Commit 0b6d253e authored by Jens Axboe's avatar Jens Axboe
Browse files

io_uring/register: provide helper to get io_ring_ctx from 'fd' 



Can be done in one of two ways:

1) Regular file descriptor, just fget()
2) Registered ring, index our own table for that

In preparation for adding another register use of needing to get a ctx
from a file descriptor, abstract out this helper and use it in the main
register syscall as well.

Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent bfc0aa7a

io_uring/register.c

+33 −21
Original line number Diff line number Diff line
@@ -550,21 +550,16 @@ static int __io_uring_register(struct io_ring_ctx *ctx, unsigned opcode, 
	return ret;

}



SYSCALL_DEFINE4(io_uring_register, unsigned int, fd, unsigned int, opcode,

		void __user *, arg, unsigned int, nr_args)

/*

 * Given an 'fd' value, return the ctx associated with if. If 'registered' is

 * true, then the registered index is used. Otherwise, the normal fd table.

 * Caller must call fput() on the returned file, unless it's an ERR_PTR.

 */

struct file *io_uring_register_get_file(int fd, bool registered)

{

	struct io_ring_ctx *ctx;

	long ret = -EBADF;

	struct file *file;

	bool use_registered_ring;



	use_registered_ring = !!(opcode & IORING_REGISTER_USE_REGISTERED_RING);

	opcode &= ~IORING_REGISTER_USE_REGISTERED_RING;



	if (opcode >= IORING_REGISTER_LAST)

		return -EINVAL;



	if (use_registered_ring) {

	if (registered) {

		/*

		 * Ring fd has been registered via IORING_REGISTER_RING_FDS, we

		 * need only dereference our task private array to find it.
@@ -572,27 +567,44 @@ SYSCALL_DEFINE4(io_uring_register, unsigned int, fd, unsigned int, opcode, 
		struct io_uring_task *tctx = current->io_uring;



		if (unlikely(!tctx || fd >= IO_RINGFD_REG_MAX))

			return -EINVAL;

			return ERR_PTR(-EINVAL);

		fd = array_index_nospec(fd, IO_RINGFD_REG_MAX);

		file = tctx->registered_rings[fd];

		if (unlikely(!file))

			return -EBADF;

	} else {

		file = fget(fd);

	}



	if (unlikely(!file))

			return -EBADF;

		ret = -EOPNOTSUPP;

		if (!io_is_uring_fops(file))

			goto out_fput;

		return ERR_PTR(-EBADF);

	if (io_is_uring_fops(file))

		return file;

	fput(file);

	return ERR_PTR(-EOPNOTSUPP);

}



SYSCALL_DEFINE4(io_uring_register, unsigned int, fd, unsigned int, opcode,

		void __user *, arg, unsigned int, nr_args)

{

	struct io_ring_ctx *ctx;

	long ret = -EBADF;

	struct file *file;

	bool use_registered_ring;



	use_registered_ring = !!(opcode & IORING_REGISTER_USE_REGISTERED_RING);

	opcode &= ~IORING_REGISTER_USE_REGISTERED_RING;



	if (opcode >= IORING_REGISTER_LAST)

		return -EINVAL;



	file = io_uring_register_get_file(fd, use_registered_ring);

	if (IS_ERR(file))

		return PTR_ERR(file);

	ctx = file->private_data;



	mutex_lock(&ctx->uring_lock);

	ret = __io_uring_register(ctx, opcode, arg, nr_args);

	mutex_unlock(&ctx->uring_lock);

	trace_io_uring_register(ctx, opcode, ctx->nr_user_files, ctx->nr_user_bufs, ret);

out_fput:

	if (!use_registered_ring)

		fput(file);

	return ret;

io_uring/register.h

+1 −0
Original line number Diff line number Diff line
@@ -4,5 +4,6 @@ 


int io_eventfd_unregister(struct io_ring_ctx *ctx);

int io_unregister_personality(struct io_ring_ctx *ctx, unsigned id);

struct file *io_uring_register_get_file(int fd, bool registered);



#endif