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vfio-ccw: Check initialized flag in cp_init()

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[ 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: 71189f263f ("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>
This commit is contained in:
Eric Farman 2021-05-11 21:56:29 +02:00 committed by Greg Kroah-Hartman
parent ee67cbc13f
commit cd37040ba9
1 changed files with 4 additions and 0 deletions
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4
drivers/s390/cio/vfio_ccw_cp.c
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@ -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.