Update Linux to v5.4.2

Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/drivers/scsi/scsi_sysfs.c b/drivers/scsi/scsi_sysfs.c
index 3aee946..6d7362e 100644
--- a/drivers/scsi/scsi_sysfs.c
+++ b/drivers/scsi/scsi_sysfs.c
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0-only
 /*
  * scsi_sysfs.c
  *
@@ -367,7 +368,6 @@
 
 static DEVICE_ATTR(eh_deadline, S_IRUGO | S_IWUSR, show_shost_eh_deadline, store_shost_eh_deadline);
 
-shost_rd_attr(use_blk_mq, "%d\n");
 shost_rd_attr(unique_id, "%u\n");
 shost_rd_attr(cmd_per_lun, "%hd\n");
 shost_rd_attr(can_queue, "%hd\n");
@@ -386,6 +386,13 @@
 }
 static DEVICE_ATTR(host_busy, S_IRUGO, show_host_busy, NULL);
 
+static ssize_t
+show_use_blk_mq(struct device *dev, struct device_attribute *attr, char *buf)
+{
+	return sprintf(buf, "1\n");
+}
+static DEVICE_ATTR(use_blk_mq, S_IRUGO, show_use_blk_mq, NULL);
+
 static struct attribute *scsi_sysfs_shost_attrs[] = {
 	&dev_attr_use_blk_mq.attr,
 	&dev_attr_unique_id.attr,
@@ -723,6 +730,14 @@
 		  const char *buf, size_t count)
 {
 	struct kernfs_node *kn;
+	struct scsi_device *sdev = to_scsi_device(dev);
+
+	/*
+	 * We need to try to get module, avoiding the module been removed
+	 * during delete.
+	 */
+	if (scsi_device_get(sdev))
+		return -ENODEV;
 
 	kn = sysfs_break_active_protection(&dev->kobj, &attr->attr);
 	WARN_ON_ONCE(!kn);
@@ -737,9 +752,10 @@
 	 * state into SDEV_DEL.
 	 */
 	device_remove_file(dev, attr);
-	scsi_remove_device(to_scsi_device(dev));
+	scsi_remove_device(sdev);
 	if (kn)
 		sysfs_unbreak_active_protection(kn);
+	scsi_device_put(sdev);
 	return count;
 };
 static DEVICE_ATTR(delete, S_IWUSR, NULL, sdev_store_delete);
@@ -760,11 +776,22 @@
 			break;
 		}
 	}
-	if (!state)
+	switch (state) {
+	case SDEV_RUNNING:
+	case SDEV_OFFLINE:
+		break;
+	default:
 		return -EINVAL;
+	}
 
 	mutex_lock(&sdev->state_mutex);
 	ret = scsi_device_set_state(sdev, state);
+	/*
+	 * If the device state changes to SDEV_RUNNING, we need to run
+	 * the queue to avoid I/O hang.
+	 */
+	if (ret == 0 && state == SDEV_RUNNING)
+		blk_mq_run_hw_queues(sdev->request_queue, true);
 	mutex_unlock(&sdev->state_mutex);
 
 	return ret == 0 ? count : -EINVAL;