1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 * Copyright (C) 2002 - 2008 Jeff Dike (jdike@{addtoit,linux.intel}.com)
  4 */
  5
  6#include <linux/minmax.h>
  7#include <unistd.h>
  8#include <errno.h>
  9#include <fcntl.h>
 10#include <poll.h>
 11#include <pty.h>
 12#include <sched.h>
 13#include <signal.h>
 14#include <string.h>
 15#include <kern_util.h>
 16#include <init.h>
 17#include <os.h>
 18#include <sigio.h>
 19#include <um_malloc.h>
 20
 21/*
 22 * Protected by sigio_lock(), also used by sigio_cleanup, which is an
 23 * exitcall.
 24 */
 25static int write_sigio_pid = -1;
 26static unsigned long write_sigio_stack;
 27
 28/*
 29 * These arrays are initialized before the sigio thread is started, and
 30 * the descriptors closed after it is killed.  So, it can't see them change.
 31 * On the UML side, they are changed under the sigio_lock.
 32 */
 33#define SIGIO_FDS_INIT {-1, -1}
 34
 35static int write_sigio_fds[2] = SIGIO_FDS_INIT;
 36static int sigio_private[2] = SIGIO_FDS_INIT;
 37
 38struct pollfds {
 39	struct pollfd *poll;
 40	int size;
 41	int used;
 42};
 43
 44/*
 45 * Protected by sigio_lock().  Used by the sigio thread, but the UML thread
 46 * synchronizes with it.
 47 */
 48static struct pollfds current_poll;
 49static struct pollfds next_poll;
 50static struct pollfds all_sigio_fds;
 51
 52static int write_sigio_thread(void *unused)
 53{
 54	struct pollfds *fds;
 55	struct pollfd *p;
 56	int i, n, respond_fd;
 57	char c;
 58
 59	os_fix_helper_signals();
 60	fds = &current_poll;
 61	while (1) {
 62		n = poll(fds->poll, fds->used, -1);
 63		if (n < 0) {
 64			if (errno == EINTR)
 65				continue;
 66			printk(UM_KERN_ERR "write_sigio_thread : poll returned "
 67			       "%d, errno = %d\n", n, errno);
 68		}
 69		for (i = 0; i < fds->used; i++) {
 70			p = &fds->poll[i];
 71			if (p->revents == 0)
 72				continue;
 73			if (p->fd == sigio_private[1]) {
 74				CATCH_EINTR(n = read(sigio_private[1], &c,
 75						     sizeof(c)));
 76				if (n != sizeof(c))
 77					printk(UM_KERN_ERR
 78					       "write_sigio_thread : "
 79					       "read on socket failed, "
 80					       "err = %d\n", errno);
 81				swap(current_poll, next_poll);
 
 
 82				respond_fd = sigio_private[1];
 83			}
 84			else {
 85				respond_fd = write_sigio_fds[1];
 86				fds->used--;
 87				memmove(&fds->poll[i], &fds->poll[i + 1],
 88					(fds->used - i) * sizeof(*fds->poll));
 89			}
 90
 91			CATCH_EINTR(n = write(respond_fd, &c, sizeof(c)));
 92			if (n != sizeof(c))
 93				printk(UM_KERN_ERR "write_sigio_thread : "
 94				       "write on socket failed, err = %d\n",
 95				       errno);
 96		}
 97	}
 98
 99	return 0;
100}
101
102static int need_poll(struct pollfds *polls, int n)
103{
104	struct pollfd *new;
105
106	if (n <= polls->size)
107		return 0;
108
109	new = uml_kmalloc(n * sizeof(struct pollfd), UM_GFP_ATOMIC);
110	if (new == NULL) {
111		printk(UM_KERN_ERR "need_poll : failed to allocate new "
112		       "pollfds\n");
113		return -ENOMEM;
114	}
115
116	memcpy(new, polls->poll, polls->used * sizeof(struct pollfd));
117	kfree(polls->poll);
118
119	polls->poll = new;
120	polls->size = n;
121	return 0;
122}
123
124/*
125 * Must be called with sigio_lock held, because it's needed by the marked
126 * critical section.
127 */
128static void update_thread(void)
129{
130	unsigned long flags;
131	int n;
132	char c;
133
134	flags = um_set_signals_trace(0);
135	CATCH_EINTR(n = write(sigio_private[0], &c, sizeof(c)));
136	if (n != sizeof(c)) {
137		printk(UM_KERN_ERR "update_thread : write failed, err = %d\n",
138		       errno);
139		goto fail;
140	}
141
142	CATCH_EINTR(n = read(sigio_private[0], &c, sizeof(c)));
143	if (n != sizeof(c)) {
144		printk(UM_KERN_ERR "update_thread : read failed, err = %d\n",
145		       errno);
146		goto fail;
147	}
148
149	um_set_signals_trace(flags);
150	return;
151 fail:
152	/* Critical section start */
153	if (write_sigio_pid != -1) {
154		os_kill_process(write_sigio_pid, 1);
155		free_stack(write_sigio_stack, 0);
156	}
157	write_sigio_pid = -1;
158	close(sigio_private[0]);
159	close(sigio_private[1]);
160	close(write_sigio_fds[0]);
161	close(write_sigio_fds[1]);
162	/* Critical section end */
163	um_set_signals_trace(flags);
164}
165
166int __add_sigio_fd(int fd)
167{
168	struct pollfd *p;
169	int err, i, n;
170
171	for (i = 0; i < all_sigio_fds.used; i++) {
172		if (all_sigio_fds.poll[i].fd == fd)
173			break;
174	}
175	if (i == all_sigio_fds.used)
176		return -ENOSPC;
177
178	p = &all_sigio_fds.poll[i];
179
180	for (i = 0; i < current_poll.used; i++) {
181		if (current_poll.poll[i].fd == fd)
182			return 0;
183	}
184
185	n = current_poll.used;
186	err = need_poll(&next_poll, n + 1);
187	if (err)
188		return err;
189
190	memcpy(next_poll.poll, current_poll.poll,
191	       current_poll.used * sizeof(struct pollfd));
192	next_poll.poll[n] = *p;
193	next_poll.used = n + 1;
194	update_thread();
195
196	return 0;
197}
198
199
200int add_sigio_fd(int fd)
201{
202	int err;
203
204	sigio_lock();
205	err = __add_sigio_fd(fd);
206	sigio_unlock();
207
208	return err;
209}
210
211int __ignore_sigio_fd(int fd)
212{
213	struct pollfd *p;
214	int err, i, n = 0;
215
216	/*
217	 * This is called from exitcalls elsewhere in UML - if
218	 * sigio_cleanup has already run, then update_thread will hang
219	 * or fail because the thread is no longer running.
220	 */
221	if (write_sigio_pid == -1)
222		return -EIO;
223
224	for (i = 0; i < current_poll.used; i++) {
225		if (current_poll.poll[i].fd == fd)
226			break;
227	}
228	if (i == current_poll.used)
229		return -ENOENT;
230
231	err = need_poll(&next_poll, current_poll.used - 1);
232	if (err)
233		return err;
234
235	for (i = 0; i < current_poll.used; i++) {
236		p = &current_poll.poll[i];
237		if (p->fd != fd)
238			next_poll.poll[n++] = *p;
239	}
240	next_poll.used = current_poll.used - 1;
241
242	update_thread();
243
244	return 0;
245}
246
247int ignore_sigio_fd(int fd)
248{
249	int err;
250
251	sigio_lock();
252	err = __ignore_sigio_fd(fd);
253	sigio_unlock();
254
255	return err;
256}
257
258static struct pollfd *setup_initial_poll(int fd)
259{
260	struct pollfd *p;
261
262	p = uml_kmalloc(sizeof(struct pollfd), UM_GFP_KERNEL);
263	if (p == NULL) {
264		printk(UM_KERN_ERR "setup_initial_poll : failed to allocate "
265		       "poll\n");
266		return NULL;
267	}
268	*p = ((struct pollfd) { .fd		= fd,
269				.events 	= POLLIN,
270				.revents 	= 0 });
271	return p;
272}
273
274static void write_sigio_workaround(void)
275{
276	struct pollfd *p;
277	int err;
278	int l_write_sigio_fds[2];
279	int l_sigio_private[2];
280	int l_write_sigio_pid;
281
282	/* We call this *tons* of times - and most ones we must just fail. */
283	sigio_lock();
284	l_write_sigio_pid = write_sigio_pid;
285	sigio_unlock();
286
287	if (l_write_sigio_pid != -1)
288		return;
289
290	err = os_pipe(l_write_sigio_fds, 1, 1);
291	if (err < 0) {
292		printk(UM_KERN_ERR "write_sigio_workaround - os_pipe 1 failed, "
293		       "err = %d\n", -err);
294		return;
295	}
296	err = os_pipe(l_sigio_private, 1, 1);
297	if (err < 0) {
298		printk(UM_KERN_ERR "write_sigio_workaround - os_pipe 2 failed, "
299		       "err = %d\n", -err);
300		goto out_close1;
301	}
302
303	p = setup_initial_poll(l_sigio_private[1]);
304	if (!p)
305		goto out_close2;
306
307	sigio_lock();
308
309	/*
310	 * Did we race? Don't try to optimize this, please, it's not so likely
311	 * to happen, and no more than once at the boot.
312	 */
313	if (write_sigio_pid != -1)
314		goto out_free;
315
316	current_poll = ((struct pollfds) { .poll 	= p,
317					   .used 	= 1,
318					   .size 	= 1 });
319
320	if (write_sigio_irq(l_write_sigio_fds[0]))
321		goto out_clear_poll;
322
323	memcpy(write_sigio_fds, l_write_sigio_fds, sizeof(l_write_sigio_fds));
324	memcpy(sigio_private, l_sigio_private, sizeof(l_sigio_private));
325
326	write_sigio_pid = run_helper_thread(write_sigio_thread, NULL,
327					    CLONE_FILES | CLONE_VM,
328					    &write_sigio_stack);
329
330	if (write_sigio_pid < 0)
331		goto out_clear;
332
333	sigio_unlock();
334	return;
335
336out_clear:
337	write_sigio_pid = -1;
338	write_sigio_fds[0] = -1;
339	write_sigio_fds[1] = -1;
340	sigio_private[0] = -1;
341	sigio_private[1] = -1;
342out_clear_poll:
343	current_poll = ((struct pollfds) { .poll	= NULL,
344					   .size	= 0,
345					   .used	= 0 });
346out_free:
347	sigio_unlock();
348	kfree(p);
349out_close2:
350	close(l_sigio_private[0]);
351	close(l_sigio_private[1]);
352out_close1:
353	close(l_write_sigio_fds[0]);
354	close(l_write_sigio_fds[1]);
355}
356
357void sigio_broken(int fd)
358{
359	int err;
360
361	write_sigio_workaround();
362
363	sigio_lock();
364	err = need_poll(&all_sigio_fds, all_sigio_fds.used + 1);
365	if (err) {
366		printk(UM_KERN_ERR "maybe_sigio_broken - failed to add pollfd "
367		       "for descriptor %d\n", fd);
368		goto out;
369	}
370
371	all_sigio_fds.poll[all_sigio_fds.used++] =
372		((struct pollfd) { .fd  	= fd,
373				   .events 	= POLLIN,
374				   .revents 	= 0 });
375out:
376	sigio_unlock();
377}
378
379/* Changed during early boot */
380static int pty_output_sigio;
381
382void maybe_sigio_broken(int fd)
383{
384	if (!isatty(fd))
385		return;
386
387	if (pty_output_sigio)
388		return;
389
390	sigio_broken(fd);
391}
392
393static void sigio_cleanup(void)
394{
395	if (write_sigio_pid == -1)
396		return;
397
398	os_kill_process(write_sigio_pid, 1);
399	free_stack(write_sigio_stack, 0);
400	write_sigio_pid = -1;
401}
402
403__uml_exitcall(sigio_cleanup);
404
405/* Used as a flag during SIGIO testing early in boot */
406static int got_sigio;
407
408static void __init handler(int sig)
409{
410	got_sigio = 1;
411}
412
413struct openpty_arg {
414	int master;
415	int slave;
416	int err;
417};
418
419static void openpty_cb(void *arg)
420{
421	struct openpty_arg *info = arg;
422
423	info->err = 0;
424	if (openpty(&info->master, &info->slave, NULL, NULL, NULL))
425		info->err = -errno;
426}
427
428static int async_pty(int master, int slave)
429{
430	int flags;
431
432	flags = fcntl(master, F_GETFL);
433	if (flags < 0)
434		return -errno;
435
436	if ((fcntl(master, F_SETFL, flags | O_NONBLOCK | O_ASYNC) < 0) ||
437	    (fcntl(master, F_SETOWN, os_getpid()) < 0))
438		return -errno;
439
440	if ((fcntl(slave, F_SETFL, flags | O_NONBLOCK) < 0))
441		return -errno;
442
443	return 0;
444}
445
446static void __init check_one_sigio(void (*proc)(int, int))
447{
448	struct sigaction old, new;
449	struct openpty_arg pty = { .master = -1, .slave = -1 };
450	int master, slave, err;
451
452	initial_thread_cb(openpty_cb, &pty);
453	if (pty.err) {
454		printk(UM_KERN_ERR "check_one_sigio failed, errno = %d\n",
455		       -pty.err);
456		return;
457	}
458
459	master = pty.master;
460	slave = pty.slave;
461
462	if ((master == -1) || (slave == -1)) {
463		printk(UM_KERN_ERR "check_one_sigio failed to allocate a "
464		       "pty\n");
465		return;
466	}
467
468	/* Not now, but complain so we now where we failed. */
469	err = raw(master);
470	if (err < 0) {
471		printk(UM_KERN_ERR "check_one_sigio : raw failed, errno = %d\n",
472		      -err);
473		return;
474	}
475
476	err = async_pty(master, slave);
477	if (err < 0) {
478		printk(UM_KERN_ERR "check_one_sigio : sigio_async failed, "
479		       "err = %d\n", -err);
480		return;
481	}
482
483	if (sigaction(SIGIO, NULL, &old) < 0) {
484		printk(UM_KERN_ERR "check_one_sigio : sigaction 1 failed, "
485		       "errno = %d\n", errno);
486		return;
487	}
488
489	new = old;
490	new.sa_handler = handler;
491	if (sigaction(SIGIO, &new, NULL) < 0) {
492		printk(UM_KERN_ERR "check_one_sigio : sigaction 2 failed, "
493		       "errno = %d\n", errno);
494		return;
495	}
496
497	got_sigio = 0;
498	(*proc)(master, slave);
499
500	close(master);
501	close(slave);
502
503	if (sigaction(SIGIO, &old, NULL) < 0)
504		printk(UM_KERN_ERR "check_one_sigio : sigaction 3 failed, "
505		       "errno = %d\n", errno);
506}
507
508static void tty_output(int master, int slave)
509{
510	int n;
511	char buf[512];
512
513	printk(UM_KERN_INFO "Checking that host ptys support output SIGIO...");
514
515	memset(buf, 0, sizeof(buf));
516
517	while (write(master, buf, sizeof(buf)) > 0) ;
518	if (errno != EAGAIN)
519		printk(UM_KERN_ERR "tty_output : write failed, errno = %d\n",
520		       errno);
521	while (((n = read(slave, buf, sizeof(buf))) > 0) &&
522	       !({ barrier(); got_sigio; }))
523		;
524
525	if (got_sigio) {
526		printk(UM_KERN_CONT "Yes\n");
527		pty_output_sigio = 1;
528	} else if (n == -EAGAIN)
529		printk(UM_KERN_CONT "No, enabling workaround\n");
530	else
531		printk(UM_KERN_CONT "tty_output : read failed, err = %d\n", n);
532}
533
534static void __init check_sigio(void)
535{
536	if ((access("/dev/ptmx", R_OK) < 0) &&
537	    (access("/dev/ptyp0", R_OK) < 0)) {
538		printk(UM_KERN_WARNING "No pseudo-terminals available - "
539		       "skipping pty SIGIO check\n");
540		return;
541	}
542	check_one_sigio(tty_output);
543}
544
545/* Here because it only does the SIGIO testing for now */
546void __init os_check_bugs(void)
547{
548	check_sigio();
549}

  1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 * Copyright (C) 2002 - 2008 Jeff Dike (jdike@{addtoit,linux.intel}.com)
  4 */
  5
 
  6#include <unistd.h>
  7#include <errno.h>
  8#include <fcntl.h>
  9#include <poll.h>
 10#include <pty.h>
 11#include <sched.h>
 12#include <signal.h>
 13#include <string.h>
 14#include <kern_util.h>
 15#include <init.h>
 16#include <os.h>
 17#include <sigio.h>
 18#include <um_malloc.h>
 19
 20/*
 21 * Protected by sigio_lock(), also used by sigio_cleanup, which is an
 22 * exitcall.
 23 */
 24static int write_sigio_pid = -1;
 25static unsigned long write_sigio_stack;
 26
 27/*
 28 * These arrays are initialized before the sigio thread is started, and
 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 */
 32#define SIGIO_FDS_INIT {-1, -1}
 33
 34static int write_sigio_fds[2] = SIGIO_FDS_INIT;
 35static int sigio_private[2] = SIGIO_FDS_INIT;
 36
 37struct pollfds {
 38	struct pollfd *poll;
 39	int size;
 40	int used;
 41};
 42
 43/*
 44 * Protected by sigio_lock().  Used by the sigio thread, but the UML thread
 45 * synchronizes with it.
 46 */
 47static struct pollfds current_poll;
 48static struct pollfds next_poll;
 49static struct pollfds all_sigio_fds;
 50
 51static 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
 58	os_fix_helper_signals();
 59	fds = &current_poll;
 60	while (1) {
 61		n = poll(fds->poll, fds->used, -1);
 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);
 67		}
 68		for (i = 0; i < fds->used; i++) {
 69			p = &fds->poll[i];
 70			if (p->revents == 0)
 71				continue;
 72			if (p->fd == sigio_private[1]) {
 73				CATCH_EINTR(n = read(sigio_private[1], &c,
 74						     sizeof(c)));
 75				if (n != sizeof(c))
 76					printk(UM_KERN_ERR
 77					       "write_sigio_thread : "
 78					       "read on socket failed, "
 79					       "err = %d\n", errno);
 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
 92			CATCH_EINTR(n = write(respond_fd, &c, sizeof(c)));
 93			if (n != sizeof(c))
 94				printk(UM_KERN_ERR "write_sigio_thread : "
 95				       "write on socket failed, err = %d\n",
 96				       errno);
 97		}
 98	}
 99
100	return 0;
101}
102
103static int need_poll(struct pollfds *polls, int n)
104{
105	struct pollfd *new;
106
107	if (n <= polls->size)
108		return 0;
109
110	new = uml_kmalloc(n * sizeof(struct pollfd), UM_GFP_ATOMIC);
111	if (new == NULL) {
112		printk(UM_KERN_ERR "need_poll : failed to allocate new "
113		       "pollfds\n");
114		return -ENOMEM;
115	}
116
117	memcpy(new, polls->poll, polls->used * sizeof(struct pollfd));
118	kfree(polls->poll);
119
120	polls->poll = new;
121	polls->size = n;
122	return 0;
123}
124
125/*
126 * Must be called with sigio_lock held, because it's needed by the marked
127 * critical section.
128 */
129static void update_thread(void)
130{
131	unsigned long flags;
132	int n;
133	char c;
134
135	flags = um_set_signals_trace(0);
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);
140		goto fail;
141	}
142
143	CATCH_EINTR(n = read(sigio_private[0], &c, sizeof(c)));
144	if (n != sizeof(c)) {
145		printk(UM_KERN_ERR "update_thread : read failed, err = %d\n",
146		       errno);
147		goto fail;
148	}
149
150	um_set_signals_trace(flags);
151	return;
152 fail:
153	/* Critical section start */
154	if (write_sigio_pid != -1) {
155		os_kill_process(write_sigio_pid, 1);
156		free_stack(write_sigio_stack, 0);
157	}
158	write_sigio_pid = -1;
159	close(sigio_private[0]);
160	close(sigio_private[1]);
161	close(write_sigio_fds[0]);
162	close(write_sigio_fds[1]);
163	/* Critical section end */
164	um_set_signals_trace(flags);
165}
166
167int __add_sigio_fd(int fd)
168{
169	struct pollfd *p;
170	int err, i, n;
171
172	for (i = 0; i < all_sigio_fds.used; i++) {
173		if (all_sigio_fds.poll[i].fd == fd)
174			break;
175	}
176	if (i == all_sigio_fds.used)
177		return -ENOSPC;
178
179	p = &all_sigio_fds.poll[i];
180
181	for (i = 0; i < current_poll.used; i++) {
182		if (current_poll.poll[i].fd == fd)
183			return 0;
184	}
185
186	n = current_poll.used;
187	err = need_poll(&next_poll, n + 1);
188	if (err)
189		return err;
190
191	memcpy(next_poll.poll, current_poll.poll,
192	       current_poll.used * sizeof(struct pollfd));
193	next_poll.poll[n] = *p;
194	next_poll.used = n + 1;
195	update_thread();
196
197	return 0;
198}
199
200
201int add_sigio_fd(int fd)
202{
203	int err;
204
205	sigio_lock();
206	err = __add_sigio_fd(fd);
207	sigio_unlock();
208
209	return err;
210}
211
212int __ignore_sigio_fd(int fd)
213{
214	struct pollfd *p;
215	int err, i, n = 0;
216
217	/*
218	 * This is called from exitcalls elsewhere in UML - if
219	 * sigio_cleanup has already run, then update_thread will hang
220	 * or fail because the thread is no longer running.
221	 */
222	if (write_sigio_pid == -1)
223		return -EIO;
224
225	for (i = 0; i < current_poll.used; i++) {
226		if (current_poll.poll[i].fd == fd)
227			break;
228	}
229	if (i == current_poll.used)
230		return -ENOENT;
231
232	err = need_poll(&next_poll, current_poll.used - 1);
233	if (err)
234		return err;
235
236	for (i = 0; i < current_poll.used; i++) {
237		p = &current_poll.poll[i];
238		if (p->fd != fd)
239			next_poll.poll[n++] = *p;
240	}
241	next_poll.used = current_poll.used - 1;
242
243	update_thread();
244
245	return 0;
246}
247
248int ignore_sigio_fd(int fd)
249{
250	int err;
251
252	sigio_lock();
253	err = __ignore_sigio_fd(fd);
254	sigio_unlock();
255
256	return err;
257}
258
259static struct pollfd *setup_initial_poll(int fd)
260{
261	struct pollfd *p;
262
263	p = uml_kmalloc(sizeof(struct pollfd), UM_GFP_KERNEL);
264	if (p == NULL) {
265		printk(UM_KERN_ERR "setup_initial_poll : failed to allocate "
266		       "poll\n");
267		return NULL;
268	}
269	*p = ((struct pollfd) { .fd		= fd,
270				.events 	= POLLIN,
271				.revents 	= 0 });
272	return p;
273}
274
275static void write_sigio_workaround(void)
276{
277	struct pollfd *p;
278	int err;
279	int l_write_sigio_fds[2];
280	int l_sigio_private[2];
281	int l_write_sigio_pid;
282
283	/* We call this *tons* of times - and most ones we must just fail. */
284	sigio_lock();
285	l_write_sigio_pid = write_sigio_pid;
286	sigio_unlock();
287
288	if (l_write_sigio_pid != -1)
289		return;
290
291	err = os_pipe(l_write_sigio_fds, 1, 1);
292	if (err < 0) {
293		printk(UM_KERN_ERR "write_sigio_workaround - os_pipe 1 failed, "
294		       "err = %d\n", -err);
295		return;
296	}
297	err = os_pipe(l_sigio_private, 1, 1);
298	if (err < 0) {
299		printk(UM_KERN_ERR "write_sigio_workaround - os_pipe 2 failed, "
300		       "err = %d\n", -err);
301		goto out_close1;
302	}
303
304	p = setup_initial_poll(l_sigio_private[1]);
305	if (!p)
306		goto out_close2;
307
308	sigio_lock();
309
310	/*
311	 * Did we race? Don't try to optimize this, please, it's not so likely
312	 * to happen, and no more than once at the boot.
313	 */
314	if (write_sigio_pid != -1)
315		goto out_free;
316
317	current_poll = ((struct pollfds) { .poll 	= p,
318					   .used 	= 1,
319					   .size 	= 1 });
320
321	if (write_sigio_irq(l_write_sigio_fds[0]))
322		goto out_clear_poll;
323
324	memcpy(write_sigio_fds, l_write_sigio_fds, sizeof(l_write_sigio_fds));
325	memcpy(sigio_private, l_sigio_private, sizeof(l_sigio_private));
326
327	write_sigio_pid = run_helper_thread(write_sigio_thread, NULL,
328					    CLONE_FILES | CLONE_VM,
329					    &write_sigio_stack);
330
331	if (write_sigio_pid < 0)
332		goto out_clear;
333
334	sigio_unlock();
335	return;
336
337out_clear:
338	write_sigio_pid = -1;
339	write_sigio_fds[0] = -1;
340	write_sigio_fds[1] = -1;
341	sigio_private[0] = -1;
342	sigio_private[1] = -1;
343out_clear_poll:
344	current_poll = ((struct pollfds) { .poll	= NULL,
345					   .size	= 0,
346					   .used	= 0 });
347out_free:
348	sigio_unlock();
349	kfree(p);
350out_close2:
351	close(l_sigio_private[0]);
352	close(l_sigio_private[1]);
353out_close1:
354	close(l_write_sigio_fds[0]);
355	close(l_write_sigio_fds[1]);
356}
357
358void sigio_broken(int fd)
359{
360	int err;
361
362	write_sigio_workaround();
363
364	sigio_lock();
365	err = need_poll(&all_sigio_fds, all_sigio_fds.used + 1);
366	if (err) {
367		printk(UM_KERN_ERR "maybe_sigio_broken - failed to add pollfd "
368		       "for descriptor %d\n", fd);
369		goto out;
370	}
371
372	all_sigio_fds.poll[all_sigio_fds.used++] =
373		((struct pollfd) { .fd  	= fd,
374				   .events 	= POLLIN,
375				   .revents 	= 0 });
376out:
377	sigio_unlock();
378}
379
380/* Changed during early boot */
381static int pty_output_sigio;
382
383void maybe_sigio_broken(int fd)
384{
385	if (!isatty(fd))
386		return;
387
388	if (pty_output_sigio)
389		return;
390
391	sigio_broken(fd);
392}
393
394static void sigio_cleanup(void)
395{
396	if (write_sigio_pid == -1)
397		return;
398
399	os_kill_process(write_sigio_pid, 1);
400	free_stack(write_sigio_stack, 0);
401	write_sigio_pid = -1;
402}
403
404__uml_exitcall(sigio_cleanup);
405
406/* Used as a flag during SIGIO testing early in boot */
407static int got_sigio;
408
409static void __init handler(int sig)
410{
411	got_sigio = 1;
412}
413
414struct openpty_arg {
415	int master;
416	int slave;
417	int err;
418};
419
420static void openpty_cb(void *arg)
421{
422	struct openpty_arg *info = arg;
423
424	info->err = 0;
425	if (openpty(&info->master, &info->slave, NULL, NULL, NULL))
426		info->err = -errno;
427}
428
429static int async_pty(int master, int slave)
430{
431	int flags;
432
433	flags = fcntl(master, F_GETFL);
434	if (flags < 0)
435		return -errno;
436
437	if ((fcntl(master, F_SETFL, flags | O_NONBLOCK | O_ASYNC) < 0) ||
438	    (fcntl(master, F_SETOWN, os_getpid()) < 0))
439		return -errno;
440
441	if ((fcntl(slave, F_SETFL, flags | O_NONBLOCK) < 0))
442		return -errno;
443
444	return 0;
445}
446
447static void __init check_one_sigio(void (*proc)(int, int))
448{
449	struct sigaction old, new;
450	struct openpty_arg pty = { .master = -1, .slave = -1 };
451	int master, slave, err;
452
453	initial_thread_cb(openpty_cb, &pty);
454	if (pty.err) {
455		printk(UM_KERN_ERR "check_one_sigio failed, errno = %d\n",
456		       -pty.err);
457		return;
458	}
459
460	master = pty.master;
461	slave = pty.slave;
462
463	if ((master == -1) || (slave == -1)) {
464		printk(UM_KERN_ERR "check_one_sigio failed to allocate a "
465		       "pty\n");
466		return;
467	}
468
469	/* Not now, but complain so we now where we failed. */
470	err = raw(master);
471	if (err < 0) {
472		printk(UM_KERN_ERR "check_one_sigio : raw failed, errno = %d\n",
473		      -err);
474		return;
475	}
476
477	err = async_pty(master, slave);
478	if (err < 0) {
479		printk(UM_KERN_ERR "check_one_sigio : sigio_async failed, "
480		       "err = %d\n", -err);
481		return;
482	}
483
484	if (sigaction(SIGIO, NULL, &old) < 0) {
485		printk(UM_KERN_ERR "check_one_sigio : sigaction 1 failed, "
486		       "errno = %d\n", errno);
487		return;
488	}
489
490	new = old;
491	new.sa_handler = handler;
492	if (sigaction(SIGIO, &new, NULL) < 0) {
493		printk(UM_KERN_ERR "check_one_sigio : sigaction 2 failed, "
494		       "errno = %d\n", errno);
495		return;
496	}
497
498	got_sigio = 0;
499	(*proc)(master, slave);
500
501	close(master);
502	close(slave);
503
504	if (sigaction(SIGIO, &old, NULL) < 0)
505		printk(UM_KERN_ERR "check_one_sigio : sigaction 3 failed, "
506		       "errno = %d\n", errno);
507}
508
509static void tty_output(int master, int slave)
510{
511	int n;
512	char buf[512];
513
514	printk(UM_KERN_INFO "Checking that host ptys support output SIGIO...");
515
516	memset(buf, 0, sizeof(buf));
517
518	while (write(master, buf, sizeof(buf)) > 0) ;
519	if (errno != EAGAIN)
520		printk(UM_KERN_ERR "tty_output : write failed, errno = %d\n",
521		       errno);
522	while (((n = read(slave, buf, sizeof(buf))) > 0) &&
523	       !({ barrier(); got_sigio; }))
524		;
525
526	if (got_sigio) {
527		printk(UM_KERN_CONT "Yes\n");
528		pty_output_sigio = 1;
529	} else if (n == -EAGAIN)
530		printk(UM_KERN_CONT "No, enabling workaround\n");
531	else
532		printk(UM_KERN_CONT "tty_output : read failed, err = %d\n", n);
533}
534
535static void __init check_sigio(void)
536{
537	if ((access("/dev/ptmx", R_OK) < 0) &&
538	    (access("/dev/ptyp0", R_OK) < 0)) {
539		printk(UM_KERN_WARNING "No pseudo-terminals available - "
540		       "skipping pty SIGIO check\n");
541		return;
542	}
543	check_one_sigio(tty_output);
544}
545
546/* Here because it only does the SIGIO testing for now */
547void __init os_check_bugs(void)
548{
549	check_sigio();
550}