public inbox for [email protected]
 help / color / mirror / Atom feed
From: Jens Axboe <[email protected]>
To: Xiaoguang Wang <[email protected]>,
	[email protected]
Cc: [email protected]
Subject: Re: [PATCH v2] io_uring: reset -EBUSY error when io sq thread is waken up
Date: Wed, 20 May 2020 07:34:41 -0600	[thread overview]
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>

On 5/20/20 7:24 AM, Xiaoguang Wang wrote:
> In io_sq_thread(), currently if we get an -EBUSY error and go to sleep,
> we will won't clear it again, which will result in io_sq_thread() will
> never have a chance to submit sqes again. Below test program test.c
> can reveal this bug:
> 
> int main(int argc, char *argv[])
> {
>         struct io_uring ring;
>         int i, fd, ret;
>         struct io_uring_sqe *sqe;
>         struct io_uring_cqe *cqe;
>         struct iovec *iovecs;
>         void *buf;
>         struct io_uring_params p;
> 
>         if (argc < 2) {
>                 printf("%s: file\n", argv[0]);
>                 return 1;
>         }
> 
>         memset(&p, 0, sizeof(p));
>         p.flags = IORING_SETUP_SQPOLL;
>         ret = io_uring_queue_init_params(4, &ring, &p);
>         if (ret < 0) {
>                 fprintf(stderr, "queue_init: %s\n", strerror(-ret));
>                 return 1;
>         }
> 
>         fd = open(argv[1], O_RDONLY | O_DIRECT);
>         if (fd < 0) {
>                 perror("open");
>                 return 1;
>         }
> 
>         iovecs = calloc(10, sizeof(struct iovec));
>         for (i = 0; i < 10; i++) {
>                 if (posix_memalign(&buf, 4096, 4096))
>                         return 1;
>                 iovecs[i].iov_base = buf;
>                 iovecs[i].iov_len = 4096;
>         }
> 
>         ret = io_uring_register_files(&ring, &fd, 1);
>         if (ret < 0) {
>                 fprintf(stderr, "%s: register %d\n", __FUNCTION__, ret);
>                 return ret;
>         }
> 
>         for (i = 0; i < 10; i++) {
>                 sqe = io_uring_get_sqe(&ring);
>                 if (!sqe)
>                         break;
> 
>                 io_uring_prep_readv(sqe, 0, &iovecs[i], 1, 0);
>                 sqe->flags |= IOSQE_FIXED_FILE;
> 
>                 ret = io_uring_submit(&ring);
>                 sleep(1);
>                 printf("submit %d\n", i);
>         }
> 
>         for (i = 0; i < 10; i++) {
>                 io_uring_wait_cqe(&ring, &cqe);
>                 printf("receive: %d\n", i);
>                 if (cqe->res != 4096) {
>                         fprintf(stderr, "ret=%d, wanted 4096\n", cqe->res);
>                         ret = 1;
>                 }
>                 io_uring_cqe_seen(&ring, cqe);
>         }
> 
>         close(fd);
>         io_uring_queue_exit(&ring);
>         return 0;
> }
> sudo ./test testfile
> above command will hang on the tenth request, to fix this bug, when io
> sq_thread is waken up, we reset the variable 'ret' to be zero.

Applied, thanks.

-- 
Jens Axboe


      reply	other threads:[~2020-05-20 13:34 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-20 13:24 [PATCH v2] io_uring: reset -EBUSY error when io sq thread is waken up Xiaoguang Wang
2020-05-20 13:34 ` Jens Axboe [this message]

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    [email protected] \
    [email protected] \
    [email protected] \
    [email protected] \
    [email protected] \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox