// SPDX-License-Identifier: GPL-2.0-only
/*
* linux/net/sunrpc/sched.c
*
* Scheduling for synchronous and asynchronous RPC requests.
*
* Copyright (C) 1996 Olaf Kirch, <[email protected]>
*
* TCP NFS related read + write fixes
* (C) 1999 Dave Airlie, University of Limerick, Ireland <[email protected]>
*/
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/interrupt.h>
#include <linux/slab.h>
#include <linux/mempool.h>
#include <linux/smp.h>
#include <linux/spinlock.h>
#include <linux/mutex.h>
#include <linux/freezer.h>
#include <linux/sched/mm.h>
#include <linux/sunrpc/clnt.h>
#include <linux/sunrpc/metrics.h>
#include "sunrpc.h"
#define CREATE_TRACE_POINTS
#include <trace/events/sunrpc.h>
/*
* RPC slabs and memory pools
*/
#define RPC_BUFFER_MAXSIZE (2048)
#define RPC_BUFFER_POOLSIZE (8)
#define RPC_TASK_POOLSIZE (8)
static struct kmem_cache *rpc_task_slabp __read_mostly;
static struct kmem_cache *rpc_buffer_slabp __read_mostly;
static mempool_t *rpc_task_mempool __read_mostly;
static mempool_t *rpc_buffer_mempool __read_mostly;
static void rpc_async_schedule(struct work_struct *);
static void rpc_release_task(struct rpc_task *task);
static void __rpc_queue_timer_fn(struct work_struct *);
/*
* RPC tasks sit here while waiting for conditions to improve.
*/
static struct rpc_wait_queue delay_queue;
/*
* rpciod-related stuff
*/
struct workqueue_struct *rpciod_workqueue __read_mostly;
struct workqueue_struct *xprtiod_workqueue __read_mostly;
EXPORT_SYMBOL_GPL(xprtiod_workqueue);
gfp_t rpc_task_gfp_mask(void)
{
if (current->flags & PF_WQ_WORKER)
return GFP_KERNEL | __GFP_NORETRY | __GFP_NOWARN;
return GFP_KERNEL;
}
EXPORT_SYMBOL_GPL(rpc_task_gfp_mask);
bool rpc_task_set_rpc_status(struct rpc_task *task, int rpc_status)
{
if (cmpxchg(&task->tk_rpc_status, 0, rpc_status) == 0)
return true;
return false;
}
unsigned long
rpc_task_timeout(const struct rpc_task *task)
{
unsigned long timeout = READ_ONCE(task->tk_timeout);
if (timeout != 0) {
unsigned long now = jiffies;
if (time_before(now, timeout))
return timeout - now;
}
return 0;
}
EXPORT_SYMBOL_GPL(rpc_task_timeout);
/*
* Disable the timer for a given RPC task. Should be called with
* queue->lock and bh_disabled in order to avoid races within
* rpc_run_timer().
*/
static void
__rpc_disable_timer(struct rpc_wait_queue *queue, struct rpc_task *task)
{
if (list_empty(&task->u.tk_wait.timer_list))
return;
task->tk_timeout = 0;
list_del(&task->u.tk_wait.timer_list);
if (list_empty(&queue->timer_list.list))
cancel_delayed_work(&queue->timer_list.dwork);
}
static void
rpc_set_queue_timer(struct rpc_wait_queue *queue, unsigned long expires)
{
unsigned long now = jiffies;
queue->timer_list.expires = expires;
if (time_before_eq(expires, now))
expires = 0;
else
expires -= now;
mod_delayed_work(rpciod_workqueue, &queue->timer_list.dwork, expires);
}
/*
* Set up a timer for the current task.
*/
static void
__rpc_add_timer(struct rpc_wait_queue *queue, struct rpc_task *task,
unsigned long timeout)
{
task->tk_timeout = timeout;
if (list_empty(&queue->timer_list.list) || time_before(timeout, queue->timer_list.expires))
rpc_set_queue_timer(queue, timeout);
list_add(&task->u.tk_wait.timer_list, &queue->timer_list.list);
}
static void rpc_set_waitqueue_priority(struct rpc_wait_queue *queue, int priority)
{
if (queue->priority != priority) {
queue->priority = priority;
queue->nr = 1U << priority;
}
}
static void rpc_reset_waitqueue_priority(struct rpc_wait_queue *queue)
{
rpc_set_waitqueue_priority(queue, queue->maxpriority);
}
/*
* Add a request to a queue list
*/
static void
__rpc_list_enqueue_task(struct list_head *q, struct rpc_task *task)
{
struct rpc_task *t;
list_for_each_entry(t, q, u.tk_wait.list) {
if (t->tk_owner == task->tk_owner) {
list_add_tail(&task->u.tk_wait.links,
&t->u.tk_wait.links);
/* Cache the queue head in task->u.tk_wait.list */
task->u.tk_wait.list.next = q;
task->u.tk_wait.list.prev = NULL;
return;
}
}
INIT_LIST_HEAD(&task->u.tk_wait.links);
list_add_tail(&task->u.tk_wait.list, q);
}
/*
* Remove request from a queue list
*/
static void
__rpc_list_dequeue_task(struct rpc_task *task)
{
struct list_head *q;
struct rpc_task *t;
if (task->u.tk_wait.list.prev == NULL) {
list_del(&task->u.tk_wait.links);
return;
}
if (!list_empty(&task->u.tk_wait.links)) {
t = list_first_entry(&task->u.tk_wait.links,
struct rpc_task,
u.tk_wait.links);
/* Assume __rpc_list_enqueue_task() cached the queue head */
q = t->u.tk_wait.list.next;
list_add_tail(&t->u.tk_wait.list, q);
list_del(&task->u.tk_wait.links);
}
list_del(&task->u.tk_wait.list);
}
/*
* Add new request to a priority queue.
*/
static void __rpc_add_wait_queue_priority(struct rpc_wait_queue *queue,
struct rpc_task *task,
unsigned char queue_priority)
{
if (unlikely(queue_priority > queue->maxpriority))
queue_priority = queue->maxpriority;
__rpc_list_enqueue_task(&queue->tasks[queue_priority], task);
}
/*
* Add new request to wait queue.
*/
static void __rpc_add_wait_queue(struct rpc_wait_queue *queue,
struct rpc_task *task,
unsigned char queue_priority)
{
INIT_LIST_HEAD(&task->u.tk_wait.timer_list);
if (RPC_IS_PRIORITY(queue))
__rpc_add_wait_queue_priority(queue, task, queue_priority);
else
list_add_tail(&task->u.tk_wait.list, &queue->tasks[0]);
task->tk_waitqueue = queue;
queue->qlen++;
/* barrier matches the read in rpc_wake_up_task_queue_locked() */
smp_wmb();
rpc_set_queued(task);
}
/*
* Remove request from a priority queue.
*/
static void __rpc_remove_wait_queue_priority(struct rpc_task *task)
{
__rpc_list_dequeue_task(task);
}
/*
* Remove request from queue.
* Note: must be called with spin lock held.
*/
static void __rpc_remove_wait_queue(struct rpc_wait_queue *queue, struct rpc_task *task)
{
__rpc_disable_timer(queue, task);
if (RPC_IS_PRIORITY(queue))
__rpc_remove_wait_queue_priority(task);
else
list_del(&task->u.tk_wait.list);
queue->qlen--;
}
static void __rpc_init_priority_wait_queue(struct rpc_wait_queue *queue, const char *qname, unsigned char nr_queues)
{
int i;
spin_lock_init(&queue->lock);
for (i = 0; i < ARRAY_SIZE(queue->tasks); i++)
INIT_LIST_HEAD(&queue->tasks[i]);
queue->maxpriority = nr_queues - 1;
rpc_reset_waitqueue_priority(queue);
queue->qlen = 0;
queue->timer_list.expires = 0;
INIT_DELAYED_WORK(&queue->timer_list.dwork, __rpc_queue_timer_fn);
INIT_LIST_HEAD(&queue->timer_list.list);
rpc_assign_waitqueue_name(queue, qname);
}
void rpc_init_priority_wait_queue(struct rpc_wait_queue *queue, const char *qname)
{
__rpc_init_priority_wait_queue(queue, qname, RPC_NR_PRIORITY);
}
EXPORT_SYMBOL_GPL(rpc_init_priority_wait_queue);
void rpc_init_wait_queue(struct rpc_wait_queue *queue, const char *qname)
{
__rpc_init_priority_wait_queue(queue, qname, 1);
}
EXPORT_SYMBOL_GPL(rpc_init_wait_queue);
void rpc_destroy_wait_queue(struct rpc_wait_queue *queue)
{
cancel_delayed_work_sync(&queue->timer_list.dwork);
}
EXPORT_SYMBOL_GPL(rpc_destroy_wait_queue);
static int rpc_wait_bit_killable(struct wait_bit_key *key, int mode)
{
schedule();
if (signal_pending_state(mode, current))
return -ERESTARTSYS;
return 0;
}
#if IS_ENABLED(CONFIG_SUNRPC_DEBUG) || IS_ENABLED(CONFIG_TRACEPOINTS)
static void rpc_task_set_debuginfo(struct rpc_task *task)
{
struct rpc_clnt *clnt = task->tk_client;
/* Might be a task carrying a reverse-direction operation */
if (!clnt) {
static atomic_t rpc_pid;
task->tk_pid = atomic_inc_return(&rpc_pid);
return;
}
task->tk_pid = atomic_inc_return(&clnt->cl_pid);
}
#else
static inline void rpc_task_set_debuginfo(struct rpc_task *task)
{
}
#endif
static void rpc_set_active(struct rpc_task *task)
{
rpc_task_set_debuginfo(task);
set_bit(RPC_TASK_ACTIVE, &task->tk_runstate);
trace_rpc_task_begin(task, NULL);
}
/*
* Mark an RPC call as having completed by clearing the 'active' bit
* and then waking up all tasks that were sleeping.
*/
static int rpc_complete_task(struct rpc_task *task)
{
void *m = &task->tk_runstate;
wait_queue_head_t *wq = bit_waitqueue(m, RPC_TASK_ACTIVE);
struct wait_bit_key k = __WAIT_BIT_KEY_INITIALIZER(m, RPC_TASK_ACTIVE);
unsigned long flags;
int ret;
trace_rpc_task_complete(task, NULL);
spin_lock_irqsave(&wq->lock, flags);
clear_bit(RPC_TASK_ACTIVE, &task->tk_runstate);
ret = atomic_dec_and_test(&task->tk_count);
if (waitqueue_active(wq))
__wake_up_locked_key(wq, TASK_NORMAL, &k);
spin_unlock_irqrestore(&wq->lock, flags);
return ret;
}
/*
* Allow callers to wait for completion of an RPC call
*
* Note the use of out_of_line_wait_on_bit() rather than wait_on_bit()
* to enforce taking of the wq->lock and hence avoid races with
* rpc_complete_task().
*/
int rpc_wait_for_completion_task(struct rpc_task *task)
{
return out_of_line_wait_on_bit(&task->tk_runstate, RPC_TASK_ACTIVE,
rpc_wait_bit_killable, TASK_KILLABLE|TASK_FREEZABLE_UNSAFE);
}
EXPORT_SYMBOL_GPL(rpc_wait_for_completion_task);
/*
* Make an RPC task runnable.
*
* Note: If the task is ASYNC, and is being made runnable after sitting on an
* rpc_wait_queue, this must be called with the queue spinlock held to protect
* the wait queue operation.
* Note the ordering of rpc_test_and_set_running() and rpc_clear_queued(),
* which is needed to ensure that __rpc_execute() doesn't loop (due to the
* lockless RPC_IS_QUEUED() test) before we've had a chance to test
* the RPC_TASK_RUNNING flag.
*/
static void rpc_make_runnable(struct workqueue_struct *wq,
struct rpc_task *task)
{
bool need_wakeup = !rpc_test_and_set_running(task);
rpc_clear_queued(task);
if (!need_wakeup)
return;
if (RPC_IS_ASYNC(task)) {
INIT_WORK(&task->u.tk_work, rpc_async_schedule);
queue_work(wq, &task->u.tk_work);
} else {
smp_mb__after_atomic();
wake_up_bit(&task->tk_runstate, RPC_TASK_QUEUED);
}
}
/*
* Prepare for sleeping on a wait queue.
* By always appending tasks to the list we ensure FIFO behavior.
* NB: An RPC task will only receive interrupt-driven events as long
* as it's on a wait queue.
*/
static void __rpc_do_sleep_on_priority(struct rpc_wait_queue *q,
struct rpc_task *task,
unsigned char queue_priority)
{
trace_rpc_task_sleep(task, q);
__rpc_add_wait_queue(q, task, queue_priority);
}
static void __rpc_sleep_on_priority(struct rpc_wait_queue *q,
struct rpc_task *task,
unsigned char queue_priority)
{
if (WARN_ON_ONCE(RPC_IS_QUEUED(task)))
return;
__rpc_do_sleep_on_priority(q, task, queue_priority);
}
static void __rpc_sleep_on_priority_timeout(struct rpc_wait_queue *q,
struct rpc_task *task, unsigned long timeout,
unsigned char queue_priority)
{
if (WARN_ON_ONCE(RPC_IS_QUEUED(task)))
return;
if (time_is_after_jiffies(timeout)) {
__rpc_do_sleep_on_priority(q, task, queue_priority);
__rpc_add_timer(q, task, timeout);
} else
task->tk_status = -ETIMEDOUT;
}
static void rpc_set_tk_callback(struct rpc_task *task, rpc_action action)
{
if (action && !WARN_ON_ONCE(task->tk_callback != NULL))
task->tk_callback = action;
}
static bool rpc_sleep_check_activated(struct rpc_task *task)
{
/* We shouldn't ever put an inactive task to sleep */
if (WARN_ON_ONCE(!RPC_IS_ACTIVATED(task))) {
task->tk_status = -EIO;
rpc_put_task_async(task);
return false;
}
return true;
}
void rpc_sleep_on_timeout(struct rpc_wait_queue *q, struct rpc_task *task,
rpc_action action, unsigned long timeout)
{
if (!rpc_sleep_check_activated(task))
return;
rpc_set_tk_callback(task, action);
/*
* Protect the queue operations.
*/
spin_lock(&q->lock);
__rpc_sleep_on_priority_timeout(q, task, timeout, task->tk_priority);
spin_unlock(&q->lock);
}
EXPORT_SYMBOL_GPL(rpc_sleep_on_timeout);
void rpc_sleep_on(struct rpc_wait_queue *q, struct rpc_task *task,
rpc_action action)
{
if (!rpc_sleep_check_activated(task))
return;
rpc_set_tk_callback(task, action);
WARN_ON_ONCE(task->tk_timeout != 0);
/*
* Protect the queue operations.
*/
spin_lock(&q->lock);
__rpc_sleep_on_priority(q, task, task->tk_priority);
spin_unlock(&q->lock);
}
EXPORT_SYMBOL_GPL(rpc_sleep_on);
void rpc_sleep_on_priority_timeout(struct rpc_wait_queue *q,
struct rpc_task *task, unsigned long timeout, int priority)
{
if (!rpc_sleep_check_activated(task))
return;
priority -= RPC_PRIORITY_LOW;
/*
* Protect the queue operations.
*/
spin_lock(&q->lock);
__rpc_sleep_on_priority_timeout(q, task, timeout, priority);
spin_unlock(&q->lock);
}
EXPORT_SYMBOL_GPL(rpc_sleep_on_priority_timeout);
void rpc_sleep_on_priority(struct rpc_wait_queue *q, struct rpc_task *task,
int priority)
{
if (!rpc_sleep_check_activated(task))
return;
WARN_ON_ONCE(task->tk_timeout != 0);
priority -= RPC_PRIORITY_LOW;
/*
* Protect the queue operations.
*/
spin_lock(&q->lock);
__rpc_sleep_on_priority(q, task, priority);
spin_unlock(&q->lock);
}
EXPORT_SYMBOL_GPL(rpc_sleep_on_priority);
/**
* __rpc_do_wake_up_task_on_wq - wake up a single rpc_task
* @wq: workqueue on which to run task
* @queue: wait queue
* @task: task to be woken up
*
* Caller must hold queue->lock, and have cleared the task queued flag.
*/
static void __rpc_do_wake_up_task_on_wq(struct workqueue_struct *wq,
struct rpc_wait_queue *queue,
struct rpc_task *task)
{
/* Has the task been executed yet? If not, we cannot wake it up! */
if (!RPC_IS_ACTIVATED(task)) {
printk(KERN_ERR "RPC: Inactive task (%p) being woken up!\n", task);
return;
}
trace_rpc_task_wakeup(task, queue);
__rpc_remove_wait_queue(queue, task);
rpc_make_runnable(wq, task);
}
/*
* Wake up a queued task while the queue lock is being held
*/
static struct rpc_task *
rpc_wake_up_task_on_wq_queue_action_locked(struct workqueue_struct *wq,
struct rpc_wait_queue *queue, struct rpc_task *task,
bool (*action)(struct rpc_task *, void *), void *data)
{
if (RPC_IS_QUEUED(task)) {
smp_rmb();
if (task->tk_waitqueue == queue) {
if (action == NULL || action(task, data)) {
__rpc_do_wake_up_task_on_wq(wq, queue, task);
return task;
}
}
}
return NULL;
}
/*
* Wake up a queued task while the queue lock is being held
*/
static void rpc_wake_up_task_queue_locked(struct rpc_wait_queue *queue,
struct rpc_task *task)
{
rpc_wake_up_task_on_wq_queue_action_locked(rpciod_workqueue, queue,
task, NULL, NULL);
}
/*
* Wake up a task on a specific queue
*/
void rpc_wake_up_queued_task(struct rpc_wait_queue *queue, struct rpc_task *task)
{
if (!RPC_IS_QUEUED(task))
return;
spin_lock(&queue->lock);
rpc_wake_up_task_queue_locked(queue, task);
spin_unlock(&queue->lock);
}
EXPORT_SYMBOL_GPL(rpc_wake_up_queued_task);
static bool rpc_task_action_set_status(struct rpc_task *task, void *status)
{
task->tk_status = *(int *)status;
return true;
}
static void
rpc_wake_up_task_queue_set_status_locked(struct rpc_wait_queue *queue,
struct rpc_task *task, int status)
{
rpc_wake_up_task_on_wq_queue_action_locked(rpciod_workqueue, queue,
task, rpc_task_action_set_status, &status);
}
/**
* rpc_wake_up_queued_task_set_status - wake up a task and set task->tk_status
* @queue: pointer to rpc_wait_queue
* @task: pointer to rpc_task
* @status: integer error value
*
* If @task is queued on @queue, then it is woken up, and @task->tk_status is
* set to the value of @status.
*/
void
rpc_wake_up_queued_task_set_status(struct rpc_wait_queue *queue,
struct rpc_task *task, int status)
{
if (!RPC_IS_QUEUED(task))
return;
spin_lock(&queue->lock);
rpc_wake_up_task_queue_set_status_locked(queue, task, status);
spin_unlock(&queue->lock);
}
/*
* Wake up the next task on a priority queue.
*/
static struct rpc_task *__rpc_find_next_queued_priority(struct rpc_wait_queue *queue)
{
struct list_head *q;
struct rpc_task *task;
/*
* Service the privileged queue.
*/
q = &queue->tasks[RPC_NR_PRIORITY - 1];
if (queue->maxpriority > RPC_PRIORITY_PRIVILEGED && !list_empty(q)) {
task = list_first_entry(q, struct rpc_task, u.tk_wait.list);
goto out;
}
/*
* Service a batch of tasks from a single owner.
*/
q = &queue->tasks[queue->priority];
if (!list_empty(q) && queue->nr) {
queue->nr--;
task = list_first_entry(q, struct rpc_task, u.tk_wait.list);
goto out;
}
/*
* Service the next queue.
*/
do {
if (q == &queue->tasks[0])
q = &queue->tasks[queue->maxpriority];
else
q = q - 1;
if (!list_empty(q)) {
task = list_first_entry(q, struct rpc_task, u.tk_wait.list);
goto new_queue;
}
} while (q != &queue->tasks[queue->priority]);
rpc_reset_waitqueue_priority(queue);
return NULL;
new_queue:
rpc_set_waitqueue_priority(queue, (unsigned int)(q - &queue->tasks[0]));
out:
return task;
}
static struct rpc_task *__rpc_find_next_queued(struct rpc_wait_queue *queue)
{
if (RPC_IS_PRIORITY(queue))
return __rpc_find_next_queued_priority(queue);
if (!list_empty(&queue->tasks[0]))
return list_first_entry(&queue->tasks[0], struct rpc_task, u.tk_wait.list);
return NULL;
}
/*
* Wake up the first task on the wait queue.
*/
struct rpc_task *rpc_wake_up_first_on_wq(struct workqueue_struct *wq,
struct rpc_wait_queue *queue,
bool (*func)(struct rpc_task *, void *), void *data)
{
struct rpc_task *task = NULL;
spin_lock(&queue->lock);
task = __rpc_find_next_queued(queue);
if (task != NULL)
task = rpc_wake_up_task_on_wq_queue_action_locked(wq, queue,
task, func, data);
spin_unlock(&queue->lock);
return task;
}
/*
* Wake up the first task on the wait queue.
*/
struct rpc_task *rpc_wake_up_first(struct rpc_wait_queue *queue,
bool (*func)(struct rpc_task *, void *), void *data)
{
return rpc_wake_up_first_on_wq(rpciod_workqueue, queue, func, data);
}
EXPORT_SYMBOL_GPL(rpc_wake_up_first);
static bool rpc_wake_up_next_func(struct rpc_task *task, void *data)
{
return true;
}
/*
* Wake up the next task on the wait queue.
*/
struct rpc_task *rpc_wake_up_next(struct rpc_wait_queue *queue)
{
return rpc_wake_up_first(queue, rpc_wake_up_next_func, NULL);
}
EXPORT_SYMBOL_GPL(rpc_wake_up_next);
/**
* rpc_wake_up_locked - wake up all rpc_tasks
* @queue: rpc_wait_queue on which the tasks are sleeping
*
*/
static void rpc_wake_up_locked(struct rpc_wait_queue *queue)
{
struct rpc_task *task;
for (;;) {
task = __rpc_find_next_queued(queue);
if (task == NULL)
break;
rpc_wake_up_task_queue_locked(queue, task);
}
}
/**
* rpc_wake_up - wake up all rpc_tasks
* @queue: rpc_wait_queue on which the tasks are sleeping
*
* Grabs queue->lock
*/
void rpc_wake_up(struct rpc_wait_queue *queue)
{
spin_lock(&queue->lock);
rpc_wake_up_locked(queue);
spin_unlock(&queue->lock);
}
EXPORT_SYMBOL_GPL(rpc_wake_up);
/**
* rpc_wake_up_status_locked - wake up all rpc_tasks and set their status value.
* @queue: rpc_wait_queue on which the tasks are sleeping
* @status: status value to set
*/
static void rpc_wake_up_status_locked(struct rpc_wait_queue *queue, int status)
{
struct rpc_task *task;
for (;;) {
task = __rpc_find_next_queued(queue);
if (task == NULL)
break;
rpc_wake_up_task_queue_set_status_locked(queue, task, status);
}
}
/**
* rpc_wake_up_status - wake up all rpc_tasks and set their status value.
* @queue: rpc_wait_queue on which the tasks are sleeping
* @status: status value to set
*
* Grabs queue->lock
*/
void rpc_wake_up_status(struct rpc_wait_queue *queue, int status)
{
spin_lock(&queue->lock);
rpc_wake_up_status_locked(queue, status);
spin_unlock(&queue->lock);
}
EXPORT_SYMBOL_GPL(rpc_wake_up_status);
static void __rpc_queue_timer_fn(struct work_struct *work)
{
struct rpc_wait_queue *queue = container_of(work,
struct rpc_wait_queue,
timer_list.dwork.work);
struct rpc_task *task, *n;
unsigned long expires, now, timeo;
spin_lock(&queue->lock);
expires = now = jiffies;
list_for_each_entry_safe(task, n, &queue->timer_list.list, u.tk_wait.timer_list) {
timeo = task->tk_timeout;
if (time_after_eq(now, timeo)) {
trace_rpc_task_timeout(task, task->tk_action);
task->tk_status = -ETIMEDOUT;
rpc_wake_up_task_queue_locked(queue, task);
continue;
}
if (expires == now || time_after(expires, timeo))
expires = timeo;
}
if (!list_empty(&queue->timer_list.list))
rpc_set_queue_timer(queue, expires);
spin_unlock(&queue->lock);
}
static void __rpc_atrun(struct rpc_task *task)
{
if (task->tk_status == -ETIMEDOUT)
task->tk_status = 0;
}
/*
* Run a task at a later time
*/
void rpc_delay(struct rpc_task *task, unsigned long delay)
{
rpc_sleep_on_timeout(&delay_queue, task, __rpc_atrun, jiffies + delay);
}
EXPORT_SYMBOL_GPL(rpc_delay);
/*
* Helper to call task->tk_ops->rpc_call_prepare
*/
void rpc_prepare_task(struct rpc_task *task)
{
task->tk_ops->rpc_call_prepare(task, task->tk_calldata);
}
static void
rpc_init_task_statistics(struct rpc_task *task)
{
/* Initialize retry counters */
task->tk_garb_retry = 2;
task->tk_cred_retry = 2;
/* starting timestamp */
task->tk_start = ktime_get();
}
static void
rpc_reset_task_statistics(struct rpc_task *task)
{
task->tk_timeouts = 0;
task->tk_flags &= ~(RPC_CALL_MAJORSEEN|RPC_TASK_SENT);
rpc_init_task_statistics(task);
}
/*
* Helper that calls task->tk_ops->rpc_call_done if it exists
*/
void rpc_exit_task(struct rpc_task *task)
{
trace_rpc_task_end(task, task->tk_action);
task->tk_action = NULL;
if (task->tk_ops->rpc_count_stats)
task->tk_ops->rpc_count_stats(task, task->tk_calldata);
else if (task->tk_client)
rpc_count_iostats(task, task->tk_client->cl_metrics);
if (task->tk_ops->rpc_call_done != NULL) {
trace_rpc_task_call_done(task, task->tk_ops->rpc_call_done);
task->tk_ops->rpc_call_done(task, task->tk_calldata);
if (task->tk_action != NULL) {
/* Always release the RPC slot and buffer memory */
xprt_release(task);
rpc_reset_task_statistics(task);
}
}
}
void rpc_signal_task(struct rpc_task *task)
{
struct rpc_wait_queue *queue;
if (!RPC_IS_ACTIVATED(task))
return;
if (!rpc_task_set_rpc_status(task, -ERESTARTSYS))
return;
trace_rpc_task_signalled(task, task->tk_action);
set_bit(RPC_TASK_SIGNALLED, &task->tk_runstate);
smp_mb__after_atomic();
queue = READ_ONCE(task->tk_waitqueue);
if (queue)
rpc_wake_up_queued_task(queue, task);
}
void rpc_task_try_cancel(struct rpc_task *task, int error)
{
struct rpc_wait_queue *queue;
if (!rpc_task_set_rpc_status(task, error))
return;
queue = READ_ONCE(task->tk_waitqueue);
if (queue)
rpc_wake_up_queued_task(queue, task);
}
void rpc_exit(struct rpc_task *task, int status)
{
task->tk_status = status;
task->tk_action = rpc_exit_task;
rpc_wake_up_queued_task(task->tk_waitqueue, task);
}
EXPORT_SYMBOL_GPL(rpc_exit);
void rpc_release_calldata(const struct rpc_call_ops *ops, void *calldata)
{
if (ops->rpc_release != NULL)
ops->rpc_release(calldata);
}
static bool xprt_needs_memalloc(struct rpc_xprt *xprt, struct rpc_task *tk)
{
if (!xprt)
return false;
if (!atomic_read(&xprt->swapper))
return false;
return test_bit(XPRT_LOCKED, &xprt->state) && xprt->snd_task == tk;
}
/*
* This is the RPC `scheduler' (or rather, the finite state machine).
*/
static void __rpc_execute(struct rpc_task *task)
{
struct rpc_wait_queue *queue;
int task_is_async = RPC_IS_ASYNC(task);
int status = 0;
unsigned long pflags = current->flags;
WARN_ON_ONCE(RPC_IS_QUEUED(task));
if (RPC_IS_QUEUED(task))
return;
for (;;) {
void (*do_action)(struct rpc_task *);
/*
* Perform the next FSM step or a pending callback.
*
* tk_action may be NULL if the task has been killed.
*/
do_action = task->tk_action;
/* Tasks with an RPC error status should exit */
if (do_action && do_action != rpc_exit_task &&
(status = READ_ONCE(task->tk_rpc_status)) != 0) {
task->tk_status = status;
do_action = rpc_exit_task;
}
/* Callbacks override all actions */
if (task->tk_callback) {
do_action = task->tk_callback;
task->tk_callback = NULL;
}
if (!do_action)
break;
if (RPC_IS_SWAPPER(task) ||
xprt_needs_memalloc(task->tk_xprt, task))
current->flags |= PF_MEMALLOC;
trace_rpc_task_run_action(task, do_action);
do_action(task);
/*
* Lockless check for whether task is sleeping or not.
*/
if (!RPC_IS_QUEUED(task)) {
cond_resched();
continue;
}
/*
* The queue->lock protects against races with
* rpc_make_runnable().
*
* Note that once we clear RPC_TASK_RUNNING on an asynchronous
* rpc_task, rpc_make_runnable() can assign it to a
* different workqueue. We therefore cannot assume that the
* rpc_task pointer may still be dereferenced.
*/
queue = task->tk_waitqueue;
spin_lock(&queue->lock);
if (!RPC_IS_QUEUED(task)) {
spin_unlock(&queue->lock);
continue;
}
/* Wake up any task that has an exit status */
if (READ_ONCE(task->tk_rpc_status) != 0) {
rpc_wake_up_task_queue_locked(queue, task);
spin_unlock(&queue->lock);
continue;
}
rpc_clear_running(task);
spin_unlock(&queue->lock);
if (task_is_async)
goto out;
/* sync task: sleep here */
trace_rpc_task_sync_sleep(task, task->tk_action);
status = out_of_line_wait_on_bit(&task->tk_runstate,
RPC_TASK_QUEUED, rpc_wait_bit_killable,
TASK_KILLABLE|TASK_FREEZABLE);
if (status < 0) {
/*
* When a sync task receives a signal, it exits with
* -ERESTARTSYS. In order to catch any callbacks that
* clean up after sleeping on some queue, we don't
* break the loop here, but go around once more.
*/
rpc_signal_task(task);
}
trace_rpc_task_sync_wake(task, task->tk_action);
}
/* Release all resources associated with the task */
rpc_release_task(task);
out:
current_restore_flags(pflags, PF_MEMALLOC);
}
/*
* User-visible entry point to the scheduler.
*
* This may be called recursively if e.g. an async NFS task updates
* the attributes and finds that dirty pages must be flushed.
* NOTE: Upon exit of this function the task is guaranteed to be
* released. In particular note that tk_release() will have
* been called, so your task memory may have been freed.
*/
void rpc_execute(struct rpc_task *task)
{
bool is_async = RPC_IS_ASYNC(task);
rpc_set_active(task);
rpc_make_runnable(rpciod_workqueue, task);
if (!is_async) {
unsigned int pflags = memalloc_nofs_save();
__rpc_execute(task);
memalloc_nofs_restore(pflags);
}
}
static void rpc_async_schedule(struct work_struct *work)
{
unsigned int pflags = memalloc_nofs_save();
__rpc_execute(container_of(work, struct rpc_task, u.tk_work));
memalloc_nofs_restore(pflags);
}
/**
* rpc_malloc - allocate RPC buffer resources
* @task: RPC task
*
* A single memory region is allocated, which is split between the
* RPC call and RPC reply that this task is being used for. When
* this RPC is retired, the memory is released by calling rpc_free.
*
* To prevent rpciod from hanging, this allocator never sleeps,
* returning -ENOMEM and suppressing warning if the request cannot
* be serviced immediately. The caller can arrange to sleep in a
* way that is safe for rpciod.
*
* Most requests are 'small' (under 2KiB) and can be serviced from a
* mempool, ensuring that NFS reads and writes can always proceed,
* and that there is good locality of reference for these buffers.
*/
int rpc_malloc(struct rpc_task *task)
{
struct rpc_rqst *rqst = task->tk_rqstp;
size_t size = rqst->rq_callsize + rqst->rq_rcvsize;
struct rpc_buffer *buf;
gfp_t gfp = rpc_task_gfp_mask();
size += sizeof(struct rpc_buffer);
if (size <= RPC_BUFFER_MAXSIZE) {
buf = kmem_cache_alloc(rpc_buffer_slabp, gfp);
/* Reach for the mempool if dynamic allocation fails */
if (!buf && RPC_IS_ASYNC(task))
buf = mempool_alloc(rpc_buffer_mempool, GFP_NOWAIT);
} else
buf = kmalloc(size, gfp);
if (!buf)
return -ENOMEM;
buf->len = size;
rqst->rq_buffer = buf->data;
rqst->rq_rbuffer = (char *)rqst->rq_buffer + rqst->rq_callsize;
return 0;
}
EXPORT_SYMBOL_GPL(rpc_malloc);
/**
* rpc_free - free RPC buffer resources allocated via rpc_malloc
* @task: RPC task
*
*/
void rpc_free(struct rpc_task *task)
{
void *buffer = task->tk_rqstp->rq_buffer;
size_t size;
struct rpc_buffer *buf;
buf = container_of(buffer, struct rpc_buffer, data);
size = buf->len;
if (size <= RPC_BUFFER_MAXSIZE)
mempool_free(buf, rpc_buffer_mempool);
else
kfree(buf);
}
EXPORT_SYMBOL_GPL(rpc_free);
/*
* Creation and deletion of RPC task structures
*/
static void rpc_init_task(struct rpc_task *task, const struct rpc_task_setup *task_setup_data)
{
memset(task, 0, sizeof(*task));
atomic_set(&task->tk_count, 1);
task->tk_flags = task_setup_data->flags;
task->tk_ops = task_setup_data->callback_ops;
task->tk_calldata = task_setup_data->callback_data;
INIT_LIST_HEAD(&task->tk_task);
task->tk_priority = task_setup_data->priority - RPC_PRIORITY_LOW;
task->tk_owner = current->tgid;
/* Initialize workqueue for async tasks */
task->tk_workqueue = task_setup_data->workqueue;
task->tk_xprt = rpc_task_get_xprt(task_setup_data->rpc_client,
xprt_get(task_setup_data->rpc_xprt));
task->tk_op_cred = get_rpccred(task_setup_data->rpc_op_cred);
if (task->tk_ops->rpc_call_prepare != NULL)
task->tk_action = rpc_prepare_task;
rpc_init_task_statistics(task);
}
static struct rpc_task *rpc_alloc_task(void)
{
struct rpc_task *task;
task = kmem_cache_alloc(rpc_task_slabp, rpc_task_gfp_mask());
if (task)
return task;
return mempool_alloc(rpc_task_mempool, GFP_NOWAIT);
}
/*
* Create a new task for the specified client.
*/
struct rpc_task *rpc_new_task(const struct rpc_task_setup *setup_data)
{
struct rpc_task *task = setup_data->task;
unsigned short flags = 0;
if (task == NULL) {
task = rpc_alloc_task();
if (task == NULL) {
rpc_release_calldata(setup_data->callback_ops,
setup_data->callback_data);
return ERR_PTR(-ENOMEM);
}
flags = RPC_TASK_DYNAMIC;
}
rpc_init_task(task, setup_data);
task->tk_flags |= flags;
return task;
}
/*
* rpc_free_task - release rpc task and perform cleanups
*
* Note that we free up the rpc_task _after_ rpc_release_calldata()
* in order to work around a workqueue dependency issue.
*
* Tejun Heo states:
* "Workqueue currently considers two work items to be the same if they're
* on the same address and won't execute them concurrently - ie. it
* makes a work item which is queued again while being executed wait
* for the previous execution to complete.
*
* If a work function frees the work item, and then waits for an event
* which should be performed by another work item and *that* work item
* recycles the freed work item, it can create a false dependency loop.
* There really is no reliable way to detect this short of verifying
* every memory free."
*
*/
static void rpc_free_task(struct rpc_task *task)
{
unsigned short tk_flags = task->tk_flags;
put_rpccred(task->tk_op_cred);
rpc_release_calldata(task->tk_ops, task->tk_calldata);
if (tk_flags & RPC_TASK_DYNAMIC)
mempool_free(task, rpc_task_mempool);
}
static void rpc_async_release(struct work_struct *work)
{
unsigned int pflags = memalloc_nofs_save();
rpc_free_task(container_of(work, struct rpc_task, u.tk_work));
memalloc_nofs_restore(pflags);
}
static void rpc_release_resources_task(struct rpc_task *task)
{
xprt_release(task);
if (task->tk_msg.rpc_cred) {
if (!(task->tk_flags & RPC_TASK_CRED_NOREF))
put_cred(task->tk_msg.rpc_cred);
task->tk_msg.rpc_cred = NULL;
}
rpc_task_release_client(task);
}
static void rpc_final_put_task(struct rpc_task *task,
struct workqueue_struct *q)
{
if (q != NULL) {
INIT_WORK(&task->u.tk_work, rpc_async_release);
queue_work(q, &task->u.tk_work);
} else
rpc_free_task(task);
}
static void rpc_do_put_task(struct rpc_task *task, struct workqueue_struct *q)
{
if (atomic_dec_and_test(&task->tk_count)) {
rpc_release_resources_task(task);
rpc_final_put_task(task, q);
}
}
void rpc_put_task(struct rpc_task *task)
{
rpc_do_put_task(task, NULL);
}
EXPORT_SYMBOL_GPL(rpc_put_task);
void rpc_put_task_async(struct rpc_task *task)
{
rpc_do_put_task(task, task->tk_workqueue);
}
EXPORT_SYMBOL_GPL(rpc_put_task_async);
static void rpc_release_task(struct rpc_task *task)
{
WARN_ON_ONCE(RPC_IS_QUEUED(task));
rpc_release_resources_task(task);
/*
* Note: at this point we have been removed from rpc_clnt->cl_tasks,
* so it should be safe to use task->tk_count as a test for whether
* or not any other processes still hold references to our rpc_task.
*/
if (atomic_read(&task->tk_count) != 1 + !RPC_IS_ASYNC(task)) {
/* Wake up anyone who may be waiting for task completion */
if (!rpc_complete_task(task))
return;
} else {
if (!atomic_dec_and_test(&task->tk_count))
return;
}
rpc_final_put_task(task, task->tk_workqueue);
}
int rpciod_up(void)
{
return try_module_get(THIS_MODULE) ? 0 : -EINVAL;
}
void rpciod_down(void)
{
module_put(THIS_MODULE);
}
/*
* Start up the rpciod workqueue.
*/
static int rpciod_start(void)
{
struct workqueue_struct *wq;
/*
* Create the rpciod thread and wait for it to start.
*/
wq = alloc_workqueue("rpciod", WQ_MEM_RECLAIM | WQ_UNBOUND, 0);
if (!wq)
goto out_failed;
rpciod_workqueue = wq;
wq = alloc_workqueue("xprtiod", WQ_UNBOUND | WQ_MEM_RECLAIM, 0);
if (!wq)
goto free_rpciod;
xprtiod_workqueue = wq;
return 1;
free_rpciod:
wq = rpciod_workqueue;
rpciod_workqueue = NULL;
destroy_workqueue(wq);
out_failed:
return 0;
}
static void rpciod_stop(void)
{
struct workqueue_struct *wq = NULL;
if (rpciod_workqueue == NULL)
return;
wq = rpciod_workqueue;
rpciod_workqueue = NULL;
destroy_workqueue(wq);
wq = xprtiod_workqueue;
xprtiod_workqueue = NULL;
destroy_workqueue(wq);
}
void
rpc_destroy_mempool(void)
{
rpciod_stop();
mempool_destroy(rpc_buffer_mempool);
mempool_destroy(rpc_task_mempool);
kmem_cache_destroy(rpc_task_slabp);
kmem_cache_destroy(rpc_buffer_slabp);
rpc_destroy_wait_queue(&delay_queue);
}
int
rpc_init_mempool(void)
{
/*
* The following is not strictly a mempool initialisation,
* but there is no harm in doing it here
*/
rpc_init_wait_queue(&delay_queue, "delayq");
if (!rpciod_start())
goto err_nomem;
rpc_task_slabp = kmem_cache_create("rpc_tasks",
sizeof(struct rpc_task),
0, SLAB_HWCACHE_ALIGN,
NULL);
if (!rpc_task_slabp)
goto err_nomem;
rpc_buffer_slabp = kmem_cache_create("rpc_buffers",
RPC_BUFFER_MAXSIZE,
0, SLAB_HWCACHE_ALIGN,
NULL);
if (!rpc_buffer_slabp)
goto err_nomem;
rpc_task_mempool = mempool_create_slab_pool(RPC_TASK_POOLSIZE,
rpc_task_slabp);
if (!rpc_task_mempool)
goto err_nomem;
rpc_buffer_mempool = mempool_create_slab_pool(RPC_BUFFER_POOLSIZE,
rpc_buffer_slabp);
if (!rpc_buffer_mempool)
goto err_nomem;
return 0;
err_nomem:
rpc_destroy_mempool();
return -ENOMEM;
}
Codebase Browser
linux