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From:   Ian Pilcher <arequipeno@gmail.com>
To:     axboe@kernel.dk, pavel@ucw.cz
Cc:     linux-leds@vger.kernel.org, linux-block@vger.kernel.org,
        linux-kernel@vger.kernel.org, gregkh@linuxfoundation.org,
        kabel@kernel.org
Subject: [PATCH v2 15/15] leds: trigger: blkdev: Add disk cleanup and init/exit functions
Date:   Thu,  9 Sep 2021 17:25:13 -0500
Message-Id: <20210909222513.2184795-16-arequipeno@gmail.com>
In-Reply-To: <20210909222513.2184795-1-arequipeno@gmail.com>
References: <20210909222513.2184795-1-arequipeno@gmail.com>
MIME-Version: 1.0
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Precedence: bulk

Disk cleanup function - blkdev_disk_cleanup():

  * Called when block device is being removed
  * Called via __ledtrig_blkdev_disk_cleanup function pointer from
    ledtrig_blkdev_disk_cleanup() in ledtrig-blkdev-core.c

Init function - blkdev_init():

  * Initialize interval (convert default value to jiffies)
  * Initialize __ledtrig_blkdev_disk_cleanup function pointer
  * Register the block device LED trigger

Exit function - blkdev_exit():

  * Unregister the LED trigger
  * Set __ledtrig_blkdev_disk_cleanup back to NULL

Make LED trigger struct (ledtrig_blkdev_trigger) static (as it's now
referenced in blkdev_init()).

Signed-off-by: Ian Pilcher <arequipeno@gmail.com>
---
 drivers/leds/trigger/ledtrig-blkdev.c | 65 ++++++++++++++++++++++++++-
 1 file changed, 64 insertions(+), 1 deletion(-)

diff --git a/drivers/leds/trigger/ledtrig-blkdev.c b/drivers/leds/trigger/ledtrig-blkdev.c
index 4b88f877ee81..96ea694ce29f 100644
--- a/drivers/leds/trigger/ledtrig-blkdev.c
+++ b/drivers/leds/trigger/ledtrig-blkdev.c
@@ -435,6 +435,23 @@ static ssize_t unlink_device_store(struct device *const dev,
 static DEVICE_ATTR_WO(unlink_device);
 
 
+/*
+ *
+ *	Disassociate all LEDs from a block device (because it's going away)
+ *
+ */
+
+static void blkdev_disk_cleanup(struct gendisk *const gd)
+{
+	struct ledtrig_blkdev_link *link;
+	struct hlist_node *next;
+
+	hlist_for_each_entry_safe(link, next,
+					&gd->ledtrig->leds, disk_leds_node)
+		blkdev_disk_unlink_locked(link->led, link, gd->ledtrig);
+}
+
+
 /*
  *
  *	Disassociate an LED from the trigger
@@ -615,9 +632,55 @@ static const struct attribute_group *ledtrig_blkdev_attr_groups[] = {
 	NULL
 };
 
-struct led_trigger ledtrig_blkdev_trigger = {
+static struct led_trigger ledtrig_blkdev_trigger = {
 	.name		= "blkdev",
 	.activate	= blkdev_activate,
 	.deactivate	= blkdev_deactivate,
 	.groups		= ledtrig_blkdev_attr_groups,
 };
+
+static int __init blkdev_init(void)
+{
+	int ret;
+
+	ret = mutex_lock_interruptible(&ledtrig_blkdev_mutex);
+	if (ret != 0)
+		return ret;
+
+	ledtrig_blkdev_interval = msecs_to_jiffies(LEDTRIG_BLKDEV_INTERVAL);
+	__ledtrig_blkdev_disk_cleanup = blkdev_disk_cleanup;
+
+	/*
+	 * Can't call led_trigger_register() with ledtrig_blkdev_mutex locked.
+	 * If an LED has blkdev as its default_trigger, blkdev_activate() will
+	 * be called for that LED, and it will try to lock the mutex, which will
+	 * hang.
+	 */
+	mutex_unlock(&ledtrig_blkdev_mutex);
+
+	ret = led_trigger_register(&ledtrig_blkdev_trigger);
+	if (ret != 0) {
+		mutex_lock(&ledtrig_blkdev_mutex);
+		__ledtrig_blkdev_disk_cleanup = NULL;
+		mutex_unlock(&ledtrig_blkdev_mutex);
+	}
+
+	return ret;
+}
+module_init(blkdev_init);
+
+static void __exit blkdev_exit(void)
+{
+	mutex_lock(&ledtrig_blkdev_mutex);
+
+	/*
+	 * It's OK to call led_trigger_unregister() with the mutex locked,
+	 * because the module can only be unloaded when no LEDs are using
+	 * the blkdev trigger, so blkdev_deactivate() won't be called.
+	 */
+	led_trigger_unregister(&ledtrig_blkdev_trigger);
+	__ledtrig_blkdev_disk_cleanup = NULL;
+
+	mutex_unlock(&ledtrig_blkdev_mutex);
+}
+module_exit(blkdev_exit);
-- 
2.31.1