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[v2,5/5] block: check_events: don't bother with events if unsupported

Message ID 20190205113741.11267-6-mwilck@suse.com (mailing list archive)
State Not Applicable
Headers show
Series block: skip media change event handling if unsupported | expand

Commit Message

Martin Wilck Feb. 5, 2019, 11:37 a.m. UTC
Drivers now report to the block layer if they support media change
events. If this is not the case, there's no need to allocate
the event structure, and all event handling code can effectively
be skipped. This simplifies code flow in particular for
non-removable sd devices.

This effectively reverts commit 75e3f3ee3c64 ("block: always allocate
genhd->ev if check_events is implemented").

The sysfs files for the events are kept in place even if no events
are supported, as user space may rely on them being present. The only
difference is that an error code is now returned if the user tries
to set poll_msecs.

Signed-off-by: Martin Wilck <mwilck@suse.com>
---
 block/genhd.c | 28 +++++++++++++++++-----------
 1 file changed, 17 insertions(+), 11 deletions(-)
diff mbox series

Patch

diff --git a/block/genhd.c b/block/genhd.c
index 7f5a370..6cc1dfd 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -1902,6 +1902,9 @@  static ssize_t disk_events_poll_msecs_show(struct device *dev,
 {
 	struct gendisk *disk = dev_to_disk(dev);
 
+	if (!disk->ev)
+		return sprintf(buf, "-1\n");
+
 	return sprintf(buf, "%ld\n", disk->ev->poll_msecs);
 }
 
@@ -1918,6 +1921,9 @@  static ssize_t disk_events_poll_msecs_store(struct device *dev,
 	if (intv < 0 && intv != -1)
 		return -EINVAL;
 
+	if (!disk->ev)
+		return -ENODEV;
+
 	disk_block_events(disk);
 	disk->ev->poll_msecs = intv;
 	__disk_unblock_events(disk, true);
@@ -1982,7 +1988,8 @@  static void disk_alloc_events(struct gendisk *disk)
 {
 	struct disk_events *ev;
 
-	if (!disk->fops->check_events)
+	if (!disk->fops->check_events ||
+	    !(disk->events & DISK_EVENT_TYPES_MASK))
 		return;
 
 	ev = kzalloc(sizeof(*ev), GFP_KERNEL);
@@ -2004,14 +2011,14 @@  static void disk_alloc_events(struct gendisk *disk)
 
 static void disk_add_events(struct gendisk *disk)
 {
-	if (!disk->ev)
-		return;
-
 	/* FIXME: error handling */
 	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);
 
+	if (!disk->ev)
+		return;
+
 	mutex_lock(&disk_events_mutex);
 	list_add_tail(&disk->ev->node, &disk_events);
 	mutex_unlock(&disk_events_mutex);
@@ -2025,14 +2032,13 @@  static void disk_add_events(struct gendisk *disk)
 
 static void disk_del_events(struct gendisk *disk)
 {
-	if (!disk->ev)
-		return;
+	if (disk->ev) {
+		disk_block_events(disk);
 
-	disk_block_events(disk);
-
-	mutex_lock(&disk_events_mutex);
-	list_del_init(&disk->ev->node);
-	mutex_unlock(&disk_events_mutex);
+		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);
 }