[linux.git] / fs / signalfd.c

/*
 *  fs/signalfd.c
 *
 *  Copyright (C) 2003  Linus Torvalds
 *
 *  Mon Mar 5, 2007: Davide Libenzi <[email protected]>
 *      Changed ->read() to return a siginfo strcture instead of signal number.
 *      Fixed locking in ->poll().
 *      Added sighand-detach notification.
 *      Added fd re-use in sys_signalfd() syscall.
 *      Now using anonymous inode source.
 *      Thanks to Oleg Nesterov for useful code review and suggestions.
 *      More comments and suggestions from Arnd Bergmann.
 *  Sat May 19, 2007: Davi E. M. Arnaut <[email protected]>
 *      Retrieve multiple signals with one read() call
 *  Sun Jul 15, 2007: Davide Libenzi <[email protected]>
 *      Attach to the sighand only during read() and poll().
 */

#include <linux/file.h>
#include <linux/poll.h>
#include <linux/init.h>
#include <linux/fs.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/kernel.h>
#include <linux/signal.h>
#include <linux/list.h>
#include <linux/anon_inodes.h>
#include <linux/signalfd.h>
#include <linux/syscalls.h>

void signalfd_cleanup(struct sighand_struct *sighand)
{
	wait_queue_head_t *wqh = &sighand->signalfd_wqh;
	/*
	 * The lockless check can race with remove_wait_queue() in progress,
	 * but in this case its caller should run under rcu_read_lock() and
	 * sighand_cachep is SLAB_DESTROY_BY_RCU, we can safely return.
	 */
	if (likely(!waitqueue_active(wqh)))
		return;

	/* wait_queue_t->func(POLLFREE) should do remove_wait_queue() */
	wake_up_poll(wqh, POLLHUP | POLLFREE);
}

struct signalfd_ctx {
	sigset_t sigmask;
};

static int signalfd_release(struct inode *inode, struct file *file)
{
	kfree(file->private_data);
	return 0;
}

static unsigned int signalfd_poll(struct file *file, poll_table *wait)
{
	struct signalfd_ctx *ctx = file->private_data;
	unsigned int events = 0;

	poll_wait(file, &current->sighand->signalfd_wqh, wait);

	spin_lock_irq(&current->sighand->siglock);
	if (next_signal(&current->pending, &ctx->sigmask) ||
	    next_signal(&current->signal->shared_pending,
			&ctx->sigmask))
		events |= POLLIN;
	spin_unlock_irq(&current->sighand->siglock);

	return events;
}

/*
 * Copied from copy_siginfo_to_user() in kernel/signal.c
 */
static int signalfd_copyinfo(struct signalfd_siginfo __user *uinfo,
			     siginfo_t const *kinfo)
{
	long err;

	BUILD_BUG_ON(sizeof(struct signalfd_siginfo) != 128);

	/*
	 * Unused members should be zero ...
	 */
	err = __clear_user(uinfo, sizeof(*uinfo));

	/*
	 * If you change siginfo_t structure, please be sure
	 * this code is fixed accordingly.
	 */
	err |= __put_user(kinfo->si_signo, &uinfo->ssi_signo);
	err |= __put_user(kinfo->si_errno, &uinfo->ssi_errno);
	err |= __put_user((short) kinfo->si_code, &uinfo->ssi_code);
	switch (kinfo->si_code & __SI_MASK) {
	case __SI_KILL:
		err |= __put_user(kinfo->si_pid, &uinfo->ssi_pid);
		err |= __put_user(kinfo->si_uid, &uinfo->ssi_uid);
		break;
	case __SI_TIMER:
		 err |= __put_user(kinfo->si_tid, &uinfo->ssi_tid);
		 err |= __put_user(kinfo->si_overrun, &uinfo->ssi_overrun);
		 err |= __put_user((long) kinfo->si_ptr, &uinfo->ssi_ptr);
		 err |= __put_user(kinfo->si_int, &uinfo->ssi_int);
		break;
	case __SI_POLL:
		err |= __put_user(kinfo->si_band, &uinfo->ssi_band);
		err |= __put_user(kinfo->si_fd, &uinfo->ssi_fd);
		break;
	case __SI_FAULT:
		err |= __put_user((long) kinfo->si_addr, &uinfo->ssi_addr);
#ifdef __ARCH_SI_TRAPNO
		err |= __put_user(kinfo->si_trapno, &uinfo->ssi_trapno);
#endif
#ifdef BUS_MCEERR_AO
		/* 
		 * Other callers might not initialize the si_lsb field,
		 * so check explicitly for the right codes here.
		 */
		if (kinfo->si_code == BUS_MCEERR_AR ||
		    kinfo->si_code == BUS_MCEERR_AO)
			err |= __put_user((short) kinfo->si_addr_lsb,
					  &uinfo->ssi_addr_lsb);
#endif
		break;
	case __SI_CHLD:
		err |= __put_user(kinfo->si_pid, &uinfo->ssi_pid);
		err |= __put_user(kinfo->si_uid, &uinfo->ssi_uid);
		err |= __put_user(kinfo->si_status, &uinfo->ssi_status);
		err |= __put_user(kinfo->si_utime, &uinfo->ssi_utime);
		err |= __put_user(kinfo->si_stime, &uinfo->ssi_stime);
		break;
	case __SI_RT: /* This is not generated by the kernel as of now. */
	case __SI_MESGQ: /* But this is */
		err |= __put_user(kinfo->si_pid, &uinfo->ssi_pid);
		err |= __put_user(kinfo->si_uid, &uinfo->ssi_uid);
		err |= __put_user((long) kinfo->si_ptr, &uinfo->ssi_ptr);
		err |= __put_user(kinfo->si_int, &uinfo->ssi_int);
		break;
	default:
		/*
		 * This case catches also the signals queued by sigqueue().
		 */
		err |= __put_user(kinfo->si_pid, &uinfo->ssi_pid);
		err |= __put_user(kinfo->si_uid, &uinfo->ssi_uid);
		err |= __put_user((long) kinfo->si_ptr, &uinfo->ssi_ptr);
		err |= __put_user(kinfo->si_int, &uinfo->ssi_int);
		break;
	}

	return err ? -EFAULT: sizeof(*uinfo);
}

static ssize_t signalfd_dequeue(struct signalfd_ctx *ctx, siginfo_t *info,
				int nonblock)
{
	ssize_t ret;
	DECLARE_WAITQUEUE(wait, current);

	spin_lock_irq(&current->sighand->siglock);
	ret = dequeue_signal(current, &ctx->sigmask, info);
	switch (ret) {
	case 0:
		if (!nonblock)
			break;
		ret = -EAGAIN;
	default:
		spin_unlock_irq(&current->sighand->siglock);
		return ret;
	}

	add_wait_queue(&current->sighand->signalfd_wqh, &wait);
	for (;;) {
		set_current_state(TASK_INTERRUPTIBLE);
		ret = dequeue_signal(current, &ctx->sigmask, info);
		if (ret != 0)
			break;
		if (signal_pending(current)) {
			ret = -ERESTARTSYS;
			break;
		}
		spin_unlock_irq(&current->sighand->siglock);
		schedule();
		spin_lock_irq(&current->sighand->siglock);
	}
	spin_unlock_irq(&current->sighand->siglock);

	remove_wait_queue(&current->sighand->signalfd_wqh, &wait);
	__set_current_state(TASK_RUNNING);

	return ret;
}

/*
 * Returns a multiple of the size of a "struct signalfd_siginfo", or a negative
 * error code. The "count" parameter must be at least the size of a
 * "struct signalfd_siginfo".
 */
static ssize_t signalfd_read(struct file *file, char __user *buf, size_t count,
			     loff_t *ppos)
{
	struct signalfd_ctx *ctx = file->private_data;
	struct signalfd_siginfo __user *siginfo;
	int nonblock = file->f_flags & O_NONBLOCK;
	ssize_t ret, total = 0;
	siginfo_t info;

	count /= sizeof(struct signalfd_siginfo);
	if (!count)
		return -EINVAL;

	siginfo = (struct signalfd_siginfo __user *) buf;
	do {
		ret = signalfd_dequeue(ctx, &info, nonblock);
		if (unlikely(ret <= 0))
			break;
		ret = signalfd_copyinfo(siginfo, &info);
		if (ret < 0)
			break;
		siginfo++;
		total += ret;
		nonblock = 1;
	} while (--count);

	return total ? total: ret;
}

static const struct file_operations signalfd_fops = {
	.release	= signalfd_release,
	.poll		= signalfd_poll,
	.read		= signalfd_read,
	.llseek		= noop_llseek,
};

SYSCALL_DEFINE4(signalfd4, int, ufd, sigset_t __user *, user_mask,
		size_t, sizemask, int, flags)
{
	sigset_t sigmask;
	struct signalfd_ctx *ctx;

	/* Check the SFD_* constants for consistency.  */
	BUILD_BUG_ON(SFD_CLOEXEC != O_CLOEXEC);
	BUILD_BUG_ON(SFD_NONBLOCK != O_NONBLOCK);

	if (flags & ~(SFD_CLOEXEC | SFD_NONBLOCK))
		return -EINVAL;

	if (sizemask != sizeof(sigset_t) ||
	    copy_from_user(&sigmask, user_mask, sizeof(sigmask)))
		return -EINVAL;
	sigdelsetmask(&sigmask, sigmask(SIGKILL) | sigmask(SIGSTOP));
	signotset(&sigmask);

	if (ufd == -1) {
		ctx = kmalloc(sizeof(*ctx), GFP_KERNEL);
		if (!ctx)
			return -ENOMEM;

		ctx->sigmask = sigmask;

		/*
		 * When we call this, the initialization must be complete, since
		 * anon_inode_getfd() will install the fd.
		 */
		ufd = anon_inode_getfd("[signalfd]", &signalfd_fops, ctx,
				       O_RDWR | (flags & (O_CLOEXEC | O_NONBLOCK)));
		if (ufd < 0)
			kfree(ctx);
	} else {
		struct fd f = fdget(ufd);
		if (!f.file)
			return -EBADF;
		ctx = f.file->private_data;
		if (f.file->f_op != &signalfd_fops) {
			fdput(f);
			return -EINVAL;
		}
		spin_lock_irq(&current->sighand->siglock);
		ctx->sigmask = sigmask;
		spin_unlock_irq(&current->sighand->siglock);

		wake_up(&current->sighand->signalfd_wqh);
		fdput(f);
	}

	return ufd;
}

SYSCALL_DEFINE3(signalfd, int, ufd, sigset_t __user *, user_mask,
		size_t, sizemask)
{
	return sys_signalfd4(ufd, user_mask, sizemask, 0);
}
Commit	Line	Data
fba2afaa DL	1	/*
	2	* fs/signalfd.c
	3	*
	4	* Copyright (C) 2003 Linus Torvalds
	5	*
	6	* Mon Mar 5, 2007: Davide Libenzi <[email protected]>
	7	* Changed ->read() to return a siginfo strcture instead of signal number.
	8	* Fixed locking in ->poll().
	9	* Added sighand-detach notification.
	10	* Added fd re-use in sys_signalfd() syscall.
	11	* Now using anonymous inode source.
	12	* Thanks to Oleg Nesterov for useful code review and suggestions.
	13	* More comments and suggestions from Arnd Bergmann.
b8fceee1	14	* Sat May 19, 2007: Davi E. M. Arnaut <[email protected]>
b3762bfc	15	* Retrieve multiple signals with one read() call
b8fceee1 DL	16	* Sun Jul 15, 2007: Davide Libenzi <[email protected]>
b8fceee1 DL	17	* Attach to the sighand only during read() and poll().
fba2afaa DL	18	*/
	19
	20	#include <linux/file.h>
	21	#include <linux/poll.h>
	22	#include <linux/init.h>
	23	#include <linux/fs.h>
	24	#include <linux/sched.h>
5a0e3ad6	25	#include <linux/slab.h>
fba2afaa DL	26	#include <linux/kernel.h>
	27	#include <linux/signal.h>
	28	#include <linux/list.h>
	29	#include <linux/anon_inodes.h>
	30	#include <linux/signalfd.h>
7ec37dfd	31	#include <linux/syscalls.h>
fba2afaa	32
d80e731e ON	33	void signalfd_cleanup(struct sighand_struct *sighand)
	34	{
	35	wait_queue_head_t *wqh = &sighand->signalfd_wqh;
971316f0 ON	36	/*
	37	* The lockless check can race with remove_wait_queue() in progress,
	38	* but in this case its caller should run under rcu_read_lock() and
	39	* sighand_cachep is SLAB_DESTROY_BY_RCU, we can safely return.
	40	*/
d80e731e ON	41	if (likely(!waitqueue_active(wqh)))
	42	return;
	43
	44	/* wait_queue_t->func(POLLFREE) should do remove_wait_queue() */
	45	wake_up_poll(wqh, POLLHUP \| POLLFREE);
	46	}
	47
fba2afaa	48	struct signalfd_ctx {
fba2afaa	49	sigset_t sigmask;
fba2afaa DL	50	};
fba2afaa DL	51
fba2afaa DL	52	static int signalfd_release(struct inode inode, struct file file)
fba2afaa DL	53	{
b8fceee1	54	kfree(file->private_data);
fba2afaa DL	55	return 0;
	56	}
	57
	58	static unsigned int signalfd_poll(struct file file, poll_table wait)
	59	{
	60	struct signalfd_ctx *ctx = file->private_data;
	61	unsigned int events = 0;
fba2afaa	62
b8fceee1	63	poll_wait(file, &current->sighand->signalfd_wqh, wait);
fba2afaa	64
b8fceee1 DL	65	spin_lock_irq(&current->sighand->siglock);
	66	if (next_signal(&current->pending, &ctx->sigmask) \|\|
	67	next_signal(&current->signal->shared_pending,
	68	&ctx->sigmask))
fba2afaa	69	events \|= POLLIN;
b8fceee1	70	spin_unlock_irq(&current->sighand->siglock);
fba2afaa DL	71
	72	return events;
	73	}
	74
	75	/*
	76	* Copied from copy_siginfo_to_user() in kernel/signal.c
	77	*/
	78	static int signalfd_copyinfo(struct signalfd_siginfo __user *uinfo,
	79	siginfo_t const *kinfo)
	80	{
	81	long err;
	82
	83	BUILD_BUG_ON(sizeof(struct signalfd_siginfo) != 128);
	84
	85	/*
14e4a0f2	86	* Unused members should be zero ...
fba2afaa DL	87	*/
	88	err = __clear_user(uinfo, sizeof(*uinfo));
	89
	90	/*
	91	* If you change siginfo_t structure, please be sure
	92	* this code is fixed accordingly.
	93	*/
96358de6 DL	94	err \|= __put_user(kinfo->si_signo, &uinfo->ssi_signo);
	95	err \|= __put_user(kinfo->si_errno, &uinfo->ssi_errno);
	96	err \|= __put_user((short) kinfo->si_code, &uinfo->ssi_code);
fba2afaa DL	97	switch (kinfo->si_code & __SI_MASK) {
fba2afaa DL	98	case __SI_KILL:
96358de6 DL	99	err \|= __put_user(kinfo->si_pid, &uinfo->ssi_pid);
96358de6 DL	100	err \|= __put_user(kinfo->si_uid, &uinfo->ssi_uid);
fba2afaa DL	101	break;
fba2afaa DL	102	case __SI_TIMER:
96358de6 DL	103	err \|= __put_user(kinfo->si_tid, &uinfo->ssi_tid);
	104	err \|= __put_user(kinfo->si_overrun, &uinfo->ssi_overrun);
	105	err \|= __put_user((long) kinfo->si_ptr, &uinfo->ssi_ptr);
a2a20c41	106	err \|= __put_user(kinfo->si_int, &uinfo->ssi_int);
fba2afaa DL	107	break;
fba2afaa DL	108	case __SI_POLL:
96358de6 DL	109	err \|= __put_user(kinfo->si_band, &uinfo->ssi_band);
96358de6 DL	110	err \|= __put_user(kinfo->si_fd, &uinfo->ssi_fd);
fba2afaa DL	111	break;
fba2afaa DL	112	case __SI_FAULT:
96358de6	113	err \|= __put_user((long) kinfo->si_addr, &uinfo->ssi_addr);
fba2afaa	114	#ifdef __ARCH_SI_TRAPNO
96358de6	115	err \|= __put_user(kinfo->si_trapno, &uinfo->ssi_trapno);
b8aeec34 HS	116	#endif
	117	#ifdef BUS_MCEERR_AO
	118	/*
	119	* Other callers might not initialize the si_lsb field,
	120	* so check explicitly for the right codes here.
	121	*/
	122	if (kinfo->si_code == BUS_MCEERR_AR \|\|
	123	kinfo->si_code == BUS_MCEERR_AO)
	124	err \|= __put_user((short) kinfo->si_addr_lsb,
	125	&uinfo->ssi_addr_lsb);
fba2afaa DL	126	#endif
	127	break;
	128	case __SI_CHLD:
96358de6 DL	129	err \|= __put_user(kinfo->si_pid, &uinfo->ssi_pid);
	130	err \|= __put_user(kinfo->si_uid, &uinfo->ssi_uid);
	131	err \|= __put_user(kinfo->si_status, &uinfo->ssi_status);
	132	err \|= __put_user(kinfo->si_utime, &uinfo->ssi_utime);
	133	err \|= __put_user(kinfo->si_stime, &uinfo->ssi_stime);
fba2afaa DL	134	break;
	135	case __SI_RT: /* This is not generated by the kernel as of now. */
	136	case __SI_MESGQ: /* But this is */
96358de6 DL	137	err \|= __put_user(kinfo->si_pid, &uinfo->ssi_pid);
	138	err \|= __put_user(kinfo->si_uid, &uinfo->ssi_uid);
	139	err \|= __put_user((long) kinfo->si_ptr, &uinfo->ssi_ptr);
a2a20c41	140	err \|= __put_user(kinfo->si_int, &uinfo->ssi_int);
fba2afaa	141	break;
0859ab59 DL	142	default:
	143	/*
	144	* This case catches also the signals queued by sigqueue().
	145	*/
96358de6 DL	146	err \|= __put_user(kinfo->si_pid, &uinfo->ssi_pid);
96358de6 DL	147	err \|= __put_user(kinfo->si_uid, &uinfo->ssi_uid);
0859ab59 DL	148	err \|= __put_user((long) kinfo->si_ptr, &uinfo->ssi_ptr);
0859ab59 DL	149	err \|= __put_user(kinfo->si_int, &uinfo->ssi_int);
fba2afaa DL	150	break;
	151	}
	152
	153	return err ? -EFAULT: sizeof(*uinfo);
	154	}
	155
b3762bfc DA	156	static ssize_t signalfd_dequeue(struct signalfd_ctx ctx, siginfo_t info,
	157	int nonblock)
	158	{
	159	ssize_t ret;
b3762bfc DA	160	DECLARE_WAITQUEUE(wait, current);
b3762bfc DA	161
b8fceee1 DL	162	spin_lock_irq(&current->sighand->siglock);
b8fceee1 DL	163	ret = dequeue_signal(current, &ctx->sigmask, info);
b3762bfc DA	164	switch (ret) {
	165	case 0:
	166	if (!nonblock)
	167	break;
	168	ret = -EAGAIN;
	169	default:
b8fceee1	170	spin_unlock_irq(&current->sighand->siglock);
b3762bfc DA	171	return ret;
	172	}
	173
b8fceee1	174	add_wait_queue(&current->sighand->signalfd_wqh, &wait);
b3762bfc DA	175	for (;;) {
b3762bfc DA	176	set_current_state(TASK_INTERRUPTIBLE);
b8fceee1	177	ret = dequeue_signal(current, &ctx->sigmask, info);
b3762bfc DA	178	if (ret != 0)
	179	break;
	180	if (signal_pending(current)) {
	181	ret = -ERESTARTSYS;
	182	break;
	183	}
b8fceee1	184	spin_unlock_irq(&current->sighand->siglock);
b3762bfc	185	schedule();
b8fceee1	186	spin_lock_irq(&current->sighand->siglock);
b3762bfc	187	}
b8fceee1	188	spin_unlock_irq(&current->sighand->siglock);
b3762bfc	189
b8fceee1	190	remove_wait_queue(&current->sighand->signalfd_wqh, &wait);
b3762bfc DA	191	__set_current_state(TASK_RUNNING);
	192
	193	return ret;
	194	}
	195
fba2afaa	196	/*
b8fceee1 DL	197	* Returns a multiple of the size of a "struct signalfd_siginfo", or a negative
	198	* error code. The "count" parameter must be at least the size of a
	199	* "struct signalfd_siginfo".
fba2afaa DL	200	*/
	201	static ssize_t signalfd_read(struct file file, char __user buf, size_t count,
	202	loff_t *ppos)
	203	{
	204	struct signalfd_ctx *ctx = file->private_data;
b3762bfc DA	205	struct signalfd_siginfo __user *siginfo;
	206	int nonblock = file->f_flags & O_NONBLOCK;
	207	ssize_t ret, total = 0;
fba2afaa	208	siginfo_t info;
fba2afaa	209
b3762bfc DA	210	count /= sizeof(struct signalfd_siginfo);
b3762bfc DA	211	if (!count)
fba2afaa	212	return -EINVAL;
fba2afaa	213
b3762bfc	214	siginfo = (struct signalfd_siginfo __user *) buf;
b3762bfc DA	215	do {
	216	ret = signalfd_dequeue(ctx, &info, nonblock);
	217	if (unlikely(ret <= 0))
	218	break;
	219	ret = signalfd_copyinfo(siginfo, &info);
	220	if (ret < 0)
	221	break;
	222	siginfo++;
	223	total += ret;
	224	nonblock = 1;
	225	} while (--count);
	226
b8fceee1	227	return total ? total: ret;
fba2afaa DL	228	}
	229
	230	static const struct file_operations signalfd_fops = {
	231	.release = signalfd_release,
	232	.poll = signalfd_poll,
	233	.read = signalfd_read,
6038f373	234	.llseek = noop_llseek,
fba2afaa DL	235	};
fba2afaa DL	236
836f92ad HC	237	SYSCALL_DEFINE4(signalfd4, int, ufd, sigset_t __user *, user_mask,
836f92ad HC	238	size_t, sizemask, int, flags)
fba2afaa	239	{
fba2afaa DL	240	sigset_t sigmask;
fba2afaa DL	241	struct signalfd_ctx *ctx;
fba2afaa	242
e38b36f3 UD	243	/* Check the SFD_* constants for consistency. */
	244	BUILD_BUG_ON(SFD_CLOEXEC != O_CLOEXEC);
	245	BUILD_BUG_ON(SFD_NONBLOCK != O_NONBLOCK);
	246
5fb5e049	247	if (flags & ~(SFD_CLOEXEC \| SFD_NONBLOCK))
9deb27ba UD	248	return -EINVAL;
9deb27ba UD	249
fba2afaa DL	250	if (sizemask != sizeof(sigset_t) \|\|
fba2afaa DL	251	copy_from_user(&sigmask, user_mask, sizeof(sigmask)))
f50cadaa	252	return -EINVAL;
fba2afaa DL	253	sigdelsetmask(&sigmask, sigmask(SIGKILL) \| sigmask(SIGSTOP));
	254	signotset(&sigmask);
	255
	256	if (ufd == -1) {
	257	ctx = kmalloc(sizeof(*ctx), GFP_KERNEL);
	258	if (!ctx)
	259	return -ENOMEM;
	260
fba2afaa	261	ctx->sigmask = sigmask;
fba2afaa DL	262
	263	/*
	264	* When we call this, the initialization must be complete, since
	265	* anon_inode_getfd() will install the fd.
	266	*/
7d9dbca3	267	ufd = anon_inode_getfd("[signalfd]", &signalfd_fops, ctx,
628ff7c1	268	O_RDWR \| (flags & (O_CLOEXEC \| O_NONBLOCK)));
2030a42c AV	269	if (ufd < 0)
2030a42c AV	270	kfree(ctx);
fba2afaa	271	} else {
2903ff01 AV	272	struct fd f = fdget(ufd);
2903ff01 AV	273	if (!f.file)
fba2afaa	274	return -EBADF;
2903ff01 AV	275	ctx = f.file->private_data;
	276	if (f.file->f_op != &signalfd_fops) {
	277	fdput(f);
fba2afaa DL	278	return -EINVAL;
fba2afaa DL	279	}
b8fceee1 DL	280	spin_lock_irq(&current->sighand->siglock);
	281	ctx->sigmask = sigmask;
	282	spin_unlock_irq(&current->sighand->siglock);
	283
	284	wake_up(&current->sighand->signalfd_wqh);
2903ff01	285	fdput(f);
fba2afaa DL	286	}
	287
	288	return ufd;
fba2afaa	289	}
9deb27ba	290
836f92ad HC	291	SYSCALL_DEFINE3(signalfd, int, ufd, sigset_t __user *, user_mask,
836f92ad HC	292	size_t, sizemask)
9deb27ba UD	293	{
	294	return sys_signalfd4(ufd, user_mask, sizemask, 0);
	295	}