diff options
Diffstat (limited to 'drivers/s390/cio/cmf.c')
| -rw-r--r-- | drivers/s390/cio/cmf.c | 29 |
1 files changed, 20 insertions, 9 deletions
diff --git a/drivers/s390/cio/cmf.c b/drivers/s390/cio/cmf.c index f18c83bacb09..268aa23afa01 100644 --- a/drivers/s390/cio/cmf.c +++ b/drivers/s390/cio/cmf.c @@ -756,6 +756,17 @@ 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 = { @@ -1156,13 +1167,8 @@ 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, @@ -1202,15 +1208,20 @@ 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) @@ -1229,7 +1240,7 @@ int enable_cmf(struct ccw_device *cdev) out: if (ret) put_device(&cdev->dev); - +out_unlock: device_unlock(&cdev->dev); return ret; } |