[net-next-2.6.git] / fs / signalfd.c

/*
 *  fs/signalfd.c
 *
 *  Copyright (C) 2003  Linus Torvalds
 *
 *  Mon Mar 5, 2007: Davide Libenzi <davidel@xmailserver.org>
 *      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 <davi@haxent.com.br>
 *      Retrieve multiple signals with one read() call
 */

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

struct signalfd_ctx {
	struct list_head lnk;
	wait_queue_head_t wqh;
	sigset_t sigmask;
	struct task_struct *tsk;
};

struct signalfd_lockctx {
	struct task_struct *tsk;
	unsigned long flags;
};

/*
 * Tries to acquire the sighand lock. We do not increment the sighand
 * use count, and we do not even pin the task struct, so we need to
 * do it inside an RCU read lock, and we must be prepared for the
 * ctx->tsk going to NULL (in signalfd_deliver()), and for the sighand
 * being detached. We return 0 if the sighand has been detached, or
 * 1 if we were able to pin the sighand lock.
 */
static int signalfd_lock(struct signalfd_ctx *ctx, struct signalfd_lockctx *lk)
{
	struct sighand_struct *sighand = NULL;

	rcu_read_lock();
	lk->tsk = rcu_dereference(ctx->tsk);
	if (likely(lk->tsk != NULL))
		sighand = lock_task_sighand(lk->tsk, &lk->flags);
	rcu_read_unlock();

	if (!sighand)
		return 0;

	if (!ctx->tsk) {
		unlock_task_sighand(lk->tsk, &lk->flags);
		return 0;
	}

	if (lk->tsk->tgid == current->tgid)
		lk->tsk = current;

	return 1;
}

static void signalfd_unlock(struct signalfd_lockctx *lk)
{
	unlock_task_sighand(lk->tsk, &lk->flags);
}

/*
 * This must be called with the sighand lock held.
 */
void signalfd_deliver(struct task_struct *tsk, int sig)
{
	struct sighand_struct *sighand = tsk->sighand;
	struct signalfd_ctx *ctx, *tmp;

	BUG_ON(!sig);
	list_for_each_entry_safe(ctx, tmp, &sighand->signalfd_list, lnk) {
		/*
		 * We use a negative signal value as a way to broadcast that the
		 * sighand has been orphaned, so that we can notify all the
		 * listeners about this. Remember the ctx->sigmask is inverted,
		 * so if the user is interested in a signal, that corresponding
		 * bit will be zero.
		 */
		if (sig < 0) {
			if (ctx->tsk == tsk) {
				ctx->tsk = NULL;
				list_del_init(&ctx->lnk);
				wake_up(&ctx->wqh);
			}
		} else {
			if (!sigismember(&ctx->sigmask, sig))
				wake_up(&ctx->wqh);
		}
	}
}

static void signalfd_cleanup(struct signalfd_ctx *ctx)
{
	struct signalfd_lockctx lk;

	/*
	 * This is tricky. If the sighand is gone, we do not need to remove
	 * context from the list, the list itself won't be there anymore.
	 */
	if (signalfd_lock(ctx, &lk)) {
		list_del(&ctx->lnk);
		signalfd_unlock(&lk);
	}
	kfree(ctx);
}

static int signalfd_release(struct inode *inode, struct file *file)
{
	signalfd_cleanup(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;
	struct signalfd_lockctx lk;

	poll_wait(file, &ctx->wqh, wait);

	/*
	 * Let the caller get a POLLIN in this case, ala socket recv() when
	 * the peer disconnects.
	 */
	if (signalfd_lock(ctx, &lk)) {
		if ((lk.tsk == current &&
		     next_signal(&lk.tsk->pending, &ctx->sigmask) > 0) ||
		    next_signal(&lk.tsk->signal->shared_pending,
				&ctx->sigmask) > 0)
			events |= POLLIN;
		signalfd_unlock(&lk);
	} else
		events |= POLLIN;

	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 memebers 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->signo);
	err |= __put_user(kinfo->si_errno, &uinfo->err);
	err |= __put_user((short)kinfo->si_code, &uinfo->code);
	switch (kinfo->si_code & __SI_MASK) {
	case __SI_KILL:
		err |= __put_user(kinfo->si_pid, &uinfo->pid);
		err |= __put_user(kinfo->si_uid, &uinfo->uid);
		break;
	case __SI_TIMER:
		 err |= __put_user(kinfo->si_tid, &uinfo->tid);
		 err |= __put_user(kinfo->si_overrun, &uinfo->overrun);
		 err |= __put_user((long)kinfo->si_ptr, &uinfo->svptr);
		break;
	case __SI_POLL:
		err |= __put_user(kinfo->si_band, &uinfo->band);
		err |= __put_user(kinfo->si_fd, &uinfo->fd);
		break;
	case __SI_FAULT:
		err |= __put_user((long)kinfo->si_addr, &uinfo->addr);
#ifdef __ARCH_SI_TRAPNO
		err |= __put_user(kinfo->si_trapno, &uinfo->trapno);
#endif
		break;
	case __SI_CHLD:
		err |= __put_user(kinfo->si_pid, &uinfo->pid);
		err |= __put_user(kinfo->si_uid, &uinfo->uid);
		err |= __put_user(kinfo->si_status, &uinfo->status);
		err |= __put_user(kinfo->si_utime, &uinfo->utime);
		err |= __put_user(kinfo->si_stime, &uinfo->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->pid);
		err |= __put_user(kinfo->si_uid, &uinfo->uid);
		err |= __put_user((long)kinfo->si_ptr, &uinfo->svptr);
		break;
	default: /* this is just in case for now ... */
		err |= __put_user(kinfo->si_pid, &uinfo->pid);
		err |= __put_user(kinfo->si_uid, &uinfo->uid);
		break;
	}

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

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

	if (!signalfd_lock(ctx, &lk))
		return 0;

	ret = dequeue_signal(lk.tsk, &ctx->sigmask, info);
	switch (ret) {
	case 0:
		if (!nonblock)
			break;
		ret = -EAGAIN;
	default:
		signalfd_unlock(&lk);
		return ret;
	}

	add_wait_queue(&ctx->wqh, &wait);
	for (;;) {
		set_current_state(TASK_INTERRUPTIBLE);
		ret = dequeue_signal(lk.tsk, &ctx->sigmask, info);
		signalfd_unlock(&lk);
		if (ret != 0)
			break;
		if (signal_pending(current)) {
			ret = -ERESTARTSYS;
			break;
		}
		schedule();
		ret = signalfd_lock(ctx, &lk);
		if (unlikely(!ret)) {
			/*
			 * Let the caller read zero byte, ala socket
			 * recv() when the peer disconnect. This test
			 * must be done before doing a dequeue_signal(),
			 * because if the sighand has been orphaned,
			 * the dequeue_signal() call is going to crash
			 * because ->sighand will be long gone.
			 */
			 break;
		}
	}

	remove_wait_queue(&ctx->wqh, &wait);
	__set_current_state(TASK_RUNNING);

	return ret;
}

/*
 * Returns either the size of a "struct signalfd_siginfo", or zero if the
 * sighand we are attached to, has been orphaned. 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,
};

/*
 * Create a file descriptor that is associated with our signal
 * state. We can pass it around to others if we want to, but
 * it will always be _our_ signal state.
 */
asmlinkage long sys_signalfd(int ufd, sigset_t __user *user_mask, size_t sizemask)
{
	int error;
	sigset_t sigmask;
	struct signalfd_ctx *ctx;
	struct sighand_struct *sighand;
	struct file *file;
	struct inode *inode;
	struct signalfd_lockctx lk;

	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;

		init_waitqueue_head(&ctx->wqh);
		ctx->sigmask = sigmask;
		ctx->tsk = current->group_leader;

		sighand = current->sighand;
		/*
		 * Add this fd to the list of signal listeners.
		 */
		spin_lock_irq(&sighand->siglock);
		list_add_tail(&ctx->lnk, &sighand->signalfd_list);
		spin_unlock_irq(&sighand->siglock);

		/*
		 * When we call this, the initialization must be complete, since
		 * anon_inode_getfd() will install the fd.
		 */
		error = anon_inode_getfd(&ufd, &inode, &file, "[signalfd]",
					 &signalfd_fops, ctx);
		if (error)
			goto err_fdalloc;
	} else {
		file = fget(ufd);
		if (!file)
			return -EBADF;
		ctx = file->private_data;
		if (file->f_op != &signalfd_fops) {
			fput(file);
			return -EINVAL;
		}
		/*
		 * We need to be prepared of the fact that the sighand this fd
		 * is attached to, has been detched. In that case signalfd_lock()
		 * will return 0, and we'll just skip setting the new mask.
		 */
		if (signalfd_lock(ctx, &lk)) {
			ctx->sigmask = sigmask;
			signalfd_unlock(&lk);
		}
		wake_up(&ctx->wqh);
		fput(file);
	}

	return ufd;

err_fdalloc:
	signalfd_cleanup(ctx);
	return error;
}
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 <davidel@xmailserver.org>
	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.
b3762bfc DA	14	* Sat May 19, 2007: Davi E. M. Arnaut <davi@haxent.com.br>
b3762bfc DA	15	* Retrieve multiple signals with one read() call
fba2afaa DL	16	*/
	17
	18	#include <linux/file.h>
	19	#include <linux/poll.h>
	20	#include <linux/init.h>
	21	#include <linux/fs.h>
	22	#include <linux/sched.h>
	23	#include <linux/kernel.h>
	24	#include <linux/signal.h>
	25	#include <linux/list.h>
	26	#include <linux/anon_inodes.h>
	27	#include <linux/signalfd.h>
	28
	29	struct signalfd_ctx {
	30	struct list_head lnk;
	31	wait_queue_head_t wqh;
	32	sigset_t sigmask;
	33	struct task_struct *tsk;
	34	};
	35
	36	struct signalfd_lockctx {
	37	struct task_struct *tsk;
	38	unsigned long flags;
	39	};
	40
	41	/*
	42	* Tries to acquire the sighand lock. We do not increment the sighand
	43	* use count, and we do not even pin the task struct, so we need to
	44	* do it inside an RCU read lock, and we must be prepared for the
	45	* ctx->tsk going to NULL (in signalfd_deliver()), and for the sighand
	46	* being detached. We return 0 if the sighand has been detached, or
	47	* 1 if we were able to pin the sighand lock.
	48	*/
	49	static int signalfd_lock(struct signalfd_ctx ctx, struct signalfd_lockctx lk)
	50	{
	51	struct sighand_struct *sighand = NULL;
	52
	53	rcu_read_lock();
	54	lk->tsk = rcu_dereference(ctx->tsk);
	55	if (likely(lk->tsk != NULL))
	56	sighand = lock_task_sighand(lk->tsk, &lk->flags);
	57	rcu_read_unlock();
	58
f9ee228b ON	59	if (!sighand)
	60	return 0;
	61
	62	if (!ctx->tsk) {
fba2afaa	63	unlock_task_sighand(lk->tsk, &lk->flags);
f9ee228b	64	return 0;
fba2afaa DL	65	}
fba2afaa DL	66
f9ee228b ON	67	if (lk->tsk->tgid == current->tgid)
	68	lk->tsk = current;
	69
	70	return 1;
fba2afaa DL	71	}
	72
	73	static void signalfd_unlock(struct signalfd_lockctx *lk)
	74	{
	75	unlock_task_sighand(lk->tsk, &lk->flags);
	76	}
	77
	78	/*
	79	* This must be called with the sighand lock held.
	80	*/
	81	void signalfd_deliver(struct task_struct *tsk, int sig)
	82	{
	83	struct sighand_struct *sighand = tsk->sighand;
	84	struct signalfd_ctx ctx, tmp;
	85
	86	BUG_ON(!sig);
	87	list_for_each_entry_safe(ctx, tmp, &sighand->signalfd_list, lnk) {
	88	/*
	89	* We use a negative signal value as a way to broadcast that the
	90	* sighand has been orphaned, so that we can notify all the
	91	* listeners about this. Remember the ctx->sigmask is inverted,
	92	* so if the user is interested in a signal, that corresponding
	93	* bit will be zero.
	94	*/
	95	if (sig < 0) {
	96	if (ctx->tsk == tsk) {
	97	ctx->tsk = NULL;
	98	list_del_init(&ctx->lnk);
	99	wake_up(&ctx->wqh);
	100	}
	101	} else {
	102	if (!sigismember(&ctx->sigmask, sig))
	103	wake_up(&ctx->wqh);
	104	}
	105	}
	106	}
	107
	108	static void signalfd_cleanup(struct signalfd_ctx *ctx)
	109	{
	110	struct signalfd_lockctx lk;
	111
	112	/*
	113	* This is tricky. If the sighand is gone, we do not need to remove
	114	* context from the list, the list itself won't be there anymore.
	115	*/
	116	if (signalfd_lock(ctx, &lk)) {
	117	list_del(&ctx->lnk);
	118	signalfd_unlock(&lk);
	119	}
	120	kfree(ctx);
	121	}
	122
	123	static int signalfd_release(struct inode inode, struct file file)
	124	{
	125	signalfd_cleanup(file->private_data);
	126	return 0;
	127	}
	128
	129	static unsigned int signalfd_poll(struct file file, poll_table wait)
	130	{
	131	struct signalfd_ctx *ctx = file->private_data;
	132	unsigned int events = 0;
	133	struct signalfd_lockctx lk;
	134
135	poll_wait(file, &ctx->wqh, wait);
136
137	/*
138	* Let the caller get a POLLIN in this case, ala socket recv() when
139	* the peer disconnects.
140	*/
141	if (signalfd_lock(ctx, &lk)) {
f8738c5c DL	142	if ((lk.tsk == current &&
f8738c5c DL	143	next_signal(&lk.tsk->pending, &ctx->sigmask) > 0) \|\|
fba2afaa DL	144	next_signal(&lk.tsk->signal->shared_pending,
	145	&ctx->sigmask) > 0)
	146	events \|= POLLIN;
	147	signalfd_unlock(&lk);
	148	} else
	149	events \|= POLLIN;
	150
	151	return events;
	152	}
	153
	154	/*
	155	* Copied from copy_siginfo_to_user() in kernel/signal.c
	156	*/
	157	static int signalfd_copyinfo(struct signalfd_siginfo __user *uinfo,
	158	siginfo_t const *kinfo)
	159	{
	160	long err;
	161
	162	BUILD_BUG_ON(sizeof(struct signalfd_siginfo) != 128);
	163
	164	/*
	165	* Unused memebers should be zero ...
	166	*/
	167	err = __clear_user(uinfo, sizeof(*uinfo));
	168
	169	/*
	170	* If you change siginfo_t structure, please be sure
	171	* this code is fixed accordingly.
	172	*/
	173	err \|= __put_user(kinfo->si_signo, &uinfo->signo);
	174	err \|= __put_user(kinfo->si_errno, &uinfo->err);
	175	err \|= __put_user((short)kinfo->si_code, &uinfo->code);
	176	switch (kinfo->si_code & __SI_MASK) {
	177	case __SI_KILL:
	178	err \|= __put_user(kinfo->si_pid, &uinfo->pid);
	179	err \|= __put_user(kinfo->si_uid, &uinfo->uid);
	180	break;
	181	case __SI_TIMER:
	182	err \|= __put_user(kinfo->si_tid, &uinfo->tid);
	183	err \|= __put_user(kinfo->si_overrun, &uinfo->overrun);
	184	err \|= __put_user((long)kinfo->si_ptr, &uinfo->svptr);
	185	break;
	186	case __SI_POLL:
	187	err \|= __put_user(kinfo->si_band, &uinfo->band);
	188	err \|= __put_user(kinfo->si_fd, &uinfo->fd);
	189	break;
	190	case __SI_FAULT:
	191	err \|= __put_user((long)kinfo->si_addr, &uinfo->addr);
	192	#ifdef __ARCH_SI_TRAPNO
	193	err \|= __put_user(kinfo->si_trapno, &uinfo->trapno);
	194	#endif
	195	break;
	196	case __SI_CHLD:
	197	err \|= __put_user(kinfo->si_pid, &uinfo->pid);
	198	err \|= __put_user(kinfo->si_uid, &uinfo->uid);
	199	err \|= __put_user(kinfo->si_status, &uinfo->status);
	200	err \|= __put_user(kinfo->si_utime, &uinfo->utime);
	201	err \|= __put_user(kinfo->si_stime, &uinfo->stime);
	202	break;
	203	case __SI_RT: /* This is not generated by the kernel as of now. */
	204	case __SI_MESGQ: /* But this is */
	205	err \|= __put_user(kinfo->si_pid, &uinfo->pid);
	206	err \|= __put_user(kinfo->si_uid, &uinfo->uid);
	207	err \|= __put_user((long)kinfo->si_ptr, &uinfo->svptr);
208	break;
209	default: /* this is just in case for now ... */
210	err \|= __put_user(kinfo->si_pid, &uinfo->pid);
211	err \|= __put_user(kinfo->si_uid, &uinfo->uid);
212	break;
213	}
214
215	return err ? -EFAULT: sizeof(*uinfo);
216	}
217
b3762bfc DA	218	static ssize_t signalfd_dequeue(struct signalfd_ctx ctx, siginfo_t info,
	219	int nonblock)
	220	{
	221	ssize_t ret;
	222	struct signalfd_lockctx lk;
	223	DECLARE_WAITQUEUE(wait, current);
	224
	225	if (!signalfd_lock(ctx, &lk))
	226	return 0;
	227
	228	ret = dequeue_signal(lk.tsk, &ctx->sigmask, info);
	229	switch (ret) {
	230	case 0:
	231	if (!nonblock)
	232	break;
	233	ret = -EAGAIN;
	234	default:
	235	signalfd_unlock(&lk);
	236	return ret;
	237	}
	238
	239	add_wait_queue(&ctx->wqh, &wait);
	240	for (;;) {
	241	set_current_state(TASK_INTERRUPTIBLE);
	242	ret = dequeue_signal(lk.tsk, &ctx->sigmask, info);
	243	signalfd_unlock(&lk);
	244	if (ret != 0)
	245	break;
	246	if (signal_pending(current)) {
	247	ret = -ERESTARTSYS;
	248	break;
	249	}
	250	schedule();
	251	ret = signalfd_lock(ctx, &lk);
	252	if (unlikely(!ret)) {
	253	/*
	254	* Let the caller read zero byte, ala socket
	255	* recv() when the peer disconnect. This test
	256	* must be done before doing a dequeue_signal(),
	257	* because if the sighand has been orphaned,
	258	* the dequeue_signal() call is going to crash
	259	* because ->sighand will be long gone.
	260	*/
	261	break;
	262	}
	263	}
	264
	265	remove_wait_queue(&ctx->wqh, &wait);
	266	__set_current_state(TASK_RUNNING);
	267
	268	return ret;
	269	}
	270
fba2afaa DL	271	/*
	272	* Returns either the size of a "struct signalfd_siginfo", or zero if the
	273	* sighand we are attached to, has been orphaned. The "count" parameter
	274	* must be at least the size of a "struct signalfd_siginfo".
	275	*/
	276	static ssize_t signalfd_read(struct file file, char __user buf, size_t count,
	277	loff_t *ppos)
	278	{
	279	struct signalfd_ctx *ctx = file->private_data;
b3762bfc DA	280	struct signalfd_siginfo __user *siginfo;
	281	int nonblock = file->f_flags & O_NONBLOCK;
	282	ssize_t ret, total = 0;
fba2afaa	283	siginfo_t info;
fba2afaa	284
b3762bfc DA	285	count /= sizeof(struct signalfd_siginfo);
b3762bfc DA	286	if (!count)
fba2afaa	287	return -EINVAL;
fba2afaa	288
b3762bfc DA	289	siginfo = (struct signalfd_siginfo __user *) buf;
	290
	291	do {
	292	ret = signalfd_dequeue(ctx, &info, nonblock);
	293	if (unlikely(ret <= 0))
	294	break;
	295	ret = signalfd_copyinfo(siginfo, &info);
	296	if (ret < 0)
	297	break;
	298	siginfo++;
	299	total += ret;
	300	nonblock = 1;
	301	} while (--count);
	302
	303	return total ? total : ret;
fba2afaa DL	304	}
	305
	306	static const struct file_operations signalfd_fops = {
	307	.release = signalfd_release,
	308	.poll = signalfd_poll,
	309	.read = signalfd_read,
	310	};
	311
	312	/*
	313	* Create a file descriptor that is associated with our signal
	314	* state. We can pass it around to others if we want to, but
	315	* it will always be _our_ signal state.
	316	*/
	317	asmlinkage long sys_signalfd(int ufd, sigset_t __user *user_mask, size_t sizemask)
	318	{
	319	int error;
	320	sigset_t sigmask;
	321	struct signalfd_ctx *ctx;
	322	struct sighand_struct *sighand;
	323	struct file *file;
	324	struct inode *inode;
	325	struct signalfd_lockctx lk;
	326
	327	if (sizemask != sizeof(sigset_t) \|\|
	328	copy_from_user(&sigmask, user_mask, sizeof(sigmask)))
f50cadaa	329	return -EINVAL;
fba2afaa DL	330	sigdelsetmask(&sigmask, sigmask(SIGKILL) \| sigmask(SIGSTOP));
	331	signotset(&sigmask);
	332
	333	if (ufd == -1) {
	334	ctx = kmalloc(sizeof(*ctx), GFP_KERNEL);
	335	if (!ctx)
	336	return -ENOMEM;
	337
	338	init_waitqueue_head(&ctx->wqh);
	339	ctx->sigmask = sigmask;
f9ee228b	340	ctx->tsk = current->group_leader;
fba2afaa DL	341
	342	sighand = current->sighand;
	343	/*
	344	* Add this fd to the list of signal listeners.
	345	*/
	346	spin_lock_irq(&sighand->siglock);
	347	list_add_tail(&ctx->lnk, &sighand->signalfd_list);
	348	spin_unlock_irq(&sighand->siglock);
	349
	350	/*
	351	* When we call this, the initialization must be complete, since
	352	* anon_inode_getfd() will install the fd.
	353	*/
	354	error = anon_inode_getfd(&ufd, &inode, &file, "[signalfd]",
	355	&signalfd_fops, ctx);
	356	if (error)
	357	goto err_fdalloc;
	358	} else {
	359	file = fget(ufd);
	360	if (!file)
	361	return -EBADF;
	362	ctx = file->private_data;
	363	if (file->f_op != &signalfd_fops) {
	364	fput(file);
	365	return -EINVAL;
	366	}
	367	/*
	368	* We need to be prepared of the fact that the sighand this fd
	369	* is attached to, has been detched. In that case signalfd_lock()
	370	* will return 0, and we'll just skip setting the new mask.
	371	*/
	372	if (signalfd_lock(ctx, &lk)) {
	373	ctx->sigmask = sigmask;
	374	signalfd_unlock(&lk);
	375	}
	376	wake_up(&ctx->wqh);
	377	fput(file);
	378	}
	379
	380	return ufd;
	381
	382	err_fdalloc:
	383	signalfd_cleanup(ctx);
	384	return error;
	385	}
	386