/*
* 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/malloc.h>
#include <linux/smp_lock.h>
#include <linux/poll.h>
#include <linux/file.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.
*/
55 void poll_freewait(poll_table* pt)
{
struct poll_table_page * p = pt->table;
58 while (p) {
struct poll_table_entry * entry;
struct poll_table_page *old;
entry = p->entry;
63 do {
entry--;
remove_wait_queue(entry->wait_address,&entry->wait);
fput(entry->filp);
67 } while (entry > p->entries);
old = p;
p = p->next;
free_page((unsigned long) old);
}
}
74 void __pollwait(struct file * filp, wait_queue_head_t * wait_address, poll_table *p)
{
struct poll_table_page *table = p->table;
78 if (!table || POLL_TABLE_FULL(table)) {
struct poll_table_page *new_table;
new_table = (struct poll_table_page *) __get_free_page(GFP_KERNEL);
82 if (!new_table) {
p->error = -ENOMEM;
84 __set_current_state(TASK_RUNNING);
85 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 __IN(fds, n) (fds->in + n)
#define __OUT(fds, n) (fds->out + n)
#define __EX(fds, n) (fds->ex + n)
#define __RES_IN(fds, n) (fds->res_in + n)
#define __RES_OUT(fds, n) (fds->res_out + n)
#define __RES_EX(fds, n) (fds->res_ex + n)
#define BITS(fds, n) (*__IN(fds, n)|*__OUT(fds, n)|*__EX(fds, n))
114 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;
125 if (set) {
set &= BITS(fds, n);
127 if (set) {
128 if (!(set & ~*open_fds))
129 goto get_max;
130 return -EBADF;
}
}
133 while (n) {
open_fds--;
n--;
set = BITS(fds, n);
137 if (!set)
138 continue;
139 if (set & ~*open_fds)
140 return -EBADF;
141 if (max)
142 continue;
get_max:
144 do {
max++;
set >>= 1;
147 } while (set);
max += n * __NFDBITS;
}
151 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)
163 int do_select(int n, fd_set_bits *fds, long *timeout)
{
poll_table table, *wait;
int retval, i, off;
long __timeout = *timeout;
read_lock(¤t->files->file_lock);
retval = max_select_fd(n, fds);
171 read_unlock(¤t->files->file_lock);
173 if (retval < 0)
174 return retval;
n = retval;
poll_initwait(&table);
wait = &table;
179 if (!__timeout)
wait = NULL;
retval = 0;
182 for (;;) {
183 set_current_state(TASK_INTERRUPTIBLE);
184 for (i = 0 ; i < n; i++) {
unsigned long bit = BIT(i);
unsigned long mask;
struct file *file;
off = i / __NFDBITS;
190 if (!(bit & BITS(fds, off)))
191 continue;
file = fget(i);
mask = POLLNVAL;
194 if (file) {
mask = DEFAULT_POLLMASK;
196 if (file->f_op && file->f_op->poll)
mask = file->f_op->poll(file, wait);
fput(file);
}
200 if ((mask & POLLIN_SET) && ISSET(bit, __IN(fds,off))) {
SET(bit, __RES_IN(fds,off));
retval++;
wait = NULL;
}
205 if ((mask & POLLOUT_SET) && ISSET(bit, __OUT(fds,off))) {
SET(bit, __RES_OUT(fds,off));
retval++;
wait = NULL;
}
210 if ((mask & POLLEX_SET) && ISSET(bit, __EX(fds,off))) {
SET(bit, __RES_EX(fds,off));
retval++;
wait = NULL;
}
}
wait = NULL;
217 if (retval || !__timeout || signal_pending(current))
218 break;
219 if(table.error) {
retval = table.error;
221 break;
}
__timeout = schedule_timeout(__timeout);
}
current->state = TASK_RUNNING;
poll_freewait(&table);
/*
* Up-to-date the caller timeout.
*/
*timeout = __timeout;
233 return retval;
}
236 static void *select_bits_alloc(int size)
{
238 return kmalloc(6 * size, GFP_KERNEL);
}
241 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
258 sys_select(int n, fd_set *inp, fd_set *outp, fd_set *exp, struct timeval *tvp)
{
fd_set_bits fds;
char *bits;
long timeout;
int ret, size;
timeout = MAX_SCHEDULE_TIMEOUT;
266 if (tvp) {
time_t sec, usec;
if ((ret = verify_area(VERIFY_READ, tvp, sizeof(*tvp)))
|| (ret = __get_user(sec, &tvp->tv_sec))
271 || (ret = __get_user(usec, &tvp->tv_usec)))
272 goto out_nofds;
ret = -EINVAL;
275 if (sec < 0 || usec < 0)
276 goto out_nofds;
278 if ((unsigned long) sec < MAX_SELECT_SECONDS) {
timeout = ROUND_UP(usec, 1000000/HZ);
timeout += sec * (unsigned long) HZ;
}
}
ret = -EINVAL;
285 if (n < 0)
286 goto out_nofds;
288 if (n > current->files->max_fdset)
n = current->files->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);
299 if (!bits)
300 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)) ||
310 (ret = get_fd_set(n, exp, fds.ex)))
311 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);
318 if (tvp && !(current->personality & STICKY_TIMEOUTS)) {
time_t sec = 0, usec = 0;
320 if (timeout) {
sec = timeout / HZ;
usec = timeout % HZ;
usec *= (1000000/HZ);
}
put_user(sec, &tvp->tv_sec);
put_user(usec, &tvp->tv_usec);
}
329 if (ret < 0)
330 goto out;
331 if (!ret) {
ret = -ERESTARTNOHAND;
333 if (signal_pending(current))
334 goto out;
ret = 0;
}
set_fd_set(n, inp, fds.res_in);
set_fd_set(n, outp, fds.res_out);
set_fd_set(n, exp, fds.res_ex);
out:
select_bits_free(bits, size);
out_nofds:
345 return ret;
}
#define POLLFD_PER_PAGE ((PAGE_SIZE) / sizeof(struct pollfd))
350 static void do_pollfd(unsigned int num, struct pollfd * fdpage,
poll_table ** pwait, int *count)
{
int i;
355 for (i = 0; i < num; i++) {
int fd;
unsigned int mask;
struct pollfd *fdp;
mask = 0;
fdp = fdpage+i;
fd = fdp->fd;
363 if (fd >= 0) {
struct file * file = fget(fd);
mask = POLLNVAL;
366 if (file != NULL) {
mask = DEFAULT_POLLMASK;
368 if (file->f_op && file->f_op->poll)
mask = file->f_op->poll(file, *pwait);
mask &= fdp->events | POLLERR | POLLHUP;
fput(file);
}
373 if (mask) {
*pwait = NULL;
(*count)++;
}
}
fdp->revents = mask;
}
}
382 static int do_poll(unsigned int nfds, unsigned int nchunks, unsigned int nleft,
struct pollfd *fds[], poll_table *wait, long timeout)
{
int count;
poll_table* pt = wait;
388 for (;;) {
unsigned int i;
391 set_current_state(TASK_INTERRUPTIBLE);
count = 0;
393 for (i=0; i < nchunks; i++)
do_pollfd(POLLFD_PER_PAGE, fds[i], &pt, &count);
395 if (nleft)
do_pollfd(nleft, fds[nchunks], &pt, &count);
pt = NULL;
398 if (count || !timeout || signal_pending(current))
399 break;
count = wait->error;
401 if (count)
402 break;
timeout = schedule_timeout(timeout);
}
current->state = TASK_RUNNING;
406 return count;
}
409 asmlinkage long sys_poll(struct pollfd * ufds, unsigned int nfds, long timeout)
{
int i, j, fdcount, err;
struct pollfd **fds;
poll_table table, *wait;
int nchunks, nleft;
/* Do a sanity check on nfds ... */
417 if (nfds > current->files->max_fds)
418 return -EINVAL;
420 if (timeout) {
/* Careful about overflow in the intermediate values */
422 if ((unsigned long) timeout < MAX_SCHEDULE_TIMEOUT / HZ)
timeout = (unsigned long)(timeout*HZ+999)/1000+1;
424 else /* Negative or overflow */
timeout = MAX_SCHEDULE_TIMEOUT;
}
poll_initwait(&table);
wait = &table;
430 if (!timeout)
wait = NULL;
err = -ENOMEM;
fds = NULL;
435 if (nfds != 0) {
fds = (struct pollfd **)kmalloc(
(1 + (nfds - 1) / POLLFD_PER_PAGE) * sizeof(struct pollfd *),
GFP_KERNEL);
439 if (fds == NULL)
440 goto out;
}
nchunks = 0;
nleft = nfds;
445 while (nleft > POLLFD_PER_PAGE) { /* allocate complete PAGE_SIZE chunks */
fds[nchunks] = (struct pollfd *)__get_free_page(GFP_KERNEL);
447 if (fds[nchunks] == NULL)
448 goto out_fds;
nchunks++;
nleft -= POLLFD_PER_PAGE;
}
452 if (nleft) { /* allocate last PAGE_SIZE chunk, only nleft elements used */
fds[nchunks] = (struct pollfd *)__get_free_page(GFP_KERNEL);
454 if (fds[nchunks] == NULL)
455 goto out_fds;
}
err = -EFAULT;
459 for (i=0; i < nchunks; i++)
460 if (copy_from_user(fds[i], ufds + i*POLLFD_PER_PAGE, PAGE_SIZE))
461 goto out_fds1;
462 if (nleft) {
if (copy_from_user(fds[nchunks], ufds + nchunks*POLLFD_PER_PAGE,
464 nleft * sizeof(struct pollfd)))
465 goto out_fds1;
}
fdcount = do_poll(nfds, nchunks, nleft, fds, wait, timeout);
/* OK, now copy the revents fields back to user space. */
471 for(i=0; i < nchunks; i++)
472 for (j=0; j < POLLFD_PER_PAGE; j++, ufds++)
__put_user((fds[i] + j)->revents, &ufds->revents);
474 if (nleft)
475 for (j=0; j < nleft; j++, ufds++)
__put_user((fds[nchunks] + j)->revents, &ufds->revents);
err = fdcount;
479 if (!fdcount && signal_pending(current))
err = -EINTR;
out_fds1:
483 if (nleft)
free_page((unsigned long)(fds[nchunks]));
out_fds:
486 for (i=0; i < nchunks; i++)
free_page((unsigned long)(fds[i]));
488 if (nfds != 0)
kfree(fds);
out:
poll_freewait(&table);
492 return err;
}