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From: Eric Farman <farman@linux.ibm.com>
To: Cornelia Huck <cohuck@redhat.com>,
	Matthew Rosato <mjrosato@linux.ibm.com>,
	Halil Pasic <pasic@linux.ibm.com>
Cc: Jared Rossi <jrossi@linux.ibm.com>,
	linux-s390@vger.kernel.org, kvm@vger.kernel.org,
	Eric Farman <farman@linux.ibm.com>
Subject: [RFC PATCH v5 1/3] vfio-ccw: Check initialized flag in cp_init()
Date: Mon, 10 May 2021 22:56:44 +0200	[thread overview]
Message-ID: <20210510205646.1845844-2-farman@linux.ibm.com> (raw)
In-Reply-To: <20210510205646.1845844-1-farman@linux.ibm.com>

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

  reply	other threads:[~2021-05-10 20:56 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-10 20:56 [RFC PATCH v5 0/3] vfio-ccw: Fix interrupt handling for HALT/CLEAR Eric Farman
2021-05-10 20:56 ` Eric Farman [this message]
2021-05-10 20:56 ` [RFC PATCH v5 2/3] vfio-ccw: Reset FSM state to IDLE inside FSM Eric Farman
2021-05-10 20:56 ` [RFC PATCH v5 3/3] vfio-ccw: Serialize FSM IDLE state with I/O completion Eric Farman
2021-05-11 11:31   ` Cornelia Huck
2021-05-11 18:02     ` Eric Farman

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