diff mbox series

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

Message ID 20190322224353.11088-6-mwilck@suse.com (mailing list archive)
State New, archived
Headers show
Series block: skip media change event handling if unsupported | expand

Commit Message

Martin Wilck March 22, 2019, 10:43 p.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(-)

Comments

Hannes Reinecke March 25, 2019, 7:39 a.m. UTC | #1 
On 3/22/19 11:43 PM, Martin Wilck wrote:
> 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(-)
> 
Reviewed-by: Hannes Reinecke <hare@suse.com>

Cheers,

Hannes
Christoph Hellwig March 27, 2019, 8:22 a.m. UTC | #2 
Looks fine,

Reviewed-by: Christoph Hellwig <hch@lst.de>
diff mbox series

Patch

diff --git a/block/genhd.c b/block/genhd.c
index cc6c52d1..0eda20b 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -1904,6 +1904,9 @@  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);
 }
 
@@ -1920,6 +1923,9 @@  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);
@@ -1984,7 +1990,8 @@  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);
@@ -2006,14 +2013,14 @@  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);
@@ -2027,14 +2034,13 @@  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);
 }