Viewing file:  sched.c (27.81 KB) -rw-r--r--
Select action/file-type:
 (+) |  (+) |  (+) | Code (+) | Session (+) |  (+) | SDB (+) |  (+) |  (+) |  (+) |  (+) |  (+) |
/*
* 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/slab.h>
#include <linux/unistd.h>
#include <linux/smp.h>
#include <linux/smp_lock.h>
#include <linux/spinlock.h>
#include <linux/sunrpc/clnt.h>
#include <linux/sunrpc/xprt.h>
#ifdef RPC_DEBUG
#define RPCDBG_FACILITY RPCDBG_SCHED
static int rpc_task_id;
#endif
/*
* We give RPC the same get_free_pages priority as NFS
*/
#define GFP_RPC GFP_NOFS
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;
/*
* 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;
static pid_t rpciod_pid;
static int rpc_inhibit;
/*
* Spinlock for wait queues. Access to the latter also has to be
* interrupt-safe in order to allow timers to wake up sleeping tasks.
*/
spinlock_t rpc_queue_lock = SPIN_LOCK_UNLOCKED;
/*
* Spinlock for other critical sections of code.
*/
static spinlock_t rpc_sched_lock = SPIN_LOCK_UNLOCKED;
/*
* This is the last-ditch buffer for NFS swap requests
*/
static u32 swap_buffer[PAGE_SIZE >> 2];
static long swap_buffer_used;
/*
* Make allocation of the swap_buffer SMP-safe
*/
static __inline__ int rpc_lock_swapbuf(void)
{
return !test_and_set_bit(1, &swap_buffer_used);
}
static __inline__ void rpc_unlock_swapbuf(void)
{
clear_bit(1, &swap_buffer_used);
}
/*
* Disable the timer for a given RPC task. Should be called with
* rpc_queue_lock and bh_disabled in order to avoid races within
* rpc_run_timer().
*/
static inline void
__rpc_disable_timer(struct rpc_task *task)
{
dprintk("RPC: %4d disabling timer\n", task->tk_pid);
task->tk_timeout_fn = NULL;
task->tk_timeout = 0;
}
/*
* Run a timeout function.
* We use the callback in order to allow __rpc_wake_up_task()
* and friends to disable the timer synchronously on SMP systems
* without calling del_timer_sync(). The latter could cause a
* deadlock if called while we're holding spinlocks...
*/
static void
rpc_run_timer(struct rpc_task *task)
{
void (*callback)(struct rpc_task *);
spin_lock_bh(&rpc_queue_lock);
callback = task->tk_timeout_fn;
task->tk_timeout_fn = NULL;
spin_unlock_bh(&rpc_queue_lock);
if (callback) {
dprintk("RPC: %4d running timer\n", task->tk_pid);
callback(task);
}
}
/*
* Set up a timer for the current task.
*/
static inline void
__rpc_add_timer(struct rpc_task *task, rpc_action timer)
{
if (!task->tk_timeout)
return;
dprintk("RPC: %4d setting alarm for %lu ms\n",
task->tk_pid, task->tk_timeout * 1000 / HZ);
if (timer)
task->tk_timeout_fn = timer;
else
task->tk_timeout_fn = __rpc_default_timer;
mod_timer(&task->tk_timer, jiffies + task->tk_timeout);
}
/*
* Set up a timer for an already sleeping task.
*/
void rpc_add_timer(struct rpc_task *task, rpc_action timer)
{
spin_lock_bh(&rpc_queue_lock);
if (!(RPC_IS_RUNNING(task) || task->tk_wakeup))
__rpc_add_timer(task, timer);
spin_unlock_bh(&rpc_queue_lock);
}
/*
* Delete any timer for the current task. Because we use del_timer_sync(),
* this function should never be called while holding rpc_queue_lock.
*/
static inline void
rpc_delete_timer(struct rpc_task *task)
{
if (timer_pending(&task->tk_timer)) {
dprintk("RPC: %4d deleting timer\n", task->tk_pid);
del_timer_sync(&task->tk_timer);
}
}
/*
* 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 inline int
__rpc_add_wait_queue(struct rpc_wait_queue *queue, struct rpc_task *task)
{
if (task->tk_rpcwait == queue)
return 0;
if (task->tk_rpcwait) {
printk(KERN_WARNING "RPC: doubly enqueued task!\n");
return -EWOULDBLOCK;
}
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;
}
int
rpc_add_wait_queue(struct rpc_wait_queue *q, struct rpc_task *task)
{
int result;
spin_lock_bh(&rpc_queue_lock);
result = __rpc_add_wait_queue(q, task);
spin_unlock_bh(&rpc_queue_lock);
return result;
}
/*
* Remove request from queue.
* Note: must be called with spin lock held.
*/
static inline void
__rpc_remove_wait_queue(struct rpc_task *task)
{
struct rpc_wait_queue *queue = task->tk_rpcwait;
if (!queue)
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));
}
void
rpc_remove_wait_queue(struct rpc_task *task)
{
if (!task->tk_rpcwait)
return;
spin_lock_bh(&rpc_queue_lock);
__rpc_remove_wait_queue(task);
spin_unlock_bh(&rpc_queue_lock);
}
/*
* Make an RPC task runnable.
*
* Note: If the task is ASYNC, this must be called with
* the spinlock held to protect the wait queue operation.
*/
static inline void
rpc_make_runnable(struct rpc_task *task)
{
if (task->tk_timeout_fn) {
printk(KERN_ERR "RPC: task w/ running timer in rpc_make_runnable!!\n");
return;
}
rpc_set_running(task);
if (RPC_IS_ASYNC(task)) {
if (RPC_IS_SLEEPING(task)) {
int status;
status = __rpc_add_wait_queue(&schedq, task);
if (status < 0) {
printk(KERN_WARNING "RPC: failed to add task to queue: error: %d!\n", status);
task->tk_status = status;
return;
}
rpc_clear_sleeping(task);
if (waitqueue_active(&rpciod_idle))
wake_up(&rpciod_idle);
}
} else {
rpc_clear_sleeping(task);
if (waitqueue_active(&task->tk_wait))
wake_up(&task->tk_wait);
}
}
/*
* Place a newly initialized task on the schedq.
*/
static inline void
rpc_schedule_run(struct rpc_task *task)
{
/* Don't run a child twice! */
if (RPC_IS_ACTIVATED(task))
return;
task->tk_active = 1;
rpc_set_sleeping(task);
rpc_make_runnable(task);
}
/*
* 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");
if (waitqueue_active(&rpciod_idle))
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)
{
int status;
dprintk("RPC: %4d sleep_on(queue \"%s\" time %ld)\n", task->tk_pid,
rpc_qname(q), jiffies);
if (!RPC_IS_ASYNC(task) && !RPC_IS_ACTIVATED(task)) {
printk(KERN_ERR "RPC: Inactive synchronous task put to sleep!\n");
return;
}
/* Mark the task as being activated if so needed */
if (!RPC_IS_ACTIVATED(task)) {
task->tk_active = 1;
rpc_set_sleeping(task);
}
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;
} else {
rpc_clear_running(task);
if (task->tk_callback) {
dprintk(KERN_ERR "RPC: %4d overwrites an active callback\n", task->tk_pid);
BUG();
}
task->tk_callback = action;
__rpc_add_timer(task, timer);
}
}
void
rpc_sleep_on(struct rpc_wait_queue *q, struct rpc_task *task,
rpc_action action, rpc_action timer)
{
/*
* Protect the queue operations.
*/
spin_lock_bh(&rpc_queue_lock);
__rpc_sleep_on(q, task, action, timer);
spin_unlock_bh(&rpc_queue_lock);
}
void
rpc_sleep_locked(struct rpc_wait_queue *q, struct rpc_task *task,
rpc_action action, rpc_action timer)
{
/*
* Protect the queue operations.
*/
spin_lock_bh(&rpc_queue_lock);
__rpc_sleep_on(q, task, action, timer);
__rpc_lock_task(task);
spin_unlock_bh(&rpc_queue_lock);
}
/**
* __rpc_wake_up_task - wake up a single rpc_task
* @task: task to be woken up
*
* If the task is locked, it is merely removed from the queue, and
* 'task->tk_wakeup' is set. rpc_unlock_task() will then ensure
* that it is woken up as soon as the lock count goes to zero.
*
* Caller must hold rpc_queue_lock
*/
static void
__rpc_wake_up_task(struct rpc_task *task)
{
dprintk("RPC: %4d __rpc_wake_up_task (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;
rpc_show_tasks();
return;
}
#endif
/* 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;
}
if (RPC_IS_RUNNING(task))
return;
__rpc_disable_timer(task);
if (task->tk_rpcwait != &schedq)
__rpc_remove_wait_queue(task);
/* If the task has been locked, then set tk_wakeup so that
* rpc_unlock_task() wakes us up... */
if (task->tk_lock) {
task->tk_wakeup = 1;
return;
} else
task->tk_wakeup = 0;
rpc_make_runnable(task);
dprintk("RPC: __rpc_wake_up_task 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;
rpc_wake_up_task(task);
}
/*
* Wake up the specified task
*/
void
rpc_wake_up_task(struct rpc_task *task)
{
if (RPC_IS_RUNNING(task))
return;
spin_lock_bh(&rpc_queue_lock);
__rpc_wake_up_task(task);
spin_unlock_bh(&rpc_queue_lock);
}
/*
* Wake up the next task on the wait queue.
*/
struct rpc_task *
rpc_wake_up_next(struct rpc_wait_queue *queue)
{
struct rpc_task *task;
dprintk("RPC: wake_up_next(%p \"%s\")\n", queue, rpc_qname(queue));
spin_lock_bh(&rpc_queue_lock);
if ((task = queue->task) != 0)
__rpc_wake_up_task(task);
spin_unlock_bh(&rpc_queue_lock);
return task;
}
/**
* rpc_wake_up - wake up all rpc_tasks
* @queue: rpc_wait_queue on which the tasks are sleeping
*
* Grabs rpc_queue_lock
*/
void
rpc_wake_up(struct rpc_wait_queue *queue)
{
spin_lock_bh(&rpc_queue_lock);
while (queue->task)
__rpc_wake_up_task(queue->task);
spin_unlock_bh(&rpc_queue_lock);
}
/**
* 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 rpc_queue_lock
*/
void
rpc_wake_up_status(struct rpc_wait_queue *queue, int status)
{
struct rpc_task *task;
spin_lock_bh(&rpc_queue_lock);
while ((task = queue->task) != NULL) {
task->tk_status = status;
__rpc_wake_up_task(task);
}
spin_unlock_bh(&rpc_queue_lock);
}
/*
* Lock down a sleeping task to prevent it from waking up
* and disappearing from beneath us.
*
* This function should always be called with the
* rpc_queue_lock held.
*/
int
__rpc_lock_task(struct rpc_task *task)
{
if (!RPC_IS_RUNNING(task))
return ++task->tk_lock;
return 0;
}
void
rpc_unlock_task(struct rpc_task *task)
{
spin_lock_bh(&rpc_queue_lock);
if (task->tk_lock && !--task->tk_lock && task->tk_wakeup)
__rpc_wake_up_task(task);
spin_unlock_bh(&rpc_queue_lock);
}
/*
* 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(task);
}
/*
* This is the RPC `scheduler' (or rather, the finite state machine).
*/
static int
__rpc_execute(struct rpc_task *task)
{
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;
}
restarted:
while (1) {
/*
* Execute any pending callback.
*/
if (RPC_DO_CALLBACK(task)) {
/* Define a callback save pointer */
void (*save_callback)(struct rpc_task *);
/*
* 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
*/
save_callback=task->tk_callback;
task->tk_callback=NULL;
save_callback(task);
}
/*
* Perform the next FSM step.
* tk_action may be NULL when the task has been killed
* by someone else.
*/
if (RPC_IS_RUNNING(task)) {
/*
* Garbage collection of pending timers...
*/
rpc_delete_timer(task);
if (!task->tk_action)
break;
task->tk_action(task);
}
/*
* Check whether task is sleeping.
*/
spin_lock_bh(&rpc_queue_lock);
if (!RPC_IS_RUNNING(task)) {
rpc_set_sleeping(task);
if (RPC_IS_ASYNC(task)) {
spin_unlock_bh(&rpc_queue_lock);
return 0;
}
}
spin_unlock_bh(&rpc_queue_lock);
while (RPC_IS_SLEEPING(task)) {
/* 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");
__wait_event(task->tk_wait, !RPC_IS_SLEEPING(task));
dprintk("RPC: %4d sync task resuming\n", task->tk_pid);
/*
* 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 (task->tk_client->cl_intr && signalled()) {
dprintk("RPC: %4d got signal\n", task->tk_pid);
task->tk_flags |= RPC_TASK_KILLED;
rpc_exit(task, -ERESTARTSYS);
rpc_wake_up_task(task);
}
}
}
if (task->tk_exit) {
task->tk_exit(task);
/* If tk_action is non-null, the user wants us to restart */
if (task->tk_action) {
if (!RPC_ASSASSINATED(task)) {
/* Release RPC slot and buffer memory */
if (task->tk_rqstp)
xprt_release(task);
if (task->tk_buffer) {
rpc_free(task->tk_buffer);
task->tk_buffer = NULL;
}
goto restarted;
}
printk(KERN_ERR "RPC: dead task tries to walk away.\n");
}
}
dprintk("RPC: %4d exit() = %d\n", task->tk_pid, task->tk_status);
status = task->tk_status;
/* Release all resources associated with the task */
rpc_release_task(task);
return status;
}
/*
* 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.
*/
int
rpc_execute(struct rpc_task *task)
{
int status = -EIO;
if (rpc_inhibit) {
printk(KERN_INFO "RPC: execution inhibited!\n");
goto out_release;
}
status = -EWOULDBLOCK;
if (task->tk_active) {
printk(KERN_ERR "RPC: active task was run twice!\n");
goto out_err;
}
task->tk_active = 1;
rpc_set_running(task);
return __rpc_execute(task);
out_release:
rpc_release_task(task);
out_err:
return status;
}
/*
* This is our own little scheduler for async RPC tasks.
*/
static void
__rpc_schedule(void)
{
struct rpc_task *task;
int count = 0;
dprintk("RPC: rpc_schedule enter\n");
while (1) {
/* Ensure equal rights for tcp tasks... */
rpciod_tcp_dispatcher();
spin_lock_bh(&rpc_queue_lock);
if (!(task = schedq.task)) {
spin_unlock_bh(&rpc_queue_lock);
break;
}
if (task->tk_lock) {
spin_unlock_bh(&rpc_queue_lock);
printk(KERN_ERR "RPC: Locked task was scheduled !!!!\n");
#ifdef RPC_DEBUG
rpc_debug = ~0;
rpc_show_tasks();
#endif
break;
}
__rpc_remove_wait_queue(task);
spin_unlock_bh(&rpc_queue_lock);
__rpc_execute(task);
if (++count >= 200 || current->need_resched) {
count = 0;
schedule();
}
}
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_NOFS)
* 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) && size <= sizeof(swap_buffer)
&& rpc_lock_swapbuf()) {
dprintk("RPC: used last-ditch swap buffer\n");
return swap_buffer;
}
if (flags & RPC_TASK_ASYNC)
return NULL;
current->policy |= SCHED_YIELD;
schedule();
} while (!signalled());
return NULL;
}
void
rpc_free(void *buffer)
{
if (buffer != swap_buffer) {
kfree(buffer);
return;
}
rpc_unlock_swapbuf();
}
/*
* 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));
init_timer(&task->tk_timer);
task->tk_timer.data = (unsigned long) task;
task->tk_timer.function = (void (*)(unsigned long)) rpc_run_timer;
task->tk_client = clnt;
task->tk_flags = 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 */
spin_lock(&rpc_sched_lock);
task->tk_next_task = all_tasks;
task->tk_prev_task = NULL;
if (all_tasks)
all_tasks->tk_prev_task = task;
all_tasks = task;
spin_unlock(&rpc_sched_lock);
if (clnt)
atomic_inc(&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);
}
static void
rpc_default_free_task(struct rpc_task *task)
{
dprintk("RPC: %4d freeing task\n", task->tk_pid);
rpc_free(task);
}
/*
* 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);
/* Replace tk_release */
task->tk_release = rpc_default_free_task;
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",
atomic_read(&clnt->cl_users), clnt->cl_oneshot);
atomic_inc(&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);
#ifdef RPC_DEBUG
if (task->tk_magic != 0xf00baa) {
printk(KERN_ERR "RPC: attempt to release a non-existing task!\n");
rpc_debug = ~0;
rpc_show_tasks();
return;
}
#endif
/* Remove from global task list */
spin_lock(&rpc_sched_lock);
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;
task->tk_next_task = task->tk_prev_task = NULL;
spin_unlock(&rpc_sched_lock);
/* Protect the execution below. */
spin_lock_bh(&rpc_queue_lock);
/* Disable timer to prevent zombie wakeup */
__rpc_disable_timer(task);
/* Remove from any wait queue we're still on */
__rpc_remove_wait_queue(task);
task->tk_active = 0;
spin_unlock_bh(&rpc_queue_lock);
/* Synchronously delete any running timer */
rpc_delete_timer(task);
/* Release resources */
if (task->tk_rqstp)
xprt_release(task);
if (task->tk_msg.rpc_cred)
rpcauth_unbindcred(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_release)
task->tk_release(task);
}
/**
* rpc_find_parent - find the parent of a child task.
* @child: child task
*
* Checks that the parent task is still sleeping on the
* queue 'childq'. If so returns a pointer to the parent.
* Upon failure returns NULL.
*
* Caller must hold rpc_queue_lock
*/
static inline struct rpc_task *
rpc_find_parent(struct rpc_task *child)
{
struct rpc_task *task, *parent;
parent = (struct rpc_task *) child->tk_calldata;
if ((task = childq.task) != NULL) {
do {
if (task == parent)
return parent;
} while ((task = task->tk_next) != childq.task);
}
return NULL;
}
static void
rpc_child_exit(struct rpc_task *child)
{
struct rpc_task *parent;
spin_lock_bh(&rpc_queue_lock);
if ((parent = rpc_find_parent(child)) != NULL) {
parent->tk_status = child->tk_status;
__rpc_wake_up_task(parent);
}
spin_unlock_bh(&rpc_queue_lock);
}
/*
* 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)
{
spin_lock_bh(&rpc_queue_lock);
/* N.B. Is it possible for the child to have already finished? */
__rpc_sleep_on(&childq, task, func, NULL);
rpc_schedule_run(child);
spin_unlock_bh(&rpc_queue_lock);
}
/*
* 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);
/*
* Spin lock all_tasks to prevent changes...
*/
spin_lock(&rpc_sched_lock);
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);
}
}
spin_unlock(&rpc_sched_lock);
}
static DECLARE_MUTEX_LOCKED(rpciod_running);
static inline int
rpciod_task_pending(void)
{
return schedq.task != NULL || xprt_tcp_pending();
}
/*
* This is the rpciod kernel thread
*/
static int
rpciod(void *ptr)
{
wait_queue_head_t *assassin = (wait_queue_head_t*) ptr;
int rounds = 0;
MOD_INC_USE_COUNT;
lock_kernel();
/*
* Let our maker know we're running ...
*/
rpciod_pid = current->pid;
up(&rpciod_running);
daemonize();
spin_lock_irq(¤t->sigmask_lock);
siginitsetinv(¤t->blocked, sigmask(SIGKILL));
recalc_sigpending(current);
spin_unlock_irq(¤t->sigmask_lock);
strcpy(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;
}
if (!rpciod_task_pending()) {
dprintk("RPC: rpciod back to sleep\n");
wait_event_interruptible(rpciod_idle, rpciod_task_pending());
dprintk("RPC: switch to rpciod\n");
rounds = 0;
}
}
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->policy |= SCHED_YIELD;
schedule();
}
}
spin_lock_irqsave(¤t->sigmask_lock, flags);
recalc_sigpending(current);
spin_unlock_irqrestore(¤t->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->policy |= SCHED_YIELD;
schedule();
/*
* 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(¤t->sigmask_lock, flags);
recalc_sigpending(current);
spin_unlock_irqrestore(¤t->sigmask_lock, flags);
out:
up(&rpciod_sema);
MOD_DEC_USE_COUNT;
}
#ifdef RPC_DEBUG
void rpc_show_tasks(void)
{
struct rpc_task *t = all_tasks, *next;
spin_lock(&rpc_sched_lock);
t = all_tasks;
if (!t) {
spin_unlock(&rpc_sched_lock);
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_msg.rpc_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);
}
spin_unlock(&rpc_sched_lock);
}
#endif
|