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Commit 616503d1 authored by Sebastian Ott's avatar Sebastian Ott Committed by Martin Schwidefsky
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s390/cio: improve locking during cmbe allocation 



During allocation of extended measurement blocks we check if the device is
already active for channel measurement and add the device to a list of
devices with active channel measurement. The check is done under ccwlock
protection and the list modification is guarded by a different lock.

To guarantee that both states are in sync make sure that both locks
are held during the allocation process (like it's already done for the
"normal" measurement block allocation).

Signed-off-by: default avatarSebastian Ott <sebott@linux.vnet.ibm.com>
Reviewed-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent a6ef1565

drivers/s390/cio/cmf.c

+23 −20
Original line number Diff line number Diff line
@@ -821,42 +821,45 @@ static inline struct cmbe *cmbe_align(struct cmbe *c) 


static int alloc_cmbe(struct ccw_device *cdev)

{

	struct cmbe *cmbe;

	struct cmb_data *cmb_data;

	int ret;

	struct cmbe *cmbe;

	int ret = -ENOMEM;



	cmbe = kzalloc (sizeof (*cmbe) * 2, GFP_KERNEL);

	if (!cmbe)

		return -ENOMEM;

		return ret;



	cmb_data = kzalloc(sizeof(struct cmb_data), GFP_KERNEL);

	if (!cmb_data) {

		ret = -ENOMEM;

	if (!cmb_data)

		goto out_free;

	}



	cmb_data->last_block = kzalloc(sizeof(struct cmbe), GFP_KERNEL);

	if (!cmb_data->last_block) {

		ret = -ENOMEM;

	if (!cmb_data->last_block)

		goto out_free;

	}



	cmb_data->size = sizeof(struct cmbe);

	spin_lock_irq(cdev->ccwlock);

	if (cdev->private->cmb) {

		spin_unlock_irq(cdev->ccwlock);

		ret = -EBUSY;

		goto out_free;

	}

	cmb_data->hw_block = cmbe;



	spin_lock(&cmb_area.lock);

	spin_lock_irq(cdev->ccwlock);

	if (cdev->private->cmb)

		goto out_unlock;



	cdev->private->cmb = cmb_data;

	spin_unlock_irq(cdev->ccwlock);



	/* activate global measurement if this is the first channel */

	spin_lock(&cmb_area.lock);

	if (list_empty(&cmb_area.list))

		cmf_activate(NULL, 1);

	list_add_tail(&cdev->private->cmb_list, &cmb_area.list);

	spin_unlock(&cmb_area.lock);



	spin_unlock_irq(cdev->ccwlock);

	spin_unlock(&cmb_area.lock);

	return 0;



out_unlock:

	spin_unlock_irq(cdev->ccwlock);

	spin_unlock(&cmb_area.lock);

	ret = -EBUSY;

out_free:

	if (cmb_data)

		kfree(cmb_data->last_block);
@@ -869,19 +872,19 @@ static void free_cmbe(struct ccw_device *cdev) 
{

	struct cmb_data *cmb_data;



	spin_lock(&cmb_area.lock);

	spin_lock_irq(cdev->ccwlock);

	cmb_data = cdev->private->cmb;

	cdev->private->cmb = NULL;

	if (cmb_data)

		kfree(cmb_data->last_block);

	kfree(cmb_data);

	spin_unlock_irq(cdev->ccwlock);



	/* deactivate global measurement if this is the last channel */

	spin_lock(&cmb_area.lock);

	list_del_init(&cdev->private->cmb_list);

	if (list_empty(&cmb_area.list))

		cmf_activate(NULL, 0);

	spin_unlock_irq(cdev->ccwlock);

	spin_unlock(&cmb_area.lock);

}