1 files changed, 85 insertions, 5 deletions

diff --git a/drivers/scsi/scsi_sysfs.c b/drivers/scsi/scsi_sysfs.c
index 21930c9ac9cd..4f18a851e2c7 100644
--- a/drivers/scsi/scsi_sysfs.c
+++ b/drivers/scsi/scsi_sysfs.c
@@ -17,6 +17,7 @@
 #include <scsi/scsi_device.h>
 #include <scsi/scsi_host.h>
 #include <scsi/scsi_tcq.h>
+#include <scsi/scsi_dh.h>
 #include <scsi/scsi_transport.h>
 #include <scsi/scsi_driver.h>
 
@@ -760,11 +761,15 @@ show_vpd_##_page(struct file *filp, struct kobject *kobj,	\
 {									\
 	struct device *dev = container_of(kobj, struct device, kobj);	\
 	struct scsi_device *sdev = to_scsi_device(dev);			\
+	int ret;							\
 	if (!sdev->vpd_##_page)						\
 		return -EINVAL;						\
-	return memory_read_from_buffer(buf, count, &off,		\
-				       sdev->vpd_##_page,		\
+	rcu_read_lock();						\
+	ret = memory_read_from_buffer(buf, count, &off,			\
+				      rcu_dereference(sdev->vpd_##_page), \
 				       sdev->vpd_##_page##_len);	\
+	rcu_read_unlock();						\
+	return ret;						\
 }									\
 static struct bin_attribute dev_attr_vpd_##_page = {		\
 	.attr =	{.name = __stringify(vpd_##_page), .mode = S_IRUGO },	\
@@ -901,6 +906,76 @@ static DEVICE_ATTR(queue_depth, S_IRUGO | S_IWUSR, sdev_show_queue_depth,
 		   sdev_store_queue_depth);
 
 static ssize_t
+sdev_show_wwid(struct device *dev, struct device_attribute *attr,
+		    char *buf)
+{
+	struct scsi_device *sdev = to_scsi_device(dev);
+	ssize_t count;
+
+	count = scsi_vpd_lun_id(sdev, buf, PAGE_SIZE);
+	if (count > 0) {
+		buf[count] = '\n';
+		count++;
+	}
+	return count;
+}
+static DEVICE_ATTR(wwid, S_IRUGO, sdev_show_wwid, NULL);
+
+#ifdef CONFIG_SCSI_DH
+static ssize_t
+sdev_show_dh_state(struct device *dev, struct device_attribute *attr,
+		   char *buf)
+{
+	struct scsi_device *sdev = to_scsi_device(dev);
+
+	if (!sdev->handler)
+		return snprintf(buf, 20, "detached\n");
+
+	return snprintf(buf, 20, "%s\n", sdev->handler->name);
+}
+
+static ssize_t
+sdev_store_dh_state(struct device *dev, struct device_attribute *attr,
+		    const char *buf, size_t count)
+{
+	struct scsi_device *sdev = to_scsi_device(dev);
+	int err = -EINVAL;
+
+	if (sdev->sdev_state == SDEV_CANCEL ||
+	    sdev->sdev_state == SDEV_DEL)
+		return -ENODEV;
+
+	if (!sdev->handler) {
+		/*
+		 * Attach to a device handler
+		 */
+		err = scsi_dh_attach(sdev->request_queue, buf);
+	} else if (!strncmp(buf, "activate", 8)) {
+		/*
+		 * Activate a device handler
+		 */
+		if (sdev->handler->activate)
+			err = sdev->handler->activate(sdev, NULL, NULL);
+		else
+			err = 0;
+	} else if (!strncmp(buf, "detach", 6)) {
+		/*
+		 * Detach from a device handler
+		 */
+		sdev_printk(KERN_WARNING, sdev,
+			    "can't detach handler %s.\n",
+			    sdev->handler->name);
+		err = -EINVAL;
+	}
+
+	return err < 0 ? err : count;
+}
+
+static DEVICE_ATTR(dh_state, S_IRUGO | S_IWUSR, sdev_show_dh_state,
+		   sdev_store_dh_state);
+#endif
+
+static ssize_t
 sdev_show_queue_ramp_up_period(struct device *dev,
 			       struct device_attribute *attr,
 			       char *buf)
@@ -969,6 +1044,10 @@ static struct attribute *scsi_sdev_attrs[] = {
 	&dev_attr_modalias.attr,
 	&dev_attr_queue_depth.attr,
 	&dev_attr_queue_type.attr,
+	&dev_attr_wwid.attr,
+#ifdef CONFIG_SCSI_DH
+	&dev_attr_dh_state.attr,
+#endif
 	&dev_attr_queue_ramp_up_period.attr,
 	REF_EVT(media_change),
 	REF_EVT(inquiry_change_reported),
@@ -1058,11 +1137,12 @@ int scsi_sysfs_add_sdev(struct scsi_device *sdev)
 	}
 
 	error = scsi_dh_add_device(sdev);
-	if (error) {
+	if (error)
+		/*
+		 * device_handler is optional, so any error can be ignored
+		 */
 		sdev_printk(KERN_INFO, sdev,
 				"failed to add device handler: %d\n", error);
-		return error;
-	}
 
 	device_enable_async_suspend(&sdev->sdev_dev);
 	error = device_add(&sdev->sdev_dev);