io_uring/cancel.c

// SPDX-License-Identifier: GPL-2.0
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/fs.h>
#include <linux/file.h>
#include <linux/mm.h>
#include <linux/slab.h>
#include <linux/namei.h>
#include <linux/io_uring.h>

#include <uapi/linux/io_uring.h>

#include "io_uring_types.h"
#include "io_uring.h"
#include "tctx.h"
#include "poll.h"
#include "timeout.h"
#include "cancel.h"

struct io_cancel {
	struct file			*file;
	u64				addr;
	u32				flags;
	s32				fd;
};

#define CANCEL_FLAGS	(IORING_ASYNC_CANCEL_ALL | IORING_ASYNC_CANCEL_FD | \
			 IORING_ASYNC_CANCEL_ANY)

static bool io_cancel_cb(struct io_wq_work *work, void *data)
{
	struct io_kiocb *req = container_of(work, struct io_kiocb, work);
	struct io_cancel_data *cd = data;

	if (req->ctx != cd->ctx)
		return false;
	if (cd->flags & IORING_ASYNC_CANCEL_ANY) {
		;
	} else if (cd->flags & IORING_ASYNC_CANCEL_FD) {
		if (req->file != cd->file)
			return false;
	} else {
		if (req->cqe.user_data != cd->data)
			return false;
	}
	if (cd->flags & (IORING_ASYNC_CANCEL_ALL|IORING_ASYNC_CANCEL_ANY)) {
		if (cd->seq == req->work.cancel_seq)
			return false;
		req->work.cancel_seq = cd->seq;
	}
	return true;
}

static int io_async_cancel_one(struct io_uring_task *tctx,
			       struct io_cancel_data *cd)
{
	enum io_wq_cancel cancel_ret;
	int ret = 0;
	bool all;

	if (!tctx || !tctx->io_wq)
		return -ENOENT;

	all = cd->flags & (IORING_ASYNC_CANCEL_ALL|IORING_ASYNC_CANCEL_ANY);
	cancel_ret = io_wq_cancel_cb(tctx->io_wq, io_cancel_cb, cd, all);
	switch (cancel_ret) {
	case IO_WQ_CANCEL_OK:
		ret = 0;
		break;
	case IO_WQ_CANCEL_RUNNING:
		ret = -EALREADY;
		break;
	case IO_WQ_CANCEL_NOTFOUND:
		ret = -ENOENT;
		break;
	}

	return ret;
}

int io_try_cancel(struct io_kiocb *req, struct io_cancel_data *cd)
{
	struct io_ring_ctx *ctx = req->ctx;
	int ret;

	WARN_ON_ONCE(!io_wq_current_is_worker() && req->task != current);

	ret = io_async_cancel_one(req->task->io_uring, cd);
	/*
	 * Fall-through even for -EALREADY, as we may have poll armed
	 * that need unarming.
	 */
	if (!ret)
		return 0;

	spin_lock(&ctx->completion_lock);
	ret = io_poll_cancel(ctx, cd);
	if (ret != -ENOENT)
		goto out;
	if (!(cd->flags & IORING_ASYNC_CANCEL_FD))
		ret = io_timeout_cancel(ctx, cd);
out:
	spin_unlock(&ctx->completion_lock);
	return ret;
}


int io_async_cancel_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
{
	struct io_cancel *cancel = io_kiocb_to_cmd(req);

	if (unlikely(req->flags & REQ_F_BUFFER_SELECT))
		return -EINVAL;
	if (sqe->off || sqe->len || sqe->splice_fd_in)
		return -EINVAL;

	cancel->addr = READ_ONCE(sqe->addr);
	cancel->flags = READ_ONCE(sqe->cancel_flags);
	if (cancel->flags & ~CANCEL_FLAGS)
		return -EINVAL;
	if (cancel->flags & IORING_ASYNC_CANCEL_FD) {
		if (cancel->flags & IORING_ASYNC_CANCEL_ANY)
			return -EINVAL;
		cancel->fd = READ_ONCE(sqe->fd);
	}

	return 0;
}

static int __io_async_cancel(struct io_cancel_data *cd, struct io_kiocb *req,
			     unsigned int issue_flags)
{
	bool all = cd->flags & (IORING_ASYNC_CANCEL_ALL|IORING_ASYNC_CANCEL_ANY);
	struct io_ring_ctx *ctx = cd->ctx;
	struct io_tctx_node *node;
	int ret, nr = 0;

	do {
		ret = io_try_cancel(req, cd);
		if (ret == -ENOENT)
			break;
		if (!all)
			return ret;
		nr++;
	} while (1);

	/* slow path, try all io-wq's */
	io_ring_submit_lock(ctx, issue_flags);
	ret = -ENOENT;
	list_for_each_entry(node, &ctx->tctx_list, ctx_node) {
		struct io_uring_task *tctx = node->task->io_uring;

		ret = io_async_cancel_one(tctx, cd);
		if (ret != -ENOENT) {
			if (!all)
				break;
			nr++;
		}
	}
	io_ring_submit_unlock(ctx, issue_flags);
	return all ? nr : ret;
}

int io_async_cancel(struct io_kiocb *req, unsigned int issue_flags)
{
	struct io_cancel *cancel = io_kiocb_to_cmd(req);
	struct io_cancel_data cd = {
		.ctx	= req->ctx,
		.data	= cancel->addr,
		.flags	= cancel->flags,
		.seq	= atomic_inc_return(&req->ctx->cancel_seq),
	};
	int ret;

	if (cd.flags & IORING_ASYNC_CANCEL_FD) {
		if (req->flags & REQ_F_FIXED_FILE)
			req->file = io_file_get_fixed(req, cancel->fd,
							issue_flags);
		else
			req->file = io_file_get_normal(req, cancel->fd);
		if (!req->file) {
			ret = -EBADF;
			goto done;
		}
		cd.file = req->file;
	}

	ret = __io_async_cancel(&cd, req, issue_flags);
done:
	if (ret < 0)
		req_set_fail(req);
	io_req_set_res(req, ret, 0);
	return IOU_OK;
}