[PATCH 11/18] ledtrig-blkdev: Add function to associate a device with an LED

Ian Pilcher
2021-09-03T20:46:15Z

If this is the first LED associated with the device, create the
/sys/block/<disk>/blkdev_leds directory. Otherwise, increment its
reference count.

Create symlinks in /sys/class/leds/<led>/block_devices and
/sys/block/<disk>/blkdev_leds

If this the first device associated with any LED, schedule delayed work
to periodically check associated devices and blink LEDs

Signed-off-by: Ian Pilcher <arequipeno@gmail.com>
---
drivers/leds/trigger/ledtrig-blkdev.c | 157 ++++++++++++++++++++++++++
1 file changed, 157 insertions(+)

diff --git a/drivers/leds/trigger/ledtrig-blkdev.c b/drivers/leds/trigger/ledtrig-blkdev.c
index bbf71ff18057..e3169d1f0e38 100644
--- a/drivers/leds/trigger/ledtrig-blkdev.c
+++ b/drivers/leds/trigger/ledtrig-blkdev.c
@@ -252,3 +252,160 @@ static int blkdev_activate(struct led_classdev *const led_dev)
exit_return:
return ret;
}
+
+
+/*
+ *
+ * Associate a block device with an LED
+ *
+ */
+
+/* Gets or allocs & initializes the blkdev disk for a gendisk */
+static int blkdev_get_disk(struct gendisk *const gd)
+{
+ struct ledtrig_blkdev_disk *disk;
+ struct kobject *dir;
+
+ if (gd->ledtrig != NULL) {
+ kobject_get(gd->ledtrig->dir);
+ return 0;
+ }
+
+ disk = kmalloc(sizeof(*disk), GFP_KERNEL);
+ if (disk == NULL)
+ return -ENOMEM;
+
+ dir = kobject_create_and_add("blkdev_leds", &disk_to_dev(gd)->kobj);
+ if (dir == NULL) {
+ kfree(disk);
+ return -ENOMEM;
+ }
+
+ INIT_HLIST_HEAD(&disk->leds);
+ disk->gd = gd;
+ disk->dir = dir;
+ disk->read_ios = 0;
+ disk->write_ios = 0;
+
+ gd->ledtrig = disk;
+
+ return 0;
+}
+
+static void blkdev_put_disk(struct ledtrig_blkdev_disk *const disk)
+{
+ kobject_put(disk->dir);
+
+ if (hlist_empty(&disk->leds)) {
+ disk->gd->ledtrig = NULL;
+ kfree(disk);
+ }
+}
+
+static int blkdev_disk_add_locked(struct ledtrig_blkdev_led *const led,
+ struct gendisk *const gd)
+{
+ struct ledtrig_blkdev_link *link;
+ struct ledtrig_blkdev_disk *disk;
+ unsigned long delay;
+ int ret;
+
+ link = kmalloc(sizeof(*link), GFP_KERNEL);
+ if (link == NULL) {
+ ret = -ENOMEM;
+ goto error_return;
+ }
+
+ ret = blkdev_get_disk(gd);
+ if (ret != 0)
+ goto error_free_link;
+
+ disk = gd->ledtrig;
+
+ ret = sysfs_create_link(disk->dir, &led->led_dev->dev->kobj,
+ led->led_dev->name);
+ if (ret != 0)
+ goto error_put_disk;
+
+ ret = sysfs_create_link(led->dir, &disk_to_dev(gd)->kobj,
+ gd->disk_name);
+ if (ret != 0)
+ goto error_remove_link;
+
+ link->disk = disk;
+ link->led = led;
+ hlist_add_head(&link->led_disks_node, &led->disks);
+ hlist_add_head(&link->disk_leds_node, &disk->leds);
+
+ if (ledtrig_blkdev_count == 0) {
+ delay = READ_ONCE(ledtrig_blkdev_interval);
+ WARN_ON(!schedule_delayed_work(&ledtrig_blkdev_work, delay));
+ }
+
+ ++ledtrig_blkdev_count;
+
+ return 0;
+
+error_remove_link:
+ sysfs_remove_link(disk->dir, led->led_dev->name);
+error_put_disk:
+ blkdev_put_disk(disk);
+error_free_link:
+ kfree(link);
+error_return:
+ return ret;
+}
+
+static bool blkdev_already_linked(const struct ledtrig_blkdev_led *const led,
+ const struct gendisk *const gd)
+{
+ const struct ledtrig_blkdev_link *link;
+
+ if (gd->ledtrig == NULL)
+ return false;
+
+ hlist_for_each_entry(link, &gd->ledtrig->leds, disk_leds_node) {
+
+ if (link->led == led) {
+ pr_info("blkdev LED: %s already associated with %s\n",
+ gd->disk_name, led->led_dev->name);
+ return true;
+ }
+ }
+
+ return false;
+}
+
+static int blkdev_disk_add(struct ledtrig_blkdev_led *const led,
+ const char *const disk_name, const size_t name_len)
+{
+ struct gendisk *gd;
+ int ret;
+
+ ret = mutex_lock_interruptible(&ledtrig_blkdev_mutex);
+ if (ret != 0)
+ goto exit_return;
+
+ gd = ledtrig_blkdev_get_disk(disk_name, name_len);
+ if (gd == NULL) {
+ pr_info("blkdev LED: no such block device %.*s\n",
+ (int)name_len, disk_name);
+ ret = -ENODEV;
+ goto exit_unlock;
+ }
+
+ if (blkdev_already_linked(led, gd)) {
+ ret = -EEXIST;
+ goto exit_put_disk;
+ }
+
+ ret = blkdev_disk_add_locked(led, gd);
+
+exit_put_disk:
+ if (ret != 0)
+ put_disk(gd);
+exit_unlock:
+ mutex_unlock(&ledtrig_blkdev_mutex);
+exit_return:
+ return ret;
+}
--
2.31.1