[net-next-2.6.git] / fs / select.c

/*
 * 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/syscalls.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/smp_lock.h>
#include <linux/poll.h>
#include <linux/personality.h> /* for STICKY_TIMEOUTS */
#include <linux/file.h>
#include <linux/fs.h>
#include <linux/rcupdate.h>

#include <asm/uaccess.h>

#define ROUND_UP(x,y) (((x)+(y)-1)/(y))
#define DEFAULT_POLLMASK (POLLIN | POLLOUT | POLLRDNORM | POLLWRNORM)

struct poll_table_entry {
	struct file * filp;
	wait_queue_t wait;
	wait_queue_head_t * wait_address;
};

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->error = 0;
	pwq->table = NULL;
}

EXPORT_SYMBOL(poll_initwait);

void poll_freewait(struct poll_wqueues *pwq)
{
	struct poll_table_page * p = pwq->table;
	while (p) {
		struct poll_table_entry * entry;
		struct poll_table_page *old;

		entry = p->entry;
		do {
			entry--;
			remove_wait_queue(entry->wait_address,&entry->wait);
			fput(entry->filp);
		} while (entry > p->entries);
		old = p;
		p = p->next;
		free_page((unsigned long) old);
	}
}

EXPORT_SYMBOL(poll_freewait);

static void __pollwait(struct file *filp, wait_queue_head_t *wait_address,
		       poll_table *_p)
{
	struct poll_wqueues *p = container_of(_p, struct poll_wqueues, pt);
	struct poll_table_page *table = p->table;

	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;
			__set_current_state(TASK_RUNNING);
			return;
		}
		new_table->entry = new_table->entries;
		new_table->next = table;
		p->table = new_table;
		table = new_table;
	}

	/* Add a new entry */
	{
		struct poll_table_entry * entry = table->entry;
		table->entry = entry+1;
	 	get_file(filp);
	 	entry->filp = filp;
		entry->wait_address = wait_address;
		init_waitqueue_entry(&entry->wait, current);
		add_wait_queue(wait_address,&entry->wait);
	}
}

#define FDS_IN(fds, n)		(fds->in + n)
#define FDS_OUT(fds, n)		(fds->out + n)
#define FDS_EX(fds, n)		(fds->ex + n)

#define BITS(fds, n)	(*FDS_IN(fds, n)|*FDS_OUT(fds, n)|*FDS_EX(fds, n))

static int max_select_fd(unsigned long n, fd_set_bits *fds)
{
	unsigned long *open_fds;
	unsigned long set;
	int max;
	struct fdtable *fdt;

	/* handle last in-complete long-word first */
	set = ~(~0UL << (n & (__NFDBITS-1)));
	n /= __NFDBITS;
	fdt = files_fdtable(current->files);
	open_fds = fdt->open_fds->fds_bits+n;
	max = 0;
	if (set) {
		set &= BITS(fds, n);
		if (set) {
			if (!(set & ~*open_fds))
				goto get_max;
			return -EBADF;
		}
	}
	while (n) {
		open_fds--;
		n--;
		set = BITS(fds, n);
		if (!set)
			continue;
		if (set & ~*open_fds)
			return -EBADF;
		if (max)
			continue;
get_max:
		do {
			max++;
			set >>= 1;
		} while (set);
		max += n * __NFDBITS;
	}

	return max;
}

#define BIT(i)		(1UL << ((i)&(__NFDBITS-1)))
#define MEM(i,m)	((m)+(unsigned)(i)/__NFDBITS)
#define ISSET(i,m)	(((i)&*(m)) != 0)
#define SET(i,m)	(*(m) |= (i))

#define POLLIN_SET (POLLRDNORM | POLLRDBAND | POLLIN | POLLHUP | POLLERR)
#define POLLOUT_SET (POLLWRBAND | POLLWRNORM | POLLOUT | POLLERR)
#define POLLEX_SET (POLLPRI)

int do_select(int n, fd_set_bits *fds, long *timeout)
{
	struct poll_wqueues table;
	poll_table *wait;
	int retval, i;
	long __timeout = *timeout;

	rcu_read_lock();
	retval = max_select_fd(n, fds);
	rcu_read_unlock();

	if (retval < 0)
		return retval;
	n = retval;

	poll_initwait(&table);
	wait = &table.pt;
	if (!__timeout)
		wait = NULL;
	retval = 0;
	for (;;) {
		unsigned long *rinp, *routp, *rexp, *inp, *outp, *exp;

		set_current_state(TASK_INTERRUPTIBLE);

		inp = fds->in; outp = fds->out; exp = fds->ex;
		rinp = fds->res_in; routp = fds->res_out; rexp = fds->res_ex;

		for (i = 0; i < n; ++rinp, ++routp, ++rexp) {
			unsigned long in, out, ex, all_bits, bit = 1, mask, j;
			unsigned long res_in = 0, res_out = 0, res_ex = 0;
			struct file_operations *f_op = NULL;
			struct file *file = NULL;

			in = *inp++; out = *outp++; ex = *exp++;
			all_bits = in | out | ex;
			if (all_bits == 0) {
				i += __NFDBITS;
				continue;
			}

			for (j = 0; j < __NFDBITS; ++j, ++i, bit <<= 1) {
				if (i >= n)
					break;
				if (!(bit & all_bits))
					continue;
				file = fget(i);
				if (file) {
					f_op = file->f_op;
					mask = DEFAULT_POLLMASK;
					if (f_op && f_op->poll)
						mask = (*f_op->poll)(file, retval ? NULL : wait);
					fput(file);
					if ((mask & POLLIN_SET) && (in & bit)) {
						res_in |= bit;
						retval++;
					}
					if ((mask & POLLOUT_SET) && (out & bit)) {
						res_out |= bit;
						retval++;
					}
					if ((mask & POLLEX_SET) && (ex & bit)) {
						res_ex |= bit;
						retval++;
					}
				}
				cond_resched();
			}
			if (res_in)
				*rinp = res_in;
			if (res_out)
				*routp = res_out;
			if (res_ex)
				*rexp = res_ex;
		}
		wait = NULL;
		if (retval || !__timeout || signal_pending(current))
			break;
		if(table.error) {
			retval = table.error;
			break;
		}
		__timeout = schedule_timeout(__timeout);
	}
	__set_current_state(TASK_RUNNING);

	poll_freewait(&table);

	/*
	 * Up-to-date the caller timeout.
	 */
	*timeout = __timeout;
	return retval;
}

static void *select_bits_alloc(int size)
{
	return kmalloc(6 * size, GFP_KERNEL);
}

static void select_bits_free(void *bits, int size)
{
	kfree(bits);
}

/*
 * We can actually return ERESTARTSYS instead of EINTR, but I'd
 * like to be certain this leads to no problems. So I return
 * EINTR just for safety.
 *
 * Update: ERESTARTSYS breaks at least the xview clock binary, so
 * I'm trying ERESTARTNOHAND which restart only when you want to.
 */
#define MAX_SELECT_SECONDS \
	((unsigned long) (MAX_SCHEDULE_TIMEOUT / HZ)-1)

asmlinkage long
sys_select(int n, fd_set __user *inp, fd_set __user *outp, fd_set __user *exp, struct timeval __user *tvp)
{
	fd_set_bits fds;
	char *bits;
	long timeout;
	int ret, size, max_fdset;
	struct fdtable *fdt;

	timeout = MAX_SCHEDULE_TIMEOUT;
	if (tvp) {
		time_t sec, usec;

		if (!access_ok(VERIFY_READ, tvp, sizeof(*tvp))
		    || __get_user(sec, &tvp->tv_sec)
		    || __get_user(usec, &tvp->tv_usec)) {
			ret = -EFAULT;
			goto out_nofds;
		}

		ret = -EINVAL;
		if (sec < 0 || usec < 0)
			goto out_nofds;

		if ((unsigned long) sec < MAX_SELECT_SECONDS) {
			timeout = ROUND_UP(usec, 1000000/HZ);
			timeout += sec * (unsigned long) HZ;
		}
	}

	ret = -EINVAL;
	if (n < 0)
		goto out_nofds;

	/* max_fdset can increase, so grab it once to avoid race */
	rcu_read_lock();
	fdt = files_fdtable(current->files);
	max_fdset = fdt->max_fdset;
	rcu_read_unlock();
	if (n > max_fdset)
		n = max_fdset;

	/*
	 * We need 6 bitmaps (in/out/ex for both incoming and outgoing),
	 * since we used fdset we need to allocate memory in units of
	 * long-words. 
	 */
	ret = -ENOMEM;
	size = FDS_BYTES(n);
	bits = select_bits_alloc(size);
	if (!bits)
		goto out_nofds;
	fds.in      = (unsigned long *)  bits;
	fds.out     = (unsigned long *) (bits +   size);
	fds.ex      = (unsigned long *) (bits + 2*size);
	fds.res_in  = (unsigned long *) (bits + 3*size);
	fds.res_out = (unsigned long *) (bits + 4*size);
	fds.res_ex  = (unsigned long *) (bits + 5*size);

	if ((ret = get_fd_set(n, inp, fds.in)) ||
	    (ret = get_fd_set(n, outp, fds.out)) ||
	    (ret = get_fd_set(n, exp, fds.ex)))
		goto out;
	zero_fd_set(n, fds.res_in);
	zero_fd_set(n, fds.res_out);
	zero_fd_set(n, fds.res_ex);

	ret = do_select(n, &fds, &timeout);

	if (tvp && !(current->personality & STICKY_TIMEOUTS)) {
		time_t sec = 0, usec = 0;
		if (timeout) {
			sec = timeout / HZ;
			usec = timeout % HZ;
			usec *= (1000000/HZ);
		}
		put_user(sec, &tvp->tv_sec);
		put_user(usec, &tvp->tv_usec);
	}

	if (ret < 0)
		goto out;
	if (!ret) {
		ret = -ERESTARTNOHAND;
		if (signal_pending(current))
			goto out;
		ret = 0;
	}

	if (set_fd_set(n, inp, fds.res_in) ||
	    set_fd_set(n, outp, fds.res_out) ||
	    set_fd_set(n, exp, fds.res_ex))
		ret = -EFAULT;

out:
	select_bits_free(bits, size);
out_nofds:
	return ret;
}

struct poll_list {
	struct poll_list *next;
	int len;
	struct pollfd entries[0];
};

#define POLLFD_PER_PAGE  ((PAGE_SIZE-sizeof(struct poll_list)) / sizeof(struct pollfd))

static void do_pollfd(unsigned int num, struct pollfd * fdpage,
	poll_table ** pwait, int *count)
{
	int i;

	for (i = 0; i < num; i++) {
		int fd;
		unsigned int mask;
		struct pollfd *fdp;

		mask = 0;
		fdp = fdpage+i;
		fd = fdp->fd;
		if (fd >= 0) {
			struct file * file = fget(fd);
			mask = POLLNVAL;
			if (file != NULL) {
				mask = DEFAULT_POLLMASK;
				if (file->f_op && file->f_op->poll)
					mask = file->f_op->poll(file, *pwait);
				mask &= fdp->events | POLLERR | POLLHUP;
				fput(file);
			}
			if (mask) {
				*pwait = NULL;
				(*count)++;
			}
		}
		fdp->revents = mask;
	}
}

static int do_poll(unsigned int nfds,  struct poll_list *list,
			struct poll_wqueues *wait, long timeout)
{
	int count = 0;
	poll_table* pt = &wait->pt;

	if (!timeout)
		pt = NULL;
 
	for (;;) {
		struct poll_list *walk;
		set_current_state(TASK_INTERRUPTIBLE);
		walk = list;
		while(walk != NULL) {
			do_pollfd( walk->len, walk->entries, &pt, &count);
			walk = walk->next;
		}
		pt = NULL;
		if (count || !timeout || signal_pending(current))
			break;
		count = wait->error;
		if (count)
			break;
		timeout = schedule_timeout(timeout);
	}
	__set_current_state(TASK_RUNNING);
	return count;
}

asmlinkage long sys_poll(struct pollfd __user * ufds, unsigned int nfds, long timeout)
{
	struct poll_wqueues table;
 	int fdcount, err;
 	unsigned int i;
	struct poll_list *head;
 	struct poll_list *walk;
	struct fdtable *fdt;
	int max_fdset;

	/* Do a sanity check on nfds ... */
	rcu_read_lock();
	fdt = files_fdtable(current->files);
	max_fdset = fdt->max_fdset;
	rcu_read_unlock();
	if (nfds > max_fdset && nfds > OPEN_MAX)
		return -EINVAL;

	if (timeout) {
		/* Careful about overflow in the intermediate values */
		if ((unsigned long) timeout < MAX_SCHEDULE_TIMEOUT / HZ)
			timeout = (unsigned long)(timeout*HZ+999)/1000+1;
		else /* Negative or overflow */
			timeout = MAX_SCHEDULE_TIMEOUT;
	}

	poll_initwait(&table);

	head = NULL;
	walk = NULL;
	i = nfds;
	err = -ENOMEM;
	while(i!=0) {
		struct poll_list *pp;
		pp = kmalloc(sizeof(struct poll_list)+
				sizeof(struct pollfd)*
				(i>POLLFD_PER_PAGE?POLLFD_PER_PAGE:i),
					GFP_KERNEL);
		if(pp==NULL)
			goto out_fds;
		pp->next=NULL;
		pp->len = (i>POLLFD_PER_PAGE?POLLFD_PER_PAGE:i);
		if (head == NULL)
			head = pp;
		else
			walk->next = pp;

		walk = pp;
		if (copy_from_user(pp->entries, ufds + nfds-i, 
				sizeof(struct pollfd)*pp->len)) {
			err = -EFAULT;
			goto out_fds;
		}
		i -= pp->len;
	}
	fdcount = do_poll(nfds, head, &table, timeout);

	/* OK, now copy the revents fields back to user space. */
	walk = head;
	err = -EFAULT;
	while(walk != NULL) {
		struct pollfd *fds = walk->entries;
		int j;

		for (j=0; j < walk->len; j++, ufds++) {
			if(__put_user(fds[j].revents, &ufds->revents))
				goto out_fds;
		}
		walk = walk->next;
  	}
	err = fdcount;
	if (!fdcount && signal_pending(current))
		err = -EINTR;
out_fds:
	walk = head;
	while(walk!=NULL) {
		struct poll_list *pp = walk->next;
		kfree(walk);
		walk = pp;
	}
	poll_freewait(&table);
	return err;
}
Commit	Line	Data
1da177e4 LT	1	/*
	2	* This file contains the procedures for the handling of select and poll
	3	*
	4	* Created for Linux based loosely upon Mathius Lattner's minix
	5	* patches by Peter MacDonald. Heavily edited by Linus.
	6	*
	7	* 4 February 1994
	8	* COFF/ELF binary emulation. If the process has the STICKY_TIMEOUTS
	9	* flag set in its personality we do not modify the given timeout
	10	* parameter to reflect time remaining.
	11	*
	12	* 24 January 2000
	13	* Changed sys_poll()/do_poll() to use PAGE_SIZE chunk-based allocation
	14	* of fds to overcome nfds < 16390 descriptors limit (Tigran Aivazian).
	15	*/
	16
	17	#include <linux/syscalls.h>
	18	#include <linux/module.h>
	19	#include <linux/slab.h>
	20	#include <linux/smp_lock.h>
	21	#include <linux/poll.h>
	22	#include <linux/personality.h> /* for STICKY_TIMEOUTS */
	23	#include <linux/file.h>
	24	#include <linux/fs.h>
b835996f	25	#include <linux/rcupdate.h>
1da177e4 LT	26
	27	#include <asm/uaccess.h>
	28
	29	#define ROUND_UP(x,y) (((x)+(y)-1)/(y))
	30	#define DEFAULT_POLLMASK (POLLIN \| POLLOUT \| POLLRDNORM \| POLLWRNORM)
	31
	32	struct poll_table_entry {
	33	struct file * filp;
	34	wait_queue_t wait;
	35	wait_queue_head_t * wait_address;
	36	};
	37
	38	struct poll_table_page {
	39	struct poll_table_page * next;
	40	struct poll_table_entry * entry;
	41	struct poll_table_entry entries[0];
	42	};
	43
	44	#define POLL_TABLE_FULL(table) \
	45	((unsigned long)((table)->entry+1) > PAGE_SIZE + (unsigned long)(table))
	46
	47	/*
	48	* Ok, Peter made a complicated, but straightforward multiple_wait() function.
	49	* I have rewritten this, taking some shortcuts: This code may not be easy to
	50	* follow, but it should be free of race-conditions, and it's practical. If you
	51	* understand what I'm doing here, then you understand how the linux
	52	* sleep/wakeup mechanism works.
	53	*
	54	* Two very simple procedures, poll_wait() and poll_freewait() make all the
	55	* work. poll_wait() is an inline-function defined in <linux/poll.h>,
	56	* as all select/poll functions have to call it to add an entry to the
	57	* poll table.
	58	*/
75c96f85 AB	59	static void __pollwait(struct file filp, wait_queue_head_t wait_address,
75c96f85 AB	60	poll_table *p);
1da177e4 LT	61
	62	void poll_initwait(struct poll_wqueues *pwq)
	63	{
	64	init_poll_funcptr(&pwq->pt, __pollwait);
	65	pwq->error = 0;
	66	pwq->table = NULL;
	67	}
	68
	69	EXPORT_SYMBOL(poll_initwait);
	70
	71	void poll_freewait(struct poll_wqueues *pwq)
	72	{
	73	struct poll_table_page * p = pwq->table;
	74	while (p) {
	75	struct poll_table_entry * entry;
	76	struct poll_table_page *old;
	77
	78	entry = p->entry;
	79	do {
	80	entry--;
	81	remove_wait_queue(entry->wait_address,&entry->wait);
	82	fput(entry->filp);
	83	} while (entry > p->entries);
	84	old = p;
	85	p = p->next;
	86	free_page((unsigned long) old);
	87	}
	88	}
	89
	90	EXPORT_SYMBOL(poll_freewait);
	91
75c96f85 AB	92	static void __pollwait(struct file filp, wait_queue_head_t wait_address,
75c96f85 AB	93	poll_table *_p)
1da177e4 LT	94	{
	95	struct poll_wqueues *p = container_of(_p, struct poll_wqueues, pt);
	96	struct poll_table_page *table = p->table;
	97
	98	if (!table \|\| POLL_TABLE_FULL(table)) {
	99	struct poll_table_page *new_table;
	100
	101	new_table = (struct poll_table_page *) __get_free_page(GFP_KERNEL);
	102	if (!new_table) {
	103	p->error = -ENOMEM;
	104	__set_current_state(TASK_RUNNING);
	105	return;
	106	}
	107	new_table->entry = new_table->entries;
	108	new_table->next = table;
	109	p->table = new_table;
	110	table = new_table;
	111	}
	112
	113	/* Add a new entry */
	114	{
	115	struct poll_table_entry * entry = table->entry;
	116	table->entry = entry+1;
	117	get_file(filp);
	118	entry->filp = filp;
	119	entry->wait_address = wait_address;
	120	init_waitqueue_entry(&entry->wait, current);
	121	add_wait_queue(wait_address,&entry->wait);
	122	}
	123	}
	124
	125	#define FDS_IN(fds, n) (fds->in + n)
	126	#define FDS_OUT(fds, n) (fds->out + n)
	127	#define FDS_EX(fds, n) (fds->ex + n)
	128
	129	#define BITS(fds, n) (FDS_IN(fds, n)\|FDS_OUT(fds, n)\|*FDS_EX(fds, n))
	130
	131	static int max_select_fd(unsigned long n, fd_set_bits *fds)
	132	{
	133	unsigned long *open_fds;
	134	unsigned long set;
	135	int max;
badf1662	136	struct fdtable *fdt;
1da177e4 LT	137
	138	/* handle last in-complete long-word first */
	139	set = ~(~0UL << (n & (__NFDBITS-1)));
	140	n /= __NFDBITS;
badf1662 DS	141	fdt = files_fdtable(current->files);
badf1662 DS	142	open_fds = fdt->open_fds->fds_bits+n;
1da177e4 LT	143	max = 0;
	144	if (set) {
	145	set &= BITS(fds, n);
	146	if (set) {
	147	if (!(set & ~*open_fds))
	148	goto get_max;
	149	return -EBADF;
	150	}
	151	}
	152	while (n) {
	153	open_fds--;
	154	n--;
	155	set = BITS(fds, n);
	156	if (!set)
	157	continue;
	158	if (set & ~*open_fds)
	159	return -EBADF;
	160	if (max)
	161	continue;
	162	get_max:
	163	do {
	164	max++;
	165	set >>= 1;
	166	} while (set);
	167	max += n * __NFDBITS;
	168	}
	169
	170	return max;
	171	}
	172
	173	#define BIT(i) (1UL << ((i)&(__NFDBITS-1)))
	174	#define MEM(i,m) ((m)+(unsigned)(i)/__NFDBITS)
	175	#define ISSET(i,m) (((i)&*(m)) != 0)
	176	#define SET(i,m) (*(m) \|= (i))
	177
	178	#define POLLIN_SET (POLLRDNORM \| POLLRDBAND \| POLLIN \| POLLHUP \| POLLERR)
	179	#define POLLOUT_SET (POLLWRBAND \| POLLWRNORM \| POLLOUT \| POLLERR)
	180	#define POLLEX_SET (POLLPRI)
	181
	182	int do_select(int n, fd_set_bits fds, long timeout)
	183	{
	184	struct poll_wqueues table;
	185	poll_table *wait;
	186	int retval, i;
	187	long __timeout = *timeout;
	188
b835996f	189	rcu_read_lock();
1da177e4	190	retval = max_select_fd(n, fds);
b835996f	191	rcu_read_unlock();
1da177e4 LT	192
	193	if (retval < 0)
	194	return retval;
	195	n = retval;
	196
	197	poll_initwait(&table);
	198	wait = &table.pt;
	199	if (!__timeout)
	200	wait = NULL;
	201	retval = 0;
	202	for (;;) {
	203	unsigned long rinp, routp, rexp, inp, outp, exp;
	204
	205	set_current_state(TASK_INTERRUPTIBLE);
	206
	207	inp = fds->in; outp = fds->out; exp = fds->ex;
	208	rinp = fds->res_in; routp = fds->res_out; rexp = fds->res_ex;
	209
	210	for (i = 0; i < n; ++rinp, ++routp, ++rexp) {
	211	unsigned long in, out, ex, all_bits, bit = 1, mask, j;
	212	unsigned long res_in = 0, res_out = 0, res_ex = 0;
	213	struct file_operations *f_op = NULL;
	214	struct file *file = NULL;
	215
	216	in = inp++; out = outp++; ex = *exp++;
	217	all_bits = in \| out \| ex;
	218	if (all_bits == 0) {
	219	i += __NFDBITS;
	220	continue;
	221	}
	222
	223	for (j = 0; j < __NFDBITS; ++j, ++i, bit <<= 1) {
	224	if (i >= n)
	225	break;
	226	if (!(bit & all_bits))
	227	continue;
	228	file = fget(i);
	229	if (file) {
	230	f_op = file->f_op;
	231	mask = DEFAULT_POLLMASK;
	232	if (f_op && f_op->poll)
	233	mask = (*f_op->poll)(file, retval ? NULL : wait);
	234	fput(file);
	235	if ((mask & POLLIN_SET) && (in & bit)) {
	236	res_in \|= bit;
	237	retval++;
	238	}
	239	if ((mask & POLLOUT_SET) && (out & bit)) {
	240	res_out \|= bit;
	241	retval++;
	242	}
	243	if ((mask & POLLEX_SET) && (ex & bit)) {
	244	res_ex \|= bit;
	245	retval++;
	246	}
	247	}
	248	cond_resched();
	249	}
	250	if (res_in)
	251	*rinp = res_in;
	252	if (res_out)
	253	*routp = res_out;
	254	if (res_ex)
	255	*rexp = res_ex;
256	}
257	wait = NULL;
258	if (retval \|\| !__timeout \|\| signal_pending(current))
259	break;
260	if(table.error) {
261	retval = table.error;
262	break;
263	}
264	__timeout = schedule_timeout(__timeout);
265	}
266	__set_current_state(TASK_RUNNING);
267
268	poll_freewait(&table);
269
270	/*
271	* Up-to-date the caller timeout.
272	*/
273	*timeout = __timeout;
274	return retval;
275	}
276
277	static void *select_bits_alloc(int size)
278	{
279	return kmalloc(6 * size, GFP_KERNEL);
280	}
281
282	static void select_bits_free(void *bits, int size)
283	{
284	kfree(bits);
285	}
286
287	/*
288	* We can actually return ERESTARTSYS instead of EINTR, but I'd
289	* like to be certain this leads to no problems. So I return
290	* EINTR just for safety.
291	*
292	* Update: ERESTARTSYS breaks at least the xview clock binary, so
293	* I'm trying ERESTARTNOHAND which restart only when you want to.
294	*/
295	#define MAX_SELECT_SECONDS \
296	((unsigned long) (MAX_SCHEDULE_TIMEOUT / HZ)-1)
297
298	asmlinkage long
299	sys_select(int n, fd_set __user inp, fd_set __user outp, fd_set __user exp, struct timeval __user tvp)
300	{
301	fd_set_bits fds;
302	char *bits;
303	long timeout;
304	int ret, size, max_fdset;
badf1662	305	struct fdtable *fdt;
1da177e4 LT	306
	307	timeout = MAX_SCHEDULE_TIMEOUT;
	308	if (tvp) {
	309	time_t sec, usec;
	310
	311	if (!access_ok(VERIFY_READ, tvp, sizeof(*tvp))
	312	\|\| __get_user(sec, &tvp->tv_sec)
	313	\|\| __get_user(usec, &tvp->tv_usec)) {
	314	ret = -EFAULT;
	315	goto out_nofds;
	316	}
	317
	318	ret = -EINVAL;
	319	if (sec < 0 \|\| usec < 0)
	320	goto out_nofds;
	321
	322	if ((unsigned long) sec < MAX_SELECT_SECONDS) {
	323	timeout = ROUND_UP(usec, 1000000/HZ);
	324	timeout += sec * (unsigned long) HZ;
	325	}
	326	}
	327
	328	ret = -EINVAL;
	329	if (n < 0)
	330	goto out_nofds;
	331
	332	/* max_fdset can increase, so grab it once to avoid race */
b835996f	333	rcu_read_lock();
badf1662 DS	334	fdt = files_fdtable(current->files);
badf1662 DS	335	max_fdset = fdt->max_fdset;
b835996f	336	rcu_read_unlock();
1da177e4 LT	337	if (n > max_fdset)
	338	n = max_fdset;
	339
	340	/*
	341	* We need 6 bitmaps (in/out/ex for both incoming and outgoing),
	342	* since we used fdset we need to allocate memory in units of
	343	* long-words.
	344	*/
	345	ret = -ENOMEM;
	346	size = FDS_BYTES(n);
	347	bits = select_bits_alloc(size);
	348	if (!bits)
	349	goto out_nofds;
	350	fds.in = (unsigned long *) bits;
	351	fds.out = (unsigned long *) (bits + size);
	352	fds.ex = (unsigned long ) (bits + 2size);
	353	fds.res_in = (unsigned long ) (bits + 3size);
	354	fds.res_out = (unsigned long ) (bits + 4size);
	355	fds.res_ex = (unsigned long ) (bits + 5size);
	356
	357	if ((ret = get_fd_set(n, inp, fds.in)) \|\|
	358	(ret = get_fd_set(n, outp, fds.out)) \|\|
	359	(ret = get_fd_set(n, exp, fds.ex)))
	360	goto out;
	361	zero_fd_set(n, fds.res_in);
	362	zero_fd_set(n, fds.res_out);
	363	zero_fd_set(n, fds.res_ex);
	364
	365	ret = do_select(n, &fds, &timeout);
	366
	367	if (tvp && !(current->personality & STICKY_TIMEOUTS)) {
	368	time_t sec = 0, usec = 0;
	369	if (timeout) {
	370	sec = timeout / HZ;
	371	usec = timeout % HZ;
	372	usec *= (1000000/HZ);
	373	}
	374	put_user(sec, &tvp->tv_sec);
	375	put_user(usec, &tvp->tv_usec);
	376	}
	377
	378	if (ret < 0)
	379	goto out;
	380	if (!ret) {
	381	ret = -ERESTARTNOHAND;
	382	if (signal_pending(current))
	383	goto out;
	384	ret = 0;
	385	}
	386
	387	if (set_fd_set(n, inp, fds.res_in) \|\|
	388	set_fd_set(n, outp, fds.res_out) \|\|
	389	set_fd_set(n, exp, fds.res_ex))
	390	ret = -EFAULT;
	391
	392	out:
	393	select_bits_free(bits, size);
	394	out_nofds:
	395	return ret;
	396	}
	397
	398	struct poll_list {
	399	struct poll_list *next;
	400	int len;
401	struct pollfd entries[0];
402	};
403
404	#define POLLFD_PER_PAGE ((PAGE_SIZE-sizeof(struct poll_list)) / sizeof(struct pollfd))
405
406	static void do_pollfd(unsigned int num, struct pollfd * fdpage,
407	poll_table ** pwait, int *count)
408	{
409	int i;
410
411	for (i = 0; i < num; i++) {
412	int fd;
413	unsigned int mask;
414	struct pollfd *fdp;
415
416	mask = 0;
417	fdp = fdpage+i;
418	fd = fdp->fd;
419	if (fd >= 0) {
420	struct file * file = fget(fd);
421	mask = POLLNVAL;
422	if (file != NULL) {
423	mask = DEFAULT_POLLMASK;
424	if (file->f_op && file->f_op->poll)
425	mask = file->f_op->poll(file, *pwait);
426	mask &= fdp->events \| POLLERR \| POLLHUP;
427	fput(file);
428	}
429	if (mask) {
430	*pwait = NULL;
431	(*count)++;
432	}
433	}
434	fdp->revents = mask;
435	}
436	}
437
438	static int do_poll(unsigned int nfds, struct poll_list *list,
439	struct poll_wqueues *wait, long timeout)
440	{
441	int count = 0;
442	poll_table* pt = &wait->pt;
443
444	if (!timeout)
445	pt = NULL;
446
447	for (;;) {
448	struct poll_list *walk;
449	set_current_state(TASK_INTERRUPTIBLE);
450	walk = list;
451	while(walk != NULL) {
452	do_pollfd( walk->len, walk->entries, &pt, &count);
453	walk = walk->next;
454	}
455	pt = NULL;
456	if (count \|\| !timeout \|\| signal_pending(current))
457	break;
458	count = wait->error;
459	if (count)
460	break;
461	timeout = schedule_timeout(timeout);
462	}
463	__set_current_state(TASK_RUNNING);
464	return count;
465	}
466
467	asmlinkage long sys_poll(struct pollfd __user * ufds, unsigned int nfds, long timeout)
468	{
469	struct poll_wqueues table;
470	int fdcount, err;
471	unsigned int i;
472	struct poll_list *head;
473	struct poll_list *walk;
badf1662	474	struct fdtable *fdt;
b835996f	475	int max_fdset;
1da177e4 LT	476
1da177e4 LT	477	/* Do a sanity check on nfds ... */
b835996f	478	rcu_read_lock();
badf1662	479	fdt = files_fdtable(current->files);
b835996f DS	480	max_fdset = fdt->max_fdset;
	481	rcu_read_unlock();
	482	if (nfds > max_fdset && nfds > OPEN_MAX)
1da177e4 LT	483	return -EINVAL;
	484
	485	if (timeout) {
	486	/* Careful about overflow in the intermediate values */
	487	if ((unsigned long) timeout < MAX_SCHEDULE_TIMEOUT / HZ)
	488	timeout = (unsigned long)(timeout*HZ+999)/1000+1;
	489	else /* Negative or overflow */
	490	timeout = MAX_SCHEDULE_TIMEOUT;
	491	}
	492
	493	poll_initwait(&table);
	494
	495	head = NULL;
	496	walk = NULL;
	497	i = nfds;
	498	err = -ENOMEM;
	499	while(i!=0) {
	500	struct poll_list *pp;
	501	pp = kmalloc(sizeof(struct poll_list)+
	502	sizeof(struct pollfd)*
	503	(i>POLLFD_PER_PAGE?POLLFD_PER_PAGE:i),
	504	GFP_KERNEL);
	505	if(pp==NULL)
	506	goto out_fds;
	507	pp->next=NULL;
	508	pp->len = (i>POLLFD_PER_PAGE?POLLFD_PER_PAGE:i);
	509	if (head == NULL)
	510	head = pp;
	511	else
	512	walk->next = pp;
	513
	514	walk = pp;
	515	if (copy_from_user(pp->entries, ufds + nfds-i,
	516	sizeof(struct pollfd)*pp->len)) {
	517	err = -EFAULT;
	518	goto out_fds;
	519	}
	520	i -= pp->len;
	521	}
	522	fdcount = do_poll(nfds, head, &table, timeout);
	523
	524	/* OK, now copy the revents fields back to user space. */
	525	walk = head;
	526	err = -EFAULT;
	527	while(walk != NULL) {
	528	struct pollfd *fds = walk->entries;
	529	int j;
	530
	531	for (j=0; j < walk->len; j++, ufds++) {
	532	if(__put_user(fds[j].revents, &ufds->revents))
	533	goto out_fds;
	534	}
	535	walk = walk->next;
	536	}
	537	err = fdcount;
	538	if (!fdcount && signal_pending(current))
	539	err = -EINTR;
	540	out_fds:
	541	walk = head;
	542	while(walk!=NULL) {
	543	struct poll_list *pp = walk->next;
	544	kfree(walk);
	545	walk = pp;
	546	}
547	poll_freewait(&table);
548	return err;
549	}