On 5/11/21 3:56 PM, Eric Farman 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@xxxxxxxxxxxxx>
Reviewed-by: Cornelia Huck <cohuck@xxxxxxxxxx>
Acked-by: Matthew Rosato <mjrosato@xxxxxxxxxxxxx>
---
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.
