Re: FAILED: patch "[PATCH] io_uring: only flush workqueues on fileset removal" failed to apply to 5.3-stable tree

[Greg KH <gregkh@linuxfoundation.org>]

On Wed, Oct 16, 2019 at 09:04:43AM -0700, gregkh@linuxfoundation.org wrote:
> 
> The patch below does not apply to the 5.3-stable tree.
> If someone wants it applied there, or to any other stable or longterm
> tree, then please email the backport, including the original git commit
> id to <stable@vger.kernel.org>.
> 
> thanks,
> 
> greg k-h
> 
> ------------------ original commit in Linus's tree ------------------
> 
> >From 8a99734081775c012a4a6c442fdef0379fe52bdf Mon Sep 17 00:00:00 2001
> From: Jens Axboe <axboe@kernel.dk>
> Date: Wed, 9 Oct 2019 14:40:13 -0600
> Subject: [PATCH] io_uring: only flush workqueues on fileset removal
> 
> We should not remove the workqueue, we just need to ensure that the
> workqueues are synced. The workqueues are torn down on ctx removal.
> 
> Cc: stable@vger.kernel.org
> Fixes: 6b06314c47e1 ("io_uring: add file set registration")
> Reported-by: Stefan Hajnoczi <stefanha@redhat.com>
> Signed-off-by: Jens Axboe <axboe@kernel.dk>
> 
> diff --git a/fs/io_uring.c b/fs/io_uring.c
> index ceb3497bdd2a..2c44648217bd 100644
> --- a/fs/io_uring.c
> +++ b/fs/io_uring.c
> @@ -2866,8 +2866,12 @@ static void io_finish_async(struct io_ring_ctx *ctx)
>  static void io_destruct_skb(struct sk_buff *skb)
>  {
>  	struct io_ring_ctx *ctx = skb->sk->sk_user_data;
> +	int i;
> +
> +	for (i = 0; i < ARRAY_SIZE(ctx->sqo_wq); i++)
> +		if (ctx->sqo_wq[i])
> +			flush_workqueue(ctx->sqo_wq[i]);
>  
> -	io_finish_async(ctx);
>  	unix_destruct_scm(skb);
>  }
>  
> 

This fails to build as sqo_wq is a pointer in 5.3, not an arrary.
Backporting that array change feels "big" for 5.3, is that needed here,
or can this be fixed differently?

thanks,

greg k-h