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[RFC,v5,1/3] vfio-ccw: Check initialized flag in cp_init()

Message ID 20210510205646.1845844-2-farman@linux.ibm.com (mailing list archive)
State New, archived
Headers show
Series vfio-ccw: Fix interrupt handling for HALT/CLEAR | expand

Commit Message

Eric Farman May 10, 2021, 8:56 p.m. UTC
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(+)
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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.