Commit d9497990 authored by Jens Axboe's avatar Jens Axboe
Browse files

timerfd: convert to ->read_iter() 



Switch timerfd to using fops->read_iter(), so it can support not just
O_NONBLOCK but IOCB_NOWAIT as well. With the latter, users like io_uring
interact with timerfds a lot better, as they can be driven purely
by the poll trigger.

Manually get and install the required fd, so that FMODE_NOWAIT can be
set before the file is installed into the file table.

No functional changes intended in this patch, it's purely a straight
conversion to using the read iterator method.

Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 1f65f52d

fs/timerfd.c

+26 −10
Original line number Diff line number Diff line
@@ -262,17 +262,18 @@ static __poll_t timerfd_poll(struct file *file, poll_table *wait) 
	return events;

}



static ssize_t timerfd_read(struct file *file, char __user *buf, size_t count,

			    loff_t *ppos)

static ssize_t timerfd_read_iter(struct kiocb *iocb, struct iov_iter *to)

{

	struct file *file = iocb->ki_filp;

	struct timerfd_ctx *ctx = file->private_data;

	ssize_t res;

	u64 ticks = 0;



	if (count < sizeof(ticks))

	if (iov_iter_count(to) < sizeof(ticks))

		return -EINVAL;



	spin_lock_irq(&ctx->wqh.lock);

	if (file->f_flags & O_NONBLOCK)

	if (file->f_flags & O_NONBLOCK || iocb->ki_flags & IOCB_NOWAIT)

		res = -EAGAIN;

	else

		res = wait_event_interruptible_locked_irq(ctx->wqh, ctx->ticks);
@@ -312,8 +313,11 @@ static ssize_t timerfd_read(struct file *file, char __user *buf, size_t count, 
		ctx->ticks = 0;

	}

	spin_unlock_irq(&ctx->wqh.lock);

	if (ticks)

		res = put_user(ticks, (u64 __user *) buf) ? -EFAULT: sizeof(ticks);

	if (ticks) {

		res = copy_to_iter(&ticks, sizeof(ticks), to);

		if (!res)

			res = -EFAULT;

	}

	return res;

}
@@ -384,7 +388,7 @@ static long timerfd_ioctl(struct file *file, unsigned int cmd, unsigned long arg 
static const struct file_operations timerfd_fops = {

	.release	= timerfd_release,

	.poll		= timerfd_poll,

	.read		= timerfd_read,

	.read_iter	= timerfd_read_iter,

	.llseek		= noop_llseek,

	.show_fdinfo	= timerfd_show,

	.unlocked_ioctl	= timerfd_ioctl,
@@ -407,6 +411,7 @@ SYSCALL_DEFINE2(timerfd_create, int, clockid, int, flags) 
{

	int ufd;

	struct timerfd_ctx *ctx;

	struct file *file;



	/* Check the TFD_* constants for consistency.  */

	BUILD_BUG_ON(TFD_CLOEXEC != O_CLOEXEC);
@@ -443,11 +448,22 @@ SYSCALL_DEFINE2(timerfd_create, int, clockid, int, flags) 


	ctx->moffs = ktime_mono_to_real(0);



	ufd = anon_inode_getfd("[timerfd]", &timerfd_fops, ctx,

	ufd = get_unused_fd_flags(flags & TFD_SHARED_FCNTL_FLAGS);

	if (ufd < 0) {

		kfree(ctx);

		return ufd;

	}



	file = anon_inode_getfile("[timerfd]", &timerfd_fops, ctx,

				    O_RDWR | (flags & TFD_SHARED_FCNTL_FLAGS));

	if (ufd < 0)

	if (IS_ERR(file)) {

		put_unused_fd(ufd);

		kfree(ctx);

		return PTR_ERR(file);

	}



	file->f_mode |= FMODE_NOWAIT;

	fd_install(ufd, file);

	return ufd;

}