linux-kernel - [RFC PATCH v3 08/18] ledtrig-blkdev: Add function to remove LED/device association

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Message-Id: <20210819025053.222710-9-arequipeno@gmail.com>
Date:   Wed, 18 Aug 2021 21:50:43 -0500
From:   Ian Pilcher <arequipeno@...il.com>
To:     linux-block@...r.kernel.org, linux-leds@...r.kernel.org
Cc:     axboe@...nel.dk, pavel@....cz, kabel@...nel.org,
        linux-kernel@...r.kernel.org, kernelnewbies@...nelnewbies.org
Subject: [RFC PATCH v3 08/18] ledtrig-blkdev: Add function to remove LED/device association

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

Decrement reference count on /sys/block/<disk>/blkdev_leds
directory (removes directory when empty)

Cancel delayed work when disassociating last device

Signed-off-by: Ian Pilcher <arequipeno@...il.com>
---
 drivers/leds/trigger/ledtrig-blkdev.c | 56 +++++++++++++++++++++++++++
 1 file changed, 56 insertions(+)

diff --git a/drivers/leds/trigger/ledtrig-blkdev.c b/drivers/leds/trigger/ledtrig-blkdev.c
index e9c23824c33c..447fc81ae0c5 100644
--- a/drivers/leds/trigger/ledtrig-blkdev.c
+++ b/drivers/leds/trigger/ledtrig-blkdev.c
@@ -225,3 +225,59 @@ static void blkdev_process(struct work_struct *const work)
 	delay = READ_ONCE(ledtrig_blkdev_interval);
 	WARN_ON_ONCE(!schedule_delayed_work(&ledtrig_blkdev_work, delay));
 }
+
+
+/*
+ *
+ *	Disassociate a block device from an LED
+ *
+ */
+
+static void blkdev_disk_del_locked(struct ledtrig_blkdev_led *const led,
+				   struct ledtrig_blkdev_link *const link,
+				   struct ledtrig_blkdev_disk *const disk)
+{
+	--ledtrig_blkdev_count;
+
+	if (ledtrig_blkdev_count == 0)
+		WARN_ON(!cancel_delayed_work_sync(&ledtrig_blkdev_work));
+
+	sysfs_remove_link(led->dir, disk->gd->disk_name);
+	sysfs_remove_link(disk->dir, led->led_dev->name);
+	kobject_put(disk->dir);
+
+	hlist_del(&link->led_disks_node);
+	hlist_del(&link->disk_leds_node);
+	kfree(link);
+
+	if (hlist_empty(&disk->leds)) {
+		disk->gd->ledtrig = NULL;
+		kfree(disk);
+	}
+
+	put_device(disk_to_dev(disk->gd));
+}
+
+static void blkdev_disk_delete(struct ledtrig_blkdev_led *const led,
+			       const char *const disk_name,
+			       const size_t name_len)
+{
+	struct ledtrig_blkdev_link *link;
+
+	mutex_lock(&ledtrig_blkdev_mutex);
+
+	hlist_for_each_entry(link, &led->disks, led_disks_node) {
+
+		if (blkdev_streq(link->disk->gd->disk_name,
+						disk_name, name_len)) {
+			blkdev_disk_del_locked(led, link, link->disk);
+			goto exit_unlock;
+		}
+	}
+
+	pr_info("blkdev LED: %.*s not associated with LED %s\n",
+		(int)name_len, disk_name, led->led_dev->name);
+
+exit_unlock:
+	mutex_unlock(&ledtrig_blkdev_mutex);
+}
-- 
2.31.1