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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: Sebastian Ott <sebott@linux.vnet.ibm.com>
Reviewed-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
This commit is contained in:
Sebastian Ott 2015-09-07 19:52:06 +02:00 committed by Martin Schwidefsky
parent a6ef15652d
commit 616503d1d8
1 changed files with 23 additions and 20 deletions
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43
drivers/s390/cio/cmf.c
View File

@ -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);
}