* better

[mascara-docs.git] / i386 / linux-2.3.21 / net / sunrpc / sched.c

/*
 * 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>

#define __KERNEL_SYSCALLS__
#include <linux/sched.h>
#include <linux/interrupt.h>
#include <linux/malloc.h>
#include <linux/unistd.h>
#include <linux/smp.h>
#include <linux/smp_lock.h>

#include <linux/sunrpc/clnt.h>

#ifdef RPC_DEBUG
#define RPCDBG_FACILITY         RPCDBG_SCHED
static int                      rpc_task_id = 0;
#endif

/*
 * We give RPC the same get_free_pages priority as NFS
 */
#define GFP_RPC                 GFP_NFS

static void                     __rpc_default_timer(struct rpc_task *task);
static void                     rpciod_killall(void);

/*
 * When an asynchronous RPC task is activated within a bottom half
 * handler, or while executing another RPC task, it is put on
 * schedq, and rpciod is woken up.
 */
static struct rpc_wait_queue    schedq = RPC_INIT_WAITQ("schedq");

/*
 * RPC tasks that create another task (e.g. for contacting the portmapper)
 * will wait on this queue for their child's completion
 */
static struct rpc_wait_queue    childq = RPC_INIT_WAITQ("childq");

/*
 * RPC tasks sit here while waiting for conditions to improve.
 */
static struct rpc_wait_queue    delay_queue = RPC_INIT_WAITQ("delayq");

/*
 * All RPC tasks are linked into this list
 */
static struct rpc_task *        all_tasks = NULL;

/*
 * rpciod-related stuff
 */
static DECLARE_WAIT_QUEUE_HEAD(rpciod_idle);
static DECLARE_WAIT_QUEUE_HEAD(rpciod_killer);
static DECLARE_MUTEX(rpciod_sema);
static unsigned int             rpciod_users = 0;
static pid_t                    rpciod_pid = 0;
static int                      rpc_inhibit = 0;

/*
 * This is the last-ditch buffer for NFS swap requests
 */
static u32                      swap_buffer[PAGE_SIZE >> 2];
static int                      swap_buffer_used = 0;

/*
 * 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.
 */
int
rpc_add_wait_queue(struct rpc_wait_queue *queue, struct rpc_task *task)
{
        if (task->tk_rpcwait) {
                if (task->tk_rpcwait != queue)
                {
                        printk(KERN_WARNING "RPC: doubly enqueued task!\n");
                        return -EWOULDBLOCK;
                }
                return 0;
        }
        if (RPC_IS_SWAPPER(task))
                rpc_insert_list(&queue->task, task);
        else
                rpc_append_list(&queue->task, task);
        task->tk_rpcwait = queue;

        dprintk("RPC: %4d added to queue %p \"%s\"\n",
                                task->tk_pid, queue, rpc_qname(queue));

        return 0;
}

/*
 * Remove request from queue.
 * Note: must be called with interrupts disabled.
 */
void
rpc_remove_wait_queue(struct rpc_task *task)
{
        struct rpc_wait_queue *queue;

        if (!(queue = task->tk_rpcwait))
                return;
        rpc_remove_list(&queue->task, task);
        task->tk_rpcwait = NULL;

        dprintk("RPC: %4d removed from queue %p \"%s\"\n",
                                task->tk_pid, queue, rpc_qname(queue));
}

/*
 * Set up a timer for the current task.
 */
inline void
rpc_add_timer(struct rpc_task *task, rpc_action timer)
{
        unsigned long   expires = jiffies + task->tk_timeout;

        dprintk("RPC: %4d setting alarm for %lu ms\n",
                        task->tk_pid, task->tk_timeout * 1000 / HZ);
        if (!timer)
                timer = __rpc_default_timer;
        if (time_before(expires, jiffies)) {
                printk(KERN_ERR "RPC: bad timeout value %ld - setting to 10 sec!\n",
                                        task->tk_timeout);
                expires = jiffies + 10 * HZ;
        }
        task->tk_timer.expires  = expires;
        task->tk_timer.data     = (unsigned long) task;
        task->tk_timer.function = (void (*)(unsigned long)) timer;
        task->tk_timer.prev     = NULL;
        task->tk_timer.next     = NULL;
        add_timer(&task->tk_timer);
}

/*
 * Delete any timer for the current task.
 * Must be called with interrupts off.
 */
inline void
rpc_del_timer(struct rpc_task *task)
{
        if (task->tk_timeout) {
                dprintk("RPC: %4d deleting timer\n", task->tk_pid);
                del_timer(&task->tk_timer);
                task->tk_timeout = 0;
        }
}

/*
 * Make an RPC task runnable.
 *
 * Note: If the task is ASYNC, this must be called with 
 * interrupts disabled to protect the wait queue operation.
 */
static inline void
rpc_make_runnable(struct rpc_task *task)
{
        if (task->tk_timeout) {
                printk(KERN_ERR "RPC: task w/ running timer in rpc_make_runnable!!\n");
                return;
        }
        task->tk_flags |= RPC_TASK_RUNNING;
        if (RPC_IS_ASYNC(task)) {
                int status;
                status = rpc_add_wait_queue(&schedq, task);
                if (status)
                {
                        printk(KERN_WARNING "RPC: failed to add task to queue: error: %d!\n", status);
                        task->tk_status = status;
                }
                wake_up(&rpciod_idle);
        } else {
                wake_up(&task->tk_wait);
        }
}


/*
 *      For other people who may need to wake the I/O daemon
 *      but should (for now) know nothing about its innards
 */
 
void rpciod_wake_up(void)
{
        if(rpciod_pid==0)
        {
                printk(KERN_ERR "rpciod: wot no daemon?\n");
        }
        wake_up(&rpciod_idle);
}

/*
 * 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(struct rpc_wait_queue *q, struct rpc_task *task,
                        rpc_action action, rpc_action timer)
{
        unsigned long   oldflags;
        int status;

        dprintk("RPC: %4d sleep_on(queue \"%s\" time %ld)\n", task->tk_pid,
                                rpc_qname(q), jiffies);

        /*
         * Protect the execution below.
         */
        save_flags(oldflags); cli();

        status = rpc_add_wait_queue(q, task);
        if (status)
        {
                printk(KERN_WARNING "RPC: failed to add task to queue: error: %d!\n", status);
                task->tk_status = status;
                task->tk_flags |= RPC_TASK_RUNNING;
        }
        else
        {
                task->tk_callback = action;
                if (task->tk_timeout)
                        rpc_add_timer(task, timer);
                task->tk_flags &= ~RPC_TASK_RUNNING;
        }

        restore_flags(oldflags);
        return;
}

void
rpc_sleep_on(struct rpc_wait_queue *q, struct rpc_task *task,
                                rpc_action action, rpc_action timer)
{
        __rpc_sleep_on(q, task, action, timer);
}

/*
 * Wake up a single task -- must be invoked with bottom halves off.
 *
 * It would probably suffice to cli/sti the del_timer and remove_wait_queue
 * operations individually.
 */
static void
__rpc_wake_up(struct rpc_task *task)
{
        dprintk("RPC: %4d __rpc_wake_up (now %ld inh %d)\n",
                                        task->tk_pid, jiffies, rpc_inhibit);

#ifdef RPC_DEBUG
        if (task->tk_magic != 0xf00baa) {
                printk(KERN_ERR "RPC: attempt to wake up non-existing task!\n");
                rpc_debug = ~0;
                return;
        }
#endif
        rpc_del_timer(task);
        if (task->tk_rpcwait != &schedq)
                rpc_remove_wait_queue(task);
        if (!RPC_IS_RUNNING(task)) {
                task->tk_flags |= RPC_TASK_CALLBACK;
                rpc_make_runnable(task);
        }
        dprintk("RPC:      __rpc_wake_up done\n");
}

/*
 * Default timeout handler if none specified by user
 */
static void
__rpc_default_timer(struct rpc_task *task)
{
        dprintk("RPC: %d timeout (default timer)\n", task->tk_pid);
        task->tk_status = -ETIMEDOUT;
        task->tk_timeout = 0;
        __rpc_wake_up(task);
}

/*
 * Wake up the specified task
 */
void
rpc_wake_up_task(struct rpc_task *task)
{
        unsigned long   oldflags;

        save_flags(oldflags); cli();
        __rpc_wake_up(task);
        restore_flags(oldflags);
}

/*
 * Wake up the next task on the wait queue.
 */
struct rpc_task *
rpc_wake_up_next(struct rpc_wait_queue *queue)
{
        unsigned long   oldflags;
        struct rpc_task *task;

        dprintk("RPC:      wake_up_next(%p \"%s\")\n", queue, rpc_qname(queue));
        save_flags(oldflags); cli();
        if ((task = queue->task) != 0)
                __rpc_wake_up(task);
        restore_flags(oldflags);

        return task;
}

/*
 * Wake up all tasks on a queue
 */
void
rpc_wake_up(struct rpc_wait_queue *queue)
{
        unsigned long   oldflags;

        save_flags(oldflags); cli();
        while (queue->task)
                __rpc_wake_up(queue->task);
        restore_flags(oldflags);
}

/*
 * Wake up all tasks on a queue, and set their status value.
 */
void
rpc_wake_up_status(struct rpc_wait_queue *queue, int status)
{
        struct rpc_task *task;
        unsigned long   oldflags;

        save_flags(oldflags); cli();
        while ((task = queue->task) != NULL) {
                task->tk_status = status;
                __rpc_wake_up(task);
        }
        restore_flags(oldflags);
}

/*
 * Run a task at a later time
 */
static void     __rpc_atrun(struct rpc_task *);
void
rpc_delay(struct rpc_task *task, unsigned long delay)
{
        task->tk_timeout = delay;
        rpc_sleep_on(&delay_queue, task, NULL, __rpc_atrun);
}

static void
__rpc_atrun(struct rpc_task *task)
{
        task->tk_status = 0;
        __rpc_wake_up(task);
}

/*
 * This is the RPC `scheduler' (or rather, the finite state machine).
 */
static int
__rpc_execute(struct rpc_task *task)
{
        unsigned long   oldflags;
        int             status = 0;

        dprintk("RPC: %4d rpc_execute flgs %x\n",
                                task->tk_pid, task->tk_flags);

        if (!RPC_IS_RUNNING(task)) {
                printk(KERN_WARNING "RPC: rpc_execute called for sleeping task!!\n");
                return 0;
        }

        while (1) {
                /*
                 * Execute any pending callback.
                 */
                if (task->tk_flags & RPC_TASK_CALLBACK) {
                        /* Define a callback save pointer */
                        void (*save_callback)(struct rpc_task *);
        
                        task->tk_flags &= ~RPC_TASK_CALLBACK;
                        /* 
                         * If a callback exists, save it, reset it,
                         * call it.
                         * The save is needed to stop from resetting
                         * another callback set within the callback handler
                         * - Dave
                         */
                        if (task->tk_callback) {
                                save_callback=task->tk_callback;
                                task->tk_callback=NULL;
                                save_callback(task);
                        }
                }

                /*
                 * No handler for next step means exit.
                 */
                if (!task->tk_action)
                        break;

                /*
                 * Perform the next FSM step.
                 * tk_action may be NULL when the task has been killed
                 * by someone else.
                 */
                if (RPC_IS_RUNNING(task) && task->tk_action)
                        task->tk_action(task);

                /*
                 * Check whether task is sleeping.
                 * Note that if the task may go to sleep in tk_action,
                 * and the RPC reply arrives before we get here, it will
                 * have state RUNNING, but will still be on schedq.
                 */
                save_flags(oldflags); cli();
                if (RPC_IS_RUNNING(task)) {
                        if (task->tk_rpcwait == &schedq)
                                rpc_remove_wait_queue(task);
                } else while (!RPC_IS_RUNNING(task)) {
                        if (RPC_IS_ASYNC(task)) {
                                restore_flags(oldflags);
                                return 0;
                        }

                        /* sync task: sleep here */
                        dprintk("RPC: %4d sync task going to sleep\n",
                                                        task->tk_pid);
                        if (current->pid == rpciod_pid)
                                printk(KERN_ERR "RPC: rpciod waiting on sync task!\n");

                        sti();
                        __wait_event(task->tk_wait, RPC_IS_RUNNING(task));
                        cli();

                        /*
                         * When the task received a signal, remove from
                         * any queues etc, and make runnable again.
                         */
                        if (signalled())
                                __rpc_wake_up(task);

                        dprintk("RPC: %4d sync task resuming\n",
                                                        task->tk_pid);
                }
                restore_flags(oldflags);

                /*
                 * 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.
                 */
                if (!RPC_IS_ASYNC(task) && signalled()) {
                        dprintk("RPC: %4d got signal\n", task->tk_pid);
                        rpc_exit(task, -ERESTARTSYS);
                }
        }

        dprintk("RPC: %4d exit() = %d\n", task->tk_pid, task->tk_status);
        if (task->tk_exit) {
                status = task->tk_status;
                task->tk_exit(task);
        }

        return status;
}

/*
 * User-visible entry point to the scheduler.
 * The recursion protection is for debugging. It should go away once
 * the code has stabilized.
 */
void
rpc_execute(struct rpc_task *task)
{
        static int      executing = 0;
        int             incr = RPC_IS_ASYNC(task)? 1 : 0;

        if (incr) {
                if (rpc_inhibit) {
                        printk(KERN_INFO "RPC: execution inhibited!\n");
                        return;
                }
                if (executing)
                        printk(KERN_WARNING "RPC: %d tasks executed\n", executing);
        }
        
        executing += incr;
        __rpc_execute(task);
        executing -= incr;
}

/*
 * This is our own little scheduler for async RPC tasks.
 */
static void
__rpc_schedule(void)
{
        struct rpc_task *task;
        int             count = 0;
        unsigned long   oldflags;
        int need_resched = current->need_resched;

        dprintk("RPC:      rpc_schedule enter\n");
        save_flags(oldflags);
        while (1) {
                cli();
                if (!(task = schedq.task))
                        break;
                rpc_del_timer(task);
                rpc_remove_wait_queue(task);
                task->tk_flags |= RPC_TASK_RUNNING;
                restore_flags(oldflags);

                __rpc_execute(task);

                if (++count >= 200) {
                        count = 0;
                        need_resched = 1;
                }
                if (need_resched)
                        schedule();
        }
        restore_flags(oldflags);
        dprintk("RPC:      rpc_schedule leave\n");
}

/*
 * Allocate memory for RPC purpose.
 *
 * This is yet another tricky issue: For sync requests issued by
 * a user process, we want to make kmalloc sleep if there isn't
 * enough memory. Async requests should not sleep too excessively
 * because that will block rpciod (but that's not dramatic when
 * it's starved of memory anyway). Finally, swapout requests should
 * never sleep at all, and should not trigger another swap_out
 * request through kmalloc which would just increase memory contention.
 *
 * I hope the following gets it right, which gives async requests
 * a slight advantage over sync requests (good for writeback, debatable
 * for readahead):
 *
 *   sync user requests:        GFP_KERNEL
 *   async requests:            GFP_RPC         (== GFP_NFS)
 *   swap requests:             GFP_ATOMIC      (or new GFP_SWAPPER)
 */
void *
rpc_allocate(unsigned int flags, unsigned int size)
{
        u32     *buffer;
        int     gfp;

        if (flags & RPC_TASK_SWAPPER)
                gfp = GFP_ATOMIC;
        else if (flags & RPC_TASK_ASYNC)
                gfp = GFP_RPC;
        else
                gfp = GFP_KERNEL;

        do {
                if ((buffer = (u32 *) kmalloc(size, gfp)) != NULL) {
                        dprintk("RPC:      allocated buffer %p\n", buffer);
                        return buffer;
                }
                if ((flags & RPC_TASK_SWAPPER) && !swap_buffer_used++) {
                        dprintk("RPC:      used last-ditch swap buffer\n");
                        return swap_buffer;
                }
                if (flags & RPC_TASK_ASYNC)
                        return NULL;
                current->state = TASK_INTERRUPTIBLE;
                schedule_timeout(HZ>>4);
        } while (!signalled());

        return NULL;
}

void
rpc_free(void *buffer)
{
        if (buffer != swap_buffer) {
                kfree(buffer);
                return;
        }
        swap_buffer_used = 0;
}

/*
 * Creation and deletion of RPC task structures
 */
inline void
rpc_init_task(struct rpc_task *task, struct rpc_clnt *clnt,
                                rpc_action callback, int flags)
{
        memset(task, 0, sizeof(*task));
        task->tk_client = clnt;
        task->tk_flags  = RPC_TASK_RUNNING | flags;
        task->tk_exit   = callback;
        init_waitqueue_head(&task->tk_wait);
        if (current->uid != current->fsuid || current->gid != current->fsgid)
                task->tk_flags |= RPC_TASK_SETUID;

        /* Initialize retry counters */
        task->tk_garb_retry = 2;
        task->tk_cred_retry = 2;
        task->tk_suid_retry = 1;

        /* Add to global list of all tasks */
        task->tk_next_task = all_tasks;
        task->tk_prev_task = NULL;
        if (all_tasks)
                all_tasks->tk_prev_task = task;
        all_tasks = task;

        if (clnt)
                clnt->cl_users++;

#ifdef RPC_DEBUG
        task->tk_magic = 0xf00baa;
        task->tk_pid = rpc_task_id++;
#endif
        dprintk("RPC: %4d new task procpid %d\n", task->tk_pid,
                                current->pid);
}

/*
 * Create a new task for the specified client.  We have to
 * clean up after an allocation failure, as the client may
 * have specified "oneshot".
 */
struct rpc_task *
rpc_new_task(struct rpc_clnt *clnt, rpc_action callback, int flags)
{
        struct rpc_task *task;

        task = (struct rpc_task *) rpc_allocate(flags, sizeof(*task));
        if (!task)
                goto cleanup;

        rpc_init_task(task, clnt, callback, flags);

        dprintk("RPC: %4d allocated task\n", task->tk_pid);
        task->tk_flags |= RPC_TASK_DYNAMIC;
out:
        return task;

cleanup:
        /* Check whether to release the client */
        if (clnt) {
                printk("rpc_new_task: failed, users=%d, oneshot=%d\n",
                        clnt->cl_users, clnt->cl_oneshot);
                clnt->cl_users++; /* pretend we were used ... */
                rpc_release_client(clnt);
        }
        goto out;
}

void
rpc_release_task(struct rpc_task *task)
{
        struct rpc_task *next, *prev;

        dprintk("RPC: %4d release task\n", task->tk_pid);

        /* Remove from global task list */
        prev = task->tk_prev_task;
        next = task->tk_next_task;
        if (next)
                next->tk_prev_task = prev;
        if (prev)
                prev->tk_next_task = next;
        else
                all_tasks = next;

        /* Release resources */
        if (task->tk_rqstp)
                xprt_release(task);
        if (task->tk_cred)
                rpcauth_releasecred(task);
        if (task->tk_buffer) {
                rpc_free(task->tk_buffer);
                task->tk_buffer = NULL;
        }
        if (task->tk_client) {
                rpc_release_client(task->tk_client);
                task->tk_client = NULL;
        }

#ifdef RPC_DEBUG
        task->tk_magic = 0;
#endif

        if (task->tk_flags & RPC_TASK_DYNAMIC) {
                dprintk("RPC: %4d freeing task\n", task->tk_pid);
                task->tk_flags &= ~RPC_TASK_DYNAMIC;
                rpc_free(task);
        }
}

/*
 * Handling of RPC child tasks
 * We can't simply call wake_up(parent) here, because the
 * parent task may already have gone away
 */
static inline struct rpc_task *
rpc_find_parent(struct rpc_task *child)
{
        struct rpc_task *temp, *parent;

        parent = (struct rpc_task *) child->tk_calldata;
        for (temp = childq.task; temp; temp = temp->tk_next) {
                if (temp == parent)
                        return parent;
        }
        return NULL;
}

static void
rpc_child_exit(struct rpc_task *child)
{
        struct rpc_task *parent;

        if ((parent = rpc_find_parent(child)) != NULL) {
                parent->tk_status = child->tk_status;
                rpc_wake_up_task(parent);
        }
        rpc_release_task(child);
}

/*
 * Note: rpc_new_task releases the client after a failure.
 */
struct rpc_task *
rpc_new_child(struct rpc_clnt *clnt, struct rpc_task *parent)
{
        struct rpc_task *task;

        task = rpc_new_task(clnt, NULL, RPC_TASK_ASYNC | RPC_TASK_CHILD);
        if (!task)
                goto fail;
        task->tk_exit = rpc_child_exit;
        task->tk_calldata = parent;
        return task;

fail:
        parent->tk_status = -ENOMEM;
        return NULL;
}

void
rpc_run_child(struct rpc_task *task, struct rpc_task *child, rpc_action func)
{
        unsigned long oldflags;

        save_flags(oldflags); cli();
        rpc_make_runnable(child);
        restore_flags(oldflags);
        /* N.B. Is it possible for the child to have already finished? */
        rpc_sleep_on(&childq, task, func, NULL);
}

/*
 * Kill all tasks for the given client.
 * XXX: kill their descendants as well?
 */
void
rpc_killall_tasks(struct rpc_clnt *clnt)
{
        struct rpc_task **q, *rovr;

        dprintk("RPC:      killing all tasks for client %p\n", clnt);
        /* N.B. Why bother to inhibit? Nothing blocks here ... */
        rpc_inhibit++;
        for (q = &all_tasks; (rovr = *q); q = &rovr->tk_next_task) {
                if (!clnt || rovr->tk_client == clnt) {
                        rovr->tk_flags |= RPC_TASK_KILLED;
                        rpc_exit(rovr, -EIO);
                        rpc_wake_up_task(rovr);
                }
        }
        rpc_inhibit--;
}

static DECLARE_MUTEX_LOCKED(rpciod_running);

/*
 * This is the rpciod kernel thread
 */
static int
rpciod(void *ptr)
{
        wait_queue_head_t *assassin = (wait_queue_head_t*) ptr;
        unsigned long   oldflags;
        int             rounds = 0;

        MOD_INC_USE_COUNT;
        lock_kernel();
        /*
         * Let our maker know we're running ...
         */
        rpciod_pid = current->pid;
        up(&rpciod_running);

        exit_files(current);
        exit_mm(current);

        spin_lock_irq(&current->sigmask_lock);
        siginitsetinv(&current->blocked, sigmask(SIGKILL));
        recalc_sigpending(current);
        spin_unlock_irq(&current->sigmask_lock);

        current->session = 1;
        current->pgrp = 1;
        sprintf(current->comm, "rpciod");

        dprintk("RPC: rpciod starting (pid %d)\n", rpciod_pid);
        while (rpciod_users) {
                if (signalled()) {
                        rpciod_killall();
                        flush_signals(current);
                }
                __rpc_schedule();

                if (++rounds >= 64) {   /* safeguard */
                        schedule();
                        rounds = 0;
                }
                save_flags(oldflags); cli();
                dprintk("RPC: rpciod running checking dispatch\n");
                rpciod_tcp_dispatcher();

                if (!schedq.task) {
                        dprintk("RPC: rpciod back to sleep\n");
                        interruptible_sleep_on(&rpciod_idle);
                        dprintk("RPC: switch to rpciod\n");
                        rpciod_tcp_dispatcher();
                        rounds = 0;
                }
                restore_flags(oldflags);
        }

        dprintk("RPC: rpciod shutdown commences\n");
        if (all_tasks) {
                printk(KERN_ERR "rpciod: active tasks at shutdown?!\n");
                rpciod_killall();
        }

        rpciod_pid = 0;
        wake_up(assassin);

        dprintk("RPC: rpciod exiting\n");
        MOD_DEC_USE_COUNT;
        return 0;
}

static void
rpciod_killall(void)
{
        unsigned long flags;

        while (all_tasks) {
                current->sigpending = 0;
                rpc_killall_tasks(NULL);
                __rpc_schedule();
                if (all_tasks) {
                        dprintk("rpciod_killall: waiting for tasks to exit\n");
                        current->state = TASK_INTERRUPTIBLE;
                        schedule_timeout(1);
                }
        }

        spin_lock_irqsave(&current->sigmask_lock, flags);
        recalc_sigpending(current);
        spin_unlock_irqrestore(&current->sigmask_lock, flags);
}

/*
 * Start up the rpciod process if it's not already running.
 */
int
rpciod_up(void)
{
        int error = 0;

        MOD_INC_USE_COUNT;
        down(&rpciod_sema);
        dprintk("rpciod_up: pid %d, users %d\n", rpciod_pid, rpciod_users);
        rpciod_users++;
        if (rpciod_pid)
                goto out;
        /*
         * If there's no pid, we should be the first user.
         */
        if (rpciod_users > 1)
                printk(KERN_WARNING "rpciod_up: no pid, %d users??\n", rpciod_users);
        /*
         * Create the rpciod thread and wait for it to start.
         */
        error = kernel_thread(rpciod, &rpciod_killer, 0);
        if (error < 0) {
                printk(KERN_WARNING "rpciod_up: create thread failed, error=%d\n", error);
                rpciod_users--;
                goto out;
        }
        down(&rpciod_running);
        error = 0;
out:
        up(&rpciod_sema);
        MOD_DEC_USE_COUNT;
        return error;
}

void
rpciod_down(void)
{
        unsigned long flags;

        MOD_INC_USE_COUNT;
        down(&rpciod_sema);
        dprintk("rpciod_down pid %d sema %d\n", rpciod_pid, rpciod_users);
        if (rpciod_users) {
                if (--rpciod_users)
                        goto out;
        } else
                printk(KERN_WARNING "rpciod_down: pid=%d, no users??\n", rpciod_pid);

        if (!rpciod_pid) {
                dprintk("rpciod_down: Nothing to do!\n");
                goto out;
        }

        kill_proc(rpciod_pid, SIGKILL, 1);
        /*
         * Usually rpciod will exit very quickly, so we
         * wait briefly before checking the process id.
         */
        current->sigpending = 0;
        current->state = TASK_INTERRUPTIBLE;
        schedule_timeout(1);
        /*
         * Display a message if we're going to wait longer.
         */
        while (rpciod_pid) {
                dprintk("rpciod_down: waiting for pid %d to exit\n", rpciod_pid);
                if (signalled()) {
                        dprintk("rpciod_down: caught signal\n");
                        break;
                }
                interruptible_sleep_on(&rpciod_killer);
        }
        spin_lock_irqsave(&current->sigmask_lock, flags);
        recalc_sigpending(current);
        spin_unlock_irqrestore(&current->sigmask_lock, flags);
out:
        up(&rpciod_sema);
        MOD_DEC_USE_COUNT;
}

#ifdef RPC_DEBUG
#include <linux/nfs_fs.h>
void rpc_show_tasks(void)
{
        struct rpc_task *t = all_tasks, *next;
        struct nfs_wreq *wreq;

        if (!t)
                return;
        printk("-pid- proc flgs status -client- -prog- --rqstp- -timeout "
                "-rpcwait -action- --exit--\n");
        for (; t; t = next) {
                next = t->tk_next_task;
                printk("%05d %04d %04x %06d %8p %6d %8p %08ld %8s %8p %8p\n",
                        t->tk_pid, t->tk_proc, t->tk_flags, t->tk_status,
                        t->tk_client, t->tk_client->cl_prog,
                        t->tk_rqstp, t->tk_timeout,
                        t->tk_rpcwait ? rpc_qname(t->tk_rpcwait) : " <NULL> ",
                        t->tk_action, t->tk_exit);

                if (!(t->tk_flags & RPC_TASK_NFSWRITE))
                        continue;
                /* NFS write requests */
                wreq = (struct nfs_wreq *) t->tk_calldata;
                printk("     NFS: flgs=%08x, pid=%d, pg=%p, off=(%d, %d)\n",
                        wreq->wb_flags, wreq->wb_pid, wreq->wb_page,
                        wreq->wb_offset, wreq->wb_bytes);
                printk("          name=%s/%s\n",
                        wreq->wb_file->f_dentry->d_parent->d_name.name,
                        wreq->wb_file->f_dentry->d_name.name);
        }
}
#endif