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-rw-r--r--net/sunrpc/sched.c1198
1 files changed, 1198 insertions, 0 deletions
diff --git a/net/sunrpc/sched.c b/net/sunrpc/sched.c
new file mode 100644
index 000000000..e36ae4d4b
--- /dev/null
+++ b/net/sunrpc/sched.c
@@ -0,0 +1,1198 @@
+/*
+ * linux/net/sunrpc/sched.c
+ *
+ * Scheduling for synchronous and asynchronous RPC requests.
+ *
+ * Copyright (C) 1996 Olaf Kirch, <okir@monad.swb.de>
+ *
+ * TCP NFS related read + write fixes
+ * (C) 1999 Dave Airlie, University of Limerick, Ireland <airlied@linux.ie>
+ */
+
+#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/sunrpc/clnt.h>
+
+#include "sunrpc.h"
+
+#if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
+#define RPCDBG_FACILITY RPCDBG_SCHED
+#endif
+
+#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 timer_list *t);
+
+/*
+ * 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;
+
+/*
+ * 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 (task->tk_timeout == 0)
+ return;
+ dprintk("RPC: %5u disabling timer\n", task->tk_pid);
+ task->tk_timeout = 0;
+ list_del(&task->u.tk_wait.timer_list);
+ if (list_empty(&queue->timer_list.list))
+ del_timer(&queue->timer_list.timer);
+}
+
+static void
+rpc_set_queue_timer(struct rpc_wait_queue *queue, unsigned long expires)
+{
+ queue->timer_list.expires = expires;
+ mod_timer(&queue->timer_list.timer, expires);
+}
+
+/*
+ * Set up a timer for the current task.
+ */
+static void
+__rpc_add_timer(struct rpc_wait_queue *queue, struct rpc_task *task)
+{
+ if (!task->tk_timeout)
+ return;
+
+ dprintk("RPC: %5u setting alarm for %u ms\n",
+ task->tk_pid, jiffies_to_msecs(task->tk_timeout));
+
+ task->u.tk_wait.expires = jiffies + task->tk_timeout;
+ if (list_empty(&queue->timer_list.list) || time_before(task->u.tk_wait.expires, queue->timer_list.expires))
+ rpc_set_queue_timer(queue, task->u.tk_wait.expires);
+ 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.
+ *
+ * Swapper tasks always get inserted at the head of the queue.
+ * This should avoid many nasty memory deadlocks and hopefully
+ * improve overall performance.
+ * Everyone else gets appended to the queue to ensure proper FIFO behavior.
+ */
+static void __rpc_add_wait_queue(struct rpc_wait_queue *queue,
+ struct rpc_task *task,
+ unsigned char queue_priority)
+{
+ WARN_ON_ONCE(RPC_IS_QUEUED(task));
+ if (RPC_IS_QUEUED(task))
+ return;
+
+ if (RPC_IS_PRIORITY(queue))
+ __rpc_add_wait_queue_priority(queue, task, queue_priority);
+ else if (RPC_IS_SWAPPER(task))
+ list_add(&task->u.tk_wait.list, &queue->tasks[0]);
+ 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);
+
+ dprintk("RPC: %5u added to queue %p \"%s\"\n",
+ task->tk_pid, queue, rpc_qname(queue));
+}
+
+/*
+ * 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--;
+ dprintk("RPC: %5u removed from queue %p \"%s\"\n",
+ task->tk_pid, queue, rpc_qname(queue));
+}
+
+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;
+ timer_setup(&queue->timer_list.timer, __rpc_queue_timer_fn, 0);
+ 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)
+{
+ del_timer_sync(&queue->timer_list.timer);
+}
+EXPORT_SYMBOL_GPL(rpc_destroy_wait_queue);
+
+static int rpc_wait_bit_killable(struct wait_bit_key *key, int mode)
+{
+ freezable_schedule_unsafe();
+ 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)
+{
+ static atomic_t rpc_pid;
+
+ task->tk_pid = atomic_inc_return(&rpc_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, wait_bit_action_f *action)
+{
+ if (action == NULL)
+ action = rpc_wait_bit_killable;
+ return out_of_line_wait_on_bit(&task->tk_runstate, RPC_TASK_ACTIVE,
+ action, TASK_KILLABLE);
+}
+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
+ 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_sleep_on_priority(struct rpc_wait_queue *q,
+ struct rpc_task *task,
+ rpc_action action,
+ unsigned char queue_priority)
+{
+ dprintk("RPC: %5u sleep_on(queue \"%s\" time %lu)\n",
+ task->tk_pid, rpc_qname(q), jiffies);
+
+ trace_rpc_task_sleep(task, q);
+
+ __rpc_add_wait_queue(q, task, queue_priority);
+
+ WARN_ON_ONCE(task->tk_callback != NULL);
+ task->tk_callback = action;
+ __rpc_add_timer(q, task);
+}
+
+void rpc_sleep_on(struct rpc_wait_queue *q, struct rpc_task *task,
+ rpc_action action)
+{
+ /* We shouldn't ever put an inactive task to sleep */
+ WARN_ON_ONCE(!RPC_IS_ACTIVATED(task));
+ if (!RPC_IS_ACTIVATED(task)) {
+ task->tk_status = -EIO;
+ rpc_put_task_async(task);
+ return;
+ }
+
+ /*
+ * Protect the queue operations.
+ */
+ spin_lock_bh(&q->lock);
+ __rpc_sleep_on_priority(q, task, action, task->tk_priority);
+ spin_unlock_bh(&q->lock);
+}
+EXPORT_SYMBOL_GPL(rpc_sleep_on);
+
+void rpc_sleep_on_priority(struct rpc_wait_queue *q, struct rpc_task *task,
+ rpc_action action, int priority)
+{
+ /* We shouldn't ever put an inactive task to sleep */
+ WARN_ON_ONCE(!RPC_IS_ACTIVATED(task));
+ if (!RPC_IS_ACTIVATED(task)) {
+ task->tk_status = -EIO;
+ rpc_put_task_async(task);
+ return;
+ }
+
+ /*
+ * Protect the queue operations.
+ */
+ spin_lock_bh(&q->lock);
+ __rpc_sleep_on_priority(q, task, action, priority - RPC_PRIORITY_LOW);
+ spin_unlock_bh(&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)
+{
+ dprintk("RPC: %5u __rpc_wake_up_task (now %lu)\n",
+ task->tk_pid, jiffies);
+
+ /* 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);
+
+ dprintk("RPC: __rpc_wake_up_task done\n");
+}
+
+/*
+ * Wake up a queued task while the queue lock is being held
+ */
+static void rpc_wake_up_task_on_wq_queue_locked(struct workqueue_struct *wq,
+ struct rpc_wait_queue *queue, struct rpc_task *task)
+{
+ if (RPC_IS_QUEUED(task)) {
+ smp_rmb();
+ if (task->tk_waitqueue == queue)
+ __rpc_do_wake_up_task_on_wq(wq, queue, task);
+ }
+}
+
+/*
+ * 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_locked(rpciod_workqueue, queue, task);
+}
+
+/*
+ * Wake up a task on a specific queue
+ */
+void rpc_wake_up_queued_task_on_wq(struct workqueue_struct *wq,
+ struct rpc_wait_queue *queue,
+ struct rpc_task *task)
+{
+ spin_lock_bh(&queue->lock);
+ rpc_wake_up_task_on_wq_queue_locked(wq, queue, task);
+ spin_unlock_bh(&queue->lock);
+}
+
+/*
+ * Wake up a task on a specific queue
+ */
+void rpc_wake_up_queued_task(struct rpc_wait_queue *queue, struct rpc_task *task)
+{
+ spin_lock_bh(&queue->lock);
+ rpc_wake_up_task_queue_locked(queue, task);
+ spin_unlock_bh(&queue->lock);
+}
+EXPORT_SYMBOL_GPL(rpc_wake_up_queued_task);
+
+/*
+ * 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;
+
+ dprintk("RPC: wake_up_first(%p \"%s\")\n",
+ queue, rpc_qname(queue));
+ spin_lock_bh(&queue->lock);
+ task = __rpc_find_next_queued(queue);
+ if (task != NULL) {
+ if (func(task, data))
+ rpc_wake_up_task_on_wq_queue_locked(wq, queue, task);
+ else
+ task = NULL;
+ }
+ spin_unlock_bh(&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 - 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)
+{
+ struct list_head *head;
+
+ spin_lock_bh(&queue->lock);
+ head = &queue->tasks[queue->maxpriority];
+ for (;;) {
+ while (!list_empty(head)) {
+ struct rpc_task *task;
+ task = list_first_entry(head,
+ struct rpc_task,
+ u.tk_wait.list);
+ rpc_wake_up_task_queue_locked(queue, task);
+ }
+ if (head == &queue->tasks[0])
+ break;
+ head--;
+ }
+ spin_unlock_bh(&queue->lock);
+}
+EXPORT_SYMBOL_GPL(rpc_wake_up);
+
+/**
+ * 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)
+{
+ struct list_head *head;
+
+ spin_lock_bh(&queue->lock);
+ head = &queue->tasks[queue->maxpriority];
+ for (;;) {
+ while (!list_empty(head)) {
+ struct rpc_task *task;
+ task = list_first_entry(head,
+ struct rpc_task,
+ u.tk_wait.list);
+ task->tk_status = status;
+ rpc_wake_up_task_queue_locked(queue, task);
+ }
+ if (head == &queue->tasks[0])
+ break;
+ head--;
+ }
+ spin_unlock_bh(&queue->lock);
+}
+EXPORT_SYMBOL_GPL(rpc_wake_up_status);
+
+static void __rpc_queue_timer_fn(struct timer_list *t)
+{
+ struct rpc_wait_queue *queue = from_timer(queue, t, timer_list.timer);
+ 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->u.tk_wait.expires;
+ if (time_after_eq(now, timeo)) {
+ dprintk("RPC: %5u timeout\n", task->tk_pid);
+ 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)
+{
+ task->tk_timeout = delay;
+ rpc_sleep_on(&delay_queue, task, __rpc_atrun);
+}
+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;
+ task->tk_rebind_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_KILLED|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)
+{
+ task->tk_action = NULL;
+ if (task->tk_ops->rpc_call_done != NULL) {
+ task->tk_ops->rpc_call_done(task, task->tk_calldata);
+ if (task->tk_action != NULL) {
+ WARN_ON(RPC_ASSASSINATED(task));
+ /* Always release the RPC slot and buffer memory */
+ xprt_release(task);
+ rpc_reset_task_statistics(task);
+ }
+ }
+}
+
+void rpc_exit(struct rpc_task *task, int status)
+{
+ task->tk_status = status;
+ task->tk_action = rpc_exit_task;
+ if (RPC_IS_QUEUED(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);
+}
+
+/*
+ * 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;
+
+ dprintk("RPC: %5u __rpc_execute flags=0x%x\n",
+ task->tk_pid, task->tk_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.
+ * In particular, note that rpc_killall_tasks may
+ * do this at any time, so beware when dereferencing.
+ */
+ do_action = task->tk_action;
+ if (task->tk_callback) {
+ do_action = task->tk_callback;
+ task->tk_callback = NULL;
+ }
+ if (!do_action)
+ break;
+ 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))
+ 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_bh(&queue->lock);
+ if (!RPC_IS_QUEUED(task)) {
+ spin_unlock_bh(&queue->lock);
+ continue;
+ }
+ rpc_clear_running(task);
+ spin_unlock_bh(&queue->lock);
+ if (task_is_async)
+ return;
+
+ /* sync task: sleep here */
+ dprintk("RPC: %5u sync task going to sleep\n", task->tk_pid);
+ status = out_of_line_wait_on_bit(&task->tk_runstate,
+ RPC_TASK_QUEUED, rpc_wait_bit_killable,
+ TASK_KILLABLE);
+ if (status == -ERESTARTSYS) {
+ /*
+ * 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.
+ */
+ dprintk("RPC: %5u got signal\n", task->tk_pid);
+ task->tk_flags |= RPC_TASK_KILLED;
+ rpc_exit(task, -ERESTARTSYS);
+ }
+ dprintk("RPC: %5u sync task resuming\n", task->tk_pid);
+ }
+
+ dprintk("RPC: %5u return %d, status %d\n", task->tk_pid, status,
+ task->tk_status);
+ /* Release all resources associated with the task */
+ rpc_release_task(task);
+}
+
+/*
+ * 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)
+ __rpc_execute(task);
+}
+
+static void rpc_async_schedule(struct work_struct *work)
+{
+ __rpc_execute(container_of(work, struct rpc_task, u.tk_work));
+}
+
+/**
+ * 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.
+ *
+ * In order to avoid memory starvation triggering more writebacks of
+ * NFS requests, we avoid using GFP_KERNEL.
+ */
+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 = GFP_NOIO | __GFP_NOWARN;
+
+ if (RPC_IS_ASYNC(task))
+ gfp = GFP_NOWAIT | __GFP_NOWARN;
+ if (RPC_IS_SWAPPER(task))
+ gfp |= __GFP_MEMALLOC;
+
+ size += sizeof(struct rpc_buffer);
+ if (size <= RPC_BUFFER_MAXSIZE)
+ buf = mempool_alloc(rpc_buffer_mempool, gfp);
+ else
+ buf = kmalloc(size, gfp);
+
+ if (!buf)
+ return -ENOMEM;
+
+ buf->len = size;
+ dprintk("RPC: %5u allocated buffer of size %zu at %p\n",
+ task->tk_pid, size, buf);
+ 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;
+
+ dprintk("RPC: freeing buffer of size %zu at %p\n",
+ size, buf);
+
+ 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 = xprt_get(task_setup_data->rpc_xprt);
+
+ if (task->tk_ops->rpc_call_prepare != NULL)
+ task->tk_action = rpc_prepare_task;
+
+ rpc_init_task_statistics(task);
+
+ dprintk("RPC: new task initialized, procpid %u\n",
+ task_pid_nr(current));
+}
+
+static struct rpc_task *
+rpc_alloc_task(void)
+{
+ return (struct rpc_task *)mempool_alloc(rpc_task_mempool, GFP_NOIO);
+}
+
+/*
+ * 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();
+ flags = RPC_TASK_DYNAMIC;
+ }
+
+ rpc_init_task(task, setup_data);
+ task->tk_flags |= flags;
+ dprintk("RPC: allocated task %p\n", task);
+ 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;
+
+ rpc_release_calldata(task->tk_ops, task->tk_calldata);
+
+ if (tk_flags & RPC_TASK_DYNAMIC) {
+ dprintk("RPC: %5u freeing task\n", task->tk_pid);
+ mempool_free(task, rpc_task_mempool);
+ }
+}
+
+static void rpc_async_release(struct work_struct *work)
+{
+ rpc_free_task(container_of(work, struct rpc_task, u.tk_work));
+}
+
+static void rpc_release_resources_task(struct rpc_task *task)
+{
+ xprt_release(task);
+ if (task->tk_msg.rpc_cred) {
+ put_rpccred(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)
+{
+ dprintk("RPC: %5u release task\n", task->tk_pid);
+
+ 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.
+ */
+ dprintk("RPC: creating workqueue rpciod\n");
+ wq = alloc_workqueue("rpciod", WQ_MEM_RECLAIM | WQ_UNBOUND, 0);
+ if (!wq)
+ goto out_failed;
+ rpciod_workqueue = wq;
+ /* Note: highpri because network receive is latency sensitive */
+ wq = alloc_workqueue("xprtiod", WQ_UNBOUND|WQ_MEM_RECLAIM|WQ_HIGHPRI, 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;
+ dprintk("RPC: destroying workqueue rpciod\n");
+
+ 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;
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-27 02:36:30 +0000