[deliverable/linux.git] / arch / um / os-Linux / sigio.c

/*
 * Copyright (C) 2002 - 2008 Jeff Dike (jdike@{addtoit,linux.intel}.com)
 * Licensed under the GPL
 */

#include <unistd.h>
#include <errno.h>
#include <fcntl.h>
#include <poll.h>
#include <pty.h>
#include <sched.h>
#include <signal.h>
#include <string.h>
#include <kern_util.h>
#include <init.h>
#include <os.h>
#include <sigio.h>
#include <um_malloc.h>

/*
 * Protected by sigio_lock(), also used by sigio_cleanup, which is an
 * exitcall.
 */
static int write_sigio_pid = -1;
static unsigned long write_sigio_stack;

/*
 * These arrays are initialized before the sigio thread is started, and
 * the descriptors closed after it is killed.  So, it can't see them change.
 * On the UML side, they are changed under the sigio_lock.
 */
#define SIGIO_FDS_INIT {-1, -1}

static int write_sigio_fds[2] = SIGIO_FDS_INIT;
static int sigio_private[2] = SIGIO_FDS_INIT;

struct pollfds {
	struct pollfd *poll;
	int size;
	int used;
};

/*
 * Protected by sigio_lock().  Used by the sigio thread, but the UML thread
 * synchronizes with it.
 */
static struct pollfds current_poll;
static struct pollfds next_poll;
static struct pollfds all_sigio_fds;

static int write_sigio_thread(void *unused)
{
	struct pollfds *fds, tmp;
	struct pollfd *p;
	int i, n, respond_fd;
	char c;

	os_fix_helper_signals();
	fds = &current_poll;
	while (1) {
		n = poll(fds->poll, fds->used, -1);
		if (n < 0) {
			if (errno == EINTR)
				continue;
			printk(UM_KERN_ERR "write_sigio_thread : poll returned "
			       "%d, errno = %d\n", n, errno);
		}
		for (i = 0; i < fds->used; i++) {
			p = &fds->poll[i];
			if (p->revents == 0)
				continue;
			if (p->fd == sigio_private[1]) {
				CATCH_EINTR(n = read(sigio_private[1], &c,
						     sizeof(c)));
				if (n != sizeof(c))
					printk(UM_KERN_ERR
					       "write_sigio_thread : "
					       "read on socket failed, "
					       "err = %d\n", errno);
				tmp = current_poll;
				current_poll = next_poll;
				next_poll = tmp;
				respond_fd = sigio_private[1];
			}
			else {
				respond_fd = write_sigio_fds[1];
				fds->used--;
				memmove(&fds->poll[i], &fds->poll[i + 1],
					(fds->used - i) * sizeof(*fds->poll));
			}

			CATCH_EINTR(n = write(respond_fd, &c, sizeof(c)));
			if (n != sizeof(c))
				printk(UM_KERN_ERR "write_sigio_thread : "
				       "write on socket failed, err = %d\n",
				       errno);
		}
	}

	return 0;
}

static int need_poll(struct pollfds *polls, int n)
{
	struct pollfd *new;

	if (n <= polls->size)
		return 0;

	new = uml_kmalloc(n * sizeof(struct pollfd), UM_GFP_ATOMIC);
	if (new == NULL) {
		printk(UM_KERN_ERR "need_poll : failed to allocate new "
		       "pollfds\n");
		return -ENOMEM;
	}

	memcpy(new, polls->poll, polls->used * sizeof(struct pollfd));
	kfree(polls->poll);

	polls->poll = new;
	polls->size = n;
	return 0;
}

/*
 * Must be called with sigio_lock held, because it's needed by the marked
 * critical section.
 */
static void update_thread(void)
{
	unsigned long flags;
	int n;
	char c;

	flags = set_signals(0);
	CATCH_EINTR(n = write(sigio_private[0], &c, sizeof(c)));
	if (n != sizeof(c)) {
		printk(UM_KERN_ERR "update_thread : write failed, err = %d\n",
		       errno);
		goto fail;
	}

	CATCH_EINTR(n = read(sigio_private[0], &c, sizeof(c)));
	if (n != sizeof(c)) {
		printk(UM_KERN_ERR "update_thread : read failed, err = %d\n",
		       errno);
		goto fail;
	}

	set_signals(flags);
	return;
 fail:
	/* Critical section start */
	if (write_sigio_pid != -1) {
		os_kill_process(write_sigio_pid, 1);
		free_stack(write_sigio_stack, 0);
	}
	write_sigio_pid = -1;
	close(sigio_private[0]);
	close(sigio_private[1]);
	close(write_sigio_fds[0]);
	close(write_sigio_fds[1]);
	/* Critical section end */
	set_signals(flags);
}

int add_sigio_fd(int fd)
{
	struct pollfd *p;
	int err = 0, i, n;

	sigio_lock();
	for (i = 0; i < all_sigio_fds.used; i++) {
		if (all_sigio_fds.poll[i].fd == fd)
			break;
	}
	if (i == all_sigio_fds.used)
		goto out;

	p = &all_sigio_fds.poll[i];

	for (i = 0; i < current_poll.used; i++) {
		if (current_poll.poll[i].fd == fd)
			goto out;
	}

	n = current_poll.used;
	err = need_poll(&next_poll, n + 1);
	if (err)
		goto out;

	memcpy(next_poll.poll, current_poll.poll,
	       current_poll.used * sizeof(struct pollfd));
	next_poll.poll[n] = *p;
	next_poll.used = n + 1;
	update_thread();
 out:
	sigio_unlock();
	return err;
}

int ignore_sigio_fd(int fd)
{
	struct pollfd *p;
	int err = 0, i, n = 0;

	/*
	 * This is called from exitcalls elsewhere in UML - if
	 * sigio_cleanup has already run, then update_thread will hang
	 * or fail because the thread is no longer running.
	 */
	if (write_sigio_pid == -1)
		return -EIO;

	sigio_lock();
	for (i = 0; i < current_poll.used; i++) {
		if (current_poll.poll[i].fd == fd)
			break;
	}
	if (i == current_poll.used)
		goto out;

	err = need_poll(&next_poll, current_poll.used - 1);
	if (err)
		goto out;

	for (i = 0; i < current_poll.used; i++) {
		p = &current_poll.poll[i];
		if (p->fd != fd)
			next_poll.poll[n++] = *p;
	}
	next_poll.used = current_poll.used - 1;

	update_thread();
 out:
	sigio_unlock();
	return err;
}

static struct pollfd *setup_initial_poll(int fd)
{
	struct pollfd *p;

	p = uml_kmalloc(sizeof(struct pollfd), UM_GFP_KERNEL);
	if (p == NULL) {
		printk(UM_KERN_ERR "setup_initial_poll : failed to allocate "
		       "poll\n");
		return NULL;
	}
	*p = ((struct pollfd) { .fd		= fd,
				.events 	= POLLIN,
				.revents 	= 0 });
	return p;
}

static void write_sigio_workaround(void)
{
	struct pollfd *p;
	int err;
	int l_write_sigio_fds[2];
	int l_sigio_private[2];
	int l_write_sigio_pid;

	/* We call this *tons* of times - and most ones we must just fail. */
	sigio_lock();
	l_write_sigio_pid = write_sigio_pid;
	sigio_unlock();

	if (l_write_sigio_pid != -1)
		return;

	err = os_pipe(l_write_sigio_fds, 1, 1);
	if (err < 0) {
		printk(UM_KERN_ERR "write_sigio_workaround - os_pipe 1 failed, "
		       "err = %d\n", -err);
		return;
	}
	err = os_pipe(l_sigio_private, 1, 1);
	if (err < 0) {
		printk(UM_KERN_ERR "write_sigio_workaround - os_pipe 2 failed, "
		       "err = %d\n", -err);
		goto out_close1;
	}

	p = setup_initial_poll(l_sigio_private[1]);
	if (!p)
		goto out_close2;

	sigio_lock();

	/*
	 * Did we race? Don't try to optimize this, please, it's not so likely
	 * to happen, and no more than once at the boot.
	 */
	if (write_sigio_pid != -1)
		goto out_free;

	current_poll = ((struct pollfds) { .poll 	= p,
					   .used 	= 1,
					   .size 	= 1 });

	if (write_sigio_irq(l_write_sigio_fds[0]))
		goto out_clear_poll;

	memcpy(write_sigio_fds, l_write_sigio_fds, sizeof(l_write_sigio_fds));
	memcpy(sigio_private, l_sigio_private, sizeof(l_sigio_private));

	write_sigio_pid = run_helper_thread(write_sigio_thread, NULL,
					    CLONE_FILES | CLONE_VM,
					    &write_sigio_stack);

	if (write_sigio_pid < 0)
		goto out_clear;

	sigio_unlock();
	return;

out_clear:
	write_sigio_pid = -1;
	write_sigio_fds[0] = -1;
	write_sigio_fds[1] = -1;
	sigio_private[0] = -1;
	sigio_private[1] = -1;
out_clear_poll:
	current_poll = ((struct pollfds) { .poll	= NULL,
					   .size	= 0,
					   .used	= 0 });
out_free:
	sigio_unlock();
	kfree(p);
out_close2:
	close(l_sigio_private[0]);
	close(l_sigio_private[1]);
out_close1:
	close(l_write_sigio_fds[0]);
	close(l_write_sigio_fds[1]);
}

void sigio_broken(int fd, int read)
{
	int err;

	write_sigio_workaround();

	sigio_lock();
	err = need_poll(&all_sigio_fds, all_sigio_fds.used + 1);
	if (err) {
		printk(UM_KERN_ERR "maybe_sigio_broken - failed to add pollfd "
		       "for descriptor %d\n", fd);
		goto out;
	}

	all_sigio_fds.poll[all_sigio_fds.used++] =
		((struct pollfd) { .fd  	= fd,
				   .events 	= read ? POLLIN : POLLOUT,
				   .revents 	= 0 });
out:
	sigio_unlock();
}

/* Changed during early boot */
static int pty_output_sigio;
static int pty_close_sigio;

void maybe_sigio_broken(int fd, int read)
{
	if (!isatty(fd))
		return;

	if ((read || pty_output_sigio) && (!read || pty_close_sigio))
		return;

	sigio_broken(fd, read);
}

static void sigio_cleanup(void)
{
	if (write_sigio_pid == -1)
		return;

	os_kill_process(write_sigio_pid, 1);
	free_stack(write_sigio_stack, 0);
	write_sigio_pid = -1;
}

__uml_exitcall(sigio_cleanup);

/* Used as a flag during SIGIO testing early in boot */
static int got_sigio;

static void __init handler(int sig)
{
	got_sigio = 1;
}

struct openpty_arg {
	int master;
	int slave;
	int err;
};

static void openpty_cb(void *arg)
{
	struct openpty_arg *info = arg;

	info->err = 0;
	if (openpty(&info->master, &info->slave, NULL, NULL, NULL))
		info->err = -errno;
}

static int async_pty(int master, int slave)
{
	int flags;

	flags = fcntl(master, F_GETFL);
	if (flags < 0)
		return -errno;

	if ((fcntl(master, F_SETFL, flags | O_NONBLOCK | O_ASYNC) < 0) ||
	    (fcntl(master, F_SETOWN, os_getpid()) < 0))
		return -errno;

	if ((fcntl(slave, F_SETFL, flags | O_NONBLOCK) < 0))
		return -errno;

	return 0;
}

static void __init check_one_sigio(void (*proc)(int, int))
{
	struct sigaction old, new;
	struct openpty_arg pty = { .master = -1, .slave = -1 };
	int master, slave, err;

	initial_thread_cb(openpty_cb, &pty);
	if (pty.err) {
		printk(UM_KERN_ERR "check_one_sigio failed, errno = %d\n",
		       -pty.err);
		return;
	}

	master = pty.master;
	slave = pty.slave;

	if ((master == -1) || (slave == -1)) {
		printk(UM_KERN_ERR "check_one_sigio failed to allocate a "
		       "pty\n");
		return;
	}

	/* Not now, but complain so we now where we failed. */
	err = raw(master);
	if (err < 0) {
		printk(UM_KERN_ERR "check_one_sigio : raw failed, errno = %d\n",
		      -err);
		return;
	}

	err = async_pty(master, slave);
	if (err < 0) {
		printk(UM_KERN_ERR "check_one_sigio : sigio_async failed, "
		       "err = %d\n", -err);
		return;
	}

	if (sigaction(SIGIO, NULL, &old) < 0) {
		printk(UM_KERN_ERR "check_one_sigio : sigaction 1 failed, "
		       "errno = %d\n", errno);
		return;
	}

	new = old;
	new.sa_handler = handler;
	if (sigaction(SIGIO, &new, NULL) < 0) {
		printk(UM_KERN_ERR "check_one_sigio : sigaction 2 failed, "
		       "errno = %d\n", errno);
		return;
	}

	got_sigio = 0;
	(*proc)(master, slave);

	close(master);
	close(slave);

	if (sigaction(SIGIO, &old, NULL) < 0)
		printk(UM_KERN_ERR "check_one_sigio : sigaction 3 failed, "
		       "errno = %d\n", errno);
}

static void tty_output(int master, int slave)
{
	int n;
	char buf[512];

	printk(UM_KERN_INFO "Checking that host ptys support output SIGIO...");

	memset(buf, 0, sizeof(buf));

	while (write(master, buf, sizeof(buf)) > 0) ;
	if (errno != EAGAIN)
		printk(UM_KERN_ERR "tty_output : write failed, errno = %d\n",
		       errno);
	while (((n = read(slave, buf, sizeof(buf))) > 0) &&
	       !({ barrier(); got_sigio; }))
		;

	if (got_sigio) {
		printk(UM_KERN_CONT "Yes\n");
		pty_output_sigio = 1;
	} else if (n == -EAGAIN)
		printk(UM_KERN_CONT "No, enabling workaround\n");
	else
		printk(UM_KERN_CONT "tty_output : read failed, err = %d\n", n);
}

static void tty_close(int master, int slave)
{
	printk(UM_KERN_INFO "Checking that host ptys support SIGIO on "
	       "close...");

	close(slave);
	if (got_sigio) {
		printk(UM_KERN_CONT "Yes\n");
		pty_close_sigio = 1;
	} else
		printk(UM_KERN_CONT "No, enabling workaround\n");
}

static void __init check_sigio(void)
{
	if ((access("/dev/ptmx", R_OK) < 0) &&
	    (access("/dev/ptyp0", R_OK) < 0)) {
		printk(UM_KERN_WARNING "No pseudo-terminals available - "
		       "skipping pty SIGIO check\n");
		return;
	}
	check_one_sigio(tty_output);
	check_one_sigio(tty_close);
}

/* Here because it only does the SIGIO testing for now */
void __init os_check_bugs(void)
{
	check_sigio();
}
Commit	Line	Data
8e367065	1	/*
5d33e4d7	2	* Copyright (C) 2002 - 2008 Jeff Dike (jdike@{addtoit,linux.intel}.com)
1da177e4 LT	3	* Licensed under the GPL
	4	*/
	5
	6	#include <unistd.h>
fee64d3c JD	7	#include <errno.h>
	8	#include <fcntl.h>
	9	#include <poll.h>
1da177e4	10	#include <pty.h>
fee64d3c	11	#include <sched.h>
1da177e4	12	#include <signal.h>
1da177e4	13	#include <string.h>
37185b33 AV	14	#include <kern_util.h>
	15	#include <init.h>
	16	#include <os.h>
	17	#include <sigio.h>
	18	#include <um_malloc.h>
1da177e4	19
fee64d3c JD	20	/*
fee64d3c JD	21	* Protected by sigio_lock(), also used by sigio_cleanup, which is an
1da177e4 LT	22	* exitcall.
	23	*/
	24	static int write_sigio_pid = -1;
c4399016	25	static unsigned long write_sigio_stack;
1da177e4	26
fee64d3c JD	27	/*
fee64d3c JD	28	* These arrays are initialized before the sigio thread is started, and
1da177e4 LT	29	* the descriptors closed after it is killed. So, it can't see them change.
	30	* On the UML side, they are changed under the sigio_lock.
	31	*/
5f4e8fd0 JD	32	#define SIGIO_FDS_INIT {-1, -1}
	33
	34	static int write_sigio_fds[2] = SIGIO_FDS_INIT;
	35	static int sigio_private[2] = SIGIO_FDS_INIT;
1da177e4 LT	36
	37	struct pollfds {
	38	struct pollfd *poll;
	39	int size;
	40	int used;
	41	};
	42
fee64d3c JD	43	/*
fee64d3c JD	44	* Protected by sigio_lock(). Used by the sigio thread, but the UML thread
1da177e4 LT	45	* synchronizes with it.
1da177e4 LT	46	*/
19bdf040 JD	47	static struct pollfds current_poll;
	48	static struct pollfds next_poll;
	49	static struct pollfds all_sigio_fds;
1da177e4 LT	50
	51	static int write_sigio_thread(void *unused)
	52	{
	53	struct pollfds *fds, tmp;
	54	struct pollfd *p;
	55	int i, n, respond_fd;
	56	char c;
	57
91d44ff8	58	os_fix_helper_signals();
1da177e4	59	fds = &current_poll;
fee64d3c	60	while (1) {
1da177e4	61	n = poll(fds->poll, fds->used, -1);
fee64d3c JD	62	if (n < 0) {
	63	if (errno == EINTR)
	64	continue;
	65	printk(UM_KERN_ERR "write_sigio_thread : poll returned "
	66	"%d, errno = %d\n", n, errno);
1da177e4	67	}
fee64d3c	68	for (i = 0; i < fds->used; i++) {
1da177e4	69	p = &fds->poll[i];
fee64d3c JD	70	if (p->revents == 0)
	71	continue;
	72	if (p->fd == sigio_private[1]) {
a61f334f JD	73	CATCH_EINTR(n = read(sigio_private[1], &c,
a61f334f JD	74	sizeof(c)));
fee64d3c JD	75	if (n != sizeof(c))
	76	printk(UM_KERN_ERR
	77	"write_sigio_thread : "
19bdf040	78	"read on socket failed, "
a61f334f	79	"err = %d\n", errno);
1da177e4 LT	80	tmp = current_poll;
	81	current_poll = next_poll;
	82	next_poll = tmp;
	83	respond_fd = sigio_private[1];
	84	}
	85	else {
	86	respond_fd = write_sigio_fds[1];
	87	fds->used--;
	88	memmove(&fds->poll[i], &fds->poll[i + 1],
	89	(fds->used - i) * sizeof(*fds->poll));
	90	}
	91
a61f334f	92	CATCH_EINTR(n = write(respond_fd, &c, sizeof(c)));
fee64d3c JD	93	if (n != sizeof(c))
	94	printk(UM_KERN_ERR "write_sigio_thread : "
	95	"write on socket failed, err = %d\n",
	96	errno);
1da177e4 LT	97	}
1da177e4 LT	98	}
1b57e9c2 JD	99
1b57e9c2 JD	100	return 0;
1da177e4 LT	101	}
1da177e4 LT	102
19bdf040	103	static int need_poll(struct pollfds *polls, int n)
1da177e4	104	{
838e56a1 JD	105	struct pollfd *new;
838e56a1 JD	106
fee64d3c	107	if (n <= polls->size)
19bdf040	108	return 0;
838e56a1	109
43f5b308	110	new = uml_kmalloc(n * sizeof(struct pollfd), UM_GFP_ATOMIC);
fee64d3c JD	111	if (new == NULL) {
	112	printk(UM_KERN_ERR "need_poll : failed to allocate new "
	113	"pollfds\n");
19bdf040	114	return -ENOMEM;
1da177e4	115	}
838e56a1 JD	116
	117	memcpy(new, polls->poll, polls->used * sizeof(struct pollfd));
	118	kfree(polls->poll);
	119
	120	polls->poll = new;
19bdf040	121	polls->size = n;
19bdf040	122	return 0;
1da177e4 LT	123	}
1da177e4 LT	124
fee64d3c JD	125	/*
fee64d3c JD	126	* Must be called with sigio_lock held, because it's needed by the marked
19bdf040 JD	127	* critical section.
19bdf040 JD	128	*/
1da177e4 LT	129	static void update_thread(void)
	130	{
	131	unsigned long flags;
	132	int n;
	133	char c;
	134
	135	flags = set_signals(0);
fee64d3c JD	136	CATCH_EINTR(n = write(sigio_private[0], &c, sizeof(c)));
	137	if (n != sizeof(c)) {
	138	printk(UM_KERN_ERR "update_thread : write failed, err = %d\n",
	139	errno);
1da177e4 LT	140	goto fail;
	141	}
	142
a61f334f	143	CATCH_EINTR(n = read(sigio_private[0], &c, sizeof(c)));
fee64d3c JD	144	if (n != sizeof(c)) {
	145	printk(UM_KERN_ERR "update_thread : read failed, err = %d\n",
	146	errno);
1da177e4 LT	147	goto fail;
	148	}
	149
	150	set_signals(flags);
	151	return;
	152	fail:
	153	/* Critical section start */
c4399016	154	if (write_sigio_pid != -1) {
1da177e4	155	os_kill_process(write_sigio_pid, 1);
c4399016 JD	156	free_stack(write_sigio_stack, 0);
c4399016 JD	157	}
1da177e4	158	write_sigio_pid = -1;
8e367065 JD	159	close(sigio_private[0]);
	160	close(sigio_private[1]);
	161	close(write_sigio_fds[0]);
	162	close(write_sigio_fds[1]);
1da177e4 LT	163	/* Critical section end */
	164	set_signals(flags);
	165	}
	166
19bdf040	167	int add_sigio_fd(int fd)
1da177e4	168	{
19bdf040 JD	169	struct pollfd *p;
19bdf040 JD	170	int err = 0, i, n;
1da177e4 LT	171
1da177e4 LT	172	sigio_lock();
fee64d3c JD	173	for (i = 0; i < all_sigio_fds.used; i++) {
fee64d3c JD	174	if (all_sigio_fds.poll[i].fd == fd)
19bdf040 JD	175	break;
19bdf040 JD	176	}
fee64d3c	177	if (i == all_sigio_fds.used)
19bdf040 JD	178	goto out;
	179
	180	p = &all_sigio_fds.poll[i];
	181
fee64d3c JD	182	for (i = 0; i < current_poll.used; i++) {
fee64d3c JD	183	if (current_poll.poll[i].fd == fd)
1da177e4 LT	184	goto out;
	185	}
	186
838e56a1 JD	187	n = current_poll.used;
838e56a1 JD	188	err = need_poll(&next_poll, n + 1);
fee64d3c	189	if (err)
1da177e4 LT	190	goto out;
1da177e4 LT	191
838e56a1 JD	192	memcpy(next_poll.poll, current_poll.poll,
	193	current_poll.used * sizeof(struct pollfd));
	194	next_poll.poll[n] = *p;
	195	next_poll.used = n + 1;
1da177e4 LT	196	update_thread();
	197	out:
	198	sigio_unlock();
19bdf040	199	return err;
1da177e4 LT	200	}
	201
	202	int ignore_sigio_fd(int fd)
	203	{
	204	struct pollfd *p;
	205	int err = 0, i, n = 0;
	206
fee64d3c JD	207	/*
fee64d3c JD	208	* This is called from exitcalls elsewhere in UML - if
61232f2f JD	209	* sigio_cleanup has already run, then update_thread will hang
	210	* or fail because the thread is no longer running.
	211	*/
fee64d3c	212	if (write_sigio_pid == -1)
61232f2f JD	213	return -EIO;
61232f2f JD	214
1da177e4	215	sigio_lock();
fee64d3c JD	216	for (i = 0; i < current_poll.used; i++) {
	217	if (current_poll.poll[i].fd == fd)
	218	break;
1da177e4	219	}
fee64d3c	220	if (i == current_poll.used)
1da177e4	221	goto out;
f206aabb	222
19bdf040	223	err = need_poll(&next_poll, current_poll.used - 1);
fee64d3c	224	if (err)
1da177e4 LT	225	goto out;
1da177e4 LT	226
fee64d3c	227	for (i = 0; i < current_poll.used; i++) {
1da177e4	228	p = &current_poll.poll[i];
fee64d3c	229	if (p->fd != fd)
19bdf040	230	next_poll.poll[n++] = *p;
1da177e4	231	}
838e56a1	232	next_poll.used = current_poll.used - 1;
1da177e4 LT	233
	234	update_thread();
	235	out:
	236	sigio_unlock();
61232f2f	237	return err;
1da177e4 LT	238	}
1da177e4 LT	239
f206aabb	240	static struct pollfd *setup_initial_poll(int fd)
1da177e4 LT	241	{
	242	struct pollfd *p;
	243
43f5b308	244	p = uml_kmalloc(sizeof(struct pollfd), UM_GFP_KERNEL);
b6a2b137	245	if (p == NULL) {
fee64d3c JD	246	printk(UM_KERN_ERR "setup_initial_poll : failed to allocate "
fee64d3c JD	247	"poll\n");
b6a2b137	248	return NULL;
1da177e4	249	}
19bdf040	250	*p = ((struct pollfd) { .fd = fd,
1da177e4 LT	251	.events = POLLIN,
1da177e4 LT	252	.revents = 0 });
b6a2b137	253	return p;
1da177e4 LT	254	}
1da177e4 LT	255
8e64d96a	256	static void write_sigio_workaround(void)
1da177e4	257	{
b6a2b137	258	struct pollfd *p;
1da177e4	259	int err;
b6a2b137 PBG	260	int l_write_sigio_fds[2];
	261	int l_sigio_private[2];
	262	int l_write_sigio_pid;
1da177e4	263
b6a2b137	264	/* We call this tons of times - and most ones we must just fail. */
1da177e4	265	sigio_lock();
b6a2b137 PBG	266	l_write_sigio_pid = write_sigio_pid;
b6a2b137 PBG	267	sigio_unlock();
1da177e4	268
b6a2b137 PBG	269	if (l_write_sigio_pid != -1)
	270	return;
	271
	272	err = os_pipe(l_write_sigio_fds, 1, 1);
fee64d3c JD	273	if (err < 0) {
fee64d3c JD	274	printk(UM_KERN_ERR "write_sigio_workaround - os_pipe 1 failed, "
1da177e4	275	"err = %d\n", -err);
b6a2b137	276	return;
1da177e4	277	}
b6a2b137	278	err = os_pipe(l_sigio_private, 1, 1);
fee64d3c JD	279	if (err < 0) {
fee64d3c JD	280	printk(UM_KERN_ERR "write_sigio_workaround - os_pipe 2 failed, "
1da177e4 LT	281	"err = %d\n", -err);
	282	goto out_close1;
	283	}
b6a2b137 PBG	284
b6a2b137 PBG	285	p = setup_initial_poll(l_sigio_private[1]);
fee64d3c	286	if (!p)
1da177e4 LT	287	goto out_close2;
1da177e4 LT	288
b6a2b137 PBG	289	sigio_lock();
b6a2b137 PBG	290
fee64d3c JD	291	/*
	292	* Did we race? Don't try to optimize this, please, it's not so likely
	293	* to happen, and no more than once at the boot.
	294	*/
	295	if (write_sigio_pid != -1)
5f4e8fd0	296	goto out_free;
1da177e4	297
5f4e8fd0 JD	298	current_poll = ((struct pollfds) { .poll = p,
	299	.used = 1,
	300	.size = 1 });
1da177e4	301
b6a2b137	302	if (write_sigio_irq(l_write_sigio_fds[0]))
5f4e8fd0	303	goto out_clear_poll;
1da177e4	304
b6a2b137 PBG	305	memcpy(write_sigio_fds, l_write_sigio_fds, sizeof(l_write_sigio_fds));
	306	memcpy(sigio_private, l_sigio_private, sizeof(l_sigio_private));
	307
5f4e8fd0	308	write_sigio_pid = run_helper_thread(write_sigio_thread, NULL,
c4399016 JD	309	CLONE_FILES \| CLONE_VM,
c4399016 JD	310	&write_sigio_stack);
b6a2b137	311
5f4e8fd0 JD	312	if (write_sigio_pid < 0)
5f4e8fd0 JD	313	goto out_clear;
1da177e4	314
b6a2b137	315	sigio_unlock();
5f4e8fd0	316	return;
b6a2b137	317
5f4e8fd0	318	out_clear:
b6a2b137	319	write_sigio_pid = -1;
5f4e8fd0 JD	320	write_sigio_fds[0] = -1;
	321	write_sigio_fds[1] = -1;
	322	sigio_private[0] = -1;
	323	sigio_private[1] = -1;
	324	out_clear_poll:
	325	current_poll = ((struct pollfds) { .poll = NULL,
	326	.size = 0,
	327	.used = 0 });
	328	out_free:
5f4e8fd0	329	sigio_unlock();
e6fb54ab	330	kfree(p);
5f4e8fd0	331	out_close2:
8e367065 JD	332	close(l_sigio_private[0]);
8e367065 JD	333	close(l_sigio_private[1]);
5f4e8fd0	334	out_close1:
8e367065 JD	335	close(l_write_sigio_fds[0]);
8e367065 JD	336	close(l_write_sigio_fds[1]);
1da177e4 LT	337	}
1da177e4 LT	338
5d33e4d7	339	void sigio_broken(int fd, int read)
8e64d96a	340	{
19bdf040 JD	341	int err;
19bdf040 JD	342
8e64d96a	343	write_sigio_workaround();
19bdf040 JD	344
	345	sigio_lock();
	346	err = need_poll(&all_sigio_fds, all_sigio_fds.used + 1);
fee64d3c JD	347	if (err) {
	348	printk(UM_KERN_ERR "maybe_sigio_broken - failed to add pollfd "
	349	"for descriptor %d\n", fd);
19bdf040	350	goto out;
04a51e66	351	}
838e56a1	352
19bdf040 JD	353	all_sigio_fds.poll[all_sigio_fds.used++] =
	354	((struct pollfd) { .fd = fd,
	355	.events = read ? POLLIN : POLLOUT,
	356	.revents = 0 });
	357	out:
	358	sigio_unlock();
8e64d96a JD	359	}
8e64d96a JD	360
5d33e4d7 JD	361	/* Changed during early boot */
	362	static int pty_output_sigio;
	363	static int pty_close_sigio;
	364
	365	void maybe_sigio_broken(int fd, int read)
	366	{
	367	if (!isatty(fd))
	368	return;
	369
	370	if ((read \|\| pty_output_sigio) && (!read \|\| pty_close_sigio))
	371	return;
	372
	373	sigio_broken(fd, read);
	374	}
	375
29ac1c21	376	static void sigio_cleanup(void)
1da177e4	377	{
c4399016 JD	378	if (write_sigio_pid == -1)
	379	return;
	380
	381	os_kill_process(write_sigio_pid, 1);
	382	free_stack(write_sigio_stack, 0);
	383	write_sigio_pid = -1;
1da177e4	384	}
29ac1c21 JD	385
29ac1c21 JD	386	__uml_exitcall(sigio_cleanup);
c65badbd JD	387
c65badbd JD	388	/* Used as a flag during SIGIO testing early in boot */
5d33e4d7	389	static int got_sigio;
c65badbd JD	390
	391	static void __init handler(int sig)
	392	{
	393	got_sigio = 1;
	394	}
	395
	396	struct openpty_arg {
	397	int master;
	398	int slave;
	399	int err;
	400	};
	401
	402	static void openpty_cb(void *arg)
	403	{
	404	struct openpty_arg *info = arg;
	405
	406	info->err = 0;
fee64d3c	407	if (openpty(&info->master, &info->slave, NULL, NULL, NULL))
c65badbd JD	408	info->err = -errno;
	409	}
	410
	411	static int async_pty(int master, int slave)
	412	{
	413	int flags;
	414
	415	flags = fcntl(master, F_GETFL);
fee64d3c	416	if (flags < 0)
c65badbd JD	417	return -errno;
c65badbd JD	418
fee64d3c JD	419	if ((fcntl(master, F_SETFL, flags \| O_NONBLOCK \| O_ASYNC) < 0) \|\|
fee64d3c JD	420	(fcntl(master, F_SETOWN, os_getpid()) < 0))
c65badbd JD	421	return -errno;
c65badbd JD	422
fee64d3c	423	if ((fcntl(slave, F_SETFL, flags \| O_NONBLOCK) < 0))
c65badbd JD	424	return -errno;
c65badbd JD	425
c0a9290e	426	return 0;
c65badbd JD	427	}
	428
	429	static void __init check_one_sigio(void (*proc)(int, int))
	430	{
	431	struct sigaction old, new;
	432	struct openpty_arg pty = { .master = -1, .slave = -1 };
	433	int master, slave, err;
	434
	435	initial_thread_cb(openpty_cb, &pty);
fee64d3c JD	436	if (pty.err) {
	437	printk(UM_KERN_ERR "check_one_sigio failed, errno = %d\n",
	438	-pty.err);
c65badbd JD	439	return;
	440	}
	441
	442	master = pty.master;
	443	slave = pty.slave;
	444
fee64d3c JD	445	if ((master == -1) \|\| (slave == -1)) {
	446	printk(UM_KERN_ERR "check_one_sigio failed to allocate a "
	447	"pty\n");
c65badbd JD	448	return;
	449	}
	450
	451	/* Not now, but complain so we now where we failed. */
	452	err = raw(master);
fee64d3c JD	453	if (err < 0) {
	454	printk(UM_KERN_ERR "check_one_sigio : raw failed, errno = %d\n",
	455	-err);
	456	return;
	457	}
c65badbd JD	458
c65badbd JD	459	err = async_pty(master, slave);
fee64d3c JD	460	if (err < 0) {
	461	printk(UM_KERN_ERR "check_one_sigio : sigio_async failed, "
	462	"err = %d\n", -err);
	463	return;
	464	}
	465
	466	if (sigaction(SIGIO, NULL, &old) < 0) {
	467	printk(UM_KERN_ERR "check_one_sigio : sigaction 1 failed, "
	468	"errno = %d\n", errno);
	469	return;
	470	}
c65badbd	471
c65badbd JD	472	new = old;
c65badbd JD	473	new.sa_handler = handler;
fee64d3c JD	474	if (sigaction(SIGIO, &new, NULL) < 0) {
	475	printk(UM_KERN_ERR "check_one_sigio : sigaction 2 failed, "
	476	"errno = %d\n", errno);
	477	return;
	478	}
c65badbd JD	479
	480	got_sigio = 0;
	481	(*proc)(master, slave);
	482
	483	close(master);
	484	close(slave);
	485
fee64d3c JD	486	if (sigaction(SIGIO, &old, NULL) < 0)
	487	printk(UM_KERN_ERR "check_one_sigio : sigaction 3 failed, "
	488	"errno = %d\n", errno);
c65badbd JD	489	}
	490
	491	static void tty_output(int master, int slave)
	492	{
	493	int n;
	494	char buf[512];
	495
fee64d3c	496	printk(UM_KERN_INFO "Checking that host ptys support output SIGIO...");
c65badbd JD	497
	498	memset(buf, 0, sizeof(buf));
	499
fee64d3c JD	500	while (write(master, buf, sizeof(buf)) > 0) ;
	501	if (errno != EAGAIN)
	502	printk(UM_KERN_ERR "tty_output : write failed, errno = %d\n",
	503	errno);
5d33e4d7 JD	504	while (((n = read(slave, buf, sizeof(buf))) > 0) &&
5d33e4d7 JD	505	!({ barrier(); got_sigio; }))
fee64d3c	506	;
c65badbd	507
fee64d3c JD	508	if (got_sigio) {
fee64d3c JD	509	printk(UM_KERN_CONT "Yes\n");
c65badbd	510	pty_output_sigio = 1;
fee64d3c JD	511	} else if (n == -EAGAIN)
	512	printk(UM_KERN_CONT "No, enabling workaround\n");
	513	else
	514	printk(UM_KERN_CONT "tty_output : read failed, err = %d\n", n);
c65badbd JD	515	}
	516
	517	static void tty_close(int master, int slave)
	518	{
fee64d3c JD	519	printk(UM_KERN_INFO "Checking that host ptys support SIGIO on "
fee64d3c JD	520	"close...");
c65badbd JD	521
c65badbd JD	522	close(slave);
fee64d3c JD	523	if (got_sigio) {
fee64d3c JD	524	printk(UM_KERN_CONT "Yes\n");
c65badbd	525	pty_close_sigio = 1;
fee64d3c JD	526	} else
fee64d3c JD	527	printk(UM_KERN_CONT "No, enabling workaround\n");
c65badbd JD	528	}
c65badbd JD	529
99764fa4	530	static void __init check_sigio(void)
c65badbd	531	{
fee64d3c JD	532	if ((access("/dev/ptmx", R_OK) < 0) &&
	533	(access("/dev/ptyp0", R_OK) < 0)) {
	534	printk(UM_KERN_WARNING "No pseudo-terminals available - "
	535	"skipping pty SIGIO check\n");
c65badbd JD	536	return;
	537	}
	538	check_one_sigio(tty_output);
	539	check_one_sigio(tty_close);
	540	}
	541
	542	/* Here because it only does the SIGIO testing for now */
	543	void __init os_check_bugs(void)
	544	{
	545	check_sigio();
	546	}