From: Eric Farman farman@linux.ibm.com
[ Upstream commit c6c82e0cd8125d30f2f1b29205c7e1a2f1a6785b ]
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 Acked-by: Matthew Rosato mjrosato@linux.ibm.com Message-Id: 20210511195631.3995081-2-farman@linux.ibm.com Signed-off-by: Cornelia Huck cohuck@redhat.com Signed-off-by: Sasha Levin sashal@kernel.org --- 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.