Re: [PATCH v6 2/3] vfio-ccw: Reset FSM state to IDLE inside FSM

From: Matthew Rosato <mjrosato@linux.ibm.com>
To: Eric Farman <farman@linux.ibm.com>,
	Cornelia Huck <cohuck@redhat.com>,
	Halil Pasic <pasic@linux.ibm.com>
Cc: Jared Rossi <jrossi@linux.ibm.com>,
	linux-s390@vger.kernel.org, kvm@vger.kernel.org
Subject: Re: [PATCH v6 2/3] vfio-ccw: Reset FSM state to IDLE inside FSM
Date: Tue, 11 May 2021 16:38:47 -0400	[thread overview]
Message-ID: <751e15e8-d1df-6ec7-134b-f97b58bde6f5@linux.ibm.com> (raw)
In-Reply-To: <20210511195631.3995081-3-farman@linux.ibm.com>

On 5/11/21 3:56 PM, Eric Farman wrote:
> When an I/O request is made, the fsm_io_request() routine
> moves the FSM state from IDLE to CP_PROCESSING, and then
> fsm_io_helper() moves it to CP_PENDING if the START SUBCHANNEL
> received a cc0. Yet, the error case to go from CP_PROCESSING
> back to IDLE is done after the FSM call returns.
> 
> Let's move this up into the FSM proper, to provide some
> better symmetry when unwinding in this case.
> 
> Signed-off-by: Eric Farman <farman@linux.ibm.com>
> Reviewed-by: Cornelia Huck <cohuck@redhat.com>

Acked-by: Matthew Rosato <mjrosato@linux.ibm.com>

> ---
>   drivers/s390/cio/vfio_ccw_fsm.c | 1 +
>   drivers/s390/cio/vfio_ccw_ops.c | 2 --
>   2 files changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/drivers/s390/cio/vfio_ccw_fsm.c b/drivers/s390/cio/vfio_ccw_fsm.c
> index 23e61aa638e4..e435a9cd92da 100644
> --- a/drivers/s390/cio/vfio_ccw_fsm.c
> +++ b/drivers/s390/cio/vfio_ccw_fsm.c
> @@ -318,6 +318,7 @@ static void fsm_io_request(struct vfio_ccw_private *private,
>   	}
>   
>   err_out:
> +	private->state = VFIO_CCW_STATE_IDLE;
>   	trace_vfio_ccw_fsm_io_request(scsw->cmd.fctl, schid,
>   				      io_region->ret_code, errstr);
>   }
> diff --git a/drivers/s390/cio/vfio_ccw_ops.c b/drivers/s390/cio/vfio_ccw_ops.c
> index 767ac41686fe..5971641964c6 100644
> --- a/drivers/s390/cio/vfio_ccw_ops.c
> +++ b/drivers/s390/cio/vfio_ccw_ops.c
> @@ -276,8 +276,6 @@ static ssize_t vfio_ccw_mdev_write_io_region(struct vfio_ccw_private *private,
>   	}
>   
>   	vfio_ccw_fsm_event(private, VFIO_CCW_EVENT_IO_REQ);
> -	if (region->ret_code != 0)
> -		private->state = VFIO_CCW_STATE_IDLE;
>   	ret = (region->ret_code != 0) ? region->ret_code : count;
>   
>   out_unlock:
>