linux-kernel - [PATCH v2 01/10] vfio: ccw: Moving state change out of IRQ context

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Date:   Fri, 25 May 2018 12:21:09 +0200
From:   Pierre Morel <pmorel@...ux.vnet.ibm.com>
To:     pasic@...ux.vnet.ibm.com, bjsdjshi@...ux.vnet.ibm.com
Cc:     linux-s390@...r.kernel.org, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org, cohuck@...hat.com
Subject: [PATCH v2 01/10] vfio: ccw: Moving state change out of IRQ context

Let's move the state change from the IRQ routine to the
workqueue callback.

Signed-off-by: Pierre Morel <pmorel@...ux.vnet.ibm.com>
---
 drivers/s390/cio/vfio_ccw_drv.c | 20 +++++++-------------
 drivers/s390/cio/vfio_ccw_fsm.c | 14 ++++++++------
 2 files changed, 15 insertions(+), 19 deletions(-)

diff --git a/drivers/s390/cio/vfio_ccw_drv.c b/drivers/s390/cio/vfio_ccw_drv.c
index ea6a2d0..57ae1ab 100644
--- a/drivers/s390/cio/vfio_ccw_drv.c
+++ b/drivers/s390/cio/vfio_ccw_drv.c
@@ -70,20 +70,9 @@ int vfio_ccw_sch_quiesce(struct subchannel *sch)
 static void vfio_ccw_sch_io_todo(struct work_struct *work)
 {
 	struct vfio_ccw_private *private;
-	struct irb *irb;
 
 	private = container_of(work, struct vfio_ccw_private, io_work);
-	irb = &private->irb;
-
-	if (scsw_is_solicited(&irb->scsw)) {
-		cp_update_scsw(&private->cp, &irb->scsw);
-		cp_free(&private->cp);
-	}
-	memcpy(private->io_region.irb_area, irb, sizeof(*irb));
-
-	if (private->io_trigger)
-		eventfd_signal(private->io_trigger, 1);
-
+	vfio_ccw_fsm_event(private, VFIO_CCW_EVENT_INTERRUPT);
 	if (private->mdev)
 		private->state = VFIO_CCW_STATE_IDLE;
 }
@@ -94,9 +83,14 @@ static void vfio_ccw_sch_io_todo(struct work_struct *work)
 static void vfio_ccw_sch_irq(struct subchannel *sch)
 {
 	struct vfio_ccw_private *private = dev_get_drvdata(&sch->dev);
+	struct irb *irb = this_cpu_ptr(&cio_irb);
 
 	inc_irq_stat(IRQIO_CIO);
-	vfio_ccw_fsm_event(private, VFIO_CCW_EVENT_INTERRUPT);
+	memcpy(&private->irb, irb, sizeof(*irb));
+
+	queue_work(vfio_ccw_work_q, &private->io_work);
+	if (private->completion)
+		complete(private->completion);
 }
 
 static int vfio_ccw_sch_probe(struct subchannel *sch)
diff --git a/drivers/s390/cio/vfio_ccw_fsm.c b/drivers/s390/cio/vfio_ccw_fsm.c
index 3c80064..24e1e04 100644
--- a/drivers/s390/cio/vfio_ccw_fsm.c
+++ b/drivers/s390/cio/vfio_ccw_fsm.c
@@ -172,14 +172,16 @@ static void fsm_io_request(struct vfio_ccw_private *private,
 static void fsm_irq(struct vfio_ccw_private *private,
 		    enum vfio_ccw_event event)
 {
-	struct irb *irb = this_cpu_ptr(&cio_irb);
+	struct irb *irb = &private->irb;
 
-	memcpy(&private->irb, irb, sizeof(*irb));
-
-	queue_work(vfio_ccw_work_q, &private->io_work);
+	if (scsw_is_solicited(&irb->scsw)) {
+		cp_update_scsw(&private->cp, &irb->scsw);
+		cp_free(&private->cp);
+	}
+	memcpy(private->io_region.irb_area, irb, sizeof(*irb));
 
-	if (private->completion)
-		complete(private->completion);
+	if (private->io_trigger)
+		eventfd_signal(private->io_trigger, 1);
 }
 
 /*
-- 
2.7.4