/*
* 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/sunrpc/clnt.h>
#include "sunrpc.h"
#ifdef RPC_DEBUG
#define RPCDBG_FACILITY RPCDBG_SCHED
#endif
/*
* 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 %lu ms\n",
task->tk_pid, task->tk_timeout * 1000 / HZ);
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);
}
/*
* Add new request to a priority queue.
*/
static void __rpc_add_wait_queue_priority(struct rpc_wait_queue *queue, struct rpc_task *task)
{
struct list_head *q;
struct rpc_task *t;
INIT_LIST_HEAD(&task->u.tk_wait.links);
q = &queue->tasks[task->tk_priority];
if (unlikely(task->tk_priority > queue->maxpriority))
q = &queue->tasks[queue->maxpriority];
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)
{
BUG_ON (RPC_IS_QUEUED(task));
if (RPC_IS_PRIORITY(queue))
__rpc_add_wait_queue_priority(queue, task);
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++;
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