Merge branch 'for-2.6.38/event-handling' into for-2.6.38/core

block/genhd.c

@@ -18,6 +18,7 @@
 #include <linux/buffer_head.h>
 #include <linux/mutex.h>
 #include <linux/idr.h>
+#include <linux/log2.h>
 
 #include "blk.h"
 
@@ -35,6 +36,10 @@ static DEFINE_IDR(ext_devt_idr);
 
 static struct device_type disk_type;
 
+static void disk_add_events(struct gendisk *disk);
+static void disk_del_events(struct gendisk *disk);
+static void disk_release_events(struct gendisk *disk);
+
 /**
  * disk_get_part - get partition
  * @disk: disk to look partition from
@@ -502,6 +507,64 @@ static int exact_lock(dev_t devt, void *data)
 	return 0;
 }
 
+void register_disk(struct gendisk *disk)
+{
+	struct device *ddev = disk_to_dev(disk);
+	struct block_device *bdev;
+	struct disk_part_iter piter;
+	struct hd_struct *part;
+	int err;
+
+	ddev->parent = disk->driverfs_dev;
+
+	dev_set_name(ddev, disk->disk_name);
+
+	/* delay uevents, until we scanned partition table */
+	dev_set_uevent_suppress(ddev, 1);
+
+	if (device_add(ddev))
+		return;
+	if (!sysfs_deprecated) {
+		err = sysfs_create_link(block_depr, &ddev->kobj,
+					kobject_name(&ddev->kobj));
+		if (err) {
+			device_del(ddev);
+			return;
+		}
+	}
+	disk->part0.holder_dir = kobject_create_and_add("holders", &ddev->kobj);
+	disk->slave_dir = kobject_create_and_add("slaves", &ddev->kobj);
+
+	/* No minors to use for partitions */
+	if (!disk_partitionable(disk))
+		goto exit;
+
+	/* No such device (e.g., media were just removed) */
+	if (!get_capacity(disk))
+		goto exit;
+
+	bdev = bdget_disk(disk, 0);
+	if (!bdev)
+		goto exit;
+
+	bdev->bd_invalidated = 1;
+	err = blkdev_get(bdev, FMODE_READ, NULL);
+	if (err < 0)
+		goto exit;
+	blkdev_put(bdev, FMODE_READ);
+
+exit:
+	/* announce disk after possible partitions are created */
+	dev_set_uevent_suppress(ddev, 0);
+	kobject_uevent(&ddev->kobj, KOBJ_ADD);
+
+	/* announce possible partitions */
+	disk_part_iter_init(&piter, disk, 0);
+	while ((part = disk_part_iter_next(&piter)))
+		kobject_uevent(&part_to_dev(part)->kobj, KOBJ_ADD);
+	disk_part_iter_exit(&piter);
+}
+
 /**
  * add_disk - add partitioning information to kernel list
  * @disk: per-device partitioning information
@@ -551,18 +614,48 @@ void add_disk(struct gendisk *disk)
 	retval = sysfs_create_link(&disk_to_dev(disk)->kobj, &bdi->dev->kobj,
 				   "bdi");
 	WARN_ON(retval);
-}
 
+	disk_add_events(disk);
+}
 EXPORT_SYMBOL(add_disk);
-EXPORT_SYMBOL(del_gendisk);	/* in partitions/check.c */
 
-void unlink_gendisk(struct gendisk *disk)
+void del_gendisk(struct gendisk *disk)
 {
+	struct disk_part_iter piter;
+	struct hd_struct *part;
+
+	disk_del_events(disk);
+
+	/* invalidate stuff */
+	disk_part_iter_init(&piter, disk,
+			     DISK_PITER_INCL_EMPTY | DISK_PITER_REVERSE);
+	while ((part = disk_part_iter_next(&piter))) {
+		invalidate_partition(disk, part->partno);
+		delete_partition(disk, part->partno);
+	}
+	disk_part_iter_exit(&piter);
+
+	invalidate_partition(disk, 0);
+	blk_free_devt(disk_to_dev(disk)->devt);
+	set_capacity(disk, 0);
+	disk->flags &= ~GENHD_FL_UP;
+
 	sysfs_remove_link(&disk_to_dev(disk)->kobj, "bdi");
 	bdi_unregister(&disk->queue->backing_dev_info);
 	blk_unregister_queue(disk);
 	blk_unregister_region(disk_devt(disk), disk->minors);
+
+	part_stat_set_all(&disk->part0, 0);
+	disk->part0.stamp = 0;
+
+	kobject_put(disk->part0.holder_dir);
+	kobject_put(disk->slave_dir);
+	disk->driverfs_dev = NULL;
+	if (!sysfs_deprecated)
+		sysfs_remove_link(block_depr, dev_name(disk_to_dev(disk)));
+	device_del(disk_to_dev(disk));
 }
+EXPORT_SYMBOL(del_gendisk);
 
 /**
  * get_gendisk - get partitioning information for a given device
@@ -1005,6 +1098,7 @@ static void disk_release(struct device *dev)
 {
 	struct gendisk *disk = dev_to_disk(dev);
 
+	disk_release_events(disk);
 	kfree(disk->random);
 	disk_replace_part_tbl(disk, NULL);
 	free_part_stats(&disk->part0);
@@ -1110,29 +1204,6 @@ static int __init proc_genhd_init(void)
 module_init(proc_genhd_init);
 #endif /* CONFIG_PROC_FS */
 
-static void media_change_notify_thread(struct work_struct *work)
-{
-	struct gendisk *gd = container_of(work, struct gendisk, async_notify);
-	char event[] = "MEDIA_CHANGE=1";
-	char *envp[] = { event, NULL };
-
-	/*
-	 * set enviroment vars to indicate which event this is for
-	 * so that user space will know to go check the media status.
-	 */
-	kobject_uevent_env(&disk_to_dev(gd)->kobj, KOBJ_CHANGE, envp);
-	put_device(gd->driverfs_dev);
-}
-
-#if 0
-void genhd_media_change_notify(struct gendisk *disk)
-{
-	get_device(disk->driverfs_dev);
-	schedule_work(&disk->async_notify);
-}
-EXPORT_SYMBOL_GPL(genhd_media_change_notify);
-#endif  /*  0  */
-
 dev_t blk_lookup_devt(const char *name, int partno)
 {
 	dev_t devt = MKDEV(0, 0);
@@ -1200,8 +1271,6 @@ struct gendisk *alloc_disk_node(int minors, int node_id)
 		disk_to_dev(disk)->class = &block_class;
 		disk_to_dev(disk)->type = &disk_type;
 		device_initialize(disk_to_dev(disk));
-		INIT_WORK(&disk->async_notify,
-			media_change_notify_thread);
 	}
 	return disk;
 }
@@ -1293,3 +1362,422 @@ int invalidate_partition(struct gendisk *disk, int partno)
 }
 
 EXPORT_SYMBOL(invalidate_partition);
+
+/*
+ * Disk events - monitor disk events like media change and eject request.
+ */
+struct disk_events {
+	struct list_head	node;		/* all disk_event's */
+	struct gendisk		*disk;		/* the associated disk */
+	spinlock_t		lock;
+
+	int			block;		/* event blocking depth */
+	unsigned int		pending;	/* events already sent out */
+	unsigned int		clearing;	/* events being cleared */
+
+	long			poll_msecs;	/* interval, -1 for default */
+	struct delayed_work	dwork;
+};
+
+static const char *disk_events_strs[] = {
+	[ilog2(DISK_EVENT_MEDIA_CHANGE)]	= "media_change",
+	[ilog2(DISK_EVENT_EJECT_REQUEST)]	= "eject_request",
+};
+
+static char *disk_uevents[] = {
+	[ilog2(DISK_EVENT_MEDIA_CHANGE)]	= "DISK_MEDIA_CHANGE=1",
+	[ilog2(DISK_EVENT_EJECT_REQUEST)]	= "DISK_EJECT_REQUEST=1",
+};
+
+/* list of all disk_events */
+static DEFINE_MUTEX(disk_events_mutex);
+static LIST_HEAD(disk_events);
+
+/* disable in-kernel polling by default */
+static unsigned long disk_events_dfl_poll_msecs	= 0;
+
+static unsigned long disk_events_poll_jiffies(struct gendisk *disk)
+{
+	struct disk_events *ev = disk->ev;
+	long intv_msecs = 0;
+
+	/*
+	 * If device-specific poll interval is set, always use it.  If
+	 * the default is being used, poll iff there are events which
+	 * can't be monitored asynchronously.
+	 */
+	if (ev->poll_msecs >= 0)
+		intv_msecs = ev->poll_msecs;
+	else if (disk->events & ~disk->async_events)
+		intv_msecs = disk_events_dfl_poll_msecs;
+
+	return msecs_to_jiffies(intv_msecs);
+}
+
+static void __disk_block_events(struct gendisk *disk, bool sync)
+{
+	struct disk_events *ev = disk->ev;
+	unsigned long flags;
+	bool cancel;
+
+	spin_lock_irqsave(&ev->lock, flags);
+	cancel = !ev->block++;
+	spin_unlock_irqrestore(&ev->lock, flags);
+
+	if (cancel) {
+		if (sync)
+			cancel_delayed_work_sync(&disk->ev->dwork);
+		else
+			cancel_delayed_work(&disk->ev->dwork);
+	}
+}
+
+static void __disk_unblock_events(struct gendisk *disk, bool check_now)
+{
+	struct disk_events *ev = disk->ev;
+	unsigned long intv;
+	unsigned long flags;
+
+	spin_lock_irqsave(&ev->lock, flags);
+
+	if (WARN_ON_ONCE(ev->block <= 0))
+		goto out_unlock;
+
+	if (--ev->block)
+		goto out_unlock;
+
+	/*
+	 * Not exactly a latency critical operation, set poll timer
+	 * slack to 25% and kick event check.
+	 */
+	intv = disk_events_poll_jiffies(disk);
+	set_timer_slack(&ev->dwork.timer, intv / 4);
+	if (check_now)
+		queue_delayed_work(system_nrt_wq, &ev->dwork, 0);
+	else if (intv)
+		queue_delayed_work(system_nrt_wq, &ev->dwork, intv);
+out_unlock:
+	spin_unlock_irqrestore(&ev->lock, flags);
+}
+
+/**
+ * disk_block_events - block and flush disk event checking
+ * @disk: disk to block events for
+ *
+ * On return from this function, it is guaranteed that event checking
+ * isn't in progress and won't happen until unblocked by
+ * disk_unblock_events().  Events blocking is counted and the actual
+ * unblocking happens after the matching number of unblocks are done.
+ *
+ * Note that this intentionally does not block event checking from
+ * disk_clear_events().
+ *
+ * CONTEXT:
+ * Might sleep.
+ */
+void disk_block_events(struct gendisk *disk)
+{
+	if (disk->ev)
+		__disk_block_events(disk, true);
+}
+
+/**
+ * disk_unblock_events - unblock disk event checking
+ * @disk: disk to unblock events for
+ *
+ * Undo disk_block_events().  When the block count reaches zero, it
+ * starts events polling if configured.
+ *
+ * CONTEXT:
+ * Don't care.  Safe to call from irq context.
+ */
+void disk_unblock_events(struct gendisk *disk)
+{
+	if (disk->ev)
+		__disk_unblock_events(disk, true);
+}
+
+/**
+ * disk_check_events - schedule immediate event checking
+ * @disk: disk to check events for
+ *
+ * Schedule immediate event checking on @disk if not blocked.
+ *
+ * CONTEXT:
+ * Don't care.  Safe to call from irq context.
+ */
+void disk_check_events(struct gendisk *disk)
+{
+	if (disk->ev) {
+		__disk_block_events(disk, false);
+		__disk_unblock_events(disk, true);
+	}
+}
+EXPORT_SYMBOL_GPL(disk_check_events);
+
+/**
+ * disk_clear_events - synchronously check, clear and return pending events
+ * @disk: disk to fetch and clear events from
+ * @mask: mask of events to be fetched and clearted
+ *
+ * Disk events are synchronously checked and pending events in @mask
+ * are cleared and returned.  This ignores the block count.
+ *
+ * CONTEXT:
+ * Might sleep.
+ */
+unsigned int disk_clear_events(struct gendisk *disk, unsigned int mask)
+{
+	const struct block_device_operations *bdops = disk->fops;
+	struct disk_events *ev = disk->ev;
+	unsigned int pending;
+
+	if (!ev) {
+		/* for drivers still using the old ->media_changed method */
+		if ((mask & DISK_EVENT_MEDIA_CHANGE) &&
+		    bdops->media_changed && bdops->media_changed(disk))
+			return DISK_EVENT_MEDIA_CHANGE;
+		return 0;
+	}
+
+	/* tell the workfn about the events being cleared */
+	spin_lock_irq(&ev->lock);
+	ev->clearing |= mask;
+	spin_unlock_irq(&ev->lock);
+
+	/* uncondtionally schedule event check and wait for it to finish */
+	__disk_block_events(disk, true);
+	queue_delayed_work(system_nrt_wq, &ev->dwork, 0);
+	flush_delayed_work(&ev->dwork);
+	__disk_unblock_events(disk, false);
+
+	/* then, fetch and clear pending events */
+	spin_lock_irq(&ev->lock);
+	WARN_ON_ONCE(ev->clearing & mask);	/* cleared by workfn */
+	pending = ev->pending & mask;
+	ev->pending &= ~mask;
+	spin_unlock_irq(&ev->lock);
+
+	return pending;
+}
+
+static void disk_events_workfn(struct work_struct *work)
+{
+	struct delayed_work *dwork = to_delayed_work(work);
+	struct disk_events *ev = container_of(dwork, struct disk_events, dwork);
+	struct gendisk *disk = ev->disk;
+	char *envp[ARRAY_SIZE(disk_uevents) + 1] = { };
+	unsigned int clearing = ev->clearing;
+	unsigned int events;
+	unsigned long intv;
+	int nr_events = 0, i;
+
+	/* check events */
+	events = disk->fops->check_events(disk, clearing);
+
+	/* accumulate pending events and schedule next poll if necessary */
+	spin_lock_irq(&ev->lock);
+
+	events &= ~ev->pending;
+	ev->pending |= events;
+	ev->clearing &= ~clearing;
+
+	intv = disk_events_poll_jiffies(disk);
+	if (!ev->block && intv)
+		queue_delayed_work(system_nrt_wq, &ev->dwork, intv);
+
+	spin_unlock_irq(&ev->lock);
+
+	/* tell userland about new events */
+	for (i = 0; i < ARRAY_SIZE(disk_uevents); i++)
+		if (events & (1 << i))
+			envp[nr_events++] = disk_uevents[i];
+
+	if (nr_events)
+		kobject_uevent_env(&disk_to_dev(disk)->kobj, KOBJ_CHANGE, envp);
+}
+
+/*
+ * A disk events enabled device has the following sysfs nodes under
+ * its /sys/block/X/ directory.
+ *
+ * events		: list of all supported events
+ * events_async		: list of events which can be detected w/o polling
+ * events_poll_msecs	: polling interval, 0: disable, -1: system default
+ */
+static ssize_t __disk_events_show(unsigned int events, char *buf)
+{
+	const char *delim = "";
+	ssize_t pos = 0;
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(disk_events_strs); i++)
+		if (events & (1 << i)) {
+			pos += sprintf(buf + pos, "%s%s",
+				       delim, disk_events_strs[i]);
+			delim = " ";
+		}
+	if (pos)
+		pos += sprintf(buf + pos, "\n");
+	return pos;
+}
+
+static ssize_t disk_events_show(struct device *dev,
+				struct device_attribute *attr, char *buf)
+{
+	struct gendisk *disk = dev_to_disk(dev);
+
+	return __disk_events_show(disk->events, buf);
+}
+
+static ssize_t disk_events_async_show(struct device *dev,
+				      struct device_attribute *attr, char *buf)
+{
+	struct gendisk *disk = dev_to_disk(dev);
+
+	return __disk_events_show(disk->async_events, buf);
+}
+
+static ssize_t disk_events_poll_msecs_show(struct device *dev,
+					   struct device_attribute *attr,
+					   char *buf)
+{
+	struct gendisk *disk = dev_to_disk(dev);
+
+	return sprintf(buf, "%ld\n", disk->ev->poll_msecs);
+}
+
+static ssize_t disk_events_poll_msecs_store(struct device *dev,
+					    struct device_attribute *attr,
+					    const char *buf, size_t count)
+{
+	struct gendisk *disk = dev_to_disk(dev);
+	long intv;
+
+	if (!count || !sscanf(buf, "%ld", &intv))
+		return -EINVAL;
+
+	if (intv < 0 && intv != -1)
+		return -EINVAL;
+
+	__disk_block_events(disk, true);
+	disk->ev->poll_msecs = intv;
+	__disk_unblock_events(disk, true);
+
+	return count;
+}
+
+static const DEVICE_ATTR(events, S_IRUGO, disk_events_show, NULL);
+static const DEVICE_ATTR(events_async, S_IRUGO, disk_events_async_show, NULL);
+static const DEVICE_ATTR(events_poll_msecs, S_IRUGO|S_IWUSR,
+			 disk_events_poll_msecs_show,
+			 disk_events_poll_msecs_store);
+
+static const struct attribute *disk_events_attrs[] = {
+	&dev_attr_events.attr,
+	&dev_attr_events_async.attr,
+	&dev_attr_events_poll_msecs.attr,
+	NULL,
+};
+
+/*
+ * The default polling interval can be specified by the kernel
+ * parameter block.events_dfl_poll_msecs which defaults to 0
+ * (disable).  This can also be modified runtime by writing to
+ * /sys/module/block/events_dfl_poll_msecs.
+ */
+static int disk_events_set_dfl_poll_msecs(const char *val,
+					  const struct kernel_param *kp)
+{
+	struct disk_events *ev;
+	int ret;
+
+	ret = param_set_ulong(val, kp);
+	if (ret < 0)
+		return ret;
+
+	mutex_lock(&disk_events_mutex);
+
+	list_for_each_entry(ev, &disk_events, node)
+		disk_check_events(ev->disk);
+
+	mutex_unlock(&disk_events_mutex);
+
+	return 0;
+}
+
+static const struct kernel_param_ops disk_events_dfl_poll_msecs_param_ops = {
+	.set	= disk_events_set_dfl_poll_msecs,
+	.get	= param_get_ulong,
+};
+
+#undef MODULE_PARAM_PREFIX
+#define MODULE_PARAM_PREFIX	"block."
+
+module_param_cb(events_dfl_poll_msecs, &disk_events_dfl_poll_msecs_param_ops,
+		&disk_events_dfl_poll_msecs, 0644);
+
+/*
+ * disk_{add|del|release}_events - initialize and destroy disk_events.
+ */
+static void disk_add_events(struct gendisk *disk)
+{
+	struct disk_events *ev;
+
+	if (!disk->fops->check_events || !(disk->events | disk->async_events))
+		return;
+
+	ev = kzalloc(sizeof(*ev), GFP_KERNEL);
+	if (!ev) {
+		pr_warn("%s: failed to initialize events\n", disk->disk_name);
+		return;
+	}
+
+	if (sysfs_create_files(&disk_to_dev(disk)->kobj,
+			       disk_events_attrs) < 0) {
+		pr_warn("%s: failed to create sysfs files for events\n",
+			disk->disk_name);
+		kfree(ev);
+		return;
+	}
+
+	disk->ev = ev;
+
+	INIT_LIST_HEAD(&ev->node);
+	ev->disk = disk;
+	spin_lock_init(&ev->lock);
+	ev->block = 1;
+	ev->poll_msecs = -1;
+	INIT_DELAYED_WORK(&ev->dwork, disk_events_workfn);
+
+	mutex_lock(&disk_events_mutex);
+	list_add_tail(&ev->node, &disk_events);
+	mutex_unlock(&disk_events_mutex);
+
+	/*
+	 * Block count is initialized to 1 and the following initial
+	 * unblock kicks it into action.
+	 */
+	__disk_unblock_events(disk, true);
+}
+
+static void disk_del_events(struct gendisk *disk)
+{
+	if (!disk->ev)
+		return;
+
+	__disk_block_events(disk, true);
+
+	mutex_lock(&disk_events_mutex);
+	list_del_init(&disk->ev->node);
+	mutex_unlock(&disk_events_mutex);
+
+	sysfs_remove_files(&disk_to_dev(disk)->kobj, disk_events_attrs);
+}
+
+static void disk_release_events(struct gendisk *disk)
+{
+	/* the block count should be 1 from disk_del_events() */
+	WARN_ON_ONCE(disk->ev && disk->ev->block != 1);
+	kfree(disk->ev);
+}

drivers/cdrom/cdrom.c

@@ -1348,7 +1348,10 @@ static int cdrom_select_disc(struct cdrom_device_info *cdi, int slot)
 	if (!CDROM_CAN(CDC_SELECT_DISC))
 		return -EDRIVE_CANT_DO_THIS;
 
-	(void) cdi->ops->media_changed(cdi, slot);
+	if (cdi->ops->check_events)
+		cdi->ops->check_events(cdi, 0, slot);
+	else
+		cdi->ops->media_changed(cdi, slot);
 
 	if (slot == CDSL_NONE) {
 		/* set media changed bits, on both queues */
@@ -1392,6 +1395,42 @@ static int cdrom_select_disc(struct cdrom_device_info *cdi, int slot)
 	return slot;
 }
 
+/*
+ * As cdrom implements an extra ioctl consumer for media changed
+ * event, it needs to buffer ->check_events() output, such that event
+ * is not lost for both the usual VFS and ioctl paths.
+ * cdi->{vfs|ioctl}_events are used to buffer pending events for each
+ * path.
+ *
+ * XXX: Locking is non-existent.  cdi->ops->check_events() can be
+ * called in parallel and buffering fields are accessed without any
+ * exclusion.  The original media_changed code had the same problem.
+ * It might be better to simply deprecate CDROM_MEDIA_CHANGED ioctl
+ * and remove this cruft altogether.  It doesn't have much usefulness
+ * at this point.
+ */
+static void cdrom_update_events(struct cdrom_device_info *cdi,
+				unsigned int clearing)
+{
+	unsigned int events;
+
+	events = cdi->ops->check_events(cdi, clearing, CDSL_CURRENT);
+	cdi->vfs_events |= events;
+	cdi->ioctl_events |= events;
+}
+
+unsigned int cdrom_check_events(struct cdrom_device_info *cdi,
+				unsigned int clearing)
+{
+	unsigned int events;
+
+	cdrom_update_events(cdi, clearing);
+	events = cdi->vfs_events;
+	cdi->vfs_events = 0;
+	return events;
+}
+EXPORT_SYMBOL(cdrom_check_events);
+
 /* We want to make media_changed accessible to the user through an
  * ioctl. The main problem now is that we must double-buffer the
  * low-level implementation, to assure that the VFS and the user both
@@ -1403,15 +1442,26 @@ int media_changed(struct cdrom_device_info *cdi, int queue)
 {
 	unsigned int mask = (1 << (queue & 1));
 	int ret = !!(cdi->mc_flags & mask);
+	bool changed;
 
 	if (!CDROM_CAN(CDC_MEDIA_CHANGED))
-	    return ret;
+		return ret;
+
 	/* changed since last call? */
-	if (cdi->ops->media_changed(cdi, CDSL_CURRENT)) {
+	if (cdi->ops->check_events) {
+		BUG_ON(!queue);	/* shouldn't be called from VFS path */
+		cdrom_update_events(cdi, DISK_EVENT_MEDIA_CHANGE);
+		changed = cdi->ioctl_events & DISK_EVENT_MEDIA_CHANGE;
+		cdi->ioctl_events = 0;
+	} else
+		changed = cdi->ops->media_changed(cdi, CDSL_CURRENT);
+
+	if (changed) {
 		cdi->mc_flags = 0x3;    /* set bit on both queues */
 		ret |= 1;
 		cdi->media_written = 0;
 	}
+
 	cdi->mc_flags &= ~mask;         /* clear bit */
 	return ret;
 }

drivers/scsi/scsi_lib.c

@@ -1984,8 +1984,7 @@ EXPORT_SYMBOL(scsi_mode_sense);
  *		in.
  *
  *	Returns zero if unsuccessful or an error if TUR failed.  For
- *	removable media, a return of NOT_READY or UNIT_ATTENTION is
- *	translated to success, with the ->changed flag updated.
+ *	removable media, UNIT_ATTENTION sets ->changed flag.
  **/
 int
 scsi_test_unit_ready(struct scsi_device *sdev, int timeout, int retries,
@@ -2012,16 +2011,6 @@ scsi_test_unit_ready(struct scsi_device *sdev, int timeout, int retries,
 	} while (scsi_sense_valid(sshdr) &&
 		 sshdr->sense_key == UNIT_ATTENTION && --retries);
 
-	if (!sshdr)
-		/* could not allocate sense buffer, so can't process it */
-		return result;
-
-	if (sdev->removable && scsi_sense_valid(sshdr) &&
-	    (sshdr->sense_key == UNIT_ATTENTION ||
-	     sshdr->sense_key == NOT_READY)) {
-		sdev->changed = 1;
-		result = 0;
-	}
 	if (!sshdr_external)
 		kfree(sshdr);
 	return result;

drivers/scsi/sd.c

@@ -1045,15 +1045,7 @@ static int sd_media_changed(struct gendisk *disk)
 					      sshdr);
 	}
 
-	/*
-	 * Unable to test, unit probably not ready.   This usually
-	 * means there is no disc in the drive.  Mark as changed,
-	 * and we will figure it out later once the drive is
-	 * available again.
-	 */
-	if (retval || (scsi_sense_valid(sshdr) &&
-		       /* 0x3a is medium not present */
-		       sshdr->asc == 0x3a)) {
+	if (retval) {
 		set_media_not_present(sdkp);
 		retval = 1;
 		goto out;

drivers/scsi/sr.c

@@ -104,14 +104,15 @@ static void sr_release(struct cdrom_device_info *);
 static void get_sectorsize(struct scsi_cd *);
 static void get_capabilities(struct scsi_cd *);
 
-static int sr_media_change(struct cdrom_device_info *, int);
+static unsigned int sr_check_events(struct cdrom_device_info *cdi,
+				    unsigned int clearing, int slot);
 static int sr_packet(struct cdrom_device_info *, struct packet_command *);
 
 static struct cdrom_device_ops sr_dops = {
 	.open			= sr_open,
 	.release	 	= sr_release,
 	.drive_status	 	= sr_drive_status,
-	.media_changed		= sr_media_change,
+	.check_events		= sr_check_events,
 	.tray_move		= sr_tray_move,
 	.lock_door		= sr_lock_door,
 	.select_speed		= sr_select_speed,
@@ -165,90 +166,96 @@ static void scsi_cd_put(struct scsi_cd *cd)
 	mutex_unlock(&sr_ref_mutex);
 }
 
-/* identical to scsi_test_unit_ready except that it doesn't
- * eat the NOT_READY returns for removable media */
-int sr_test_unit_ready(struct scsi_device *sdev, struct scsi_sense_hdr *sshdr)
+static unsigned int sr_get_events(struct scsi_device *sdev)
 {
-	int retries = MAX_RETRIES;
-	int the_result;
-	u8 cmd[] = {TEST_UNIT_READY, 0, 0, 0, 0, 0 };
+	u8 buf[8];
+	u8 cmd[] = { GET_EVENT_STATUS_NOTIFICATION,
+		     1,			/* polled */
+		     0, 0,		/* reserved */
+		     1 << 4,		/* notification class: media */
+		     0, 0,		/* reserved */
+		     0, sizeof(buf),	/* allocation length */
+		     0,			/* control */
+	};
+	struct event_header *eh = (void *)buf;
+	struct media_event_desc *med = (void *)(buf + 4);
+	struct scsi_sense_hdr sshdr;
+	int result;
 
-	/* issue TEST_UNIT_READY until the initial startup UNIT_ATTENTION
-	 * conditions are gone, or a timeout happens
-	 */
-	do {
-		the_result = scsi_execute_req(sdev, cmd, DMA_NONE, NULL,
-					      0, sshdr, SR_TIMEOUT,
-					      retries--, NULL);
-		if (scsi_sense_valid(sshdr) &&
-		    sshdr->sense_key == UNIT_ATTENTION)
-			sdev->changed = 1;
-
-	} while (retries > 0 &&
-		 (!scsi_status_is_good(the_result) ||
-		  (scsi_sense_valid(sshdr) &&
-		   sshdr->sense_key == UNIT_ATTENTION)));
-	return the_result;
+	result = scsi_execute_req(sdev, cmd, DMA_FROM_DEVICE, buf, sizeof(buf),
+				  &sshdr, SR_TIMEOUT, MAX_RETRIES, NULL);
+	if (scsi_sense_valid(&sshdr) && sshdr.sense_key == UNIT_ATTENTION)
+		return DISK_EVENT_MEDIA_CHANGE;
+
+	if (result || be16_to_cpu(eh->data_len) < sizeof(*med))
+		return 0;
+
+	if (eh->nea || eh->notification_class != 0x4)
+		return 0;
+
+	if (med->media_event_code == 1)
+		return DISK_EVENT_EJECT_REQUEST;
+	else if (med->media_event_code == 2)
+		return DISK_EVENT_MEDIA_CHANGE;
+	return 0;
 }
 
 /*
- * This function checks to see if the media has been changed in the
- * CDROM drive.  It is possible that we have already sensed a change,
- * or the drive may have sensed one and not yet reported it.  We must
- * be ready for either case. This function always reports the current
- * value of the changed bit.  If flag is 0, then the changed bit is reset.
- * This function could be done as an ioctl, but we would need to have
- * an inode for that to work, and we do not always have one.
+ * This function checks to see if the media has been changed or eject
+ * button has been pressed.  It is possible that we have already
+ * sensed a change, or the drive may have sensed one and not yet
+ * reported it.  The past events are accumulated in sdev->changed and
+ * returned together with the current state.
  */
-
-static int sr_media_change(struct cdrom_device_info *cdi, int slot)
+static unsigned int sr_check_events(struct cdrom_device_info *cdi,
+				    unsigned int clearing, int slot)
 {
 	struct scsi_cd *cd = cdi->handle;
-	int retval;
-	struct scsi_sense_hdr *sshdr;
+	bool last_present;
+	struct scsi_sense_hdr sshdr;
+	unsigned int events;
+	int ret;
 
-	if (CDSL_CURRENT != slot) {
-		/* no changer support */
-		return -EINVAL;
-	}
+	/* no changer support */
+	if (CDSL_CURRENT != slot)
+		return 0;
 
-	sshdr =  kzalloc(sizeof(*sshdr), GFP_KERNEL);
-	retval = sr_test_unit_ready(cd->device, sshdr);
-	if (retval || (scsi_sense_valid(sshdr) &&
-		       /* 0x3a is medium not present */
-		       sshdr->asc == 0x3a)) {
-		/* Media not present or unable to test, unit probably not
-		 * ready. This usually means there is no disc in the drive.
-		 * Mark as changed, and we will figure it out later once
-		 * the drive is available again.
-		 */
-		cd->device->changed = 1;
-		/* This will force a flush, if called from check_disk_change */
-		retval = 1;
-		goto out;
-	};
+	events = sr_get_events(cd->device);
+	/*
+	 * GET_EVENT_STATUS_NOTIFICATION is enough unless MEDIA_CHANGE
+	 * is being cleared.  Note that there are devices which hang
+	 * if asked to execute TUR repeatedly.
+	 */
+	if (!(clearing & DISK_EVENT_MEDIA_CHANGE))
+		goto skip_tur;
+
+	/* let's see whether the media is there with TUR */
+	last_present = cd->media_present;
+	ret = scsi_test_unit_ready(cd->device, SR_TIMEOUT, MAX_RETRIES, &sshdr);
+
+	/*
+	 * Media is considered to be present if TUR succeeds or fails with
+	 * sense data indicating something other than media-not-present
+	 * (ASC 0x3a).
+	 */
+	cd->media_present = scsi_status_is_good(ret) ||
+		(scsi_sense_valid(&sshdr) && sshdr.asc != 0x3a);
 
-	retval = cd->device->changed;
-	cd->device->changed = 0;
-	/* If the disk changed, the capacity will now be different,
-	 * so we force a re-read of this information */
-	if (retval) {
-		/* check multisession offset etc */
-		sr_cd_check(cdi);
-		get_sectorsize(cd);
+	if (last_present != cd->media_present)
+		events |= DISK_EVENT_MEDIA_CHANGE;
+skip_tur:
+	if (cd->device->changed) {
+		events |= DISK_EVENT_MEDIA_CHANGE;
+		cd->device->changed = 0;
 	}
 
-out:
-	/* Notify userspace, that media has changed. */
-	if (retval != cd->previous_state)
+	/* for backward compatibility */
+	if (events & DISK_EVENT_MEDIA_CHANGE)
 		sdev_evt_send_simple(cd->device, SDEV_EVT_MEDIA_CHANGE,
 				     GFP_KERNEL);
-	cd->previous_state = retval;
-	kfree(sshdr);
-
-	return retval;
+	return events;
 }
- 
+
 /*
  * sr_done is the interrupt routine for the device driver.
  *
@@ -533,10 +540,25 @@ out:
 	return ret;
 }
 
-static int sr_block_media_changed(struct gendisk *disk)
+static unsigned int sr_block_check_events(struct gendisk *disk,
+					  unsigned int clearing)
 {
 	struct scsi_cd *cd = scsi_cd(disk);
-	return cdrom_media_changed(&cd->cdi);
+	return cdrom_check_events(&cd->cdi, clearing);
+}
+
+static int sr_block_revalidate_disk(struct gendisk *disk)
+{
+	struct scsi_cd *cd = scsi_cd(disk);
+	struct scsi_sense_hdr sshdr;
+
+	/* if the unit is not ready, nothing more to do */
+	if (scsi_test_unit_ready(cd->device, SR_TIMEOUT, MAX_RETRIES, &sshdr))
+		return 0;
+
+	sr_cd_check(&cd->cdi);
+	get_sectorsize(cd);
+	return 0;
 }
 
 static const struct block_device_operations sr_bdops =
@@ -545,7 +567,8 @@ static const struct block_device_operations sr_bdops =
 	.open		= sr_block_open,
 	.release	= sr_block_release,
 	.ioctl		= sr_block_ioctl,
-	.media_changed	= sr_block_media_changed,
+	.check_events	= sr_block_check_events,
+	.revalidate_disk = sr_block_revalidate_disk,
 	/* 
 	 * No compat_ioctl for now because sr_block_ioctl never
 	 * seems to pass arbitary ioctls down to host drivers.
@@ -618,6 +641,7 @@ static int sr_probe(struct device *dev)
 	sprintf(disk->disk_name, "sr%d", minor);
 	disk->fops = &sr_bdops;
 	disk->flags = GENHD_FL_CD;
+	disk->events = DISK_EVENT_MEDIA_CHANGE | DISK_EVENT_EJECT_REQUEST;
 
 	blk_queue_rq_timeout(sdev->request_queue, SR_TIMEOUT);
 
@@ -627,7 +651,7 @@ static int sr_probe(struct device *dev)
 	cd->disk = disk;
 	cd->capacity = 0x1fffff;
 	cd->device->changed = 1;	/* force recheck CD type */
-	cd->previous_state = 1;
+	cd->media_present = 1;
 	cd->use = 1;
 	cd->readcd_known = 0;
 	cd->readcd_cdda = 0;
@@ -780,7 +804,7 @@ static void get_capabilities(struct scsi_cd *cd)
 	}
 
 	/* eat unit attentions */
-	sr_test_unit_ready(cd->device, &sshdr);
+	scsi_test_unit_ready(cd->device, SR_TIMEOUT, MAX_RETRIES, &sshdr);
 
 	/* ask for mode page 0x2a */
 	rc = scsi_mode_sense(cd->device, 0, 0x2a, buffer, 128,

drivers/scsi/sr.h

@@ -40,7 +40,7 @@ typedef struct scsi_cd {
 	unsigned xa_flag:1;	/* CD has XA sectors ? */
 	unsigned readcd_known:1;	/* drive supports READ_CD (0xbe) */
 	unsigned readcd_cdda:1;	/* reading audio data using READ_CD */
-	unsigned previous_state:1;	/* media has changed */
+	unsigned media_present:1;	/* media is present */
 	struct cdrom_device_info cdi;
 	/* We hold gendisk and scsi_device references on probe and use
 	 * the refs on this kref to decide when to release them */
@@ -61,7 +61,6 @@ int sr_select_speed(struct cdrom_device_info *cdi, int speed);
 int sr_audio_ioctl(struct cdrom_device_info *, unsigned int, void *);
 
 int sr_is_xa(Scsi_CD *);
-int sr_test_unit_ready(struct scsi_device *sdev, struct scsi_sense_hdr *sshdr);
 
 /* sr_vendor.c */
 void sr_vendor_init(Scsi_CD *);

drivers/scsi/sr_ioctl.c

@@ -307,7 +307,7 @@ int sr_drive_status(struct cdrom_device_info *cdi, int slot)
 		/* we have no changer support */
 		return -EINVAL;
 	}
-	if (0 == sr_test_unit_ready(cd->device, &sshdr))
+	if (!scsi_test_unit_ready(cd->device, SR_TIMEOUT, MAX_RETRIES, &sshdr))
 		return CDS_DISC_OK;
 
 	/* SK/ASC/ASCQ of 2/4/1 means "unit is becoming ready" */

fs/block_dev.c

@@ -948,10 +948,11 @@ int check_disk_change(struct block_device *bdev)
 {
 	struct gendisk *disk = bdev->bd_disk;
 	const struct block_device_operations *bdops = disk->fops;
+	unsigned int events;
 
-	if (!bdops->media_changed)
-		return 0;
-	if (!bdops->media_changed(bdev->bd_disk))
+	events = disk_clear_events(disk, DISK_EVENT_MEDIA_CHANGE |
+				   DISK_EVENT_EJECT_REQUEST);
+	if (!(events & DISK_EVENT_MEDIA_CHANGE))
 		return 0;
 
 	flush_disk(bdev);
@@ -1158,9 +1159,10 @@ int blkdev_get(struct block_device *bdev, fmode_t mode, void *holder)
 
 	if (whole) {
 		/* finish claiming */
+		mutex_lock(&bdev->bd_mutex);
 		spin_lock(&bdev_lock);
 
-		if (res == 0) {
+		if (!res) {
 			BUG_ON(!bd_may_claim(bdev, whole, holder));
 			/*
 			 * Note that for a whole device bd_holders
@@ -1180,6 +1182,20 @@ int blkdev_get(struct block_device *bdev, fmode_t mode, void *holder)
 		wake_up_bit(&whole->bd_claiming, 0);
 
 		spin_unlock(&bdev_lock);
+
+		/*
+		 * Block event polling for write claims.  Any write
+		 * holder makes the write_holder state stick until all
+		 * are released.  This is good enough and tracking
+		 * individual writeable reference is too fragile given
+		 * the way @mode is used in blkdev_get/put().
+		 */
+		if (!res && (mode & FMODE_WRITE) && !bdev->bd_write_holder) {
+			bdev->bd_write_holder = true;
+			disk_block_events(bdev->bd_disk);
+		}
+
+		mutex_unlock(&bdev->bd_mutex);
 		bdput(whole);
 	}
 
@@ -1353,12 +1369,23 @@ int blkdev_put(struct block_device *bdev, fmode_t mode)
 
 		spin_unlock(&bdev_lock);
 
-		/* if this was the last claim, holder link should go too */
-		if (bdev_free)
+		/*
+		 * If this was the last claim, remove holder link and
+		 * unblock evpoll if it was a write holder.
+		 */
+		if (bdev_free) {
 			bd_unlink_disk_holder(bdev);
+			if (bdev->bd_write_holder) {
+				disk_unblock_events(bdev->bd_disk);
+				bdev->bd_write_holder = false;
+			} else
+				disk_check_events(bdev->bd_disk);
+		}
 
 		mutex_unlock(&bdev->bd_mutex);
-	}
+	} else
+		disk_check_events(bdev->bd_disk);
+
 	return __blkdev_put(bdev, mode, 0);
 }
 EXPORT_SYMBOL(blkdev_put);

fs/partitions/check.c

@@ -522,65 +522,6 @@ out_put:
 	return ERR_PTR(err);
 }
 
-/* Not exported, helper to add_disk(). */
-void register_disk(struct gendisk *disk)
-{
-	struct device *ddev = disk_to_dev(disk);
-	struct block_device *bdev;
-	struct disk_part_iter piter;
-	struct hd_struct *part;
-	int err;
-
-	ddev->parent = disk->driverfs_dev;
-
-	dev_set_name(ddev, disk->disk_name);
-
-	/* delay uevents, until we scanned partition table */
-	dev_set_uevent_suppress(ddev, 1);
-
-	if (device_add(ddev))
-		return;
-	if (!sysfs_deprecated) {
-		err = sysfs_create_link(block_depr, &ddev->kobj,
-					kobject_name(&ddev->kobj));
-		if (err) {
-			device_del(ddev);
-			return;
-		}
-	}
-	disk->part0.holder_dir = kobject_create_and_add("holders", &ddev->kobj);
-	disk->slave_dir = kobject_create_and_add("slaves", &ddev->kobj);
-
-	/* No minors to use for partitions */
-	if (!disk_partitionable(disk))
-		goto exit;
-
-	/* No such device (e.g., media were just removed) */
-	if (!get_capacity(disk))
-		goto exit;
-
-	bdev = bdget_disk(disk, 0);
-	if (!bdev)
-		goto exit;
-
-	bdev->bd_invalidated = 1;
-	err = blkdev_get(bdev, FMODE_READ, NULL);
-	if (err < 0)
-		goto exit;
-	blkdev_put(bdev, FMODE_READ);
-
-exit:
-	/* announce disk after possible partitions are created */
-	dev_set_uevent_suppress(ddev, 0);
-	kobject_uevent(&ddev->kobj, KOBJ_ADD);
-
-	/* announce possible partitions */
-	disk_part_iter_init(&piter, disk, 0);
-	while ((part = disk_part_iter_next(&piter)))
-		kobject_uevent(&part_to_dev(part)->kobj, KOBJ_ADD);
-	disk_part_iter_exit(&piter);
-}
-
 static bool disk_unlock_native_capacity(struct gendisk *disk)
 {
 	const struct block_device_operations *bdops = disk->fops;
@@ -743,33 +684,3 @@ fail:
 }
 
 EXPORT_SYMBOL(read_dev_sector);
-
-void del_gendisk(struct gendisk *disk)
-{
-	struct disk_part_iter piter;
-	struct hd_struct *part;
-
-	/* invalidate stuff */
-	disk_part_iter_init(&piter, disk,
-			     DISK_PITER_INCL_EMPTY | DISK_PITER_REVERSE);
-	while ((part = disk_part_iter_next(&piter))) {
-		invalidate_partition(disk, part->partno);
-		delete_partition(disk, part->partno);
-	}
-	disk_part_iter_exit(&piter);
-
-	invalidate_partition(disk, 0);
-	blk_free_devt(disk_to_dev(disk)->devt);
-	set_capacity(disk, 0);
-	disk->flags &= ~GENHD_FL_UP;
-	unlink_gendisk(disk);
-	part_stat_set_all(&disk->part0, 0);
-	disk->part0.stamp = 0;
-
-	kobject_put(disk->part0.holder_dir);
-	kobject_put(disk->slave_dir);
-	disk->driverfs_dev = NULL;
-	if (!sysfs_deprecated)
-		sysfs_remove_link(block_depr, dev_name(disk_to_dev(disk)));
-	device_del(disk_to_dev(disk));
-}

include/linux/blkdev.h

@@ -644,7 +644,6 @@ static inline void rq_flush_dcache_pages(struct request *rq)
 
 extern int blk_register_queue(struct gendisk *disk);
 extern void blk_unregister_queue(struct gendisk *disk);
-extern void register_disk(struct gendisk *dev);
 extern void generic_make_request(struct bio *bio);
 extern void blk_rq_init(struct request_queue *q, struct request *rq);
 extern void blk_put_request(struct request *);
@@ -1253,6 +1252,9 @@ struct block_device_operations {
 	int (*compat_ioctl) (struct block_device *, fmode_t, unsigned, unsigned long);
 	int (*direct_access) (struct block_device *, sector_t,
 						void **, unsigned long *);
+	unsigned int (*check_events) (struct gendisk *disk,
+				      unsigned int clearing);
+	/* ->media_changed() is DEPRECATED, use ->check_events() instead */
 	int (*media_changed) (struct gendisk *);
 	void (*unlock_native_capacity) (struct gendisk *);
 	int (*revalidate_disk) (struct gendisk *);

include/linux/cdrom.h

@@ -946,6 +946,8 @@ struct cdrom_device_info {
 /* device-related storage */
 	unsigned int options	: 30;	/* options flags */
 	unsigned mc_flags	: 2;	/* media change buffer flags */
+	unsigned int vfs_events;	/* cached events for vfs path */
+	unsigned int ioctl_events;	/* cached events for ioctl path */
     	int use_count;                  /* number of times device opened */
     	char name[20];                  /* name of the device type */
 /* per-device flags */
@@ -965,6 +967,8 @@ struct cdrom_device_ops {
 	int (*open) (struct cdrom_device_info *, int);
 	void (*release) (struct cdrom_device_info *);
 	int (*drive_status) (struct cdrom_device_info *, int);
+	unsigned int (*check_events) (struct cdrom_device_info *cdi,
+				      unsigned int clearing, int slot);
 	int (*media_changed) (struct cdrom_device_info *, int);
 	int (*tray_move) (struct cdrom_device_info *, int);
 	int (*lock_door) (struct cdrom_device_info *, int);
@@ -993,6 +997,8 @@ extern int cdrom_open(struct cdrom_device_info *cdi, struct block_device *bdev,
 extern void cdrom_release(struct cdrom_device_info *cdi, fmode_t mode);
 extern int cdrom_ioctl(struct cdrom_device_info *cdi, struct block_device *bdev,
 		       fmode_t mode, unsigned int cmd, unsigned long arg);
+extern unsigned int cdrom_check_events(struct cdrom_device_info *cdi,
+				       unsigned int clearing);
 extern int cdrom_media_changed(struct cdrom_device_info *);
 
 extern int register_cdrom(struct cdrom_device_info *cdi);

include/linux/fs.h

@@ -662,6 +662,7 @@ struct block_device {
 	void *			bd_claiming;
 	void *			bd_holder;
 	int			bd_holders;
+	bool			bd_write_holder;
 #ifdef CONFIG_SYSFS
 	struct gendisk *	bd_holder_disk;	/* for sysfs slave linkng */
 #endif

include/linux/genhd.h

@@ -128,6 +128,11 @@ struct hd_struct {
 #define GENHD_FL_EXT_DEVT			64 /* allow extended devt */
 #define GENHD_FL_NATIVE_CAPACITY		128
 
+enum {
+	DISK_EVENT_MEDIA_CHANGE			= 1 << 0, /* media changed */
+	DISK_EVENT_EJECT_REQUEST		= 1 << 1, /* eject requested */
+};
+
 #define BLK_SCSI_MAX_CMDS	(256)
 #define BLK_SCSI_CMD_PER_LONG	(BLK_SCSI_MAX_CMDS / (sizeof(long) * 8))
 
@@ -144,6 +149,8 @@ struct disk_part_tbl {
 	struct hd_struct __rcu *part[];
 };
 
+struct disk_events;
+
 struct gendisk {
 	/* major, first_minor and minors are input parameters only,
 	 * don't use directly.  Use disk_devt() and disk_max_parts().
@@ -155,6 +162,10 @@ struct gendisk {
 
 	char disk_name[DISK_NAME_LEN];	/* name of major driver */
 	char *(*devnode)(struct gendisk *gd, mode_t *mode);
+
+	unsigned int events;		/* supported events */
+	unsigned int async_events;	/* async events, subset of all */
+
 	/* Array of pointers to partitions indexed by partno.
 	 * Protected with matching bdev lock but stat and other
 	 * non-critical accesses use RCU.  Always access through
@@ -172,9 +183,8 @@ struct gendisk {
 	struct kobject *slave_dir;
 
 	struct timer_rand_state *random;
-
 	atomic_t sync_io;		/* RAID */
-	struct work_struct async_notify;
+	struct disk_events *ev;
 #ifdef  CONFIG_BLK_DEV_INTEGRITY
 	struct blk_integrity *integrity;
 #endif
@@ -396,7 +406,6 @@ extern void part_round_stats(int cpu, struct hd_struct *part);
 /* block/genhd.c */
 extern void add_disk(struct gendisk *disk);
 extern void del_gendisk(struct gendisk *gp);
-extern void unlink_gendisk(struct gendisk *gp);
 extern struct gendisk *get_gendisk(dev_t dev, int *partno);
 extern struct block_device *bdget_disk(struct gendisk *disk, int partno);
 
@@ -408,6 +417,11 @@ static inline int get_disk_ro(struct gendisk *disk)
 	return disk->part0.policy;
 }
 
+extern void disk_block_events(struct gendisk *disk);
+extern void disk_unblock_events(struct gendisk *disk);
+extern void disk_check_events(struct gendisk *disk);
+extern unsigned int disk_clear_events(struct gendisk *disk, unsigned int mask);
+
 /* drivers/char/random.c */
 extern void add_disk_randomness(struct gendisk *disk);
 extern void rand_initialize_disk(struct gendisk *disk);

include/scsi/scsi.h

@@ -104,6 +104,7 @@ struct scsi_cmnd;
 #define UNMAP		      0x42
 #define READ_TOC              0x43
 #define READ_HEADER           0x44
+#define GET_EVENT_STATUS_NOTIFICATION 0x4a
 #define LOG_SELECT            0x4c
 #define LOG_SENSE             0x4d
 #define XDWRITEREAD_10        0x53