linux-kernel - Re: [PATCH 1/4] io_uring: fix open/close/statx with {SQ,IO}POLL

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Message-ID: <b3e14e84-727a-9edc-8e69-d41282123241@gmail.com>
Date:   Tue, 2 Jun 2020 17:12:33 +0300
From:   Pavel Begunkov <asml.silence@...il.com>
To:     Jens Axboe <axboe@...nel.dk>, io-uring@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/4] io_uring: fix open/close/statx with {SQ,IO}POLL

On 02/06/2020 15:34, Pavel Begunkov wrote:
> Trying to use them with IORING_SETUP_IOPOLL:
> 
> RIP: 0010:io_iopoll_getevents+0x111/0x5a0
> Call Trace:
>  ? _raw_spin_unlock_irqrestore+0x24/0x40
>  ? do_send_sig_info+0x64/0x90
>  io_iopoll_reap_events.part.0+0x5e/0xa0
>  io_ring_ctx_wait_and_kill+0x132/0x1c0
>  io_uring_release+0x20/0x30
>  __fput+0xcd/0x230
>  ____fput+0xe/0x10
>  task_work_run+0x67/0xa0
>  do_exit+0x353/0xb10
>  ? handle_mm_fault+0xd4/0x200
>  ? syscall_trace_enter+0x18c/0x2c0
>  do_group_exit+0x43/0xa0
>  __x64_sys_exit_group+0x18/0x20
>  do_syscall_64+0x60/0x1e0
>  entry_SYSCALL_64_after_hwframe+0x44/0xa9

io_do_iopoll()
{
	...
	ret = kiocb->*ki_filp*->f_op->iopoll(kiocb, spin);
}

Hmm, I'll double check later that only read*/write* can be done
with IOPOLL, and send a follow-up patch if necessary.

> 
> Also SQPOLL thread can't know which file table to use with
> open/close. Disallow all these cases.
> 
> Signed-off-by: Pavel Begunkov <asml.silence@...il.com>
> ---
>  fs/io_uring.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/fs/io_uring.c b/fs/io_uring.c
> index 732ec73ec3c0..7208f91e9e77 100644
> --- a/fs/io_uring.c
> +++ b/fs/io_uring.c
> @@ -2990,6 +2990,8 @@ static int io_openat_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
>  	const char __user *fname;
>  	int ret;
>  
> +	if (unlikely(req->ctx->flags & (IORING_SETUP_IOPOLL|IORING_SETUP_SQPOLL)))
> +		return -EINVAL;
>  	if (sqe->ioprio || sqe->buf_index)
>  		return -EINVAL;
>  	if (req->flags & REQ_F_FIXED_FILE)
> @@ -3023,6 +3025,8 @@ static int io_openat2_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
>  	size_t len;
>  	int ret;
>  
> +	if (unlikely(req->ctx->flags & (IORING_SETUP_IOPOLL|IORING_SETUP_SQPOLL)))
> +		return -EINVAL;
>  	if (sqe->ioprio || sqe->buf_index)
>  		return -EINVAL;
>  	if (req->flags & REQ_F_FIXED_FILE)
> @@ -3373,6 +3377,8 @@ static int io_fadvise(struct io_kiocb *req, bool force_nonblock)
>  
>  static int io_statx_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
>  {
> +	if (unlikely(req->ctx->flags & IORING_SETUP_IOPOLL))
> +		return -EINVAL;
>  	if (sqe->ioprio || sqe->buf_index)
>  		return -EINVAL;
>  	if (req->flags & REQ_F_FIXED_FILE)
> @@ -3417,6 +3423,8 @@ static int io_close_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
>  	 */
>  	req->work.flags |= IO_WQ_WORK_NO_CANCEL;
>  
> +	if (unlikely(req->ctx->flags & (IORING_SETUP_IOPOLL|IORING_SETUP_SQPOLL)))
> +		return -EINVAL;
>  	if (sqe->ioprio || sqe->off || sqe->addr || sqe->len ||
>  	    sqe->rw_flags || sqe->buf_index)
>  		return -EINVAL;
> 

-- 
Pavel Begunkov