Commit 9b402849 authored by Jens Axboe's avatar Jens Axboe
Browse files

io_uring: add support for eventfd notifications 



Allow registration of an eventfd, which will trigger an event every
time a completion event happens for this io_uring instance.

Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 5d17b4a4

fs/io_uring.c

+48 −0
Original line number Diff line number Diff line
@@ -241,6 +241,7 @@ struct io_ring_ctx { 
		unsigned		cq_mask;

		struct wait_queue_head	cq_wait;

		struct fasync_struct	*cq_fasync;

		struct eventfd_ctx	*cq_ev_fd;

	} ____cacheline_aligned_in_smp;



	/*
@@ -516,6 +517,8 @@ static void io_cqring_ev_posted(struct io_ring_ctx *ctx) 
		wake_up(&ctx->wait);

	if (waitqueue_active(&ctx->sqo_wait))

		wake_up(&ctx->sqo_wait);

	if (ctx->cq_ev_fd)

		eventfd_signal(ctx->cq_ev_fd, 1);

}



static void io_cqring_add_event(struct io_ring_ctx *ctx, u64 user_data,
@@ -2757,6 +2760,38 @@ err: 
	return ret;

}



static int io_eventfd_register(struct io_ring_ctx *ctx, void __user *arg)

{

	__s32 __user *fds = arg;

	int fd;



	if (ctx->cq_ev_fd)

		return -EBUSY;



	if (copy_from_user(&fd, fds, sizeof(*fds)))

		return -EFAULT;



	ctx->cq_ev_fd = eventfd_ctx_fdget(fd);

	if (IS_ERR(ctx->cq_ev_fd)) {

		int ret = PTR_ERR(ctx->cq_ev_fd);

		ctx->cq_ev_fd = NULL;

		return ret;

	}



	return 0;

}



static int io_eventfd_unregister(struct io_ring_ctx *ctx)

{

	if (ctx->cq_ev_fd) {

		eventfd_ctx_put(ctx->cq_ev_fd);

		ctx->cq_ev_fd = NULL;

		return 0;

	}



	return -ENXIO;

}



static void io_ring_ctx_free(struct io_ring_ctx *ctx)

{

	io_finish_async(ctx);
@@ -2766,6 +2801,7 @@ static void io_ring_ctx_free(struct io_ring_ctx *ctx) 
	io_iopoll_reap_events(ctx);

	io_sqe_buffer_unregister(ctx);

	io_sqe_files_unregister(ctx);

	io_eventfd_unregister(ctx);



#if defined(CONFIG_UNIX)

	if (ctx->ring_sock)
@@ -3179,6 +3215,18 @@ static int __io_uring_register(struct io_ring_ctx *ctx, unsigned opcode, 
			break;

		ret = io_sqe_files_unregister(ctx);

		break;

	case IORING_REGISTER_EVENTFD:

		ret = -EINVAL;

		if (nr_args != 1)

			break;

		ret = io_eventfd_register(ctx, arg);

		break;

	case IORING_UNREGISTER_EVENTFD:

		ret = -EINVAL;

		if (arg || nr_args)

			break;

		ret = io_eventfd_unregister(ctx);

		break;

	default:

		ret = -EINVAL;

		break;

include/uapi/linux/io_uring.h

+2 −0
Original line number Diff line number Diff line
@@ -136,5 +136,7 @@ struct io_uring_params { 
#define IORING_UNREGISTER_BUFFERS	1

#define IORING_REGISTER_FILES		2

#define IORING_UNREGISTER_FILES		3

#define IORING_REGISTER_EVENTFD		4

#define IORING_UNREGISTER_EVENTFD	5



#endif