Commit cec0c58d authored by Vineeth Vijayan's avatar Vineeth Vijayan Committed by Vasily Gorbik
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s390/cio: add rescan functionality on channel subsystem 



This patch introduces a new rescan sys-interface for channel-subsystem.
The rescan interface allows the user to invoke an evaluation of all
subchannels defined in the I/O configuration.

The new rescan interface can be found at /sys/devices/css0/rescan
and can be triggered by,

echo > /sys/devices/css0/rescan

Writing to this interface triggers subchannel evaluation. The write
request completes only after scan-related work has completed

This user-invoked subchannel evaluation allows manual recovery in error
situations such as:
 - restart of device discovery after resolution of temporary device
   error
 - inconsistent OS view of subchannel state due to missing state-change
   interrupts (CRWs)

Signed-off-by: default avatarVineeth Vijayan <vneethv@linux.ibm.com>
Reviewed-by: default avatarPeter Oberparleiter <oberpar@linux.ibm.com>
Signed-off-by: default avatarVasily Gorbik <gor@linux.ibm.com>
parent c78d0c74

drivers/s390/cio/css.c

+13 −0
Original line number Diff line number Diff line
@@ -886,6 +886,18 @@ static ssize_t real_cssid_show(struct device *dev, struct device_attribute *a, 
}

static DEVICE_ATTR_RO(real_cssid);



static ssize_t rescan_store(struct device *dev, struct device_attribute *a,

			    const char *buf, size_t count)

{

	CIO_TRACE_EVENT(4, "usr-rescan");



	css_schedule_eval_all();

	css_complete_work();



	return count;

}

static DEVICE_ATTR_WO(rescan);



static ssize_t cm_enable_show(struct device *dev, struct device_attribute *a,

			      char *buf)

{
@@ -932,6 +944,7 @@ static umode_t cm_enable_mode(struct kobject *kobj, struct attribute *attr, 


static struct attribute *cssdev_attrs[] = {

	&dev_attr_real_cssid.attr,

	&dev_attr_rescan.attr,

	NULL,

};