| From | Greg Kroah-Hartman <> | Subject | [PATCH 5.4 138/177] vfio-ccw: Check initialized flag in cp_init() | Date | Mon, 31 May 2021 15:14:55 +0200 |
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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 3645d1720c4b..9628e0f3add3 100644 --- a/drivers/s390/cio/vfio_ccw_cp.c +++ b/drivers/s390/cio/vfio_ccw_cp.c @@ -636,6 +636,10 @@ int cp_init(struct channel_program *cp, struct device *mdev, union orb *orb) { int ret; + /* this is an error in the caller */ + if (cp->initialized) + return -EBUSY; + /* * XXX: * Only support prefetch enable mode now. -- 2.30.2
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