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From: Ming Lei <[email protected]>
To: Pavel Begunkov <[email protected]>
Cc: [email protected], [email protected],
	Jens Axboe <[email protected]>, Kanchan Joshi <[email protected]>
Subject: Re: [PATCH v2 03/14] io_uring/cmd: make io_uring_cmd_done irq safe
Date: Mon, 18 Mar 2024 16:10:15 +0800	[thread overview]
Message-ID: <Zff25z0fPGBPfJs1@fedora> (raw)
In-Reply-To: <faeec0d1e7c740a582f51f80626f61c745ed9a52.1710720150.git.asml.silence@gmail.com>

On Mon, Mar 18, 2024 at 12:41:48AM +0000, Pavel Begunkov wrote:
> io_uring_cmd_done() is called from the irq context and is considered to
> be irq safe, however that's not the case if the driver requires
> cancellations because io_uring_cmd_del_cancelable() could try to take
> the uring_lock mutex.
> 
> Clean up the confusion, by deferring cancellation handling to
> locked task_work if we came into io_uring_cmd_done() from iowq
> or other IO_URING_F_UNLOCKED path.
> 
> Signed-off-by: Pavel Begunkov <[email protected]>
> ---
>  io_uring/uring_cmd.c | 24 +++++++++++++++++-------
>  1 file changed, 17 insertions(+), 7 deletions(-)
> 
> diff --git a/io_uring/uring_cmd.c b/io_uring/uring_cmd.c
> index ec38a8d4836d..9590081feb2d 100644
> --- a/io_uring/uring_cmd.c
> +++ b/io_uring/uring_cmd.c
> @@ -14,19 +14,18 @@
>  #include "rsrc.h"
>  #include "uring_cmd.h"
>  
> -static void io_uring_cmd_del_cancelable(struct io_uring_cmd *cmd,
> -		unsigned int issue_flags)
> +static void io_uring_cmd_del_cancelable(struct io_uring_cmd *cmd)
>  {
>  	struct io_kiocb *req = cmd_to_io_kiocb(cmd);
>  	struct io_ring_ctx *ctx = req->ctx;
>  
> +	lockdep_assert_held(&ctx->uring_lock);
> +
>  	if (!(cmd->flags & IORING_URING_CMD_CANCELABLE))
>  		return;
>  
>  	cmd->flags &= ~IORING_URING_CMD_CANCELABLE;
> -	io_ring_submit_lock(ctx, issue_flags);
>  	hlist_del(&req->hash_node);
> -	io_ring_submit_unlock(ctx, issue_flags);
>  }
>  
>  /*
> @@ -44,6 +43,9 @@ void io_uring_cmd_mark_cancelable(struct io_uring_cmd *cmd,
>  	struct io_kiocb *req = cmd_to_io_kiocb(cmd);
>  	struct io_ring_ctx *ctx = req->ctx;
>  
> +	if (WARN_ON_ONCE(ctx->flags & IORING_SETUP_IOPOLL))
> +		return;
> +

This way limits cancelable command can't be used in iopoll context, and
it isn't reasonable, and supporting iopoll has been in ublk todo list,
especially single ring context is shared for both command and normal IO.


Thanks,
Ming


  reply	other threads:[~2024-03-18  8:10 UTC|newest]

Thread overview: 41+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-03-18  0:41 [PATCH v2 00/14] remove aux CQE caches Pavel Begunkov
2024-03-18  0:41 ` [PATCH v2 01/14] io_uring/cmd: kill one issue_flags to tw conversion Pavel Begunkov
2024-03-18  0:41 ` [PATCH v2 02/14] io_uring/cmd: fix tw <-> issue_flags conversion Pavel Begunkov
2024-03-18  2:23   ` Ming Lei
2024-03-18  2:25     ` Jens Axboe
2024-03-18  2:32       ` Pavel Begunkov
2024-03-18  2:40         ` Jens Axboe
2024-03-18  2:43           ` Pavel Begunkov
2024-03-18  2:46             ` Jens Axboe
2024-03-18  2:47           ` Ming Lei
2024-03-18  3:11             ` Jens Axboe
2024-03-18  3:24               ` Pavel Begunkov
2024-03-18  6:59               ` Ming Lei
2024-03-18 11:45                 ` Pavel Begunkov
2024-03-18  0:41 ` [PATCH v2 03/14] io_uring/cmd: make io_uring_cmd_done irq safe Pavel Begunkov
2024-03-18  8:10   ` Ming Lei [this message]
2024-03-18 11:50     ` Pavel Begunkov
2024-03-18 11:59       ` Ming Lei
2024-03-18 12:46         ` Pavel Begunkov
2024-03-18 13:09           ` Ming Lei
2024-03-18  0:41 ` [PATCH v2 04/14] io_uring/cmd: introduce io_uring_cmd_complete Pavel Begunkov
2024-03-18  0:41 ` [PATCH v2 05/14] ublk: don't hard code IO_URING_F_UNLOCKED Pavel Begunkov
2024-03-18  8:16   ` Ming Lei
2024-03-18 12:52     ` Pavel Begunkov
2024-03-18 13:37       ` Pavel Begunkov
2024-03-18 14:32         ` Pavel Begunkov
2024-03-18 14:39           ` Ming Lei
2024-03-18 14:34       ` Ming Lei
2024-03-18 15:08         ` Pavel Begunkov
2024-03-18 15:16           ` Ming Lei
2024-03-18  0:41 ` [PATCH v2 06/14] nvme/io_uring: " Pavel Begunkov
2024-03-18 13:26   ` Kanchan Joshi
2024-03-18 13:38     ` Pavel Begunkov
2024-03-18  0:41 ` [PATCH v2 07/14] io_uring/rw: avoid punting to io-wq directly Pavel Begunkov
2024-03-18  0:41 ` [PATCH v2 08/14] io_uring: force tw ctx locking Pavel Begunkov
2024-03-18  0:41 ` [PATCH v2 09/14] io_uring: remove struct io_tw_state::locked Pavel Begunkov
2024-03-18  0:41 ` [PATCH v2 10/14] io_uring: refactor io_fill_cqe_req_aux Pavel Begunkov
2024-03-18  0:41 ` [PATCH v2 11/14] io_uring: get rid of intermediate aux cqe caches Pavel Begunkov
2024-03-18  0:41 ` [PATCH v2 12/14] io_uring: remove current check from complete_post Pavel Begunkov
2024-03-18  0:41 ` [PATCH v2 13/14] io_uring: refactor io_req_complete_post() Pavel Begunkov
2024-03-18  0:41 ` [PATCH v2 14/14] io_uring: clean up io_lockdep_assert_cq_locked Pavel Begunkov

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