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Commit 0c609fca authored by Sebastian Ott's avatar Sebastian Ott Committed by Martin Schwidefsky
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[S390] cio: handle busy subchannel in ccw_device_move_to_sch 



Try to disable the old subchannel before we ask the driver core
to move the attached device to a new parent. This way we can use
the QUIESCE state during shutdown which prevents a possible use
after free situation in some error cases.

Signed-off-by: default avatarSebastian Ott <sebott@linux.vnet.ibm.com>
Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent ec64333c

drivers/s390/cio/device.c

+22 −2
Original line number Diff line number Diff line
@@ -892,12 +892,27 @@ static int ccw_device_move_to_sch(struct ccw_device *cdev, 
				  struct subchannel *sch)

{

	struct subchannel *old_sch;

	int rc;

	int rc, old_enabled = 0;



	old_sch = to_subchannel(cdev->dev.parent);

	/* Obtain child reference for new parent. */

	if (!get_device(&sch->dev))

		return -ENODEV;



	if (!sch_is_pseudo_sch(old_sch)) {

		spin_lock_irq(old_sch->lock);

		old_enabled = old_sch->schib.pmcw.ena;

		rc = 0;

		if (old_enabled)

			rc = cio_disable_subchannel(old_sch);

		spin_unlock_irq(old_sch->lock);

		if (rc == -EBUSY) {

			/* Release child reference for new parent. */

			put_device(&sch->dev);

			return rc;

		}

	}



	mutex_lock(&sch->reg_mutex);

	rc = device_move(&cdev->dev, &sch->dev, DPM_ORDER_PARENT_BEFORE_DEV);

	mutex_unlock(&sch->reg_mutex);
@@ -906,6 +921,12 @@ static int ccw_device_move_to_sch(struct ccw_device *cdev, 
			      cdev->private->dev_id.ssid,

			      cdev->private->dev_id.devno, sch->schid.ssid,

			      sch->schib.pmcw.dev, rc);

		if (old_enabled) {

			/* Try to reenable the old subchannel. */

			spin_lock_irq(old_sch->lock);

			cio_enable_subchannel(old_sch, (u32)(addr_t)old_sch);

			spin_unlock_irq(old_sch->lock);

		}

		/* Release child reference for new parent. */

		put_device(&sch->dev);

		return rc;
@@ -914,7 +935,6 @@ static int ccw_device_move_to_sch(struct ccw_device *cdev, 
	if (!sch_is_pseudo_sch(old_sch)) {

		spin_lock_irq(old_sch->lock);

		sch_set_cdev(old_sch, NULL);

		cio_disable_subchannel(old_sch);

		spin_unlock_irq(old_sch->lock);

		css_schedule_eval(old_sch->schid);

	}