OpenCloudOS-Kernel/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
nfs41: Add backchannel processing support to RPC state machine Adds rpc_run_bc_task() which is called by the NFS callback service to process backchannel requests. It performs similar work to rpc_run_task() though "schedules" the backchannel task to be executed starting at the call_trasmit state in the RPC state machine. It also introduces some miscellaneous updates to the argument validation, call_transmit, and transport cleanup functions to take into account that there are now forechannel and backchannel tasks. Backchannel requests do not carry an RPC message structure, since the payload has already been XDR encoded using the existing NFSv4 callback mechanism. Introduce a new transmit state for the client to reply on to backchannel requests. This new state simply reserves the transport and issues the reply. In case of a connection related error, disconnects the transport and drops the reply. It requires the forechannel to re-establish the connection and the server to retransmit the request, as stated in NFSv4.1 section 2.9.2 "Client and Server Transport Behavior". Note: There is no need to loop attempting to reserve the transport. If EAGAIN is returned by xprt_prepare_transmit(), return with tk_status == 0, setting tk_action to call_bc_transmit. rpc_execute() will invoke it again after the task is taken off the sleep queue. [nfs41: rpc_run_bc_task() need not be exported outside RPC module] [nfs41: New call_bc_transmit RPC state] Signed-off-by: Ricardo Labiaga <Ricardo.Labiaga@netapp.com> Signed-off-by: Benny Halevy <bhalevy@panasas.com> [nfs41: Backchannel: No need to loop in call_bc_transmit()] Signed-off-by: Andy Adamson <andros@netapp.com> Signed-off-by: Ricardo Labiaga <Ricardo.Labiaga@netapp.com> Signed-off-by: Benny Halevy <bhalevy@panasas.com> [rpc_count_iostats incorrectly exits early] Signed-off-by: Ricardo Labiaga <Ricardo.Labiaga@netapp.com> Signed-off-by: Benny Halevy <bhalevy@panasas.com> [Convert rpc_reply_expected() to inline function] [Remove unnecessary BUG_ON()] [Rename variable] Signed-off-by: Ricardo Labiaga <Ricardo.Labiaga@netapp.com> Signed-off-by: Benny Halevy <bhalevy@panasas.com>
2009-04-01 21:23:03 +08:00
* 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>
nfs41: Add backchannel processing support to RPC state machine Adds rpc_run_bc_task() which is called by the NFS callback service to process backchannel requests. It performs similar work to rpc_run_task() though "schedules" the backchannel task to be executed starting at the call_trasmit state in the RPC state machine. It also introduces some miscellaneous updates to the argument validation, call_transmit, and transport cleanup functions to take into account that there are now forechannel and backchannel tasks. Backchannel requests do not carry an RPC message structure, since the payload has already been XDR encoded using the existing NFSv4 callback mechanism. Introduce a new transmit state for the client to reply on to backchannel requests. This new state simply reserves the transport and issues the reply. In case of a connection related error, disconnects the transport and drops the reply. It requires the forechannel to re-establish the connection and the server to retransmit the request, as stated in NFSv4.1 section 2.9.2 "Client and Server Transport Behavior". Note: There is no need to loop attempting to reserve the transport. If EAGAIN is returned by xprt_prepare_transmit(), return with tk_status == 0, setting tk_action to call_bc_transmit. rpc_execute() will invoke it again after the task is taken off the sleep queue. [nfs41: rpc_run_bc_task() need not be exported outside RPC module] [nfs41: New call_bc_transmit RPC state] Signed-off-by: Ricardo Labiaga <Ricardo.Labiaga@netapp.com> Signed-off-by: Benny Halevy <bhalevy@panasas.com> [nfs41: Backchannel: No need to loop in call_bc_transmit()] Signed-off-by: Andy Adamson <andros@netapp.com> Signed-off-by: Ricardo Labiaga <Ricardo.Labiaga@netapp.com> Signed-off-by: Benny Halevy <bhalevy@panasas.com> [rpc_count_iostats incorrectly exits early] Signed-off-by: Ricardo Labiaga <Ricardo.Labiaga@netapp.com> Signed-off-by: Benny Halevy <bhalevy@panasas.com> [Convert rpc_reply_expected() to inline function] [Remove unnecessary BUG_ON()] [Rename variable] Signed-off-by: Ricardo Labiaga <Ricardo.Labiaga@netapp.com> Signed-off-by: Benny Halevy <bhalevy@panasas.com>
2009-04-01 21:23:03 +08:00
#include "sunrpc.h"
#include "sysfs.h"
#include "fail.h"
nfs41: Add backchannel processing support to RPC state machine Adds rpc_run_bc_task() which is called by the NFS callback service to process backchannel requests. It performs similar work to rpc_run_task() though "schedules" the backchannel task to be executed starting at the call_trasmit state in the RPC state machine. It also introduces some miscellaneous updates to the argument validation, call_transmit, and transport cleanup functions to take into account that there are now forechannel and backchannel tasks. Backchannel requests do not carry an RPC message structure, since the payload has already been XDR encoded using the existing NFSv4 callback mechanism. Introduce a new transmit state for the client to reply on to backchannel requests. This new state simply reserves the transport and issues the reply. In case of a connection related error, disconnects the transport and drops the reply. It requires the forechannel to re-establish the connection and the server to retransmit the request, as stated in NFSv4.1 section 2.9.2 "Client and Server Transport Behavior". Note: There is no need to loop attempting to reserve the transport. If EAGAIN is returned by xprt_prepare_transmit(), return with tk_status == 0, setting tk_action to call_bc_transmit. rpc_execute() will invoke it again after the task is taken off the sleep queue. [nfs41: rpc_run_bc_task() need not be exported outside RPC module] [nfs41: New call_bc_transmit RPC state] Signed-off-by: Ricardo Labiaga <Ricardo.Labiaga@netapp.com> Signed-off-by: Benny Halevy <bhalevy@panasas.com> [nfs41: Backchannel: No need to loop in call_bc_transmit()] Signed-off-by: Andy Adamson <andros@netapp.com> Signed-off-by: Ricardo Labiaga <Ricardo.Labiaga@netapp.com> Signed-off-by: Benny Halevy <bhalevy@panasas.com> [rpc_count_iostats incorrectly exits early] Signed-off-by: Ricardo Labiaga <Ricardo.Labiaga@netapp.com> Signed-off-by: Benny Halevy <bhalevy@panasas.com> [Convert rpc_reply_expected() to inline function] [Remove unnecessary BUG_ON()] [Rename variable] Signed-off-by: Ricardo Labiaga <Ricardo.Labiaga@netapp.com> Signed-off-by: Benny Halevy <bhalevy@panasas.com>
2009-04-01 21:23:03 +08:00
/*
* 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 void xprt_request_init(struct rpc_task *task);
static int xprt_request_prepare(struct rpc_rqst *req);
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))
clear_bit_unlock(XPRT_LOCKED, &xprt->state);
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);
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_majortimeo)) {
2021-04-05 09:29:26 +08:00
if (time_before(jiffies, req->rq_minortimeo))
return status;
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;
}
2006-11-22 22:55:48 +08:00
static void xprt_autoclose(struct work_struct *work)
{
2006-11-22 22:55:48 +08:00
struct rpc_xprt *xprt =
container_of(work, struct rpc_xprt, task_cleanup);
unsigned int pflags = memalloc_nofs_save();
trace_xprt_disconnect_auto(xprt);
xprt->connect_cookie++;
smp_mb__before_atomic();
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_schedule_autoclose_locked - Try to schedule an autoclose RPC call
* @xprt: transport to disconnect
*/
static void xprt_schedule_autoclose_locked(struct rpc_xprt *xprt)
{
if (test_and_set_bit(XPRT_CLOSE_WAIT, &xprt->state))
return;
if (test_and_set_bit(XPRT_LOCKED, &xprt->state) == 0)
queue_work(xprtiod_workqueue, &xprt->task_cleanup);
else if (xprt->snd_task && !test_bit(XPRT_SND_IS_COOKIE, &xprt->state))
rpc_wake_up_queued_task_set_status(&xprt->pending,
xprt->snd_task, -ENOTCONN);
}
/**
* 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);
xprt_schedule_autoclose_locked(xprt);
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;
xprt_schedule_autoclose_locked(xprt);
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);
}
#if IS_ENABLED(CONFIG_FAIL_SUNRPC)
static void xprt_inject_disconnect(struct rpc_xprt *xprt)
{
if (!fail_sunrpc.ignore_client_disconnect &&
should_fail(&fail_sunrpc.attr, 1))
xprt->ops->inject_disconnect(xprt);
}
#else
static inline void xprt_inject_disconnect(struct rpc_xprt *xprt)
{
}
#endif
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;
set_bit(XPRT_SND_IS_COOKIE, &xprt->state);
xprt->snd_task = cookie;
ret = true;
out:
spin_unlock(&xprt->transport_lock);
return ret;
}
EXPORT_SYMBOL_GPL(xprt_lock_connect);
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;
clear_bit(XPRT_SND_IS_COOKIE, &xprt->state);
xprt->ops->release_xprt(xprt, NULL);
xprt_schedule_autodisconnect(xprt);
out:
spin_unlock(&xprt->transport_lock);
wake_up_bit(&xprt->state, XPRT_LOCKED);
}
EXPORT_SYMBOL_GPL(xprt_unlock_connect);
/**
* 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 (!xprt_connected(xprt) && !test_bit(XPRT_CLOSE_WAIT, &xprt->state)) {
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
*
*/
int
xprt_request_enqueue_receive(struct rpc_task *task)
{
struct rpc_rqst *req = task->tk_rqstp;
struct rpc_xprt *xprt = req->rq_xprt;
int ret;
if (!xprt_request_need_enqueue_receive(task, req))
return 0;
ret = xprt_request_prepare(task->tk_rqstp);
if (ret)
return ret;
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);
return 0;
}
/**
* 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 (!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:
atomic_long_inc(&xprt->xmit_queuelen);
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);
atomic_long_dec(&req->rq_xprt->xmit_queuelen);
}
/**
* 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.
* Returns error, or zero.
*/
static int
xprt_request_prepare(struct rpc_rqst *req)
{
struct rpc_xprt *xprt = req->rq_xprt;
if (xprt->ops->prepare_request)
return xprt->ops->prepare_request(req);
return 0;
}
/**
* 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)) {
/* 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;
}
SUNRPC: improve 'swap' handling: scheduling and PF_MEMALLOC rpc tasks can be marked as RPC_TASK_SWAPPER. This causes GFP_MEMALLOC to be used for some allocations. This is needed in some cases, but not in all where it is currently provided, and in some where it isn't provided. Currently *all* tasks associated with a rpc_client on which swap is enabled get the flag and hence some GFP_MEMALLOC support. GFP_MEMALLOC is provided for ->buf_alloc() but only swap-writes need it. However xdr_alloc_bvec does not get GFP_MEMALLOC - though it often does need it. xdr_alloc_bvec is called while the XPRT_LOCK is held. If this blocks, then it blocks all other queued tasks. So this allocation needs GFP_MEMALLOC for *all* requests, not just writes, when the xprt is used for any swap writes. Similarly, if the transport is not connected, that will block all requests including swap writes, so memory allocations should get GFP_MEMALLOC if swap writes are possible. So with this patch: 1/ we ONLY set RPC_TASK_SWAPPER for swap writes. 2/ __rpc_execute() sets PF_MEMALLOC while handling any task with RPC_TASK_SWAPPER set, or when handling any task that holds the XPRT_LOCKED lock on an xprt used for swap. This removes the need for the RPC_IS_SWAPPER() test in ->buf_alloc handlers. 3/ xprt_prepare_transmit() sets PF_MEMALLOC after locking any task to a swapper xprt. __rpc_execute() will clear it. 3/ PF_MEMALLOC is set for all the connect workers. Reviewed-by: Chuck Lever <chuck.lever@oracle.com> (for xprtrdma parts) Signed-off-by: NeilBrown <neilb@suse.de> Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
2022-03-07 07:41:44 +08:00
if (atomic_read(&xprt->swapper))
/* This will be clear in __rpc_execute */
current->flags |= PF_MEMALLOC;
return true;
}
void xprt_end_transmit(struct rpc_task *task)
{
struct rpc_xprt *xprt = task->tk_rqstp->rq_xprt;
xprt_inject_disconnect(xprt);
xprt_release_write(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++;
trace_xprt_retransmit(req);
}
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 status;
spin_lock(&xprt->queue_lock);
for (;;) {
next = list_first_entry_or_null(&xprt->xmit_queue,
struct rpc_rqst, rq_xmit);
if (!next)
break;
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 (test_bit(RPC_TASK_NEED_XMIT, &task->tk_runstate))
task->tk_status = status;
break;
}
/* Was @task transmitted, and has it received a reply? */
if (xprt_request_data_received(task) &&
!test_bit(RPC_TASK_NEED_XMIT, &task->tk_runstate))
break;
cond_resched_lock(&xprt->queue_lock);
}
spin_unlock(&xprt->queue_lock);
}
static void xprt_complete_request_init(struct rpc_task *task)
{
if (task->tk_rqstp)
xprt_request_init(task);
}
void xprt_add_backlog(struct rpc_xprt *xprt, struct rpc_task *task)
{
set_bit(XPRT_CONGESTED, &xprt->state);
rpc_sleep_on(&xprt->backlog, task, xprt_complete_request_init);
}
EXPORT_SYMBOL_GPL(xprt_add_backlog);
SUNRPC in case of backlog, hand free slots directly to waiting task If sunrpc.tcp_max_slot_table_entries is small and there are tasks on the backlog queue, then when a request completes it is freed and the first task on the queue is woken. The expectation is that it will wake and claim that request. However if it was a sync task and the waiting process was killed at just that moment, it will wake and NOT claim the request. As long as TASK_CONGESTED remains set, requests can only be claimed by tasks woken from the backlog, and they are woken only as requests are freed, so when a task doesn't claim a request, no other task can ever get that request until TASK_CONGESTED is cleared. Each time this happens the number of available requests is decreased by one. With a sufficiently high workload and sufficiently low setting of max_slot (16 in the case where this was seen), TASK_CONGESTED can remain set for an extended period, and the above scenario (of a process being killed just as its task was woken) can repeat until no requests can be allocated. Then traffic stops. This patch addresses the problem by introducing a positive handover of a request from a completing task to a backlog task - the request is never freed when there is a backlog. When a task is woken it might not already have a request attached in which case it is *not* freed (as with current code) but is initialised (if needed) and used. If it isn't used it will eventually be freed by rpc_exit_task(). xprt_release() is enhanced to be able to correctly release an uninitialised request. Fixes: ba60eb25ff6b ("SUNRPC: Fix a livelock problem in the xprt->backlog queue") Signed-off-by: NeilBrown <neilb@suse.de> Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
2021-05-17 07:59:10 +08:00
static bool __xprt_set_rq(struct rpc_task *task, void *data)
{
SUNRPC in case of backlog, hand free slots directly to waiting task If sunrpc.tcp_max_slot_table_entries is small and there are tasks on the backlog queue, then when a request completes it is freed and the first task on the queue is woken. The expectation is that it will wake and claim that request. However if it was a sync task and the waiting process was killed at just that moment, it will wake and NOT claim the request. As long as TASK_CONGESTED remains set, requests can only be claimed by tasks woken from the backlog, and they are woken only as requests are freed, so when a task doesn't claim a request, no other task can ever get that request until TASK_CONGESTED is cleared. Each time this happens the number of available requests is decreased by one. With a sufficiently high workload and sufficiently low setting of max_slot (16 in the case where this was seen), TASK_CONGESTED can remain set for an extended period, and the above scenario (of a process being killed just as its task was woken) can repeat until no requests can be allocated. Then traffic stops. This patch addresses the problem by introducing a positive handover of a request from a completing task to a backlog task - the request is never freed when there is a backlog. When a task is woken it might not already have a request attached in which case it is *not* freed (as with current code) but is initialised (if needed) and used. If it isn't used it will eventually be freed by rpc_exit_task(). xprt_release() is enhanced to be able to correctly release an uninitialised request. Fixes: ba60eb25ff6b ("SUNRPC: Fix a livelock problem in the xprt->backlog queue") Signed-off-by: NeilBrown <neilb@suse.de> Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
2021-05-17 07:59:10 +08:00
struct rpc_rqst *req = data;
if (task->tk_rqstp == NULL) {
memset(req, 0, sizeof(*req)); /* mark unused */
task->tk_rqstp = req;
return true;
}
return false;
}
bool xprt_wake_up_backlog(struct rpc_xprt *xprt, struct rpc_rqst *req)
SUNRPC in case of backlog, hand free slots directly to waiting task If sunrpc.tcp_max_slot_table_entries is small and there are tasks on the backlog queue, then when a request completes it is freed and the first task on the queue is woken. The expectation is that it will wake and claim that request. However if it was a sync task and the waiting process was killed at just that moment, it will wake and NOT claim the request. As long as TASK_CONGESTED remains set, requests can only be claimed by tasks woken from the backlog, and they are woken only as requests are freed, so when a task doesn't claim a request, no other task can ever get that request until TASK_CONGESTED is cleared. Each time this happens the number of available requests is decreased by one. With a sufficiently high workload and sufficiently low setting of max_slot (16 in the case where this was seen), TASK_CONGESTED can remain set for an extended period, and the above scenario (of a process being killed just as its task was woken) can repeat until no requests can be allocated. Then traffic stops. This patch addresses the problem by introducing a positive handover of a request from a completing task to a backlog task - the request is never freed when there is a backlog. When a task is woken it might not already have a request attached in which case it is *not* freed (as with current code) but is initialised (if needed) and used. If it isn't used it will eventually be freed by rpc_exit_task(). xprt_release() is enhanced to be able to correctly release an uninitialised request. Fixes: ba60eb25ff6b ("SUNRPC: Fix a livelock problem in the xprt->backlog queue") Signed-off-by: NeilBrown <neilb@suse.de> Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
2021-05-17 07:59:10 +08:00
{
if (rpc_wake_up_first(&xprt->backlog, __xprt_set_rq, req) == NULL) {
clear_bit(XPRT_CONGESTED, &xprt->state);
SUNRPC in case of backlog, hand free slots directly to waiting task If sunrpc.tcp_max_slot_table_entries is small and there are tasks on the backlog queue, then when a request completes it is freed and the first task on the queue is woken. The expectation is that it will wake and claim that request. However if it was a sync task and the waiting process was killed at just that moment, it will wake and NOT claim the request. As long as TASK_CONGESTED remains set, requests can only be claimed by tasks woken from the backlog, and they are woken only as requests are freed, so when a task doesn't claim a request, no other task can ever get that request until TASK_CONGESTED is cleared. Each time this happens the number of available requests is decreased by one. With a sufficiently high workload and sufficiently low setting of max_slot (16 in the case where this was seen), TASK_CONGESTED can remain set for an extended period, and the above scenario (of a process being killed just as its task was woken) can repeat until no requests can be allocated. Then traffic stops. This patch addresses the problem by introducing a positive handover of a request from a completing task to a backlog task - the request is never freed when there is a backlog. When a task is woken it might not already have a request attached in which case it is *not* freed (as with current code) but is initialised (if needed) and used. If it isn't used it will eventually be freed by rpc_exit_task(). xprt_release() is enhanced to be able to correctly release an uninitialised request. Fixes: ba60eb25ff6b ("SUNRPC: Fix a livelock problem in the xprt->backlog queue") Signed-off-by: NeilBrown <neilb@suse.de> Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
2021-05-17 07:59:10 +08:00
return false;
}
return true;
}
EXPORT_SYMBOL_GPL(xprt_wake_up_backlog);
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)) {
xprt_add_backlog(xprt, task);
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(*req), rpc_task_gfp_mask());
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);
SUNRPC in case of backlog, hand free slots directly to waiting task If sunrpc.tcp_max_slot_table_entries is small and there are tasks on the backlog queue, then when a request completes it is freed and the first task on the queue is woken. The expectation is that it will wake and claim that request. However if it was a sync task and the waiting process was killed at just that moment, it will wake and NOT claim the request. As long as TASK_CONGESTED remains set, requests can only be claimed by tasks woken from the backlog, and they are woken only as requests are freed, so when a task doesn't claim a request, no other task can ever get that request until TASK_CONGESTED is cleared. Each time this happens the number of available requests is decreased by one. With a sufficiently high workload and sufficiently low setting of max_slot (16 in the case where this was seen), TASK_CONGESTED can remain set for an extended period, and the above scenario (of a process being killed just as its task was woken) can repeat until no requests can be allocated. Then traffic stops. This patch addresses the problem by introducing a positive handover of a request from a completing task to a backlog task - the request is never freed when there is a backlog. When a task is woken it might not already have a request attached in which case it is *not* freed (as with current code) but is initialised (if needed) and used. If it isn't used it will eventually be freed by rpc_exit_task(). xprt_release() is enhanced to be able to correctly release an uninitialised request. Fixes: ba60eb25ff6b ("SUNRPC: Fix a livelock problem in the xprt->backlog queue") Signed-off-by: NeilBrown <neilb@suse.de> Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
2021-05-17 07:59:10 +08:00
if (!xprt_wake_up_backlog(xprt, req) &&
!xprt_dynamic_free_slot(xprt, req)) {
memset(req, 0, sizeof(*req)); /* mark unused */
list_add(&req->rq_list, &xprt->free);
}
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);
}
}
static DEFINE_IDA(rpc_xprt_ids);
void xprt_cleanup_ids(void)
{
ida_destroy(&rpc_xprt_ids);
}
static int xprt_alloc_id(struct rpc_xprt *xprt)
{
int id;
id = ida_simple_get(&rpc_xprt_ids, 0, 0, GFP_KERNEL);
if (id < 0)
return id;
xprt->id = id;
return 0;
}
static void xprt_free_id(struct rpc_xprt *xprt)
{
ida_simple_remove(&rpc_xprt_ids, xprt->id);
}
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_alloc_id(xprt);
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_track(xprt->xprt_net, &xprt->ns_tracker);
xprt_free_all_slots(xprt);
xprt_free_id(xprt);
rpc_sysfs_xprt_destroy(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)
{
nfs41: Add backchannel processing support to RPC state machine Adds rpc_run_bc_task() which is called by the NFS callback service to process backchannel requests. It performs similar work to rpc_run_task() though "schedules" the backchannel task to be executed starting at the call_trasmit state in the RPC state machine. It also introduces some miscellaneous updates to the argument validation, call_transmit, and transport cleanup functions to take into account that there are now forechannel and backchannel tasks. Backchannel requests do not carry an RPC message structure, since the payload has already been XDR encoded using the existing NFSv4 callback mechanism. Introduce a new transmit state for the client to reply on to backchannel requests. This new state simply reserves the transport and issues the reply. In case of a connection related error, disconnects the transport and drops the reply. It requires the forechannel to re-establish the connection and the server to retransmit the request, as stated in NFSv4.1 section 2.9.2 "Client and Server Transport Behavior". Note: There is no need to loop attempting to reserve the transport. If EAGAIN is returned by xprt_prepare_transmit(), return with tk_status == 0, setting tk_action to call_bc_transmit. rpc_execute() will invoke it again after the task is taken off the sleep queue. [nfs41: rpc_run_bc_task() need not be exported outside RPC module] [nfs41: New call_bc_transmit RPC state] Signed-off-by: Ricardo Labiaga <Ricardo.Labiaga@netapp.com> Signed-off-by: Benny Halevy <bhalevy@panasas.com> [nfs41: Backchannel: No need to loop in call_bc_transmit()] Signed-off-by: Andy Adamson <andros@netapp.com> Signed-off-by: Ricardo Labiaga <Ricardo.Labiaga@netapp.com> Signed-off-by: Benny Halevy <bhalevy@panasas.com> [rpc_count_iostats incorrectly exits early] Signed-off-by: Ricardo Labiaga <Ricardo.Labiaga@netapp.com> Signed-off-by: Benny Halevy <bhalevy@panasas.com> [Convert rpc_reply_expected() to inline function] [Remove unnecessary BUG_ON()] [Rename variable] Signed-off-by: Ricardo Labiaga <Ricardo.Labiaga@netapp.com> Signed-off-by: Benny Halevy <bhalevy@panasas.com>
2009-04-01 21:23:03 +08:00
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;
}
nfs41: Add backchannel processing support to RPC state machine Adds rpc_run_bc_task() which is called by the NFS callback service to process backchannel requests. It performs similar work to rpc_run_task() though "schedules" the backchannel task to be executed starting at the call_trasmit state in the RPC state machine. It also introduces some miscellaneous updates to the argument validation, call_transmit, and transport cleanup functions to take into account that there are now forechannel and backchannel tasks. Backchannel requests do not carry an RPC message structure, since the payload has already been XDR encoded using the existing NFSv4 callback mechanism. Introduce a new transmit state for the client to reply on to backchannel requests. This new state simply reserves the transport and issues the reply. In case of a connection related error, disconnects the transport and drops the reply. It requires the forechannel to re-establish the connection and the server to retransmit the request, as stated in NFSv4.1 section 2.9.2 "Client and Server Transport Behavior". Note: There is no need to loop attempting to reserve the transport. If EAGAIN is returned by xprt_prepare_transmit(), return with tk_status == 0, setting tk_action to call_bc_transmit. rpc_execute() will invoke it again after the task is taken off the sleep queue. [nfs41: rpc_run_bc_task() need not be exported outside RPC module] [nfs41: New call_bc_transmit RPC state] Signed-off-by: Ricardo Labiaga <Ricardo.Labiaga@netapp.com> Signed-off-by: Benny Halevy <bhalevy@panasas.com> [nfs41: Backchannel: No need to loop in call_bc_transmit()] Signed-off-by: Andy Adamson <andros@netapp.com> Signed-off-by: Ricardo Labiaga <Ricardo.Labiaga@netapp.com> Signed-off-by: Benny Halevy <bhalevy@panasas.com> [rpc_count_iostats incorrectly exits early] Signed-off-by: Ricardo Labiaga <Ricardo.Labiaga@netapp.com> Signed-off-by: Benny Halevy <bhalevy@panasas.com> [Convert rpc_reply_expected() to inline function] [Remove unnecessary BUG_ON()] [Rename variable] Signed-off-by: Ricardo Labiaga <Ricardo.Labiaga@netapp.com> Signed-off-by: Benny Halevy <bhalevy@panasas.com>
2009-04-01 21:23:03 +08:00
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);
xdr_free_bvec(&req->rq_rcv_buf);
xdr_free_bvec(&req->rq_snd_buf);
if (req->rq_cred != NULL)
put_rpccred(req->rq_cred);
if (req->rq_release_snd_buf)
req->rq_release_snd_buf(req);
nfs41: Add backchannel processing support to RPC state machine Adds rpc_run_bc_task() which is called by the NFS callback service to process backchannel requests. It performs similar work to rpc_run_task() though "schedules" the backchannel task to be executed starting at the call_trasmit state in the RPC state machine. It also introduces some miscellaneous updates to the argument validation, call_transmit, and transport cleanup functions to take into account that there are now forechannel and backchannel tasks. Backchannel requests do not carry an RPC message structure, since the payload has already been XDR encoded using the existing NFSv4 callback mechanism. Introduce a new transmit state for the client to reply on to backchannel requests. This new state simply reserves the transport and issues the reply. In case of a connection related error, disconnects the transport and drops the reply. It requires the forechannel to re-establish the connection and the server to retransmit the request, as stated in NFSv4.1 section 2.9.2 "Client and Server Transport Behavior". Note: There is no need to loop attempting to reserve the transport. If EAGAIN is returned by xprt_prepare_transmit(), return with tk_status == 0, setting tk_action to call_bc_transmit. rpc_execute() will invoke it again after the task is taken off the sleep queue. [nfs41: rpc_run_bc_task() need not be exported outside RPC module] [nfs41: New call_bc_transmit RPC state] Signed-off-by: Ricardo Labiaga <Ricardo.Labiaga@netapp.com> Signed-off-by: Benny Halevy <bhalevy@panasas.com> [nfs41: Backchannel: No need to loop in call_bc_transmit()] Signed-off-by: Andy Adamson <andros@netapp.com> Signed-off-by: Ricardo Labiaga <Ricardo.Labiaga@netapp.com> Signed-off-by: Benny Halevy <bhalevy@panasas.com> [rpc_count_iostats incorrectly exits early] Signed-off-by: Ricardo Labiaga <Ricardo.Labiaga@netapp.com> Signed-off-by: Benny Halevy <bhalevy@panasas.com> [Convert rpc_reply_expected() to inline function] [Remove unnecessary BUG_ON()] [Rename variable] Signed-off-by: Ricardo Labiaga <Ricardo.Labiaga@netapp.com> Signed-off-by: Benny Halevy <bhalevy@panasas.com>
2009-04-01 21:23:03 +08:00
SUNRPC in case of backlog, hand free slots directly to waiting task If sunrpc.tcp_max_slot_table_entries is small and there are tasks on the backlog queue, then when a request completes it is freed and the first task on the queue is woken. The expectation is that it will wake and claim that request. However if it was a sync task and the waiting process was killed at just that moment, it will wake and NOT claim the request. As long as TASK_CONGESTED remains set, requests can only be claimed by tasks woken from the backlog, and they are woken only as requests are freed, so when a task doesn't claim a request, no other task can ever get that request until TASK_CONGESTED is cleared. Each time this happens the number of available requests is decreased by one. With a sufficiently high workload and sufficiently low setting of max_slot (16 in the case where this was seen), TASK_CONGESTED can remain set for an extended period, and the above scenario (of a process being killed just as its task was woken) can repeat until no requests can be allocated. Then traffic stops. This patch addresses the problem by introducing a positive handover of a request from a completing task to a backlog task - the request is never freed when there is a backlog. When a task is woken it might not already have a request attached in which case it is *not* freed (as with current code) but is initialised (if needed) and used. If it isn't used it will eventually be freed by rpc_exit_task(). xprt_release() is enhanced to be able to correctly release an uninitialised request. Fixes: ba60eb25ff6b ("SUNRPC: Fix a livelock problem in the xprt->backlog queue") Signed-off-by: NeilBrown <neilb@suse.de> Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
2021-05-17 07:59:10 +08:00
task->tk_rqstp = NULL;
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_track(net, &xprt->ns_tracker, GFP_KERNEL);
}
/**
* 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);
/*
* xprt_schedule_autodisconnect() can run after XPRT_LOCKED
* is cleared. We use ->transport_lock to ensure the mod_timer()
* can only run *before* del_time_sync(), never after.
*/
spin_lock(&xprt->transport_lock);
del_timer_sync(&xprt->timer);
spin_unlock(&xprt->transport_lock);
/*
* 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);