE_SPACE, &xprt->state))
return false;
spin_lock(&xprt->transport_lock);
ret = xprt_clear_write_space_locked(xprt);
spin_unlock(&xprt->transport_lock);
return ret;
}
EXPORT_SYMBOL_GPL(xprt_write_space);
static unsigned long xprt_abs_ktime_to_jiffies(ktime_t abstime)
{
s64 delta = ktime_to_ns(ktime_get() - abstime);
return likely(delta >= 0) ?
jiffies - nsecs_to_jiffies(delta) :
jiffies + nsecs_to_jiffies(-delta);
}
static unsigned long xprt_calc_majortimeo(struct rpc_rqst *req)
{
const struct rpc_timeout *to = req->rq_task->tk_client->cl_timeout;
unsigned long majortimeo = req->rq_timeout;
if (to->to_exponential)
majortimeo <<= to->to_retries;
else
majortimeo += to->to_increment * to->to_retries;
if (majortimeo > to->to_maxval || majortimeo == 0)
majortimeo = to->to_maxval;
return majortimeo;
}
static void xprt_reset_majortimeo(struct rpc_rqst *req)
{
req->rq_majortimeo += xprt_calc_majortimeo(req);
}
static void xprt_reset_minortimeo(struct rpc_rqst *req)
{
req->rq_minortimeo += req->rq_timeout;
}
static void xprt_init_majortimeo(struct rpc_task *task, struct rpc_rqst *req)
{
unsigned long time_init;
struct rpc_xprt *xprt = req->rq_xprt;
if (likely(xprt && xprt_connected(xprt)))
time_init = jiffies;
else
time_init = xprt_abs_ktime_to_jiffies(task->tk_start);
req->rq_timeout = task->tk_client->cl_timeout->to_initval;
req->rq_majortimeo = time_init + xprt_calc_majortimeo(req);
req->rq_minortimeo = time_init + req->rq_timeout;
}
/**
* 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_minortimeo))
return status;
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(&xprt->transport_lock);
rpc_init_rtt(req->rq_task->tk_client->cl_rtt, to->to_initval);
spin_unlock(&xprt->transport_lock);
status = -ETIMEDOUT;
}
xprt_reset_minortimeo(req);
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);
unsigned int pflags = memalloc_nofs_save();
trace_xprt_disconnect_auto(xprt);
clear_bit(XPRT_CLOSE_WAIT, &xprt->state);
xprt->ops->close(xprt);
xprt_release_write(xprt, NULL);
wake_up_bit(&xprt->state, XPRT_LOCKED);
memalloc_nofs_restore(pflags);
}
/**
* xprt_disconnect_done - mark a transport as disconnected
* @xprt: transport to flag for disconnect
*
*/
void xprt_disconnect_done(struct rpc_xprt *xprt)
{
trace_xprt_disconnect_done(xprt);
spin_lock(&xprt->transport_lock);
xprt_clear_connected(xprt);
xprt_clear_write_space_locked(xprt);
xprt_clear_congestion_window_wait_locked(xprt);
xprt_wake_pending_tasks(xprt, -ENOTCONN);
spin_unlock(&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)
{
trace_xprt_disconnect_force(xprt);
/* Don't race with the test_bit() in xprt_clear_locked() */
spin_lock(&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);
else if (xprt->snd_task)
rpc_wake_up_queued_task_set_status(&xprt->pending,
xprt->snd_task, -ENOTCONN);
spin_unlock(&xprt->transport_lock);
}
EXPORT_SYMBOL_GPL(xprt_force_disconnect);
static unsigned int
xprt_connect_cookie(struct rpc_xprt *xprt)
{
return READ_ONCE(xprt->connect_cookie);
}
static bool
xprt_request_retransmit_after_disconnect(struct rpc_task *task)
{
struct rpc_rqst *req = task->tk_rqstp;
struct rpc_xprt *xprt = req->rq_xprt;
return req->rq_connect_cookie != xprt_connect_cookie(xprt) ||
!xprt_connected(xprt);
}
/**
* 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(&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(&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)
{
xprt->last_used = jiffies;
if (RB_EMPTY_ROOT(&xprt->recv_queue) && 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);
if (!RB_EMPTY_ROOT(&xprt->recv_queue))
return;
/* Reset xprt->last_used to avoid connect/autodisconnect cycling */
xprt->last_used = jiffies;
if (test_and_set_bit(XPRT_LOCKED, &xprt->state))
return;
queue_work(xprtiod_workqueue, &xprt->task_cleanup);
}
bool xprt_lock_connect(struct rpc_xprt *xprt,
struct rpc_task *task,
void *cookie)
{
bool ret = false;
spin_lock(&xprt->transport_lock);
if (!test_bit(XPRT_LOCKED, &xprt->state))
goto out;
if (xprt->snd_task != task)
goto out;
xprt->snd_task = cookie;
ret = true;
out:
spin_unlock(&xprt->transport_lock);
return ret;
}
void xprt_unlock_connect(struct rpc_xprt *xprt, void *cookie)
{
spin_lock(&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(&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;
trace_xprt_connect(xprt);
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)) {
trace_xprt_disconnect_cleanup(xprt);
xprt->ops->close(xprt);
}
if (!xprt_connected(xprt)) {
task->tk_rqstp->rq_connect_cookie = xprt->connect_cookie;
rpc_sleep_on_timeout(&xprt->pending, task, NULL,
xprt_request_timeout(task->tk_rqstp));
if (test_bit(XPRT_CLOSING, &xprt->state))
return;
if (xprt_test_and_set_connecting(xprt))
return;
/* Race breaker */
if (!xprt_connected(xprt)) {
xprt->stat.connect_start = jiffies;
xprt->ops->connect(xprt, task);
} else {
xprt_clear_connecting(xprt);
task->tk_status = 0;
rpc_wake_up_queued_task(&xprt->pending, task);
}
}
xprt_release_write(xprt, task);
}
/**
* xprt_reconnect_delay - compute the wait before scheduling a connect
* @xprt: transport instance
*
*/
unsigned long xprt_reconnect_delay(const struct rpc_xprt *xprt)
{
unsigned long start, now = jiffies;
start = xprt->stat.connect_start + xprt->reestablish_timeout;
if (time_after(start, now))
return start - now;
return 0;
}
EXPORT_SYMBOL_GPL(xprt_reconnect_delay);
/**
* xprt_reconnect_backoff - compute the new re-establish timeout
* @xprt: transport instance
* @init_to: initial reestablish timeout
*
*/
void xprt_reconnect_backoff(struct rpc_xprt *xprt, unsigned long init_to)
{
xprt->reestablish_timeout <<= 1;
if (xprt->reestablish_timeout > xprt->max_reconnect_timeout)
xprt->reestablish_timeout = xprt->max_reconnect_timeout;
if (xprt->reestablish_timeout < init_to)
xprt->reestablish_timeout = init_to;
}
EXPORT_SYMBOL_GPL(xprt_reconnect_backoff);
enum xprt_xid_rb_cmp {
XID_RB_EQUAL,
XID_RB_LEFT,
XID_RB_RIGHT,
};
static enum xprt_xid_rb_cmp
xprt_xid_cmp(__be32 xid1, __be32 xid2)
{
if (xid1 == xid2)
return XID_RB_EQUAL;
if ((__force u32)xid1 < (__force u32)xid2)
return XID_RB_LEFT;
return XID_RB_RIGHT;
}
static struct rpc_rqst *
xprt_request_rb_find(struct rpc_xprt *xprt, __be32 xid)
{
struct rb_node *n = xprt->recv_queue.rb_node;
struct rpc_rqst *req;
while (n != NULL) {
req = rb_entry(n, struct rpc_rqst, rq_recv);
switch (xprt_xid_cmp(xid, req->rq_xid)) {
case XID_RB_LEFT:
n = n->rb_left;
break;
case XID_RB_RIGHT:
n = n->rb_right;
break;
case XID_RB_EQUAL:
return req;
}
}
return NULL;
}
static void
xprt_request_rb_insert(struct rpc_xprt *xprt, struct rpc_rqst *new)
{
struct rb_node **p = &xprt->recv_queue.rb_node;
struct rb_node *n = NULL;
struct rpc_rqst *req;
while (*p != NULL) {
n = *p;
req = rb_entry(n, struct rpc_rqst, rq_recv);
switch(xprt_xid_cmp(new->rq_xid, req->rq_xid)) {
case XID_RB_LEFT:
p = &n->rb_left;
break;
case XID_RB_RIGHT:
p = &n->rb_right;
break;
case XID_RB_EQUAL:
WARN_ON_ONCE(new != req);
return;
}
}
rb_link_node(&new->rq_recv, n, p);
rb_insert_color(&new->rq_recv, &xprt->recv_queue);
}
static void
xprt_request_rb_remove(struct rpc_xprt *xprt, struct rpc_rqst *req)
{
rb_erase(&req->rq_recv, &xprt->recv_queue);
}
/**
* 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
*
* Caller holds xprt->queue_lock.
*/
struct rpc_rqst *xprt_lookup_rqst(struct rpc_xprt *xprt, __be32 xid)
{
struct rpc_rqst *entry;
entry = xprt_request_rb_find(xprt, xid);
if (entry != NULL) {
trace_xprt_lookup_rqst(xprt, xid, 0);
entry->rq_rtt = ktime_sub(ktime_get(), entry->rq_xtime);
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);
static bool
xprt_is_pinned_rqst(struct rpc_rqst *req)
{
return atomic_read(&req->rq_pin) != 0;
}
/**
* 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 xprt->queue_lock.
*/
void xprt_pin_rqst(struct rpc_rqst *req)
{
atomic_inc(&req->rq_pin);
}
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 xprt->queue_lock.
*/
void xprt_unpin_rqst(struct rpc_rqst *req)
{
if (!test_bit(RPC_TASK_MSG_PIN_WAIT, &req->rq_task->tk_runstate)) {
atomic_dec(&req->rq_pin);
return;
}
if (atomic_dec_and_test(&req->rq_pin))
wake_up_var(&req->rq_pin);
}
EXPORT_SYMBOL_GPL(xprt_unpin_rqst);
static void xprt_wait_on_pinned_rqst(struct rpc_rqst *req)
{
wait_var_event(&req->rq_pin, !xprt_is_pinned_rqst(req));
}
static bool
xprt_request_data_received(struct rpc_task *task)
{
return !test_bit(RPC_TASK_NEED_RECV, &task->tk_runstate) &&
READ_ONCE(task->tk_rqstp->rq_reply_bytes_recvd) != 0;
}
static bool
xprt_request_need_enqueue_receive(struct rpc_task *task, struct rpc_rqst *req)
{
return !test_bit(RPC_TASK_NEED_RECV, &task->tk_runstate) &&
READ_ONCE(task->tk_rqstp->rq_reply_bytes_recvd) == 0;
}
/**
* xprt_request_enqueue_receive - Add an request to the receive queue
* @task: RPC task
*
*/
void
xprt_request_enqueue_receive(struct rpc_task *task)
{
struct rpc_rqst *req = task->tk_rqstp;
struct rpc_xprt *xprt = req->rq_xprt;
if (!xprt_request_need_enqueue_receive(task, req))
return;
xprt_request_prepare(task->tk_rqstp);
spin_lock(&xprt->queue_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 */
xprt_request_rb_insert(xprt, req);
set_bit(RPC_TASK_NEED_RECV, &task->tk_runstate);
spin_unlock(&xprt->queue_lock);
/* Turn off autodisconnect */
del_singleshot_timer_sync(&xprt->timer);
}
/**
* xprt_request_dequeue_receive_locked - Remove a request from the receive queue
* @task: RPC task
*
* Caller must hold xprt->queue_lock.
*/
static void
xprt_request_dequeue_receive_locked(struct rpc_task *task)
{
struct rpc_rqst *req = task->tk_rqstp;
if (test_and_clear_bit(RPC_TASK_NEED_RECV, &task->tk_runstate))
xprt_request_rb_remove(req->rq_xprt, req);
}
/**
* xprt_update_rtt - Update RPC RTT statistics
* @task: RPC request that recently completed
*
* Caller holds xprt->queue_lock.
*/
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);
}
}
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 xprt->queue_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;
xprt->stat.recvs++;
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;
xprt_request_dequeue_receive_locked(task);
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_wait_for_reply_request_def - wait for reply
* @task: pointer to rpc_task
*
* 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,
* and put the task to sleep on the pending queue.
*/
void xprt_wait_for_reply_request_def(struct rpc_task *task)
{
struct rpc_rqst *req = task->tk_rqstp;
rpc_sleep_on_timeout(&req->rq_xprt->pending, task, xprt_timer,
xprt_request_timeout(req));
}
EXPORT_SYMBOL_GPL(xprt_wait_for_reply_request_def);
/**
* xprt_wait_for_reply_request_rtt - wait for reply using RTT estimator
* @task: pointer to rpc_task
*
* Set a request's retransmit timeout using the RTT estimator,
* and put the task to sleep on the pending queue.
*/
void xprt_wait_for_reply_request_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;
unsigned long timeout;
timeout = rpc_calc_rto(rtt, timer);
timeout <<= rpc_ntimeo(rtt, timer) + req->rq_retries;
if (timeout > max_timeout || timeout == 0)
timeout = max_timeout;
rpc_sleep_on_timeout(&req->rq_xprt->pending, task, xprt_timer,
jiffies + timeout);
}
EXPORT_SYMBOL_GPL(xprt_wait_for_reply_request_rtt);
/**
* xprt_request_wait_receive - wait for the reply to an RPC request
* @task: RPC task about to send a request
*
*/
void xprt_request_wait_receive(struct rpc_task *task)
{
struct rpc_rqst *req = task->tk_rqstp;
struct rpc_xprt *xprt = req->rq_xprt;
if (!test_bit(RPC_TASK_NEED_RECV, &task->tk_runstate))
return;
/*
* 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->queue_lock);
if (test_bit(RPC_TASK_NEED_RECV, &task->tk_runstate)) {
xprt->ops->wait_for_reply_request(task);
/*
* Send an extra queue wakeup call if the
* connection was dropped in case the call to
* rpc_sleep_on() raced.
*/
if (xprt_request_retransmit_after_disconnect(task))
rpc_wake_up_queued_task_set_status(&xprt->pending,
task, -ENOTCONN);
}
spin_unlock(&xprt->queue_lock);
}
static bool
xprt_request_need_enqueue_transmit(struct rpc_task *task, struct rpc_rqst *req)
{
return !test_bit(RPC_TASK_NEED_XMIT, &task->tk_runstate);
}
/**
* xprt_request_enqueue_transmit - queue a task for transmission
* @task: pointer to rpc_task
*
* Add a task to the transmission queue.
*/
void
xprt_request_enqueue_transmit(struct rpc_task *task)
{
struct rpc_rqst *pos, *req = task->tk_rqstp;
struct rpc_xprt *xprt = req->rq_xprt;
if (xprt_request_need_enqueue_transmit(task, req)) {
req->rq_bytes_sent = 0;
spin_lock(&xprt->queue_lock);
/*
* Requests that carry congestion control credits are added
* to the head of the list to avoid starvation issues.
*/
if (req->rq_cong) {
xprt_clear_congestion_window_wait(xprt);
list_for_each_entry(pos, &xprt->xmit_queue, rq_xmit) {
if (pos->rq_cong)
continue;
/* Note: req is added _before_ pos */
list_add_tail(&req->rq_xmit, &pos->rq_xmit);
INIT_LIST_HEAD(&req->rq_xmit2);
goto out;
}
} else if (RPC_IS_SWAPPER(task)) {
list_for_each_entry(pos, &xprt->xmit_queue, rq_xmit) {
if (pos->rq_cong || pos->rq_bytes_sent)
continue;
if (RPC_IS_SWAPPER(pos->rq_task))
continue;
/* Note: req is added _before_ pos */
list_add_tail(&req->rq_xmit, &pos->rq_xmit);
INIT_LIST_HEAD(&req->rq_xmit2);
goto out;
}
} else if (!req->rq_seqno) {
list_for_each_entry(pos, &xprt->xmit_queue, rq_xmit) {
if (pos->rq_task->tk_owner != task->tk_owner)
continue;
list_add_tail(&req->rq_xmit2, &pos->rq_xmit2);
INIT_LIST_HEAD(&req->rq_xmit);
goto out;
}
}
list_add_tail(&req->rq_xmit, &xprt->xmit_queue);
INIT_LIST_HEAD(&req->rq_xmit2);
out:
set_bit(RPC_TASK_NEED_XMIT, &task->tk_runstate);
spin_unlock(&xprt->queue_lock);
}
}
/**
* xprt_request_dequeue_transmit_locked - remove a task from the transmission queue
* @task: pointer to rpc_task
*
* Remove a task from the transmission queue
* Caller must hold xprt->queue_lock
*/
static void
xprt_request_dequeue_transmit_locked(struct rpc_task *task)
{
struct rpc_rqst *req = task->tk_rqstp;
if (!test_and_clear_bit(RPC_TASK_NEED_XMIT, &task->tk_runstate))
return;
if (!list_empty(&req->rq_xmit)) {
list_del(&req->rq_xmit);
if (!list_empty(&req->rq_xmit2)) {
struct rpc_rqst *next = list_first_entry(&req->rq_xmit2,
struct rpc_rqst, rq_xmit2);
list_del(&req->rq_xmit2);
list_add_tail(&next->rq_xmit, &next->rq_xprt->xmit_queue);
}
} else
list_del(&req->rq_xmit2);
}
/**
* xprt_request_dequeue_transmit - remove a task from the transmission queue
* @task: pointer to rpc_task
*
* Remove a task from the transmission queue
*/
static void
xprt_request_dequeue_transmit(struct rpc_task *task)
{
struct rpc_rqst *req = task->tk_rqstp;
struct rpc_xprt *xprt = req->rq_xprt;
spin_lock(&xprt->queue_lock);
xprt_request_dequeue_transmit_locked(task);
spin_unlock(&xprt->queue_lock);
}
/**
* xprt_request_dequeue_xprt - remove a task from the transmit+receive queue
* @task: pointer to rpc_task
*
* Remove a task from the transmit and receive queues, and ensure that
* it is not pinned by the receive work item.
*/
void
xprt_request_dequeue_xprt(struct rpc_task *task)
{
struct rpc_rqst *req = task->tk_rqstp;
struct rpc_xprt *xprt = req->rq_xprt;
if (test_bit(RPC_TASK_NEED_XMIT, &task->tk_runstate) ||
test_bit(RPC_TASK_NEED_RECV, &task->tk_runstate) ||
xprt_is_pinned_rqst(req)) {
spin_lock(&xprt->queue_lock);
xprt_request_dequeue_transmit_locked(task);
xprt_request_dequeue_receive_locked(task);
while (xprt_is_pinned_rqst(req)) {
set_bit(RPC_TASK_MSG_PIN_WAIT, &task->tk_runstate);
spin_unlock(&xprt->queue_lock);
xprt_wait_on_pinned_rqst(req);
spin_lock(&xprt->queue_lock);
clear_bit(RPC_TASK_MSG_PIN_WAIT, &task->tk_runstate);
}
spin_unlock(&xprt->queue_lock);
}
}
/**
* xprt_request_prepare - prepare an encoded request for transport
* @req: pointer to rpc_rqst
*
* Calls into the transport layer to do whatever is needed to prepare
* the request for transmission or receive.
*/
void
xprt_request_prepare(struct rpc_rqst *req)
{
struct rpc_xprt *xprt = req->rq_xprt;
if (xprt->ops->prepare_request)
xprt->ops->prepare_request(req);
}
/**
* xprt_request_need_retransmit - Test if a task needs retransmission
* @task: pointer to rpc_task
*
* Test for whether a connection breakage requires the task to retransmit
*/
bool
xprt_request_need_retransmit(struct rpc_task *task)
{
return xprt_request_retransmit_after_disconnect(task);
}
/**
* 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;
if (!xprt_lock_write(xprt, task)) {
trace_xprt_transmit_queued(xprt, task);
/* Race breaker: someone may have transmitted us */
if (!test_bit(RPC_TASK_NEED_XMIT, &task->tk_runstate))
rpc_wake_up_queued_task_set_status(&xprt->sending,
task, 0);
return false;
}
return true;
}
void xprt_end_transmit(struct rpc_task *task)
{
xprt_release_write(task->tk_rqstp->rq_xprt, task);
}
/**
* xprt_request_transmit - send an RPC request on a transport
* @req: pointer to request to transmit
* @snd_task: RPC task that owns the transport lock
*
* This performs the transmission of a single request.
* Note that if the request is not the same as snd_task, then it
* does need to be pinned.
* Returns '0' on success.
*/
static int
xprt_request_transmit(struct rpc_rqst *req, struct rpc_task *snd_task)
{
struct rpc_xprt *xprt = req->rq_xprt;
struct rpc_task *task = req->rq_task;
unsigned int connect_cookie;
int is_retrans = RPC_WAS_SENT(task);
int status;
if (!req->rq_bytes_sent) {
if (xprt_request_data_received(task)) {
status = 0;
goto out_dequeue;
}
/* Verify that our message lies in the RPCSEC_GSS window */
if (rpcauth_xmit_need_reencode(task)) {
status = -EBADMSG;
goto out_dequeue;
}
if (RPC_SIGNALLED(task)) {
status = -ERESTARTSYS;
goto out_dequeue;
}
}
/*
* Update req->rq_ntrans before transmitting to avoid races with
* xprt_update_rtt(), which needs to know that it is recording a
* reply to the first transmission.
*/
req->rq_ntrans++;
trace_rpc_xdr_sendto(task, &req->rq_snd_buf);
connect_cookie = xprt->connect_cookie;
status = xprt->ops->send_request(req);
if (status != 0) {
req->rq_ntrans--;
trace_xprt_transmit(req, status);
return status;
}
if (is_retrans)
task->tk_client->cl_stats->rpcretrans++;
xprt_inject_disconnect(xprt);
task->tk_flags |= RPC_TASK_SENT;
spin_lock(&xprt->transport_lock);
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(&xprt->transport_lock);
req->rq_connect_cookie = connect_cookie;
out_dequeue:
trace_xprt_transmit(req, status);
xprt_request_dequeue_transmit(task);
rpc_wake_up_queued_task_set_status(&xprt->sending, task, status);
return status;
}
/**
* xprt_transmit - send an RPC request on a transport
* @task: controlling RPC task
*
* Attempts to drain the transmit queue. On exit, either the transport
* signalled an error that needs to be handled before transmission can
* resume, or @task finished transmitting, and detected that it already
* received a reply.
*/
void
xprt_transmit(struct rpc_task *task)
{
struct rpc_rqst *next, *req = task->tk_rqstp;
struct rpc_xprt *xprt = req->rq_xprt;
int counter, status;
spin_lock(&xprt->queue_lock);
counter = 0;
while (!list_empty(&xprt->xmit_queue)) {
if (++counter == 20)
break;
next = list_first_entry(&xprt->xmit_queue,
struct rpc_rqst, rq_xmit);
xprt_pin_rqst(next);
spin_unlock(&xprt->queue_lock);
status = xprt_request_transmit(next, task);
if (status == -EBADMSG && next != req)
status = 0;
spin_lock(&xprt->queue_lock);
xprt_unpin_rqst(next);
if (status == 0) {
if (!xprt_request_data_received(task) ||
test_bit(RPC_TASK_NEED_XMIT, &task->tk_runstate))
continue;
} else if (test_bit(RPC_TASK_NEED_XMIT, &task->tk_runstate))
task->tk_status = status;
break;
}
spin_unlock(&xprt->queue_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 (xprt->num_reqs >= xprt->max_reqs)
goto out;
++xprt->num_reqs;
spin_unlock(&xprt->reserve_lock);
req = kzalloc(sizeof(struct rpc_rqst), GFP_NOFS);
spin_lock(&xprt->reserve_lock);
if (req != NULL)
goto out;
--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 (xprt->num_reqs > xprt->min_reqs) {
--xprt->num_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");
fallthrough;
default:
task->tk_status = -EAGAIN;
}
spin_unlock(&xprt->reserve_lock);
return;
out_init_req:
xprt->stat.max_slots = max_t(unsigned int, xprt->stat.max_slots,
xprt->num_reqs);
spin_unlock(&xprt->reserve_lock);
task->tk_status = 0;
task->tk_rqstp = req;
}
EXPORT_SYMBOL_GPL(xprt_alloc_slot);
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);
}
EXPORT_SYMBOL_GPL(xprt_free_slot);
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;
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);
static void
xprt_init_connect_cookie(struct rpc_rqst *req, struct rpc_xprt *xprt)
{
req->rq_connect_cookie = xprt_connect_cookie(xprt) - 1;
}
static __be32
xprt_alloc_xid(struct rpc_xprt *xprt)
{
__be32 xid;
spin_lock(&xprt->reserve_lock);
xid = (__force __be32)xprt->xid++;
spin_unlock(&xprt->reserve_lock);
return xid;
}
static 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 = task->tk_xprt;
struct rpc_rqst *req = task->tk_rqstp;
req->rq_task = task;
req->rq_xprt = xprt;
req->rq_buffer = NULL;
req->rq_xid = xprt_alloc_xid(xprt);
xprt_init_connect_cookie(req, xprt);
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_snd_buf.bvec = NULL;
req->rq_rcv_buf.bvec = NULL;
req->rq_release_snd_buf = NULL;
xprt_init_majortimeo(task, req);
trace_xprt_reserve(req);
}
static void
xprt_do_reserve(struct rpc_xprt *xprt, struct rpc_task *task)
{
xprt->ops->alloc_slot(xprt, task);
if (task->tk_rqstp != NULL)
xprt_request_init(task);
}
/**
* 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_status = -EAGAIN;
if (!xprt_throttle_congested(xprt, task))
xprt_do_reserve(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_status = -EAGAIN;
xprt_do_reserve(xprt, task);
}
/**
* 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;
xprt_release_write(xprt, task);
}
return;
}
xprt = req->rq_xprt;
xprt_request_dequeue_xprt(task);
spin_lock(&xprt->transport_lock);
xprt->ops->release_xprt(xprt, task);
if (xprt->ops->release_request)
xprt->ops->release_request(task);
xprt_schedule_autodisconnect(xprt);
spin_unlock(&xprt->transport_lock);
if (req->rq_buffer)
xprt->ops->buf_free(task);
xprt_inject_disconnect(xprt);
xdr_free_bvec(&req->rq_rcv_buf);
xdr_free_bvec(&req->rq_snd_buf);
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);
if (likely(!bc_prealloc(req)))
xprt->ops->free_slot(xprt, req);
else
xprt_free_bc_request(req);
}
#ifdef CONFIG_SUNRPC_BACKCHANNEL
void
xprt_init_bc_request(struct rpc_rqst *req, struct rpc_task *task)
{
struct xdr_buf *xbufp = &req->rq_snd_buf;
task->tk_rqstp = req;
req->rq_task = task;
xprt_init_connect_cookie(req, req->rq_xprt);
/*
* Set up the xdr_buf length.
* This also indicates that the buffer is XDR encoded already.
*/
xbufp->len = xbufp->head[0].iov_len + xbufp->page_len +
xbufp->tail[0].iov_len;
}
#endif
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->queue_lock);
INIT_LIST_HEAD(&xprt->free);
xprt->recv_queue = RB_ROOT;
INIT_LIST_HEAD(&xprt->xmit_queue);
#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_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;
const struct xprt_class *t;
t = xprt_class_find_by_ident(args->ident);
if (!t) {
dprintk("RPC: transport (%d) not supported\n", args->ident);
return ERR_PTR(-EIO);
}
xprt = t->setup(args);
xprt_class_release(t);
if (IS_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);
trace_xprt_create(xprt);
out:
return xprt;
}
static void xprt_destroy_cb(struct work_struct *work)
{
struct rpc_xprt *xprt =
container_of(work, struct rpc_xprt, task_cleanup);
trace_xprt_destroy(xprt);
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);
/*
* Destroy any existing back channel
*/
xprt_destroy_backchannel(xprt, UINT_MAX);
/*
* 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)
{
/*
* 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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