From mboxrd@z Thu Jan  1 00:00:00 1970
From: Halil Pasic <pasic@linux.ibm.com>
Subject: Re: [PATCH v2 2/5] vfio-ccw: concurrent I/O handling
Date: Tue, 22 Jan 2019 19:33:46 +0100
Message-ID: <20190122193346.4e23e018@oc2783563651>
References: <20190121110354.2247-1-cohuck@redhat.com>
	<20190121110354.2247-3-cohuck@redhat.com>
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Cc: linux-s390@vger.kernel.org, Eric Farman <farman@linux.ibm.com>,
	Pierre Morel <pmorel@linux.ibm.com>, kvm@vger.kernel.org,
	qemu-s390x@nongnu.org, Farhan Ali <alifm@linux.ibm.com>,
	qemu-devel@nongnu.org, Alex Williamson <alex.williamson@redhat.com>
To: Cornelia Huck <cohuck@redhat.com>
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On Mon, 21 Jan 2019 12:03:51 +0100
Cornelia Huck <cohuck@redhat.com> wrote:

> --- a/drivers/s390/cio/vfio_ccw_private.h
> +++ b/drivers/s390/cio/vfio_ccw_private.h
> @@ -28,6 +28,7 @@
>   * @mdev: pointer to the mediated device
>   * @nb: notifier for vfio events
>   * @io_region: MMIO region to input/output I/O arguments/results
> + * @io_mutex: protect against concurrent update of I/O structures

We could be a bit more specific about what does this mutex guard.
Is it only io_region, or cp, irb and the new regions a well? ->state does
not seem to be covered, but should need some sort of synchronisation
too, or?

>   * @cp: channel program for the current I/O operation
>   * @irb: irb info received from interrupt
>   * @scsw: scsw info
> @@ -42,6 +43,7 @@ struct vfio_ccw_private {
>  	struct mdev_device	*mdev;
>  	struct notifier_block	nb;
>  	struct ccw_io_region	*io_region;
> +	struct mutex		io_mutex;
>  
>  	struct channel_program	cp;
>  	struct irb		irb;
> --