[PATCH v3 03/11] vfio/ccw: Do not change FSM state in subchannel event

From: Eric Farman <farman@linux.ibm.com>
To: Matthew Rosato <mjrosato@linux.ibm.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>,
	Alex Williamson <alex.williamson@redhat.com>,
	Cornelia Huck <cohuck@redhat.com>,
	Halil Pasic <pasic@linux.ibm.com>,
	kvm@vger.kernel.org, linux-s390@vger.kernel.org,
	Eric Farman <farman@linux.ibm.com>
Subject: [PATCH v3 03/11] vfio/ccw: Do not change FSM state in subchannel event
Date: Thu, 30 Jun 2022 22:36:39 +0200	[thread overview]
Message-ID: <20220630203647.2529815-4-farman@linux.ibm.com> (raw)
In-Reply-To: <20220630203647.2529815-1-farman@linux.ibm.com>

The routine vfio_ccw_sch_event() is tasked with handling subchannel events,
specifically machine checks, on behalf of vfio-ccw. It correctly calls
cio_update_schib(), and if that fails (meaning the subchannel is gone)
it makes an FSM event call to mark the subchannel Not Operational.

If that worked, however, then it decides that if the FSM state was already
Not Operational (implying the subchannel just came back), then it should
simply change the FSM to partially- or fully-open.

Remove this trickery, since a subchannel returning will require more
probing than simply "oh all is well again" to ensure it works correctly.

Fixes: bbe37e4cb8970 ("vfio: ccw: introduce a finite state machine")
Signed-off-by: Eric Farman <farman@linux.ibm.com>
Reviewed-by: Matthew Rosato <mjrosato@linux.ibm.com>
---
 drivers/s390/cio/vfio_ccw_drv.c | 14 +++-----------
 1 file changed, 3 insertions(+), 11 deletions(-)

diff --git a/drivers/s390/cio/vfio_ccw_drv.c b/drivers/s390/cio/vfio_ccw_drv.c
index 179eb614fa5b..279ad2161f17 100644
--- a/drivers/s390/cio/vfio_ccw_drv.c
+++ b/drivers/s390/cio/vfio_ccw_drv.c
@@ -301,19 +301,11 @@ static int vfio_ccw_sch_event(struct subchannel *sch, int process)
 	if (work_pending(&sch->todo_work))
 		goto out_unlock;
 
-	if (cio_update_schib(sch)) {
-		vfio_ccw_fsm_event(private, VFIO_CCW_EVENT_NOT_OPER);
-		rc = 0;
-		goto out_unlock;
-	}
-
-	private = dev_get_drvdata(&sch->dev);
-	if (private->state == VFIO_CCW_STATE_NOT_OPER) {
-		private->state = private->mdev ? VFIO_CCW_STATE_IDLE :
-				 VFIO_CCW_STATE_STANDBY;
-	}
 	rc = 0;
 
+	if (cio_update_schib(sch))
+		vfio_ccw_fsm_event(private, VFIO_CCW_EVENT_NOT_OPER);
+
 out_unlock:
 	spin_unlock_irqrestore(sch->lock, flags);
 
-- 
2.32.0

