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Commit 9cd67421 authored by Cornelia Huck's avatar Cornelia Huck Committed by Martin Schwidefsky
Browse files

[S390] cio: Fix reference counting for online/offline. 



The current code attempts to get an extra reference count
for online devices by doing a get_device() in ccw_device_online()
and a put_device() in ccw_device_done(). However, this
- incorrectly obtains an extra reference for disconnected
  devices becoming available again (since they are already
  online)
- needs special checks for css_init_done in order to handle
  the console device
- is not obvious and
- may incorretly drop a reference count in ccw_device_done() if
  that function is called after path verification for a device
  that just became not operational.

So let's just get the reference in ccw_device_set_online() and
drop it in ccw_device_set_offline(). (Unfortunately, we still
need the special case in io_subchannel_probe().)

Signed-off-by: default avatarCornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent 97166f52

drivers/s390/cio/device.c

+22 −7
Original line number Diff line number Diff line
@@ -376,12 +376,16 @@ int ccw_device_set_offline(struct ccw_device *cdev) 
			dev_fsm_event(cdev, DEV_EVENT_NOTOPER);

		}

		spin_unlock_irq(cdev->ccwlock);

		/* Give up reference from ccw_device_set_online(). */

		put_device(&cdev->dev);

		return ret;

	}

	spin_unlock_irq(cdev->ccwlock);

	if (ret == 0)

	if (ret == 0) {

		wait_event(cdev->private->wait_q, dev_fsm_final_state(cdev));

	else {

		/* Give up reference from ccw_device_set_online(). */

		put_device(&cdev->dev);

	} else {

		CIO_MSG_EVENT(0, "ccw_device_offline returned %d, "

			      "device 0.%x.%04x\n",

			      ret, cdev->private->dev_id.ssid,
@@ -411,6 +415,9 @@ int ccw_device_set_online(struct ccw_device *cdev) 
		return -ENODEV;

	if (cdev->online || !cdev->drv)

		return -EINVAL;

	/* Hold on to an extra reference while device is online. */

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

		return -ENODEV;



	spin_lock_irq(cdev->ccwlock);

	ret = ccw_device_online(cdev);
@@ -422,10 +429,15 @@ int ccw_device_set_online(struct ccw_device *cdev) 
			      "device 0.%x.%04x\n",

			      ret, cdev->private->dev_id.ssid,

			      cdev->private->dev_id.devno);

		/* Give up online reference since onlining failed. */

		put_device(&cdev->dev);

		return ret;

	}

	if (cdev->private->state != DEV_STATE_ONLINE)

	if (cdev->private->state != DEV_STATE_ONLINE) {

		/* Give up online reference since onlining failed. */

		put_device(&cdev->dev);

		return -ENODEV;

	}

	if (!cdev->drv->set_online || cdev->drv->set_online(cdev) == 0) {

		cdev->online = 1;

		return 0;
@@ -440,6 +452,8 @@ int ccw_device_set_online(struct ccw_device *cdev) 
			      "device 0.%x.%04x\n",

			      ret, cdev->private->dev_id.ssid,

			      cdev->private->dev_id.devno);

	/* Give up online reference since onlining failed. */

	put_device(&cdev->dev);

	return (ret == 0) ? -ENODEV : ret;

}
@@ -1168,9 +1182,8 @@ static int io_subchannel_probe(struct subchannel *sch) 
		ccw_device_register(cdev);

		/*

		 * Check if the device is already online. If it is

		 * the reference count needs to be corrected

		 * (see ccw_device_online and css_init_done for the

		 * ugly details).

		 * the reference count needs to be corrected since we

		 * didn't obtain a reference in ccw_device_set_online.

		 */

		if (cdev->private->state != DEV_STATE_NOT_OPER &&

		    cdev->private->state != DEV_STATE_OFFLINE &&
@@ -1806,6 +1819,8 @@ ccw_device_remove (struct device *dev) 
				      "device 0.%x.%04x\n",

				      ret, cdev->private->dev_id.ssid,

				      cdev->private->dev_id.devno);

		/* Give up reference obtained in ccw_device_set_online(). */

		put_device(&cdev->dev);

	}

	ccw_device_set_timeout(cdev, 0);

	cdev->drv = NULL;

drivers/s390/cio/device_fsm.c

+0 −5
Original line number Diff line number Diff line
@@ -399,9 +399,6 @@ ccw_device_done(struct ccw_device *cdev, int state) 
		ccw_device_oper_notify(cdev);

	}

	wake_up(&cdev->private->wait_q);



	if (css_init_done && state != DEV_STATE_ONLINE)

		put_device (&cdev->dev);

}



static int cmp_pgid(struct pgid *p1, struct pgid *p2)
@@ -611,8 +608,6 @@ ccw_device_online(struct ccw_device *cdev) 
	    (cdev->private->state != DEV_STATE_BOXED))

		return -EINVAL;

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

	if (css_init_done && !get_device(&cdev->dev))

		return -ENODEV;

	ret = cio_enable_subchannel(sch, (u32)(addr_t)sch);

	if (ret != 0) {

		/* Couldn't enable the subchannel for i/o. Sick device. */