535 lines
12 KiB
C
535 lines
12 KiB
C
/*
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* This file contains the procedures for the handling of select and poll
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*
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* Created for Linux based loosely upon Mathius Lattner's minix
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* patches by Peter MacDonald. Heavily edited by Linus.
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*
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* 4 February 1994
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* COFF/ELF binary emulation. If the process has the STICKY_TIMEOUTS
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* flag set in its personality we do *not* modify the given timeout
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* parameter to reflect time remaining.
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*
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* 24 January 2000
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* Changed sys_poll()/do_poll() to use PAGE_SIZE chunk-based allocation
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* of fds to overcome nfds < 16390 descriptors limit (Tigran Aivazian).
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*/
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#include <linux/syscalls.h>
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#include <linux/module.h>
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#include <linux/slab.h>
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#include <linux/smp_lock.h>
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#include <linux/poll.h>
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#include <linux/personality.h> /* for STICKY_TIMEOUTS */
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#include <linux/file.h>
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#include <linux/fs.h>
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#include <asm/uaccess.h>
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#define ROUND_UP(x,y) (((x)+(y)-1)/(y))
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#define DEFAULT_POLLMASK (POLLIN | POLLOUT | POLLRDNORM | POLLWRNORM)
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struct poll_table_entry {
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struct file * filp;
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wait_queue_t wait;
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wait_queue_head_t * wait_address;
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};
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struct poll_table_page {
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struct poll_table_page * next;
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struct poll_table_entry * entry;
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struct poll_table_entry entries[0];
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};
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#define POLL_TABLE_FULL(table) \
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((unsigned long)((table)->entry+1) > PAGE_SIZE + (unsigned long)(table))
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/*
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* Ok, Peter made a complicated, but straightforward multiple_wait() function.
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* I have rewritten this, taking some shortcuts: This code may not be easy to
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* follow, but it should be free of race-conditions, and it's practical. If you
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* understand what I'm doing here, then you understand how the linux
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* sleep/wakeup mechanism works.
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*
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* Two very simple procedures, poll_wait() and poll_freewait() make all the
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* work. poll_wait() is an inline-function defined in <linux/poll.h>,
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* as all select/poll functions have to call it to add an entry to the
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* poll table.
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*/
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void __pollwait(struct file *filp, wait_queue_head_t *wait_address, poll_table *p);
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void poll_initwait(struct poll_wqueues *pwq)
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{
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init_poll_funcptr(&pwq->pt, __pollwait);
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pwq->error = 0;
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pwq->table = NULL;
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}
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EXPORT_SYMBOL(poll_initwait);
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void poll_freewait(struct poll_wqueues *pwq)
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{
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struct poll_table_page * p = pwq->table;
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while (p) {
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struct poll_table_entry * entry;
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struct poll_table_page *old;
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entry = p->entry;
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do {
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entry--;
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remove_wait_queue(entry->wait_address,&entry->wait);
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fput(entry->filp);
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} while (entry > p->entries);
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old = p;
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p = p->next;
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free_page((unsigned long) old);
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}
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}
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EXPORT_SYMBOL(poll_freewait);
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void __pollwait(struct file *filp, wait_queue_head_t *wait_address, poll_table *_p)
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{
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struct poll_wqueues *p = container_of(_p, struct poll_wqueues, pt);
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struct poll_table_page *table = p->table;
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if (!table || POLL_TABLE_FULL(table)) {
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struct poll_table_page *new_table;
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new_table = (struct poll_table_page *) __get_free_page(GFP_KERNEL);
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if (!new_table) {
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p->error = -ENOMEM;
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__set_current_state(TASK_RUNNING);
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return;
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}
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new_table->entry = new_table->entries;
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new_table->next = table;
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p->table = new_table;
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table = new_table;
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}
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/* Add a new entry */
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{
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struct poll_table_entry * entry = table->entry;
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table->entry = entry+1;
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get_file(filp);
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entry->filp = filp;
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entry->wait_address = wait_address;
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init_waitqueue_entry(&entry->wait, current);
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add_wait_queue(wait_address,&entry->wait);
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}
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}
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#define FDS_IN(fds, n) (fds->in + n)
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#define FDS_OUT(fds, n) (fds->out + n)
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#define FDS_EX(fds, n) (fds->ex + n)
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#define BITS(fds, n) (*FDS_IN(fds, n)|*FDS_OUT(fds, n)|*FDS_EX(fds, n))
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static int max_select_fd(unsigned long n, fd_set_bits *fds)
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{
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unsigned long *open_fds;
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unsigned long set;
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int max;
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/* handle last in-complete long-word first */
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set = ~(~0UL << (n & (__NFDBITS-1)));
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n /= __NFDBITS;
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open_fds = current->files->open_fds->fds_bits+n;
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max = 0;
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if (set) {
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set &= BITS(fds, n);
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if (set) {
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if (!(set & ~*open_fds))
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goto get_max;
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return -EBADF;
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}
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}
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while (n) {
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open_fds--;
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n--;
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set = BITS(fds, n);
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if (!set)
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continue;
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if (set & ~*open_fds)
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return -EBADF;
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if (max)
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continue;
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get_max:
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do {
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max++;
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set >>= 1;
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} while (set);
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max += n * __NFDBITS;
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}
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return max;
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}
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#define BIT(i) (1UL << ((i)&(__NFDBITS-1)))
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#define MEM(i,m) ((m)+(unsigned)(i)/__NFDBITS)
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#define ISSET(i,m) (((i)&*(m)) != 0)
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#define SET(i,m) (*(m) |= (i))
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#define POLLIN_SET (POLLRDNORM | POLLRDBAND | POLLIN | POLLHUP | POLLERR)
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#define POLLOUT_SET (POLLWRBAND | POLLWRNORM | POLLOUT | POLLERR)
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#define POLLEX_SET (POLLPRI)
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int do_select(int n, fd_set_bits *fds, long *timeout)
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{
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struct poll_wqueues table;
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poll_table *wait;
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int retval, i;
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long __timeout = *timeout;
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spin_lock(¤t->files->file_lock);
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retval = max_select_fd(n, fds);
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spin_unlock(¤t->files->file_lock);
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if (retval < 0)
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return retval;
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n = retval;
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poll_initwait(&table);
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wait = &table.pt;
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if (!__timeout)
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wait = NULL;
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retval = 0;
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for (;;) {
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unsigned long *rinp, *routp, *rexp, *inp, *outp, *exp;
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set_current_state(TASK_INTERRUPTIBLE);
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inp = fds->in; outp = fds->out; exp = fds->ex;
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rinp = fds->res_in; routp = fds->res_out; rexp = fds->res_ex;
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for (i = 0; i < n; ++rinp, ++routp, ++rexp) {
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unsigned long in, out, ex, all_bits, bit = 1, mask, j;
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unsigned long res_in = 0, res_out = 0, res_ex = 0;
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struct file_operations *f_op = NULL;
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struct file *file = NULL;
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in = *inp++; out = *outp++; ex = *exp++;
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all_bits = in | out | ex;
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if (all_bits == 0) {
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i += __NFDBITS;
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continue;
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}
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for (j = 0; j < __NFDBITS; ++j, ++i, bit <<= 1) {
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if (i >= n)
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break;
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if (!(bit & all_bits))
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continue;
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file = fget(i);
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if (file) {
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f_op = file->f_op;
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mask = DEFAULT_POLLMASK;
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if (f_op && f_op->poll)
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mask = (*f_op->poll)(file, retval ? NULL : wait);
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fput(file);
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if ((mask & POLLIN_SET) && (in & bit)) {
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res_in |= bit;
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retval++;
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}
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if ((mask & POLLOUT_SET) && (out & bit)) {
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res_out |= bit;
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retval++;
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}
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if ((mask & POLLEX_SET) && (ex & bit)) {
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res_ex |= bit;
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retval++;
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}
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}
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cond_resched();
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}
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if (res_in)
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*rinp = res_in;
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if (res_out)
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*routp = res_out;
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if (res_ex)
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*rexp = res_ex;
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}
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wait = NULL;
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if (retval || !__timeout || signal_pending(current))
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break;
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if(table.error) {
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retval = table.error;
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break;
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}
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__timeout = schedule_timeout(__timeout);
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}
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__set_current_state(TASK_RUNNING);
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poll_freewait(&table);
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/*
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* Up-to-date the caller timeout.
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*/
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*timeout = __timeout;
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return retval;
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}
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static void *select_bits_alloc(int size)
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{
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return kmalloc(6 * size, GFP_KERNEL);
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}
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static void select_bits_free(void *bits, int size)
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{
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kfree(bits);
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}
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/*
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* We can actually return ERESTARTSYS instead of EINTR, but I'd
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* like to be certain this leads to no problems. So I return
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* EINTR just for safety.
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*
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* Update: ERESTARTSYS breaks at least the xview clock binary, so
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* I'm trying ERESTARTNOHAND which restart only when you want to.
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*/
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#define MAX_SELECT_SECONDS \
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((unsigned long) (MAX_SCHEDULE_TIMEOUT / HZ)-1)
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asmlinkage long
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sys_select(int n, fd_set __user *inp, fd_set __user *outp, fd_set __user *exp, struct timeval __user *tvp)
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{
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fd_set_bits fds;
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char *bits;
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long timeout;
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int ret, size, max_fdset;
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timeout = MAX_SCHEDULE_TIMEOUT;
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if (tvp) {
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time_t sec, usec;
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if (!access_ok(VERIFY_READ, tvp, sizeof(*tvp))
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|| __get_user(sec, &tvp->tv_sec)
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|| __get_user(usec, &tvp->tv_usec)) {
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ret = -EFAULT;
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goto out_nofds;
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}
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ret = -EINVAL;
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if (sec < 0 || usec < 0)
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goto out_nofds;
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if ((unsigned long) sec < MAX_SELECT_SECONDS) {
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timeout = ROUND_UP(usec, 1000000/HZ);
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timeout += sec * (unsigned long) HZ;
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}
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}
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ret = -EINVAL;
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if (n < 0)
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goto out_nofds;
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/* max_fdset can increase, so grab it once to avoid race */
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max_fdset = current->files->max_fdset;
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if (n > max_fdset)
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n = max_fdset;
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/*
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* We need 6 bitmaps (in/out/ex for both incoming and outgoing),
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* since we used fdset we need to allocate memory in units of
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* long-words.
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*/
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ret = -ENOMEM;
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size = FDS_BYTES(n);
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bits = select_bits_alloc(size);
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if (!bits)
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goto out_nofds;
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fds.in = (unsigned long *) bits;
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fds.out = (unsigned long *) (bits + size);
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fds.ex = (unsigned long *) (bits + 2*size);
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fds.res_in = (unsigned long *) (bits + 3*size);
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fds.res_out = (unsigned long *) (bits + 4*size);
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fds.res_ex = (unsigned long *) (bits + 5*size);
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if ((ret = get_fd_set(n, inp, fds.in)) ||
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(ret = get_fd_set(n, outp, fds.out)) ||
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(ret = get_fd_set(n, exp, fds.ex)))
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goto out;
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zero_fd_set(n, fds.res_in);
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zero_fd_set(n, fds.res_out);
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zero_fd_set(n, fds.res_ex);
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ret = do_select(n, &fds, &timeout);
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if (tvp && !(current->personality & STICKY_TIMEOUTS)) {
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time_t sec = 0, usec = 0;
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if (timeout) {
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sec = timeout / HZ;
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usec = timeout % HZ;
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usec *= (1000000/HZ);
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}
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put_user(sec, &tvp->tv_sec);
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put_user(usec, &tvp->tv_usec);
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}
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if (ret < 0)
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goto out;
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if (!ret) {
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ret = -ERESTARTNOHAND;
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if (signal_pending(current))
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goto out;
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ret = 0;
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}
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if (set_fd_set(n, inp, fds.res_in) ||
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set_fd_set(n, outp, fds.res_out) ||
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set_fd_set(n, exp, fds.res_ex))
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ret = -EFAULT;
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out:
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select_bits_free(bits, size);
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out_nofds:
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return ret;
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}
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struct poll_list {
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struct poll_list *next;
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int len;
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struct pollfd entries[0];
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};
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#define POLLFD_PER_PAGE ((PAGE_SIZE-sizeof(struct poll_list)) / sizeof(struct pollfd))
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static void do_pollfd(unsigned int num, struct pollfd * fdpage,
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poll_table ** pwait, int *count)
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{
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int i;
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for (i = 0; i < num; i++) {
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int fd;
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unsigned int mask;
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struct pollfd *fdp;
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mask = 0;
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fdp = fdpage+i;
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fd = fdp->fd;
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if (fd >= 0) {
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struct file * file = fget(fd);
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mask = POLLNVAL;
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if (file != NULL) {
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mask = DEFAULT_POLLMASK;
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if (file->f_op && file->f_op->poll)
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mask = file->f_op->poll(file, *pwait);
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mask &= fdp->events | POLLERR | POLLHUP;
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fput(file);
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}
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if (mask) {
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*pwait = NULL;
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(*count)++;
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}
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}
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fdp->revents = mask;
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}
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}
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static int do_poll(unsigned int nfds, struct poll_list *list,
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struct poll_wqueues *wait, long timeout)
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{
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int count = 0;
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poll_table* pt = &wait->pt;
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if (!timeout)
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pt = NULL;
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for (;;) {
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struct poll_list *walk;
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set_current_state(TASK_INTERRUPTIBLE);
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walk = list;
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while(walk != NULL) {
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do_pollfd( walk->len, walk->entries, &pt, &count);
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walk = walk->next;
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}
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pt = NULL;
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if (count || !timeout || signal_pending(current))
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break;
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count = wait->error;
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if (count)
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break;
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timeout = schedule_timeout(timeout);
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}
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__set_current_state(TASK_RUNNING);
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return count;
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}
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asmlinkage long sys_poll(struct pollfd __user * ufds, unsigned int nfds, long timeout)
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{
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struct poll_wqueues table;
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int fdcount, err;
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unsigned int i;
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struct poll_list *head;
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struct poll_list *walk;
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/* Do a sanity check on nfds ... */
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if (nfds > current->files->max_fdset && nfds > OPEN_MAX)
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return -EINVAL;
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if (timeout) {
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/* Careful about overflow in the intermediate values */
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if ((unsigned long) timeout < MAX_SCHEDULE_TIMEOUT / HZ)
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timeout = (unsigned long)(timeout*HZ+999)/1000+1;
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else /* Negative or overflow */
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timeout = MAX_SCHEDULE_TIMEOUT;
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}
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poll_initwait(&table);
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head = NULL;
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walk = NULL;
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i = nfds;
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err = -ENOMEM;
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while(i!=0) {
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struct poll_list *pp;
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pp = kmalloc(sizeof(struct poll_list)+
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sizeof(struct pollfd)*
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(i>POLLFD_PER_PAGE?POLLFD_PER_PAGE:i),
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GFP_KERNEL);
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if(pp==NULL)
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goto out_fds;
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pp->next=NULL;
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pp->len = (i>POLLFD_PER_PAGE?POLLFD_PER_PAGE:i);
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if (head == NULL)
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head = pp;
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else
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walk->next = pp;
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walk = pp;
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if (copy_from_user(pp->entries, ufds + nfds-i,
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sizeof(struct pollfd)*pp->len)) {
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err = -EFAULT;
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goto out_fds;
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}
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i -= pp->len;
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}
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fdcount = do_poll(nfds, head, &table, timeout);
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/* OK, now copy the revents fields back to user space. */
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walk = head;
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err = -EFAULT;
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while(walk != NULL) {
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struct pollfd *fds = walk->entries;
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int j;
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for (j=0; j < walk->len; j++, ufds++) {
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if(__put_user(fds[j].revents, &ufds->revents))
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goto out_fds;
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}
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walk = walk->next;
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}
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err = fdcount;
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if (!fdcount && signal_pending(current))
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err = -EINTR;
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out_fds:
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walk = head;
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while(walk!=NULL) {
|
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struct poll_list *pp = walk->next;
|
|
kfree(walk);
|
|
walk = pp;
|
|
}
|
|
poll_freewait(&table);
|
|
return err;
|
|
}
|