[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 <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;

	/* handle last in-complete long-word first */
	set = ~(~0UL << (n & (__NFDBITS-1)));
	n /= __NFDBITS;
	open_fds = current->files->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;

 	spin_lock(&current->files->file_lock);
	retval = max_select_fd(n, fds);
	spin_unlock(&current->files->file_lock);

	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;

	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 */
	max_fdset = current->files->max_fdset;
	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;

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