[wasi-libc.git] / libc-top-half / musl / src / aio / aio.c

#include <aio.h>
#include <pthread.h>
#include <semaphore.h>
#include <limits.h>
#include <errno.h>
#include <unistd.h>
#include <stdlib.h>
#include <sys/auxv.h>
#include "syscall.h"
#include "atomic.h"
#include "pthread_impl.h"
#include "aio_impl.h"

#define malloc __libc_malloc
#define calloc __libc_calloc
#define realloc __libc_realloc
#define free __libc_free

/* The following is a threads-based implementation of AIO with minimal
 * dependence on implementation details. Most synchronization is
 * performed with pthread primitives, but atomics and futex operations
 * are used for notification in a couple places where the pthread
 * primitives would be inefficient or impractical.
 *
 * For each fd with outstanding aio operations, an aio_queue structure
 * is maintained. These are reference-counted and destroyed by the last
 * aio worker thread to exit. Accessing any member of the aio_queue
 * structure requires a lock on the aio_queue. Adding and removing aio
 * queues themselves requires a write lock on the global map object,
 * a 4-level table mapping file descriptor numbers to aio queues. A
 * read lock on the map is used to obtain locks on existing queues by
 * excluding destruction of the queue by a different thread while it is
 * being locked.
 *
 * Each aio queue has a list of active threads/operations. Presently there
 * is a one to one relationship between threads and operations. The only
 * members of the aio_thread structure which are accessed by other threads
 * are the linked list pointers, op (which is immutable), running (which
 * is updated atomically), and err (which is synchronized via running),
 * so no locking is necessary. Most of the other other members are used
 * for sharing data between the main flow of execution and cancellation
 * cleanup handler.
 *
 * Taking any aio locks requires having all signals blocked. This is
 * necessary because aio_cancel is needed by close, and close is required
 * to be async-signal safe. All aio worker threads run with all signals
 * blocked permanently.
 */

struct aio_thread {
	pthread_t td;
	struct aiocb *cb;
	struct aio_thread *next, *prev;
	struct aio_queue *q;
	volatile int running;
	int err, op;
	ssize_t ret;
};

struct aio_queue {
	int fd, seekable, append, ref, init;
	pthread_mutex_t lock;
	pthread_cond_t cond;
	struct aio_thread *head;
};

struct aio_args {
	struct aiocb *cb;
	struct aio_queue *q;
	int op;
	sem_t sem;
};

static pthread_rwlock_t maplock = PTHREAD_RWLOCK_INITIALIZER;
static struct aio_queue *****map;
static volatile int aio_fd_cnt;
volatile int __aio_fut;

static size_t io_thread_stack_size;

#define MAX(a,b) ((a)>(b) ? (a) : (b))

static struct aio_queue *__aio_get_queue(int fd, int need)
{
	if (fd < 0) {
		errno = EBADF;
		return 0;
	}
	int a=fd>>24;
	unsigned char b=fd>>16, c=fd>>8, d=fd;
	struct aio_queue *q = 0;
	pthread_rwlock_rdlock(&maplock);
	if ((!map || !map[a] || !map[a][b] || !map[a][b][c] || !(q=map[a][b][c][d])) && need) {
		pthread_rwlock_unlock(&maplock);
		if (fcntl(fd, F_GETFD) < 0) return 0;
		pthread_rwlock_wrlock(&maplock);
		if (!io_thread_stack_size) {
			unsigned long val = __getauxval(AT_MINSIGSTKSZ);
			io_thread_stack_size = MAX(MINSIGSTKSZ+2048, val+512);
		}
		if (!map) map = calloc(sizeof *map, (-1U/2+1)>>24);
		if (!map) goto out;
		if (!map[a]) map[a] = calloc(sizeof **map, 256);
		if (!map[a]) goto out;
		if (!map[a][b]) map[a][b] = calloc(sizeof ***map, 256);
		if (!map[a][b]) goto out;
		if (!map[a][b][c]) map[a][b][c] = calloc(sizeof ****map, 256);
		if (!map[a][b][c]) goto out;
		if (!(q = map[a][b][c][d])) {
			map[a][b][c][d] = q = calloc(sizeof *****map, 1);
			if (q) {
				q->fd = fd;
				pthread_mutex_init(&q->lock, 0);
				pthread_cond_init(&q->cond, 0);
				a_inc(&aio_fd_cnt);
			}
		}
	}
	if (q) pthread_mutex_lock(&q->lock);
out:
	pthread_rwlock_unlock(&maplock);
	return q;
}

static void __aio_unref_queue(struct aio_queue *q)
{
	if (q->ref > 1) {
		q->ref--;
		pthread_mutex_unlock(&q->lock);
		return;
	}

	/* This is potentially the last reference, but a new reference
	 * may arrive since we cannot free the queue object without first
	 * taking the maplock, which requires releasing the queue lock. */
	pthread_mutex_unlock(&q->lock);
	pthread_rwlock_wrlock(&maplock);
	pthread_mutex_lock(&q->lock);
	if (q->ref == 1) {
		int fd=q->fd;
		int a=fd>>24;
		unsigned char b=fd>>16, c=fd>>8, d=fd;
		map[a][b][c][d] = 0;
		a_dec(&aio_fd_cnt);
		pthread_rwlock_unlock(&maplock);
		pthread_mutex_unlock(&q->lock);
		free(q);
	} else {
		q->ref--;
		pthread_rwlock_unlock(&maplock);
		pthread_mutex_unlock(&q->lock);
	}
}

static void cleanup(void *ctx)
{
	struct aio_thread *at = ctx;
	struct aio_queue *q = at->q;
	struct aiocb *cb = at->cb;
	struct sigevent sev = cb->aio_sigevent;

	/* There are four potential types of waiters we could need to wake:
	 *   1. Callers of aio_cancel/close.
	 *   2. Callers of aio_suspend with a single aiocb.
	 *   3. Callers of aio_suspend with a list.
	 *   4. AIO worker threads waiting for sequenced operations.
	 * Types 1-3 are notified via atomics/futexes, mainly for AS-safety
	 * considerations. Type 4 is notified later via a cond var. */

	cb->__ret = at->ret;
	if (a_swap(&at->running, 0) < 0)
		__wake(&at->running, -1, 1);
	if (a_swap(&cb->__err, at->err) != EINPROGRESS)
		__wake(&cb->__err, -1, 1);
	if (a_swap(&__aio_fut, 0))
		__wake(&__aio_fut, -1, 1);

	pthread_mutex_lock(&q->lock);

	if (at->next) at->next->prev = at->prev;
	if (at->prev) at->prev->next = at->next;
	else q->head = at->next;

	/* Signal aio worker threads waiting for sequenced operations. */
	pthread_cond_broadcast(&q->cond);

	__aio_unref_queue(q);

	if (sev.sigev_notify == SIGEV_SIGNAL) {
		siginfo_t si = {
			.si_signo = sev.sigev_signo,
			.si_value = sev.sigev_value,
			.si_code = SI_ASYNCIO,
			.si_pid = getpid(),
			.si_uid = getuid()
		};
		__syscall(SYS_rt_sigqueueinfo, si.si_pid, si.si_signo, &si);
	}
	if (sev.sigev_notify == SIGEV_THREAD) {
		a_store(&__pthread_self()->cancel, 0);
		sev.sigev_notify_function(sev.sigev_value);
	}
}

static void *io_thread_func(void *ctx)
{
	struct aio_thread at, *p;

	struct aio_args *args = ctx;
	struct aiocb *cb = args->cb;
	int fd = cb->aio_fildes;
	int op = args->op;
	void *buf = (void *)cb->aio_buf;
	size_t len = cb->aio_nbytes;
	off_t off = cb->aio_offset;

	struct aio_queue *q = args->q;
	ssize_t ret;

	pthread_mutex_lock(&q->lock);
	sem_post(&args->sem);

	at.op = op;
	at.running = 1;
	at.ret = -1;
	at.err = ECANCELED;
	at.q = q;
	at.td = __pthread_self();
	at.cb = cb;
	at.prev = 0;
	if ((at.next = q->head)) at.next->prev = &at;
	q->head = &at;

	if (!q->init) {
		int seekable = lseek(fd, 0, SEEK_CUR) >= 0;
		q->seekable = seekable;
		q->append = !seekable || (fcntl(fd, F_GETFL) & O_APPEND);
		q->init = 1;
	}

	pthread_cleanup_push(cleanup, &at);

	/* Wait for sequenced operations. */
	if (op!=LIO_READ && (op!=LIO_WRITE || q->append)) {
		for (;;) {
			for (p=at.next; p && p->op!=LIO_WRITE; p=p->next);
			if (!p) break;
			pthread_cond_wait(&q->cond, &q->lock);
		}
	}

	pthread_mutex_unlock(&q->lock);

	switch (op) {
	case LIO_WRITE:
		ret = q->append ? write(fd, buf, len) : pwrite(fd, buf, len, off);
		break;
	case LIO_READ:
		ret = !q->seekable ? read(fd, buf, len) : pread(fd, buf, len, off);
		break;
	case O_SYNC:
		ret = fsync(fd);
		break;
	case O_DSYNC:
		ret = fdatasync(fd);
		break;
	}
	at.ret = ret;
	at.err = ret<0 ? errno : 0;
	
	pthread_cleanup_pop(1);

	return 0;
}

static int submit(struct aiocb *cb, int op)
{
	int ret = 0;
	pthread_attr_t a;
	sigset_t allmask, origmask;
	pthread_t td;
	struct aio_queue *q = __aio_get_queue(cb->aio_fildes, 1);
	struct aio_args args = { .cb = cb, .op = op, .q = q };
	sem_init(&args.sem, 0, 0);

	if (!q) {
		if (errno != EBADF) errno = EAGAIN;
		cb->__ret = -1;
		cb->__err = errno;
		return -1;
	}
	q->ref++;
	pthread_mutex_unlock(&q->lock);

	if (cb->aio_sigevent.sigev_notify == SIGEV_THREAD) {
		if (cb->aio_sigevent.sigev_notify_attributes)
			a = *cb->aio_sigevent.sigev_notify_attributes;
		else
			pthread_attr_init(&a);
	} else {
		pthread_attr_init(&a);
		pthread_attr_setstacksize(&a, io_thread_stack_size);
		pthread_attr_setguardsize(&a, 0);
	}
	pthread_attr_setdetachstate(&a, PTHREAD_CREATE_DETACHED);
	sigfillset(&allmask);
	pthread_sigmask(SIG_BLOCK, &allmask, &origmask);
	cb->__err = EINPROGRESS;
	if (pthread_create(&td, &a, io_thread_func, &args)) {
		pthread_mutex_lock(&q->lock);
		__aio_unref_queue(q);
		cb->__err = errno = EAGAIN;
		cb->__ret = ret = -1;
	}
	pthread_sigmask(SIG_SETMASK, &origmask, 0);

	if (!ret) {
		while (sem_wait(&args.sem));
	}

	return ret;
}

int aio_read(struct aiocb *cb)
{
	return submit(cb, LIO_READ);
}

int aio_write(struct aiocb *cb)
{
	return submit(cb, LIO_WRITE);
}

int aio_fsync(int op, struct aiocb *cb)
{
	if (op != O_SYNC && op != O_DSYNC) {
		errno = EINVAL;
		return -1;
	}
	return submit(cb, op);
}

ssize_t aio_return(struct aiocb *cb)
{
	return cb->__ret;
}

int aio_error(const struct aiocb *cb)
{
	a_barrier();
	return cb->__err & 0x7fffffff;
}

int aio_cancel(int fd, struct aiocb *cb)
{
	sigset_t allmask, origmask;
	int ret = AIO_ALLDONE;
	struct aio_thread *p;
	struct aio_queue *q;

	/* Unspecified behavior case. Report an error. */
	if (cb && fd != cb->aio_fildes) {
		errno = EINVAL;
		return -1;
	}

	sigfillset(&allmask);
	pthread_sigmask(SIG_BLOCK, &allmask, &origmask);

	errno = ENOENT;
	if (!(q = __aio_get_queue(fd, 0))) {
		if (errno == EBADF) ret = -1;
		goto done;
	}

	for (p = q->head; p; p = p->next) {
		if (cb && cb != p->cb) continue;
		/* Transition target from running to running-with-waiters */
		if (a_cas(&p->running, 1, -1)) {
			pthread_cancel(p->td);
			__wait(&p->running, 0, -1, 1);
			if (p->err == ECANCELED) ret = AIO_CANCELED;
		}
	}

	pthread_mutex_unlock(&q->lock);
done:
	pthread_sigmask(SIG_SETMASK, &origmask, 0);
	return ret;
}

int __aio_close(int fd)
{
	a_barrier();
	if (aio_fd_cnt) aio_cancel(fd, 0);
	return fd;
}

void __aio_atfork(int who)
{
	if (who<0) {
		pthread_rwlock_rdlock(&maplock);
		return;
	}
	if (who>0 && map) for (int a=0; a<(-1U/2+1)>>24; a++)
		if (map[a]) for (int b=0; b<256; b++)
			if (map[a][b]) for (int c=0; c<256; c++)
				if (map[a][b][c]) for (int d=0; d<256; d++)
					map[a][b][c][d] = 0;
	pthread_rwlock_unlock(&maplock);
}

weak_alias(aio_cancel, aio_cancel64);
weak_alias(aio_error, aio_error64);
weak_alias(aio_fsync, aio_fsync64);
weak_alias(aio_read, aio_read64);
weak_alias(aio_write, aio_write64);
weak_alias(aio_return, aio_return64);
Commit	Line	Data
320054e8 DG	1	#include <aio.h>
	2	#include <pthread.h>
	3	#include <semaphore.h>
	4	#include <limits.h>
	5	#include <errno.h>
	6	#include <unistd.h>
	7	#include <stdlib.h>
	8	#include <sys/auxv.h>
	9	#include "syscall.h"
	10	#include "atomic.h"
	11	#include "pthread_impl.h"
322bd4ff DG	12	#include "aio_impl.h"
	13
	14	#define malloc __libc_malloc
	15	#define calloc __libc_calloc
	16	#define realloc __libc_realloc
	17	#define free __libc_free
320054e8 DG	18
	19	/* The following is a threads-based implementation of AIO with minimal
	20	* dependence on implementation details. Most synchronization is
	21	* performed with pthread primitives, but atomics and futex operations
	22	* are used for notification in a couple places where the pthread
	23	* primitives would be inefficient or impractical.
	24	*
	25	* For each fd with outstanding aio operations, an aio_queue structure
	26	* is maintained. These are reference-counted and destroyed by the last
	27	* aio worker thread to exit. Accessing any member of the aio_queue
	28	* structure requires a lock on the aio_queue. Adding and removing aio
	29	* queues themselves requires a write lock on the global map object,
	30	* a 4-level table mapping file descriptor numbers to aio queues. A
	31	* read lock on the map is used to obtain locks on existing queues by
	32	* excluding destruction of the queue by a different thread while it is
	33	* being locked.
	34	*
	35	* Each aio queue has a list of active threads/operations. Presently there
	36	* is a one to one relationship between threads and operations. The only
	37	* members of the aio_thread structure which are accessed by other threads
	38	* are the linked list pointers, op (which is immutable), running (which
	39	* is updated atomically), and err (which is synchronized via running),
	40	* so no locking is necessary. Most of the other other members are used
	41	* for sharing data between the main flow of execution and cancellation
	42	* cleanup handler.
	43	*
	44	* Taking any aio locks requires having all signals blocked. This is
	45	* necessary because aio_cancel is needed by close, and close is required
	46	* to be async-signal safe. All aio worker threads run with all signals
	47	* blocked permanently.
	48	*/
	49
	50	struct aio_thread {
	51	pthread_t td;
	52	struct aiocb *cb;
	53	struct aio_thread next, prev;
	54	struct aio_queue *q;
	55	volatile int running;
	56	int err, op;
	57	ssize_t ret;
	58	};
	59
	60	struct aio_queue {
	61	int fd, seekable, append, ref, init;
	62	pthread_mutex_t lock;
	63	pthread_cond_t cond;
	64	struct aio_thread *head;
	65	};
	66
	67	struct aio_args {
	68	struct aiocb *cb;
	69	struct aio_queue *q;
	70	int op;
	71	sem_t sem;
	72	};
	73
	74	static pthread_rwlock_t maplock = PTHREAD_RWLOCK_INITIALIZER;
	75	static struct aio_queue *****map;
	76	static volatile int aio_fd_cnt;
	77	volatile int __aio_fut;
	78
322bd4ff DG	79	static size_t io_thread_stack_size;
	80
	81	#define MAX(a,b) ((a)>(b) ? (a) : (b))
	82
320054e8 DG	83	static struct aio_queue *__aio_get_queue(int fd, int need)
	84	{
	85	if (fd < 0) {
	86	errno = EBADF;
	87	return 0;
	88	}
	89	int a=fd>>24;
	90	unsigned char b=fd>>16, c=fd>>8, d=fd;
	91	struct aio_queue *q = 0;
	92	pthread_rwlock_rdlock(&maplock);
	93	if ((!map \|\| !map[a] \|\| !map[a][b] \|\| !map[a][b][c] \|\| !(q=map[a][b][c][d])) && need) {
	94	pthread_rwlock_unlock(&maplock);
	95	if (fcntl(fd, F_GETFD) < 0) return 0;
	96	pthread_rwlock_wrlock(&maplock);
322bd4ff DG	97	if (!io_thread_stack_size) {
	98	unsigned long val = __getauxval(AT_MINSIGSTKSZ);
	99	io_thread_stack_size = MAX(MINSIGSTKSZ+2048, val+512);
	100	}
320054e8 DG	101	if (!map) map = calloc(sizeof *map, (-1U/2+1)>>24);
	102	if (!map) goto out;
	103	if (!map[a]) map[a] = calloc(sizeof **map, 256);
	104	if (!map[a]) goto out;
	105	if (!map[a][b]) map[a][b] = calloc(sizeof ***map, 256);
	106	if (!map[a][b]) goto out;
	107	if (!map[a][b][c]) map[a][b][c] = calloc(sizeof ****map, 256);
	108	if (!map[a][b][c]) goto out;
	109	if (!(q = map[a][b][c][d])) {
	110	map[a][b][c][d] = q = calloc(sizeof *****map, 1);
	111	if (q) {
	112	q->fd = fd;
	113	pthread_mutex_init(&q->lock, 0);
	114	pthread_cond_init(&q->cond, 0);
	115	a_inc(&aio_fd_cnt);
	116	}
	117	}
	118	}
	119	if (q) pthread_mutex_lock(&q->lock);
	120	out:
	121	pthread_rwlock_unlock(&maplock);
	122	return q;
	123	}
	124
	125	static void __aio_unref_queue(struct aio_queue *q)
	126	{
	127	if (q->ref > 1) {
	128	q->ref--;
	129	pthread_mutex_unlock(&q->lock);
	130	return;
	131	}
	132
	133	/* This is potentially the last reference, but a new reference
	134	* may arrive since we cannot free the queue object without first
	135	* taking the maplock, which requires releasing the queue lock. */
	136	pthread_mutex_unlock(&q->lock);
	137	pthread_rwlock_wrlock(&maplock);
	138	pthread_mutex_lock(&q->lock);
	139	if (q->ref == 1) {
	140	int fd=q->fd;
	141	int a=fd>>24;
	142	unsigned char b=fd>>16, c=fd>>8, d=fd;
	143	map[a][b][c][d] = 0;
	144	a_dec(&aio_fd_cnt);
	145	pthread_rwlock_unlock(&maplock);
	146	pthread_mutex_unlock(&q->lock);
	147	free(q);
	148	} else {
	149	q->ref--;
	150	pthread_rwlock_unlock(&maplock);
	151	pthread_mutex_unlock(&q->lock);
	152	}
	153	}
	154
	155	static void cleanup(void *ctx)
	156	{
	157	struct aio_thread *at = ctx;
	158	struct aio_queue *q = at->q;
	159	struct aiocb *cb = at->cb;
	160	struct sigevent sev = cb->aio_sigevent;
	161
	162	/* There are four potential types of waiters we could need to wake:
	163	* 1. Callers of aio_cancel/close.
	164	* 2. Callers of aio_suspend with a single aiocb.
165	* 3. Callers of aio_suspend with a list.
166	* 4. AIO worker threads waiting for sequenced operations.
167	* Types 1-3 are notified via atomics/futexes, mainly for AS-safety
168	* considerations. Type 4 is notified later via a cond var. */
169
170	cb->__ret = at->ret;
171	if (a_swap(&at->running, 0) < 0)
172	__wake(&at->running, -1, 1);
173	if (a_swap(&cb->__err, at->err) != EINPROGRESS)
174	__wake(&cb->__err, -1, 1);
175	if (a_swap(&__aio_fut, 0))
176	__wake(&__aio_fut, -1, 1);
177
178	pthread_mutex_lock(&q->lock);
179
180	if (at->next) at->next->prev = at->prev;
181	if (at->prev) at->prev->next = at->next;
182	else q->head = at->next;
183
184	/* Signal aio worker threads waiting for sequenced operations. */
185	pthread_cond_broadcast(&q->cond);
186
187	__aio_unref_queue(q);
188
189	if (sev.sigev_notify == SIGEV_SIGNAL) {
190	siginfo_t si = {
191	.si_signo = sev.sigev_signo,
192	.si_value = sev.sigev_value,
193	.si_code = SI_ASYNCIO,
194	.si_pid = getpid(),
195	.si_uid = getuid()
196	};
197	__syscall(SYS_rt_sigqueueinfo, si.si_pid, si.si_signo, &si);
198	}
199	if (sev.sigev_notify == SIGEV_THREAD) {
200	a_store(&__pthread_self()->cancel, 0);
201	sev.sigev_notify_function(sev.sigev_value);
202	}
203	}
204
205	static void io_thread_func(void ctx)
206	{
207	struct aio_thread at, *p;
208
209	struct aio_args *args = ctx;
210	struct aiocb *cb = args->cb;
211	int fd = cb->aio_fildes;
212	int op = args->op;
213	void buf = (void )cb->aio_buf;
214	size_t len = cb->aio_nbytes;
215	off_t off = cb->aio_offset;
216
217	struct aio_queue *q = args->q;
218	ssize_t ret;
219
220	pthread_mutex_lock(&q->lock);
221	sem_post(&args->sem);
222
223	at.op = op;
224	at.running = 1;
225	at.ret = -1;
226	at.err = ECANCELED;
227	at.q = q;
228	at.td = __pthread_self();
229	at.cb = cb;
230	at.prev = 0;
231	if ((at.next = q->head)) at.next->prev = &at;
232	q->head = &at;
233
234	if (!q->init) {
235	int seekable = lseek(fd, 0, SEEK_CUR) >= 0;
236	q->seekable = seekable;
237	q->append = !seekable \|\| (fcntl(fd, F_GETFL) & O_APPEND);
238	q->init = 1;
239	}
240
241	pthread_cleanup_push(cleanup, &at);
242
243	/* Wait for sequenced operations. */
244	if (op!=LIO_READ && (op!=LIO_WRITE \|\| q->append)) {
245	for (;;) {
246	for (p=at.next; p && p->op!=LIO_WRITE; p=p->next);
247	if (!p) break;
248	pthread_cond_wait(&q->cond, &q->lock);
249	}
250	}
251
252	pthread_mutex_unlock(&q->lock);
253
254	switch (op) {
255	case LIO_WRITE:
256	ret = q->append ? write(fd, buf, len) : pwrite(fd, buf, len, off);
257	break;
258	case LIO_READ:
259	ret = !q->seekable ? read(fd, buf, len) : pread(fd, buf, len, off);
260	break;
261	case O_SYNC:
262	ret = fsync(fd);
263	break;
264	case O_DSYNC:
265	ret = fdatasync(fd);
266	break;
267	}
268	at.ret = ret;
269	at.err = ret<0 ? errno : 0;
270
271	pthread_cleanup_pop(1);
272
273	return 0;
274	}
275
320054e8 DG	276	static int submit(struct aiocb *cb, int op)
	277	{
	278	int ret = 0;
	279	pthread_attr_t a;
	280	sigset_t allmask, origmask;
	281	pthread_t td;
	282	struct aio_queue *q = __aio_get_queue(cb->aio_fildes, 1);
	283	struct aio_args args = { .cb = cb, .op = op, .q = q };
	284	sem_init(&args.sem, 0, 0);
	285
	286	if (!q) {
	287	if (errno != EBADF) errno = EAGAIN;
	288	cb->__ret = -1;
	289	cb->__err = errno;
	290	return -1;
	291	}
	292	q->ref++;
	293	pthread_mutex_unlock(&q->lock);
	294
	295	if (cb->aio_sigevent.sigev_notify == SIGEV_THREAD) {
	296	if (cb->aio_sigevent.sigev_notify_attributes)
	297	a = *cb->aio_sigevent.sigev_notify_attributes;
	298	else
	299	pthread_attr_init(&a);
	300	} else {
320054e8 DG	301	pthread_attr_init(&a);
	302	pthread_attr_setstacksize(&a, io_thread_stack_size);
	303	pthread_attr_setguardsize(&a, 0);
	304	}
	305	pthread_attr_setdetachstate(&a, PTHREAD_CREATE_DETACHED);
	306	sigfillset(&allmask);
	307	pthread_sigmask(SIG_BLOCK, &allmask, &origmask);
	308	cb->__err = EINPROGRESS;
	309	if (pthread_create(&td, &a, io_thread_func, &args)) {
	310	pthread_mutex_lock(&q->lock);
	311	__aio_unref_queue(q);
	312	cb->__err = errno = EAGAIN;
	313	cb->__ret = ret = -1;
	314	}
	315	pthread_sigmask(SIG_SETMASK, &origmask, 0);
	316
	317	if (!ret) {
	318	while (sem_wait(&args.sem));
	319	}
	320
	321	return ret;
	322	}
	323
	324	int aio_read(struct aiocb *cb)
	325	{
	326	return submit(cb, LIO_READ);
	327	}
	328
	329	int aio_write(struct aiocb *cb)
	330	{
	331	return submit(cb, LIO_WRITE);
	332	}
	333
	334	int aio_fsync(int op, struct aiocb *cb)
	335	{
	336	if (op != O_SYNC && op != O_DSYNC) {
	337	errno = EINVAL;
	338	return -1;
	339	}
	340	return submit(cb, op);
	341	}
	342
	343	ssize_t aio_return(struct aiocb *cb)
	344	{
	345	return cb->__ret;
	346	}
	347
	348	int aio_error(const struct aiocb *cb)
	349	{
	350	a_barrier();
	351	return cb->__err & 0x7fffffff;
	352	}
	353
	354	int aio_cancel(int fd, struct aiocb *cb)
	355	{
	356	sigset_t allmask, origmask;
	357	int ret = AIO_ALLDONE;
	358	struct aio_thread *p;
	359	struct aio_queue *q;
	360
	361	/* Unspecified behavior case. Report an error. */
	362	if (cb && fd != cb->aio_fildes) {
	363	errno = EINVAL;
	364	return -1;
365	}
366
367	sigfillset(&allmask);
368	pthread_sigmask(SIG_BLOCK, &allmask, &origmask);
369
370	errno = ENOENT;
371	if (!(q = __aio_get_queue(fd, 0))) {
372	if (errno == EBADF) ret = -1;
373	goto done;
374	}
375
376	for (p = q->head; p; p = p->next) {
377	if (cb && cb != p->cb) continue;
378	/* Transition target from running to running-with-waiters */
379	if (a_cas(&p->running, 1, -1)) {
380	pthread_cancel(p->td);
381	__wait(&p->running, 0, -1, 1);
382	if (p->err == ECANCELED) ret = AIO_CANCELED;
383	}
384	}
385
386	pthread_mutex_unlock(&q->lock);
387	done:
388	pthread_sigmask(SIG_SETMASK, &origmask, 0);
389	return ret;
390	}
391
392	int __aio_close(int fd)
393	{
394	a_barrier();
395	if (aio_fd_cnt) aio_cancel(fd, 0);
396	return fd;
397	}
398
322bd4ff DG	399	void __aio_atfork(int who)
	400	{
	401	if (who<0) {
	402	pthread_rwlock_rdlock(&maplock);
	403	return;
	404	}
	405	if (who>0 && map) for (int a=0; a<(-1U/2+1)>>24; a++)
	406	if (map[a]) for (int b=0; b<256; b++)
	407	if (map[a][b]) for (int c=0; c<256; c++)
	408	if (map[a][b][c]) for (int d=0; d<256; d++)
	409	map[a][b][c][d] = 0;
	410	pthread_rwlock_unlock(&maplock);
	411	}
	412
320054e8 DG	413	weak_alias(aio_cancel, aio_cancel64);
	414	weak_alias(aio_error, aio_error64);
	415	weak_alias(aio_fsync, aio_fsync64);
	416	weak_alias(aio_read, aio_read64);
	417	weak_alias(aio_write, aio_write64);
	418	weak_alias(aio_return, aio_return64);