linux-kernel - Re: [PATCH V4 15/27] ublk: abort requests filled in event kfifo

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Message-ID: <CADUfDZoTueDL9ReuGO0TntffmT4JfpUdt0=QfepBJYKVRWwDyA@mail.gmail.com>
Date: Mon, 1 Dec 2025 11:00:03 -0800
From: Caleb Sander Mateos <csander@...estorage.com>
To: Ming Lei <ming.lei@...hat.com>
Cc: Jens Axboe <axboe@...nel.dk>, linux-block@...r.kernel.org, 
	Uday Shankar <ushankar@...estorage.com>, Stefani Seibold <stefani@...bold.net>, 
	Andrew Morton <akpm@...ux-foundation.org>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH V4 15/27] ublk: abort requests filled in event kfifo

On Thu, Nov 20, 2025 at 6:00 PM Ming Lei <ming.lei@...hat.com> wrote:
>
> In case of BATCH_IO, any request filled in event kfifo, they don't get
> chance to be dispatched any more when releasing ublk char device, so
> we have to abort them too.
>
> Add ublk_abort_batch_queue() for aborting this kind of requests.
>
> Signed-off-by: Ming Lei <ming.lei@...hat.com>
> ---
>  drivers/block/ublk_drv.c | 26 +++++++++++++++++++++++++-
>  1 file changed, 25 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c
> index 2e5e392c939e..849199771f86 100644
> --- a/drivers/block/ublk_drv.c
> +++ b/drivers/block/ublk_drv.c
> @@ -2241,7 +2241,8 @@ static int ublk_ch_mmap(struct file *filp, struct vm_area_struct *vma)
>  static void __ublk_fail_req(struct ublk_device *ub, struct ublk_io *io,
>                 struct request *req)
>  {
> -       WARN_ON_ONCE(io->flags & UBLK_IO_FLAG_ACTIVE);
> +       WARN_ON_ONCE(!ublk_dev_support_batch_io(ub) &&
> +                       io->flags & UBLK_IO_FLAG_ACTIVE);
>
>         if (ublk_nosrv_should_reissue_outstanding(ub))
>                 blk_mq_requeue_request(req, false);
> @@ -2251,6 +2252,26 @@ static void __ublk_fail_req(struct ublk_device *ub, struct ublk_io *io,
>         }
>  }
>
> +/*
> + * Request tag may just be filled to event kfifo, not get chance to
> + * dispatch, abort these requests too
> + */
> +static void ublk_abort_batch_queue(struct ublk_device *ub,
> +                                  struct ublk_queue *ubq)
> +{
> +       while (true) {
> +               struct request *req;
> +               short tag;
> +
> +               if (!kfifo_out(&ubq->evts_fifo, &tag, 1))
> +                       break;

This loop could also be written a bit more simply as while
(kfifo_out(&ubq->evts_fifo, &tag, 1)).

Best,
Caleb

> +
> +               req = blk_mq_tag_to_rq(ub->tag_set.tags[ubq->q_id], tag);
> +               if (req && blk_mq_request_started(req))
> +                       __ublk_fail_req(ub, &ubq->ios[tag], req);
> +       }
> +}
> +
>  /*
>   * Called from ublk char device release handler, when any uring_cmd is
>   * done, meantime request queue is "quiesced" since all inflight requests
> @@ -2269,6 +2290,9 @@ static void ublk_abort_queue(struct ublk_device *ub, struct ublk_queue *ubq)
>                 if (io->flags & UBLK_IO_FLAG_OWNED_BY_SRV)
>                         __ublk_fail_req(ub, io, io->req);
>         }
> +
> +       if (ublk_support_batch_io(ubq))
> +               ublk_abort_batch_queue(ub, ubq);
>  }
>
>  static void ublk_start_cancel(struct ublk_device *ub)
> --
> 2.47.0
>