/* * linux/net/sunrpc/sched.c * * Scheduling for synchronous and asynchronous RPC requests. * * Copyright (C) 1996 Olaf Kirch, * * TCP NFS related read + write fixes * (C) 1999 Dave Airlie, University of Limerick, Ireland */ #include #include #include #include #include #include #include #include #include #include #include "sunrpc.h" #if IS_ENABLED(CONFIG_SUNRPC_DEBUG) #define RPCDBG_FACILITY RPCDBG_SCHED #endif #define CREATE_TRACE_POINTS #include /* * 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 __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_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, 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) { 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 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->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_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->tk_client, 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(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_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(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(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_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 -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; return 0; } 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; 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(); 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"); wq = alloc_workqueue("rpciod", WQ_MEM_RECLAIM, 0); if (!wq) goto out_failed; rpciod_workqueue = wq; /* Note: highpri because network receive is latency sensitive */ wq = alloc_workqueue("xprtiod", 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; }