Re: [Qemu-devel] [PATCH v2 1/5] vfio-ccw: make it safe to access channel programs

[Halil Pasic <pasic@linux.ibm.com>]

On Mon, 21 Jan 2019 12:03:50 +0100
Cornelia Huck <cohuck@redhat.com> wrote:

> When we get a solicited interrupt, the start function may have
> been cleared by a csch, but we still have a channel program
> structure allocated. Make it safe to call the cp accessors in
> any case, so we can call them unconditionally.
> 
> Signed-off-by: Cornelia Huck <cohuck@redhat.com>
> ---
>  drivers/s390/cio/vfio_ccw_cp.c | 3 +++
>  drivers/s390/cio/vfio_ccw_cp.h | 2 ++
>  2 files changed, 5 insertions(+)
> 
> diff --git a/drivers/s390/cio/vfio_ccw_cp.c b/drivers/s390/cio/vfio_ccw_cp.c
> index 70a006ba4d05..714987ceea9a 100644
> --- a/drivers/s390/cio/vfio_ccw_cp.c
> +++ b/drivers/s390/cio/vfio_ccw_cp.c
> @@ -335,6 +335,7 @@ static void cp_unpin_free(struct channel_program *cp)
>  	struct ccwchain *chain, *temp;
>  	int i;
>  
> +	cp->initialized = false;
>  	list_for_each_entry_safe(chain, temp, &cp->ccwchain_list, next) {
>  		for (i = 0; i < chain->ch_len; i++) {
>  			pfn_array_table_unpin_free(chain->ch_pat + i,
> @@ -701,6 +702,8 @@ int cp_init(struct channel_program *cp, struct device *mdev, union orb *orb)
>  	 */
>  	cp->orb.cmd.c64 = 1;
>  
> +	cp->initialized = true;
> +
>  	return ret;
>  }
>  
> diff --git a/drivers/s390/cio/vfio_ccw_cp.h b/drivers/s390/cio/vfio_ccw_cp.h
> index a4b74fb1aa57..3c20cd208da5 100644
> --- a/drivers/s390/cio/vfio_ccw_cp.h
> +++ b/drivers/s390/cio/vfio_ccw_cp.h
> @@ -21,6 +21,7 @@
>   * @ccwchain_list: list head of ccwchains
>   * @orb: orb for the currently processed ssch request
>   * @mdev: the mediated device to perform page pinning/unpinning
> + * @initialized: whether this instance is actually initialized
>   *
>   * @ccwchain_list is the head of a ccwchain list, that contents the
>   * translated result of the guest channel program that pointed out by
> @@ -30,6 +31,7 @@ struct channel_program {
>  	struct list_head ccwchain_list;
>  	union orb orb;
>  	struct device *mdev;
> +	bool initialized;
>  };
>  
>  extern int cp_init(struct channel_program *cp, struct device *mdev,

I fail to see how is this patch delivering on the promise made by it's
title. I see only code that sets cp->initialized but none that reads it.
The follow-up patches don't seem to care for cp->initialized either.

Regards,
Halil