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}

  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_set_pdeathsig();
 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				tmp = current_poll;
 82				current_poll = next_poll;
 83				next_poll = tmp;
 84				respond_fd = sigio_private[1];
 85			}
 86			else {
 87				respond_fd = write_sigio_fds[1];
 88				fds->used--;
 89				memmove(&fds->poll[i], &fds->poll[i + 1],
 90					(fds->used - i) * sizeof(*fds->poll));
 91			}
 92
 93			CATCH_EINTR(n = write(respond_fd, &c, sizeof(c)));
 94			if (n != sizeof(c))
 95				printk(UM_KERN_ERR "write_sigio_thread : "
 96				       "write on socket failed, err = %d\n",
 97				       errno);
 98		}
 99	}
100
101	return 0;
102}
103
104static int need_poll(struct pollfds *polls, int n)
105{
106	struct pollfd *new;
107
108	if (n <= polls->size)
109		return 0;
110
111	new = uml_kmalloc(n * sizeof(struct pollfd), UM_GFP_ATOMIC);
112	if (new == NULL) {
113		printk(UM_KERN_ERR "need_poll : failed to allocate new "
114		       "pollfds\n");
115		return -ENOMEM;
116	}
117
118	memcpy(new, polls->poll, polls->used * sizeof(struct pollfd));
119	kfree(polls->poll);
120
121	polls->poll = new;
122	polls->size = n;
123	return 0;
124}
125
126/*
127 * Must be called with sigio_lock held, because it's needed by the marked
128 * critical section.
129 */
130static void update_thread(void)
131{
132	unsigned long flags;
133	int n;
134	char c;
135
136	flags = um_set_signals_trace(0);
137	CATCH_EINTR(n = write(sigio_private[0], &c, sizeof(c)));
138	if (n != sizeof(c)) {
139		printk(UM_KERN_ERR "update_thread : write failed, err = %d\n",
140		       errno);
141		goto fail;
142	}
143
144	CATCH_EINTR(n = read(sigio_private[0], &c, sizeof(c)));
145	if (n != sizeof(c)) {
146		printk(UM_KERN_ERR "update_thread : read failed, err = %d\n",
147		       errno);
148		goto fail;
149	}
150
151	um_set_signals_trace(flags);
152	return;
153 fail:
154	/* Critical section start */
155	if (write_sigio_pid != -1) {
156		os_kill_process(write_sigio_pid, 1);
157		free_stack(write_sigio_stack, 0);
158	}
159	write_sigio_pid = -1;
160	close(sigio_private[0]);
161	close(sigio_private[1]);
162	close(write_sigio_fds[0]);
163	close(write_sigio_fds[1]);
164	/* Critical section end */
165	um_set_signals_trace(flags);
166}
167
168int __add_sigio_fd(int fd)
169{
170	struct pollfd *p;
171	int err, i, n;
172
173	for (i = 0; i < all_sigio_fds.used; i++) {
174		if (all_sigio_fds.poll[i].fd == fd)
175			break;
176	}
177	if (i == all_sigio_fds.used)
178		return -ENOSPC;
179
180	p = &all_sigio_fds.poll[i];
181
182	for (i = 0; i < current_poll.used; i++) {
183		if (current_poll.poll[i].fd == fd)
184			return 0;
185	}
186
187	n = current_poll.used;
188	err = need_poll(&next_poll, n + 1);
189	if (err)
190		return err;
191
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;
196	update_thread();
197
198	return 0;
199}
200
201
202int add_sigio_fd(int fd)
203{
204	int err;
205
206	sigio_lock();
207	err = __add_sigio_fd(fd);
208	sigio_unlock();
209
210	return err;
211}
212
213int __ignore_sigio_fd(int fd)
214{
215	struct pollfd *p;
216	int err, i, n = 0;
217
218	/*
219	 * This is called from exitcalls elsewhere in UML - if
220	 * sigio_cleanup has already run, then update_thread will hang
221	 * or fail because the thread is no longer running.
222	 */
223	if (write_sigio_pid == -1)
224		return -EIO;
225
226	for (i = 0; i < current_poll.used; i++) {
227		if (current_poll.poll[i].fd == fd)
228			break;
229	}
230	if (i == current_poll.used)
231		return -ENOENT;
232
233	err = need_poll(&next_poll, current_poll.used - 1);
234	if (err)
235		return err;
236
237	for (i = 0; i < current_poll.used; i++) {
238		p = &current_poll.poll[i];
239		if (p->fd != fd)
240			next_poll.poll[n++] = *p;
241	}
242	next_poll.used = current_poll.used - 1;
243
244	update_thread();
245
246	return 0;
247}
248
249int ignore_sigio_fd(int fd)
250{
251	int err;
252
253	sigio_lock();
254	err = __ignore_sigio_fd(fd);
255	sigio_unlock();
256
257	return err;
258}
259
260static struct pollfd *setup_initial_poll(int fd)
261{
262	struct pollfd *p;
263
264	p = uml_kmalloc(sizeof(struct pollfd), UM_GFP_KERNEL);
265	if (p == NULL) {
266		printk(UM_KERN_ERR "setup_initial_poll : failed to allocate "
267		       "poll\n");
268		return NULL;
269	}
270	*p = ((struct pollfd) { .fd		= fd,
271				.events 	= POLLIN,
272				.revents 	= 0 });
273	return p;
274}
275
276static void write_sigio_workaround(void)
277{
278	struct pollfd *p;
279	int err;
280	int l_write_sigio_fds[2];
281	int l_sigio_private[2];
282	int l_write_sigio_pid;
283
284	/* We call this *tons* of times - and most ones we must just fail. */
285	sigio_lock();
286	l_write_sigio_pid = write_sigio_pid;
287	sigio_unlock();
288
289	if (l_write_sigio_pid != -1)
290		return;
291
292	err = os_pipe(l_write_sigio_fds, 1, 1);
293	if (err < 0) {
294		printk(UM_KERN_ERR "write_sigio_workaround - os_pipe 1 failed, "
295		       "err = %d\n", -err);
296		return;
297	}
298	err = os_pipe(l_sigio_private, 1, 1);
299	if (err < 0) {
300		printk(UM_KERN_ERR "write_sigio_workaround - os_pipe 2 failed, "
301		       "err = %d\n", -err);
302		goto out_close1;
303	}
304
305	p = setup_initial_poll(l_sigio_private[1]);
306	if (!p)
307		goto out_close2;
308
309	sigio_lock();
310
311	/*
312	 * Did we race? Don't try to optimize this, please, it's not so likely
313	 * to happen, and no more than once at the boot.
314	 */
315	if (write_sigio_pid != -1)
316		goto out_free;
317
318	current_poll = ((struct pollfds) { .poll 	= p,
319					   .used 	= 1,
320					   .size 	= 1 });
321
322	if (write_sigio_irq(l_write_sigio_fds[0]))
323		goto out_clear_poll;
324
325	memcpy(write_sigio_fds, l_write_sigio_fds, sizeof(l_write_sigio_fds));
326	memcpy(sigio_private, l_sigio_private, sizeof(l_sigio_private));
327
328	write_sigio_pid = run_helper_thread(write_sigio_thread, NULL,
329					    CLONE_FILES | CLONE_VM,
330					    &write_sigio_stack);
331
332	if (write_sigio_pid < 0)
333		goto out_clear;
334
335	sigio_unlock();
336	return;
337
338out_clear:
339	write_sigio_pid = -1;
340	write_sigio_fds[0] = -1;
341	write_sigio_fds[1] = -1;
342	sigio_private[0] = -1;
343	sigio_private[1] = -1;
344out_clear_poll:
345	current_poll = ((struct pollfds) { .poll	= NULL,
346					   .size	= 0,
347					   .used	= 0 });
348out_free:
349	sigio_unlock();
350	kfree(p);
351out_close2:
352	close(l_sigio_private[0]);
353	close(l_sigio_private[1]);
354out_close1:
355	close(l_write_sigio_fds[0]);
356	close(l_write_sigio_fds[1]);
357}
358
359void sigio_broken(int fd)
360{
361	int err;
362
363	write_sigio_workaround();
364
365	sigio_lock();
366	err = need_poll(&all_sigio_fds, all_sigio_fds.used + 1);
367	if (err) {
368		printk(UM_KERN_ERR "maybe_sigio_broken - failed to add pollfd "
369		       "for descriptor %d\n", fd);
370		goto out;
371	}
372
373	all_sigio_fds.poll[all_sigio_fds.used++] =
374		((struct pollfd) { .fd  	= fd,
375				   .events 	= POLLIN,
376				   .revents 	= 0 });
377out:
378	sigio_unlock();
379}
380
381/* Changed during early boot */
382static int pty_output_sigio;
383
384void maybe_sigio_broken(int fd)
385{
386	if (!isatty(fd))
387		return;
388
389	if (pty_output_sigio)
390		return;
391
392	sigio_broken(fd);
393}
394
395static void sigio_cleanup(void)
396{
397	if (write_sigio_pid == -1)
398		return;
399
400	os_kill_process(write_sigio_pid, 1);
401	free_stack(write_sigio_stack, 0);
402	write_sigio_pid = -1;
403}
404
405__uml_exitcall(sigio_cleanup);
406
407/* Used as a flag during SIGIO testing early in boot */
408static int got_sigio;
409
410static void __init handler(int sig)
411{
412	got_sigio = 1;
413}
414
415struct openpty_arg {
416	int master;
417	int slave;
418	int err;
419};
420
421static void openpty_cb(void *arg)
422{
423	struct openpty_arg *info = arg;
424
425	info->err = 0;
426	if (openpty(&info->master, &info->slave, NULL, NULL, NULL))
427		info->err = -errno;
428}
429
430static int async_pty(int master, int slave)
431{
432	int flags;
433
434	flags = fcntl(master, F_GETFL);
435	if (flags < 0)
436		return -errno;
437
438	if ((fcntl(master, F_SETFL, flags | O_NONBLOCK | O_ASYNC) < 0) ||
439	    (fcntl(master, F_SETOWN, os_getpid()) < 0))
440		return -errno;
441
442	if ((fcntl(slave, F_SETFL, flags | O_NONBLOCK) < 0))
443		return -errno;
444
445	return 0;
446}
447
448static void __init check_one_sigio(void (*proc)(int, int))
449{
450	struct sigaction old, new;
451	struct openpty_arg pty = { .master = -1, .slave = -1 };
452	int master, slave, err;
453
454	initial_thread_cb(openpty_cb, &pty);
455	if (pty.err) {
456		printk(UM_KERN_ERR "check_one_sigio failed, errno = %d\n",
457		       -pty.err);
458		return;
459	}
460
461	master = pty.master;
462	slave = pty.slave;
463
464	if ((master == -1) || (slave == -1)) {
465		printk(UM_KERN_ERR "check_one_sigio failed to allocate a "
466		       "pty\n");
467		return;
468	}
469
470	/* Not now, but complain so we now where we failed. */
471	err = raw(master);
472	if (err < 0) {
473		printk(UM_KERN_ERR "check_one_sigio : raw failed, errno = %d\n",
474		      -err);
475		return;
476	}
477
478	err = async_pty(master, slave);
479	if (err < 0) {
480		printk(UM_KERN_ERR "check_one_sigio : sigio_async failed, "
481		       "err = %d\n", -err);
482		return;
483	}
484
485	if (sigaction(SIGIO, NULL, &old) < 0) {
486		printk(UM_KERN_ERR "check_one_sigio : sigaction 1 failed, "
487		       "errno = %d\n", errno);
488		return;
489	}
490
491	new = old;
492	new.sa_handler = handler;
493	if (sigaction(SIGIO, &new, NULL) < 0) {
494		printk(UM_KERN_ERR "check_one_sigio : sigaction 2 failed, "
495		       "errno = %d\n", errno);
496		return;
497	}
498
499	got_sigio = 0;
500	(*proc)(master, slave);
501
502	close(master);
503	close(slave);
504
505	if (sigaction(SIGIO, &old, NULL) < 0)
506		printk(UM_KERN_ERR "check_one_sigio : sigaction 3 failed, "
507		       "errno = %d\n", errno);
508}
509
510static void tty_output(int master, int slave)
511{
512	int n;
513	char buf[512];
514
515	printk(UM_KERN_INFO "Checking that host ptys support output SIGIO...");
516
517	memset(buf, 0, sizeof(buf));
518
519	while (write(master, buf, sizeof(buf)) > 0) ;
520	if (errno != EAGAIN)
521		printk(UM_KERN_ERR "tty_output : write failed, errno = %d\n",
522		       errno);
523	while (((n = read(slave, buf, sizeof(buf))) > 0) &&
524	       !({ barrier(); got_sigio; }))
525		;
526
527	if (got_sigio) {
528		printk(UM_KERN_CONT "Yes\n");
529		pty_output_sigio = 1;
530	} else if (n == -EAGAIN)
531		printk(UM_KERN_CONT "No, enabling workaround\n");
532	else
533		printk(UM_KERN_CONT "tty_output : read failed, err = %d\n", n);
534}
535
536static void __init check_sigio(void)
537{
538	if ((access("/dev/ptmx", R_OK) < 0) &&
539	    (access("/dev/ptyp0", R_OK) < 0)) {
540		printk(UM_KERN_WARNING "No pseudo-terminals available - "
541		       "skipping pty SIGIO check\n");
542		return;
543	}
544	check_one_sigio(tty_output);
545}
546
547/* Here because it only does the SIGIO testing for now */
548void __init os_check_bugs(void)
549{
550	check_sigio();
551}