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30dab608c3
We know the request is either being removed, or already in the process of being removed through task_work, so we can delete it from our futex list upfront. This is important for remove all conditions, as we otherwise will find it multiple times and prevent cancelation progress. Cc: stable@vger.kernel.org Fixes:194bb58c60
("io_uring: add support for futex wake and wait") Fixes:8f350194d5
("io_uring: add support for vectored futex waits") Signed-off-by: Jens Axboe <axboe@kernel.dk>
388 lines
9.5 KiB
C
388 lines
9.5 KiB
C
// SPDX-License-Identifier: GPL-2.0
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#include <linux/kernel.h>
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#include <linux/errno.h>
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#include <linux/fs.h>
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#include <linux/file.h>
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#include <linux/io_uring.h>
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#include <uapi/linux/io_uring.h>
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#include "../kernel/futex/futex.h"
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#include "io_uring.h"
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#include "rsrc.h"
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#include "futex.h"
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struct io_futex {
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struct file *file;
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union {
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u32 __user *uaddr;
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struct futex_waitv __user *uwaitv;
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};
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unsigned long futex_val;
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unsigned long futex_mask;
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unsigned long futexv_owned;
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u32 futex_flags;
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unsigned int futex_nr;
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bool futexv_unqueued;
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};
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struct io_futex_data {
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union {
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struct futex_q q;
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struct io_cache_entry cache;
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};
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struct io_kiocb *req;
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};
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void io_futex_cache_init(struct io_ring_ctx *ctx)
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{
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io_alloc_cache_init(&ctx->futex_cache, IO_NODE_ALLOC_CACHE_MAX,
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sizeof(struct io_futex_data));
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}
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static void io_futex_cache_entry_free(struct io_cache_entry *entry)
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{
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kfree(container_of(entry, struct io_futex_data, cache));
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}
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void io_futex_cache_free(struct io_ring_ctx *ctx)
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{
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io_alloc_cache_free(&ctx->futex_cache, io_futex_cache_entry_free);
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}
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static void __io_futex_complete(struct io_kiocb *req, struct io_tw_state *ts)
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{
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req->async_data = NULL;
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hlist_del_init(&req->hash_node);
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io_req_task_complete(req, ts);
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}
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static void io_futex_complete(struct io_kiocb *req, struct io_tw_state *ts)
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{
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struct io_futex_data *ifd = req->async_data;
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struct io_ring_ctx *ctx = req->ctx;
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io_tw_lock(ctx, ts);
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if (!io_alloc_cache_put(&ctx->futex_cache, &ifd->cache))
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kfree(ifd);
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__io_futex_complete(req, ts);
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}
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static void io_futexv_complete(struct io_kiocb *req, struct io_tw_state *ts)
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{
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struct io_futex *iof = io_kiocb_to_cmd(req, struct io_futex);
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struct futex_vector *futexv = req->async_data;
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io_tw_lock(req->ctx, ts);
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if (!iof->futexv_unqueued) {
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int res;
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res = futex_unqueue_multiple(futexv, iof->futex_nr);
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if (res != -1)
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io_req_set_res(req, res, 0);
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}
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kfree(req->async_data);
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req->flags &= ~REQ_F_ASYNC_DATA;
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__io_futex_complete(req, ts);
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}
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static bool io_futexv_claim(struct io_futex *iof)
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{
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if (test_bit(0, &iof->futexv_owned) ||
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test_and_set_bit_lock(0, &iof->futexv_owned))
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return false;
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return true;
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}
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static bool __io_futex_cancel(struct io_ring_ctx *ctx, struct io_kiocb *req)
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{
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/* futex wake already done or in progress */
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if (req->opcode == IORING_OP_FUTEX_WAIT) {
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struct io_futex_data *ifd = req->async_data;
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if (!futex_unqueue(&ifd->q))
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return false;
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req->io_task_work.func = io_futex_complete;
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} else {
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struct io_futex *iof = io_kiocb_to_cmd(req, struct io_futex);
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if (!io_futexv_claim(iof))
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return false;
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req->io_task_work.func = io_futexv_complete;
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}
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hlist_del_init(&req->hash_node);
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io_req_set_res(req, -ECANCELED, 0);
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io_req_task_work_add(req);
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return true;
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}
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int io_futex_cancel(struct io_ring_ctx *ctx, struct io_cancel_data *cd,
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unsigned int issue_flags)
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{
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struct hlist_node *tmp;
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struct io_kiocb *req;
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int nr = 0;
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if (cd->flags & (IORING_ASYNC_CANCEL_FD|IORING_ASYNC_CANCEL_FD_FIXED))
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return -ENOENT;
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io_ring_submit_lock(ctx, issue_flags);
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hlist_for_each_entry_safe(req, tmp, &ctx->futex_list, hash_node) {
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if (req->cqe.user_data != cd->data &&
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!(cd->flags & IORING_ASYNC_CANCEL_ANY))
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continue;
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if (__io_futex_cancel(ctx, req))
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nr++;
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if (!(cd->flags & IORING_ASYNC_CANCEL_ALL))
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break;
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}
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io_ring_submit_unlock(ctx, issue_flags);
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if (nr)
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return nr;
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return -ENOENT;
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}
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bool io_futex_remove_all(struct io_ring_ctx *ctx, struct task_struct *task,
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bool cancel_all)
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{
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struct hlist_node *tmp;
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struct io_kiocb *req;
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bool found = false;
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lockdep_assert_held(&ctx->uring_lock);
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hlist_for_each_entry_safe(req, tmp, &ctx->futex_list, hash_node) {
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if (!io_match_task_safe(req, task, cancel_all))
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continue;
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hlist_del_init(&req->hash_node);
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__io_futex_cancel(ctx, req);
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found = true;
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}
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return found;
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}
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int io_futex_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
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{
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struct io_futex *iof = io_kiocb_to_cmd(req, struct io_futex);
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u32 flags;
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if (unlikely(sqe->len || sqe->futex_flags || sqe->buf_index ||
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sqe->file_index))
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return -EINVAL;
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iof->uaddr = u64_to_user_ptr(READ_ONCE(sqe->addr));
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iof->futex_val = READ_ONCE(sqe->addr2);
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iof->futex_mask = READ_ONCE(sqe->addr3);
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flags = READ_ONCE(sqe->fd);
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if (flags & ~FUTEX2_VALID_MASK)
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return -EINVAL;
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iof->futex_flags = futex2_to_flags(flags);
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if (!futex_flags_valid(iof->futex_flags))
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return -EINVAL;
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if (!futex_validate_input(iof->futex_flags, iof->futex_val) ||
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!futex_validate_input(iof->futex_flags, iof->futex_mask))
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return -EINVAL;
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return 0;
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}
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static void io_futex_wakev_fn(struct wake_q_head *wake_q, struct futex_q *q)
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{
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struct io_kiocb *req = q->wake_data;
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struct io_futex *iof = io_kiocb_to_cmd(req, struct io_futex);
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if (!io_futexv_claim(iof))
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return;
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if (unlikely(!__futex_wake_mark(q)))
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return;
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io_req_set_res(req, 0, 0);
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req->io_task_work.func = io_futexv_complete;
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io_req_task_work_add(req);
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}
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int io_futexv_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
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{
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struct io_futex *iof = io_kiocb_to_cmd(req, struct io_futex);
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struct futex_vector *futexv;
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int ret;
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/* No flags or mask supported for waitv */
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if (unlikely(sqe->fd || sqe->buf_index || sqe->file_index ||
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sqe->addr2 || sqe->futex_flags || sqe->addr3))
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return -EINVAL;
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iof->uaddr = u64_to_user_ptr(READ_ONCE(sqe->addr));
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iof->futex_nr = READ_ONCE(sqe->len);
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if (!iof->futex_nr || iof->futex_nr > FUTEX_WAITV_MAX)
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return -EINVAL;
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futexv = kcalloc(iof->futex_nr, sizeof(*futexv), GFP_KERNEL);
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if (!futexv)
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return -ENOMEM;
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ret = futex_parse_waitv(futexv, iof->uwaitv, iof->futex_nr,
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io_futex_wakev_fn, req);
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if (ret) {
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kfree(futexv);
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return ret;
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}
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iof->futexv_owned = 0;
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iof->futexv_unqueued = 0;
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req->flags |= REQ_F_ASYNC_DATA;
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req->async_data = futexv;
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return 0;
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}
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static void io_futex_wake_fn(struct wake_q_head *wake_q, struct futex_q *q)
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{
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struct io_futex_data *ifd = container_of(q, struct io_futex_data, q);
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struct io_kiocb *req = ifd->req;
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if (unlikely(!__futex_wake_mark(q)))
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return;
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io_req_set_res(req, 0, 0);
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req->io_task_work.func = io_futex_complete;
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io_req_task_work_add(req);
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}
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static struct io_futex_data *io_alloc_ifd(struct io_ring_ctx *ctx)
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{
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struct io_cache_entry *entry;
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entry = io_alloc_cache_get(&ctx->futex_cache);
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if (entry)
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return container_of(entry, struct io_futex_data, cache);
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return kmalloc(sizeof(struct io_futex_data), GFP_NOWAIT);
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}
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int io_futexv_wait(struct io_kiocb *req, unsigned int issue_flags)
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{
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struct io_futex *iof = io_kiocb_to_cmd(req, struct io_futex);
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struct futex_vector *futexv = req->async_data;
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struct io_ring_ctx *ctx = req->ctx;
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int ret, woken = -1;
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io_ring_submit_lock(ctx, issue_flags);
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ret = futex_wait_multiple_setup(futexv, iof->futex_nr, &woken);
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/*
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* Error case, ret is < 0. Mark the request as failed.
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*/
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if (unlikely(ret < 0)) {
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io_ring_submit_unlock(ctx, issue_flags);
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req_set_fail(req);
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io_req_set_res(req, ret, 0);
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kfree(futexv);
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req->async_data = NULL;
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req->flags &= ~REQ_F_ASYNC_DATA;
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return IOU_OK;
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}
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/*
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* 0 return means that we successfully setup the waiters, and that
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* nobody triggered a wakeup while we were doing so. If the wakeup
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* happened post setup, the task_work will be run post this issue and
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* under the submission lock. 1 means We got woken while setting up,
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* let that side do the completion. Note that
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* futex_wait_multiple_setup() will have unqueued all the futexes in
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* this case. Mark us as having done that already, since this is
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* different from normal wakeup.
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*/
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if (!ret) {
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/*
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* If futex_wait_multiple_setup() returns 0 for a
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* successful setup, then the task state will not be
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* runnable. This is fine for the sync syscall, as
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* it'll be blocking unless we already got one of the
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* futexes woken, but it obviously won't work for an
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* async invocation. Mark us runnable again.
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*/
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__set_current_state(TASK_RUNNING);
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hlist_add_head(&req->hash_node, &ctx->futex_list);
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} else {
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iof->futexv_unqueued = 1;
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if (woken != -1)
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io_req_set_res(req, woken, 0);
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}
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io_ring_submit_unlock(ctx, issue_flags);
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return IOU_ISSUE_SKIP_COMPLETE;
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}
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int io_futex_wait(struct io_kiocb *req, unsigned int issue_flags)
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{
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struct io_futex *iof = io_kiocb_to_cmd(req, struct io_futex);
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struct io_ring_ctx *ctx = req->ctx;
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struct io_futex_data *ifd = NULL;
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struct futex_hash_bucket *hb;
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int ret;
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if (!iof->futex_mask) {
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ret = -EINVAL;
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goto done;
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}
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io_ring_submit_lock(ctx, issue_flags);
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ifd = io_alloc_ifd(ctx);
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if (!ifd) {
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ret = -ENOMEM;
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goto done_unlock;
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}
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req->async_data = ifd;
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ifd->q = futex_q_init;
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ifd->q.bitset = iof->futex_mask;
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ifd->q.wake = io_futex_wake_fn;
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ifd->req = req;
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ret = futex_wait_setup(iof->uaddr, iof->futex_val, iof->futex_flags,
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&ifd->q, &hb);
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if (!ret) {
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hlist_add_head(&req->hash_node, &ctx->futex_list);
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io_ring_submit_unlock(ctx, issue_flags);
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futex_queue(&ifd->q, hb);
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return IOU_ISSUE_SKIP_COMPLETE;
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}
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done_unlock:
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io_ring_submit_unlock(ctx, issue_flags);
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done:
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if (ret < 0)
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req_set_fail(req);
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io_req_set_res(req, ret, 0);
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kfree(ifd);
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return IOU_OK;
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}
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int io_futex_wake(struct io_kiocb *req, unsigned int issue_flags)
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{
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struct io_futex *iof = io_kiocb_to_cmd(req, struct io_futex);
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int ret;
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/*
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* Strict flags - ensure that waking 0 futexes yields a 0 result.
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* See commit 43adf8449510 ("futex: FLAGS_STRICT") for details.
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*/
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ret = futex_wake(iof->uaddr, FLAGS_STRICT | iof->futex_flags,
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iof->futex_val, iof->futex_mask);
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if (ret < 0)
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req_set_fail(req);
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io_req_set_res(req, ret, 0);
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return IOU_OK;
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}
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