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-rw-r--r--drivers/s390/cio/cmf.c29
1 files changed, 20 insertions, 9 deletions
diff --git a/drivers/s390/cio/cmf.c b/drivers/s390/cio/cmf.c
index b2afad5a5..2a34eb5f6 100644
--- a/drivers/s390/cio/cmf.c
+++ b/drivers/s390/cio/cmf.c
@@ -753,6 +753,17 @@ static void reset_cmb(struct ccw_device *cdev)
cmf_generic_reset(cdev);
}
+static int cmf_enabled(struct ccw_device *cdev)
+{
+ int enabled;
+
+ spin_lock_irq(cdev->ccwlock);
+ enabled = !!cdev->private->cmb;
+ spin_unlock_irq(cdev->ccwlock);
+
+ return enabled;
+}
+
static struct attribute_group cmf_attr_group;
static struct cmb_operations cmbops_basic = {
@@ -1153,13 +1164,8 @@ static ssize_t cmb_enable_show(struct device *dev,
char *buf)
{
struct ccw_device *cdev = to_ccwdev(dev);
- int enabled;
- spin_lock_irq(cdev->ccwlock);
- enabled = !!cdev->private->cmb;
- spin_unlock_irq(cdev->ccwlock);
-
- return sprintf(buf, "%d\n", enabled);
+ return sprintf(buf, "%d\n", cmf_enabled(cdev));
}
static ssize_t cmb_enable_store(struct device *dev,
@@ -1199,15 +1205,20 @@ int ccw_set_cmf(struct ccw_device *cdev, int enable)
* @cdev: The ccw device to be enabled
*
* Returns %0 for success or a negative error value.
- *
+ * Note: If this is called on a device for which channel measurement is already
+ * enabled a reset of the measurement data is triggered.
* Context:
* non-atomic
*/
int enable_cmf(struct ccw_device *cdev)
{
- int ret;
+ int ret = 0;
device_lock(&cdev->dev);
+ if (cmf_enabled(cdev)) {
+ cmbops->reset(cdev);
+ goto out_unlock;
+ }
get_device(&cdev->dev);
ret = cmbops->alloc(cdev);
if (ret)
@@ -1226,7 +1237,7 @@ int enable_cmf(struct ccw_device *cdev)
out:
if (ret)
put_device(&cdev->dev);
-
+out_unlock:
device_unlock(&cdev->dev);
return ret;
}