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From: Cornelia Huck <cohuck@redhat.com>
To: Eric Farman <farman@linux.ibm.com>
Cc: Halil Pasic <pasic@linux.ibm.com>,
	Matthew Rosato <mjrosato@linux.ibm.com>,
	Jared Rossi <jrossi@linux.ibm.com>,
	linux-s390@vger.kernel.org, kvm@vger.kernel.org
Subject: Re: [RFC PATCH v4 1/4] vfio-ccw: Check initialized flag in cp_init()
Date: Wed, 14 Apr 2021 18:30:28 +0200	[thread overview]
Message-ID: <20210414183028.1285311e.cohuck@redhat.com> (raw)
In-Reply-To: <20210413182410.1396170-2-farman@linux.ibm.com>

On Tue, 13 Apr 2021 20:24:07 +0200
Eric Farman <farman@linux.ibm.com> wrote:

> We have a really nice flag in the channel_program struct that
> indicates if it had been initialized by cp_init(), and use it
> as a guard in the other cp accessor routines, but not for a
> duplicate call into cp_init(). The possibility of this occurring
> is low, because that flow is protected by the private->io_mutex
> and FSM CP_PROCESSING state. But then why bother checking it
> in (for example) cp_prefetch() then?
> 
> Let's just be consistent and check for that in cp_init() too.
> 
> Fixes: 71189f263f8a3 ("vfio-ccw: make it safe to access channel programs")
> Signed-off-by: Eric Farman <farman@linux.ibm.com>
> ---
>  drivers/s390/cio/vfio_ccw_cp.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/s390/cio/vfio_ccw_cp.c b/drivers/s390/cio/vfio_ccw_cp.c
> index b9febc581b1f..8d1b2771c1aa 100644
> --- a/drivers/s390/cio/vfio_ccw_cp.c
> +++ b/drivers/s390/cio/vfio_ccw_cp.c
> @@ -638,6 +638,10 @@ int cp_init(struct channel_program *cp, struct device *mdev, union orb *orb)
>  	static DEFINE_RATELIMIT_STATE(ratelimit_state, 5 * HZ, 1);
>  	int ret;
>  
> +	/* this is an error in the caller */
> +	if (cp->initialized)
> +		return -EBUSY;
> +
>  	/*
>  	 * We only support prefetching the channel program. We assume all channel
>  	 * programs executed by supported guests likewise support prefetching.

Reviewed-by: Cornelia Huck <cohuck@redhat.com>


  reply	other threads:[~2021-04-14 16:30 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-13 18:24 [RFC PATCH v4 0/4] vfio-ccw: Fix interrupt handling for HALT/CLEAR Eric Farman
2021-04-13 18:24 ` [RFC PATCH v4 1/4] vfio-ccw: Check initialized flag in cp_init() Eric Farman
2021-04-14 16:30   ` Cornelia Huck [this message]
2021-04-13 18:24 ` [RFC PATCH v4 2/4] vfio-ccw: Check workqueue before doing START Eric Farman
2021-04-15 10:51   ` Cornelia Huck
2021-04-15 13:48     ` Eric Farman
2021-04-15 16:19       ` Cornelia Huck
2021-04-15 18:42         ` Eric Farman
2021-04-16 14:41           ` Cornelia Huck
2021-04-13 18:24 ` [RFC PATCH v4 3/4] vfio-ccw: Reset FSM state to IDLE inside FSM Eric Farman
2021-04-15 10:54   ` Cornelia Huck
2021-04-13 18:24 ` [RFC PATCH v4 4/4] vfio-ccw: Reset FSM state to IDLE before io_mutex Eric Farman
2021-04-21 10:25   ` Cornelia Huck
2021-04-21 12:58     ` Eric Farman
2021-04-22 16:16       ` Eric Farman
2021-04-22  0:52 ` [RFC PATCH v4 0/4] vfio-ccw: Fix interrupt handling for HALT/CLEAR Halil Pasic
2021-04-22 20:49   ` Eric Farman
2021-04-23 11:06     ` Cornelia Huck
2021-04-23 13:23       ` Halil Pasic
2021-04-23 13:28         ` Niklas Schnelle
2021-04-23 15:53         ` Eric Farman
2021-04-23 11:50     ` Halil Pasic
2021-04-23 15:53       ` Eric Farman
2021-04-23 17:08         ` Halil Pasic
2021-04-23 19:07           ` Eric Farman
2021-04-24  0:18             ` Halil Pasic

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