diff options
Diffstat (limited to 'net/sunrpc/sched.c')
| -rw-r--r-- | net/sunrpc/sched.c | 1141 |
1 files changed, 1141 insertions, 0 deletions
diff --git a/net/sunrpc/sched.c b/net/sunrpc/sched.c new file mode 100644 index 000000000..337ca851a --- /dev/null +++ b/net/sunrpc/sched.c @@ -0,0 +1,1141 @@ +/* + * 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(unsigned long ptr); + +/* + * 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; + +/* + * 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_rotate_queue_owner(struct rpc_wait_queue *queue) +{ + struct list_head *q = &queue->tasks[queue->priority]; + struct rpc_task *task; + + if (!list_empty(q)) { + task = list_first_entry(q, struct rpc_task, u.tk_wait.list); + if (task->tk_owner == queue->owner) + list_move_tail(&task->u.tk_wait.list, q); + } +} + +static void rpc_set_waitqueue_priority(struct rpc_wait_queue *queue, int priority) +{ + if (queue->priority != priority) { + /* Fairness: rotate the list when changing priority */ + rpc_rotate_queue_owner(queue); + queue->priority = priority; + } +} + +static void rpc_set_waitqueue_owner(struct rpc_wait_queue *queue, pid_t pid) +{ + queue->owner = pid; + queue->nr = RPC_BATCH_COUNT; +} + +static void rpc_reset_waitqueue_priority(struct rpc_wait_queue *queue) +{ + rpc_set_waitqueue_priority(queue, queue->maxpriority); + rpc_set_waitqueue_owner(queue, 0); +} + +/* + * 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) +{ + struct list_head *q; + struct rpc_task *t; + + INIT_LIST_HEAD(&task->u.tk_wait.links); + if (unlikely(queue_priority > queue->maxpriority)) + queue_priority = queue->maxpriority; + if (queue_priority > queue->priority) + rpc_set_waitqueue_priority(queue, queue_priority); + q = &queue->tasks[queue_priority]; + list_for_each_entry(t, q, u.tk_wait.list) { + if (t->tk_owner == task->tk_owner) { + list_add_tail(&task->u.tk_wait.list, &t->u.tk_wait.links); + return; + } + } + list_add_tail(&task->u.tk_wait.list, q); +} + +/* + * 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) +{ + struct rpc_task *t; + + if (!list_empty(&task->u.tk_wait.links)) { + t = list_entry(task->u.tk_wait.links.next, struct rpc_task, u.tk_wait.list); + list_move(&t->u.tk_wait.list, &task->u.tk_wait.list); + list_splice_init(&task->u.tk_wait.links, &t->u.tk_wait.links); + } +} + +/* + * 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); + 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; + setup_timer(&queue->timer_list.timer, __rpc_queue_timer_fn, (unsigned long)queue); + 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) +{ + if (fatal_signal_pending(current)) + return -ERESTARTSYS; + freezable_schedule_unsafe(); + 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) +{ + trace_rpc_task_begin(task->tk_client, task, NULL); + + rpc_task_set_debuginfo(task); + set_bit(RPC_TASK_ACTIVE, &task->tk_runstate); +} + +/* + * 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->tk_client, 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 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(rpciod_workqueue, &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->tk_client, 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 - wake up a single rpc_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(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->tk_client, task, queue); + + __rpc_remove_wait_queue(queue, task); + + rpc_make_runnable(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_queue_locked(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(queue, task); + } +} + +/* + * 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 a batch of tasks from a single owner. + */ + q = &queue->tasks[queue->priority]; + if (!list_empty(q)) { + task = list_entry(q->next, struct rpc_task, u.tk_wait.list); + if (queue->owner == task->tk_owner) { + if (--queue->nr) + goto out; + list_move_tail(&task->u.tk_wait.list, q); + } + /* + * Check if we need to switch queues. + */ + goto new_owner; + } + + /* + * 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_entry(q->next, 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])); +new_owner: + rpc_set_waitqueue_owner(queue, task->tk_owner); +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(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_queue_locked(queue, task); + else + task = NULL; + } + spin_unlock_bh(&queue->lock); + + return task; +} +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(unsigned long ptr) +{ + struct rpc_wait_queue *queue = (struct rpc_wait_queue *)ptr; + 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 *); + + /* + * Execute any pending callback first. + */ + do_action = task->tk_callback; + task->tk_callback = NULL; + if (do_action == NULL) { + /* + * Perform the next FSM step. + * 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 (do_action == NULL) + break; + } + trace_rpc_task_run_action(task->tk_client, task, task->tk_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(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 an RPC buffer + * @task: RPC task that will use this buffer + * @size: requested byte size + * + * To prevent rpciod from hanging, this allocator never sleeps, + * returning NULL 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. + */ +void *rpc_malloc(struct rpc_task *task, size_t size) +{ + struct rpc_buffer *buf; + gfp_t gfp = GFP_NOIO | __GFP_NOWARN; + + if (RPC_IS_SWAPPER(task)) + gfp = __GFP_MEMALLOC | GFP_NOWAIT | __GFP_NOWARN; + + 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 NULL; + + buf->len = size; + dprintk("RPC: %5u allocated buffer of size %zu at %p\n", + task->tk_pid, size, buf); + return &buf->data; +} +EXPORT_SYMBOL_GPL(rpc_malloc); + +/** + * rpc_free - free buffer allocated via rpc_malloc + * @buffer: buffer to free + * + */ +void rpc_free(void *buffer) +{ + size_t size; + struct rpc_buffer *buf; + + if (!buffer) + return; + + 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; + + 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(); + 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; + 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"); + /* Note: highpri because network receive is latency sensitive */ + wq = alloc_workqueue("rpciod", WQ_MEM_RECLAIM | WQ_HIGHPRI, 0); + rpciod_workqueue = wq; + return rpciod_workqueue != NULL; +} + +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); +} + +void +rpc_destroy_mempool(void) +{ + rpciod_stop(); + if (rpc_buffer_mempool) + mempool_destroy(rpc_buffer_mempool); + if (rpc_task_mempool) + mempool_destroy(rpc_task_mempool); + if (rpc_task_slabp) + kmem_cache_destroy(rpc_task_slabp); + if (rpc_buffer_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; +} |