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author	Dave Jones <davej@redhat.com>	2006-08-11 18:02:27 -0400
committer	Dave Jones <davej@redhat.com>	2006-08-11 18:02:27 -0400
commit	e7745d4e0299a3460128917ceb6b6a807fa7f9e8 (patch)
tree	a2137ac22bfbe838faa00e49529f7cbfb9bf55dd /include/linux/workqueue.h
parent	804af2cf6e7af31d2e664b54e657dddd9b531dbd (diff)

[AGPGART] Const'ify the agpgart driver version.

Signed-off-by: Dave Jones <davej@redhat.com>

Diffstat (limited to 'include/linux/workqueue.h')

0 files changed, 0 insertions, 0 deletions

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/*
 * This file contains the procedures for the handling of select and poll
 *
 * Created for Linux based loosely upon Mathius Lattner's minix
 * patches by Peter MacDonald. Heavily edited by Linus.
 *
 *  4 February 1994
 *     COFF/ELF binary emulation. If the process has the STICKY_TIMEOUTS
 *     flag set in its personality we do *not* modify the given timeout
 *     parameter to reflect time remaining.
 *
 *  24 January 2000
 *     Changed sys_poll()/do_poll() to use PAGE_SIZE chunk-based allocation 
 *     of fds to overcome nfds < 16390 descriptors limit (Tigran Aivazian).
 */

#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/syscalls.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/poll.h>
#include <linux/personality.h> /* for STICKY_TIMEOUTS */
#include <linux/file.h>
#include <linux/fdtable.h>
#include <linux/fs.h>
#include <linux/rcupdate.h>
#include <linux/hrtimer.h>

#include <asm/uaccess.h>


/*
 * Estimate expected accuracy in ns from a timeval.
 *
 * After quite a bit of churning around, we've settled on
 * a simple thing of taking 0.1% of the timeout as the
 * slack, with a cap of 100 msec.
 * "nice" tasks get a 0.5% slack instead.
 *
 * Consider this comment an open invitation to come up with even
 * better solutions..
 */

#define MAX_SLACK	(100 * NSEC_PER_MSEC)

static long __estimate_accuracy(struct timespec *tv)
{
	long slack;
	int divfactor = 1000;

	if (tv->tv_sec < 0)
		return 0;

	if (task_nice(current) > 0)
		divfactor = divfactor / 5;

	if (tv->tv_sec > MAX_SLACK / (NSEC_PER_SEC/divfactor))
		return MAX_SLACK;

	slack = tv->tv_nsec / divfactor;
	slack += tv->tv_sec * (NSEC_PER_SEC/divfactor);

	if (slack > MAX_SLACK)
		return MAX_SLACK;

	return slack;
}

static long estimate_accuracy(struct timespec *tv)
{
	unsigned long ret;
	struct timespec now;

	/*
	 * Realtime tasks get a slack of 0 for obvious reasons.
	 */

	if (rt_task(current))
		return 0;

	ktime_get_ts(&now);
	now = timespec_sub(*tv, now);
	ret = __estimate_accuracy(&now);
	if (ret < current->timer_slack_ns)
		return current->timer_slack_ns;
	return ret;
}



struct poll_table_page {
	struct poll_table_page * next;
	struct poll_table_entry * entry;
	struct poll_table_entry entries[0];
};

#define POLL_TABLE_FULL(table) \
	((unsigned long)((table)->entry+1) > PAGE_SIZE + (unsigned long)(table))

/*
 * Ok, Peter made a complicated, but straightforward multiple_wait() function.
 * I have rewritten this, taking some shortcuts: This code may not be easy to
 * follow, but it should be free of race-conditions, and it's practical. If you
 * understand what I'm doing here, then you understand how the linux
 * sleep/wakeup mechanism works.
 *
 * Two very simple procedures, poll_wait() and poll_freewait() make all the
 * work.  poll_wait() is an inline-function defined in <linux/poll.h>,
 * as all select/poll functions have to call it to add an entry to the
 * poll table.
 */
static void __pollwait(struct file *filp, wait_queue_head_t *wait_address,
		       poll_table *p);

void poll_initwait(struct poll_wqueues *pwq)
{
	init_poll_funcptr(&pwq->pt, __pollwait);
	pwq->polling_task = current;
	pwq->triggered = 0;
	pwq->error = 0;
	pwq->table = NULL;
	pwq->inline_index = 0;
}
EXPORT_SYMBOL(poll_initwait);

static void free_poll_entry(struct poll_table_entry *entry)
{
	remove_wait_queue(entry->wait_address, &entry->wait);
	fput(entry->filp);
}

void poll_freewait(struct poll_wqueues *pwq)
{
	struct poll_table_page * p = pwq->table;
	int i;
	for (i = 0; i < pwq->inline_index; i++)
		free_poll_entry(pwq->inline_entries + i);
	while (p) {
		struct poll_table_entry * entry;
		struct poll_table_page *old;

		entry = p->entry;
		do {
			entry--;
			free_poll_entry(entry);
		} while (entry > p->entries);
		old = p;
		p = p->next;
		free_page((unsigned long) old);
	}
}
EXPORT_SYMBOL(poll_freewait);

static struct poll_table_entry *poll_get_entry(struct poll_wqueues *p)
{
	struct poll_table_page *table = p->table;

	if (p->inline_index < N_INLINE_POLL_ENTRIES)
		return p->inline_entries + p->inline_index++;

	if (!table || POLL_TABLE_FULL(table)) {
		struct poll_table_page *new_table;

		new_table = (struct poll_table_page *) __get_free_page(GFP_KERNEL);
		if (!new_table) {
			p->error = -ENOMEM;
			return NULL;
		}
		new_table->entry = new_table->entries;
		new_table->next = table;
		p->table = new_table;
		table = new_table;
	}

	return table->entry++;
}

static int __pollwake(wait_queue_t *wait, unsigned mode, int sync, void *key)
{
	struct poll_wqueues *pwq = wait->private;
	DECLARE_WAITQUEUE(dummy_wait, pwq->polling_task);

	/*
	 * Although this function is called under waitqueue lock, LOCK
	 * doesn't imply write barrier and the users expect write
	 * barrier semantics on wakeup functions.  The following
	 * smp_wmb() is equivalent to smp_wmb() in try_to_wake_up()
	 * and is paired with set_mb() in poll_schedule_timeout.
	 */
	smp_wmb();
	pwq->triggered = 1;

	/*
	 * Perform the default wake up operation using a dummy
	 * waitqueue.
	 *
	 * TODO: This is hacky but there currently is no interface to
	 * pass in @sync.  @sync is scheduled to be removed and once
	 * that happens, wake_up_process() can be used directly.
	 */
	return default_wake_function(&dummy_wait, mode, sync, key);
}

static int pollwake(wait_queue_t *wait, unsigned mode, int sync, void *key)
{
	struct poll_table_entry *entry;

	entry = container_of(wait, struct poll_table_entry, wait);
	if (key && !((unsigned long)key & entry->key))
		return 0;
	return __pollwake(wait, mode, sync, key);
}

/* Add a new entry */
static void __pollwait(struct file *filp, wait_queue_head_t *wait_address,
				poll_table *p)
{
	struct poll_wqueues *pwq = container_of(p, struct poll_wqueues, pt);
	struct poll_table_entry *entry = poll_get_entry(pwq);
	if (!entry)
		return;
	get_file(filp);
	entry->filp = filp;
	entry->wait_address = wait_address;
	entry->key = p->key;
	init_waitqueue_func_entry(&entry->wait, pollwake);
	entry->wait.private = pwq;
	add_wait_queue(wait_address, &entry->wait);
}

int poll_schedule_timeout(struct poll_wqueues *pwq, int state,
			  ktime_t *expires, unsigned long slack)
{
	int rc = -EINTR;

	set_current_state(state);
	if (!pwq->triggered)
		rc = schedule_hrtimeout_range(expires, slack, HRTIMER_MODE_ABS);
	__set_current_state(TASK_RUNNING);

	/*
	 * Prepare for the next iteration.
	 *
	 * The following set_mb() serves two purposes.  First, it's
	 * the counterpart rmb of the wmb in pollwake() such that data
	 * written before wake up is always visible after wake up.
	 * Second, the full barrier guarantees that triggered clearing
	 * doesn't pass event check of the next iteration.  Note that
	 * this problem doesn't exist for the first iteration as
	 * add_wait_queue() has full barrier semantics.
	 */
	set_mb(pwq->triggered, 0);

	return rc;
}
EXPORT_SYMBOL(poll_schedule_timeout);

/**
 * poll_select_set_timeout - helper function to setup the timeout value
 * @to:		pointer to timespec variable for the final timeout
 * @sec:	seconds (from user space)
 * @nsec:	nanoseconds (from user space)
 *
 * Note, we do not use a timespec for the user space value here, That
 * way we can use the function for timeval and compat interfaces as well.
 *
 * Returns -EINVAL if sec/nsec are not normalized. Otherwise 0.
 */
int poll_select_set_timeout(struct timespec *to, long sec, long nsec)
{
	struct timespec ts = {.tv_sec = sec, .tv_nsec = nsec};

	if (!timespec_valid(&ts))
		return -EINVAL;

	/* Optimize for the zero timeout value here */
	if (!sec && !nsec) {
		to->tv_sec = to->tv_nsec = 0;
	} else {
		ktime_get_ts(to);
		*to = timespec_add_safe(*to, ts);
	}
	return 0;
}

static int poll_select_copy_remaining(struct timespec *end_time, void __user *p,
				      int timeval, int ret)
{
	struct timespec rts;
	struct timeval rtv;

	if (!p)
		return ret;

	if (current->personality & STICKY_TIMEOUTS)
		goto sticky;


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