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![Alex Dewar](/assets/img/avatar_default.png)
Convert files to use SPDX header. All files are licensed under the GPLv2. Signed-off-by: Alex Dewar <alex.dewar@gmx.co.uk> Signed-off-by: Richard Weinberger <richard@nod.at>
546 lines
11 KiB
C
546 lines
11 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Copyright (C) 2002 - 2008 Jeff Dike (jdike@{addtoit,linux.intel}.com)
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*/
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#include <unistd.h>
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#include <errno.h>
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#include <fcntl.h>
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#include <poll.h>
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#include <pty.h>
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#include <sched.h>
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#include <signal.h>
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#include <string.h>
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#include <kern_util.h>
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#include <init.h>
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#include <os.h>
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#include <sigio.h>
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#include <um_malloc.h>
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/*
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* Protected by sigio_lock(), also used by sigio_cleanup, which is an
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* exitcall.
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*/
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static int write_sigio_pid = -1;
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static unsigned long write_sigio_stack;
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/*
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* These arrays are initialized before the sigio thread is started, and
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* the descriptors closed after it is killed. So, it can't see them change.
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* On the UML side, they are changed under the sigio_lock.
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*/
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#define SIGIO_FDS_INIT {-1, -1}
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static int write_sigio_fds[2] = SIGIO_FDS_INIT;
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static int sigio_private[2] = SIGIO_FDS_INIT;
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struct pollfds {
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struct pollfd *poll;
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int size;
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int used;
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};
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/*
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* Protected by sigio_lock(). Used by the sigio thread, but the UML thread
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* synchronizes with it.
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*/
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static struct pollfds current_poll;
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static struct pollfds next_poll;
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static struct pollfds all_sigio_fds;
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static int write_sigio_thread(void *unused)
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{
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struct pollfds *fds, tmp;
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struct pollfd *p;
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int i, n, respond_fd;
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char c;
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os_fix_helper_signals();
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fds = ¤t_poll;
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while (1) {
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n = poll(fds->poll, fds->used, -1);
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if (n < 0) {
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if (errno == EINTR)
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continue;
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printk(UM_KERN_ERR "write_sigio_thread : poll returned "
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"%d, errno = %d\n", n, errno);
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}
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for (i = 0; i < fds->used; i++) {
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p = &fds->poll[i];
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if (p->revents == 0)
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continue;
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if (p->fd == sigio_private[1]) {
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CATCH_EINTR(n = read(sigio_private[1], &c,
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sizeof(c)));
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if (n != sizeof(c))
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printk(UM_KERN_ERR
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"write_sigio_thread : "
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"read on socket failed, "
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"err = %d\n", errno);
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tmp = current_poll;
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current_poll = next_poll;
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next_poll = tmp;
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respond_fd = sigio_private[1];
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}
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else {
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respond_fd = write_sigio_fds[1];
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fds->used--;
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memmove(&fds->poll[i], &fds->poll[i + 1],
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(fds->used - i) * sizeof(*fds->poll));
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}
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CATCH_EINTR(n = write(respond_fd, &c, sizeof(c)));
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if (n != sizeof(c))
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printk(UM_KERN_ERR "write_sigio_thread : "
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"write on socket failed, err = %d\n",
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errno);
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}
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}
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return 0;
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}
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static int need_poll(struct pollfds *polls, int n)
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{
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struct pollfd *new;
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if (n <= polls->size)
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return 0;
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new = uml_kmalloc(n * sizeof(struct pollfd), UM_GFP_ATOMIC);
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if (new == NULL) {
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printk(UM_KERN_ERR "need_poll : failed to allocate new "
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"pollfds\n");
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return -ENOMEM;
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}
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memcpy(new, polls->poll, polls->used * sizeof(struct pollfd));
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kfree(polls->poll);
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polls->poll = new;
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polls->size = n;
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return 0;
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}
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/*
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* Must be called with sigio_lock held, because it's needed by the marked
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* critical section.
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*/
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static void update_thread(void)
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{
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unsigned long flags;
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int n;
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char c;
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flags = set_signals_trace(0);
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CATCH_EINTR(n = write(sigio_private[0], &c, sizeof(c)));
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if (n != sizeof(c)) {
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printk(UM_KERN_ERR "update_thread : write failed, err = %d\n",
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errno);
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goto fail;
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}
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CATCH_EINTR(n = read(sigio_private[0], &c, sizeof(c)));
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if (n != sizeof(c)) {
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printk(UM_KERN_ERR "update_thread : read failed, err = %d\n",
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errno);
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goto fail;
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}
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set_signals_trace(flags);
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return;
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fail:
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/* Critical section start */
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if (write_sigio_pid != -1) {
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os_kill_process(write_sigio_pid, 1);
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free_stack(write_sigio_stack, 0);
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}
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write_sigio_pid = -1;
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close(sigio_private[0]);
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close(sigio_private[1]);
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close(write_sigio_fds[0]);
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close(write_sigio_fds[1]);
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/* Critical section end */
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set_signals_trace(flags);
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}
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int add_sigio_fd(int fd)
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{
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struct pollfd *p;
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int err = 0, i, n;
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sigio_lock();
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for (i = 0; i < all_sigio_fds.used; i++) {
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if (all_sigio_fds.poll[i].fd == fd)
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break;
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}
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if (i == all_sigio_fds.used)
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goto out;
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p = &all_sigio_fds.poll[i];
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for (i = 0; i < current_poll.used; i++) {
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if (current_poll.poll[i].fd == fd)
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goto out;
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}
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n = current_poll.used;
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err = need_poll(&next_poll, n + 1);
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if (err)
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goto out;
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memcpy(next_poll.poll, current_poll.poll,
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current_poll.used * sizeof(struct pollfd));
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next_poll.poll[n] = *p;
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next_poll.used = n + 1;
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update_thread();
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out:
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sigio_unlock();
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return err;
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}
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int ignore_sigio_fd(int fd)
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{
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struct pollfd *p;
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int err = 0, i, n = 0;
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/*
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* This is called from exitcalls elsewhere in UML - if
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* sigio_cleanup has already run, then update_thread will hang
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* or fail because the thread is no longer running.
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*/
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if (write_sigio_pid == -1)
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return -EIO;
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sigio_lock();
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for (i = 0; i < current_poll.used; i++) {
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if (current_poll.poll[i].fd == fd)
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break;
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}
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if (i == current_poll.used)
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goto out;
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err = need_poll(&next_poll, current_poll.used - 1);
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if (err)
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goto out;
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for (i = 0; i < current_poll.used; i++) {
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p = ¤t_poll.poll[i];
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if (p->fd != fd)
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next_poll.poll[n++] = *p;
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}
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next_poll.used = current_poll.used - 1;
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update_thread();
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out:
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sigio_unlock();
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return err;
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}
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static struct pollfd *setup_initial_poll(int fd)
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{
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struct pollfd *p;
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p = uml_kmalloc(sizeof(struct pollfd), UM_GFP_KERNEL);
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if (p == NULL) {
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printk(UM_KERN_ERR "setup_initial_poll : failed to allocate "
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"poll\n");
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return NULL;
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}
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*p = ((struct pollfd) { .fd = fd,
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.events = POLLIN,
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.revents = 0 });
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return p;
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}
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static void write_sigio_workaround(void)
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{
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struct pollfd *p;
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int err;
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int l_write_sigio_fds[2];
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int l_sigio_private[2];
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int l_write_sigio_pid;
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/* We call this *tons* of times - and most ones we must just fail. */
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sigio_lock();
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l_write_sigio_pid = write_sigio_pid;
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sigio_unlock();
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if (l_write_sigio_pid != -1)
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return;
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err = os_pipe(l_write_sigio_fds, 1, 1);
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if (err < 0) {
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printk(UM_KERN_ERR "write_sigio_workaround - os_pipe 1 failed, "
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"err = %d\n", -err);
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return;
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}
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err = os_pipe(l_sigio_private, 1, 1);
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if (err < 0) {
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printk(UM_KERN_ERR "write_sigio_workaround - os_pipe 2 failed, "
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"err = %d\n", -err);
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goto out_close1;
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}
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p = setup_initial_poll(l_sigio_private[1]);
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if (!p)
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goto out_close2;
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sigio_lock();
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/*
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* Did we race? Don't try to optimize this, please, it's not so likely
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* to happen, and no more than once at the boot.
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*/
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if (write_sigio_pid != -1)
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goto out_free;
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current_poll = ((struct pollfds) { .poll = p,
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.used = 1,
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.size = 1 });
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if (write_sigio_irq(l_write_sigio_fds[0]))
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goto out_clear_poll;
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memcpy(write_sigio_fds, l_write_sigio_fds, sizeof(l_write_sigio_fds));
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memcpy(sigio_private, l_sigio_private, sizeof(l_sigio_private));
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write_sigio_pid = run_helper_thread(write_sigio_thread, NULL,
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CLONE_FILES | CLONE_VM,
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&write_sigio_stack);
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if (write_sigio_pid < 0)
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goto out_clear;
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sigio_unlock();
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return;
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out_clear:
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write_sigio_pid = -1;
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write_sigio_fds[0] = -1;
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write_sigio_fds[1] = -1;
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sigio_private[0] = -1;
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sigio_private[1] = -1;
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out_clear_poll:
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current_poll = ((struct pollfds) { .poll = NULL,
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.size = 0,
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.used = 0 });
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out_free:
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sigio_unlock();
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kfree(p);
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out_close2:
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close(l_sigio_private[0]);
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close(l_sigio_private[1]);
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out_close1:
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close(l_write_sigio_fds[0]);
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close(l_write_sigio_fds[1]);
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}
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void sigio_broken(int fd, int read)
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{
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int err;
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write_sigio_workaround();
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sigio_lock();
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err = need_poll(&all_sigio_fds, all_sigio_fds.used + 1);
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if (err) {
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printk(UM_KERN_ERR "maybe_sigio_broken - failed to add pollfd "
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"for descriptor %d\n", fd);
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goto out;
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}
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all_sigio_fds.poll[all_sigio_fds.used++] =
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((struct pollfd) { .fd = fd,
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.events = read ? POLLIN : POLLOUT,
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.revents = 0 });
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out:
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sigio_unlock();
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}
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/* Changed during early boot */
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static int pty_output_sigio;
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static int pty_close_sigio;
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void maybe_sigio_broken(int fd, int read)
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{
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if (!isatty(fd))
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return;
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if ((read || pty_output_sigio) && (!read || pty_close_sigio))
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return;
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sigio_broken(fd, read);
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}
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static void sigio_cleanup(void)
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{
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if (write_sigio_pid == -1)
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return;
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os_kill_process(write_sigio_pid, 1);
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free_stack(write_sigio_stack, 0);
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write_sigio_pid = -1;
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}
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__uml_exitcall(sigio_cleanup);
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/* Used as a flag during SIGIO testing early in boot */
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static int got_sigio;
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static void __init handler(int sig)
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{
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got_sigio = 1;
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}
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struct openpty_arg {
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int master;
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int slave;
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int err;
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};
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static void openpty_cb(void *arg)
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{
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struct openpty_arg *info = arg;
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info->err = 0;
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if (openpty(&info->master, &info->slave, NULL, NULL, NULL))
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info->err = -errno;
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}
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static int async_pty(int master, int slave)
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{
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int flags;
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flags = fcntl(master, F_GETFL);
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if (flags < 0)
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return -errno;
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if ((fcntl(master, F_SETFL, flags | O_NONBLOCK | O_ASYNC) < 0) ||
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(fcntl(master, F_SETOWN, os_getpid()) < 0))
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return -errno;
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if ((fcntl(slave, F_SETFL, flags | O_NONBLOCK) < 0))
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return -errno;
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return 0;
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}
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static void __init check_one_sigio(void (*proc)(int, int))
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{
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struct sigaction old, new;
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struct openpty_arg pty = { .master = -1, .slave = -1 };
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int master, slave, err;
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initial_thread_cb(openpty_cb, &pty);
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if (pty.err) {
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printk(UM_KERN_ERR "check_one_sigio failed, errno = %d\n",
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-pty.err);
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return;
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}
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master = pty.master;
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slave = pty.slave;
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if ((master == -1) || (slave == -1)) {
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printk(UM_KERN_ERR "check_one_sigio failed to allocate a "
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"pty\n");
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return;
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}
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/* Not now, but complain so we now where we failed. */
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err = raw(master);
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if (err < 0) {
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printk(UM_KERN_ERR "check_one_sigio : raw failed, errno = %d\n",
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-err);
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return;
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}
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err = async_pty(master, slave);
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if (err < 0) {
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printk(UM_KERN_ERR "check_one_sigio : sigio_async failed, "
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"err = %d\n", -err);
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return;
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}
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if (sigaction(SIGIO, NULL, &old) < 0) {
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printk(UM_KERN_ERR "check_one_sigio : sigaction 1 failed, "
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"errno = %d\n", errno);
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return;
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}
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new = old;
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new.sa_handler = handler;
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if (sigaction(SIGIO, &new, NULL) < 0) {
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printk(UM_KERN_ERR "check_one_sigio : sigaction 2 failed, "
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"errno = %d\n", errno);
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return;
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}
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got_sigio = 0;
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(*proc)(master, slave);
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close(master);
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close(slave);
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if (sigaction(SIGIO, &old, NULL) < 0)
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printk(UM_KERN_ERR "check_one_sigio : sigaction 3 failed, "
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"errno = %d\n", errno);
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}
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static void tty_output(int master, int slave)
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{
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int n;
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char buf[512];
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printk(UM_KERN_INFO "Checking that host ptys support output SIGIO...");
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memset(buf, 0, sizeof(buf));
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while (write(master, buf, sizeof(buf)) > 0) ;
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if (errno != EAGAIN)
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printk(UM_KERN_ERR "tty_output : write failed, errno = %d\n",
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errno);
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while (((n = read(slave, buf, sizeof(buf))) > 0) &&
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!({ barrier(); got_sigio; }))
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;
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if (got_sigio) {
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printk(UM_KERN_CONT "Yes\n");
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pty_output_sigio = 1;
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} else if (n == -EAGAIN)
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printk(UM_KERN_CONT "No, enabling workaround\n");
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else
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printk(UM_KERN_CONT "tty_output : read failed, err = %d\n", n);
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}
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static void tty_close(int master, int slave)
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{
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printk(UM_KERN_INFO "Checking that host ptys support SIGIO on "
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"close...");
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close(slave);
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if (got_sigio) {
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printk(UM_KERN_CONT "Yes\n");
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pty_close_sigio = 1;
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} else
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printk(UM_KERN_CONT "No, enabling workaround\n");
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}
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static void __init check_sigio(void)
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{
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if ((access("/dev/ptmx", R_OK) < 0) &&
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(access("/dev/ptyp0", R_OK) < 0)) {
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printk(UM_KERN_WARNING "No pseudo-terminals available - "
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"skipping pty SIGIO check\n");
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return;
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}
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check_one_sigio(tty_output);
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check_one_sigio(tty_close);
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}
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|
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/* Here because it only does the SIGIO testing for now */
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void __init os_check_bugs(void)
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|
{
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|
check_sigio();
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|
}
|