[PATCH 09/18] ledtrig-blkdev: Periodically check devices for activity & blink LEDs

Ian Pilcher
2021-09-03T20:46:13Z

Use a delayed workqueue to periodically check configured block devices for
activity since the last check. Blink LEDs associated with devices on which
the configured type of activity (read/write) has occurred.

Signed-off-by: Ian Pilcher <arequipeno@gmail.com>
---
drivers/leds/trigger/ledtrig-blkdev.c | 88 +++++++++++++++++++++++++++
1 file changed, 88 insertions(+)

diff --git a/drivers/leds/trigger/ledtrig-blkdev.c b/drivers/leds/trigger/ledtrig-blkdev.c
index 1f319529c3be..37ba9bb3542e 100644
--- a/drivers/leds/trigger/ledtrig-blkdev.c
+++ b/drivers/leds/trigger/ledtrig-blkdev.c
@@ -7,7 +7,9 @@
*/

#include <linux/ctype.h>
+#include <linux/leds.h>
#include <linux/module.h>
+#include <linux/part_stat.h>

#include "ledtrig-blkdev.h"

@@ -68,6 +70,10 @@ static unsigned int ledtrig_blkdev_count;
/* How often to check for drive activity - in jiffies */
static unsigned int ledtrig_blkdev_interval;

+/* Delayed work used to periodically check for activity & blink LEDs */
+static void blkdev_process(struct work_struct *const work);
+static DECLARE_DELAYED_WORK(ledtrig_blkdev_work, blkdev_process);
+

/*
*
@@ -110,3 +116,85 @@ static bool blkdev_write_mode(const enum ledtrig_blkdev_mode mode)
{
return mode != LEDTRIG_BLKDEV_MODE_RO;
}
+
+
+/*
+ *
+ * Periodically check for device acitivity and blink LEDs
+ *
+ */
+
+static void blkdev_blink(const struct ledtrig_blkdev_led *const led)
+{
+ unsigned long delay_on = READ_ONCE(led->blink_msec);
+ unsigned long delay_off = 1; /* 0 leaves LED turned on */
+
+ led_blink_set_oneshot(led->led_dev, &delay_on, &delay_off, 0);
+}
+
+static void blkdev_update_disk(struct ledtrig_blkdev_disk *const disk,
+ const unsigned int generation)
+{
+ const struct block_device *const part0 = disk->gd->part0;
+ const unsigned long read_ios = part_stat_read(part0, ios[STAT_READ]);
+ const unsigned long write_ios = part_stat_read(part0, ios[STAT_WRITE])
+ + part_stat_read(part0, ios[STAT_DISCARD])
+ + part_stat_read(part0, ios[STAT_FLUSH]);
+
+ if (disk->read_ios != read_ios) {
+ disk->read_act = true;
+ disk->read_ios = read_ios;
+ } else {
+ disk->read_act = false;
+ }
+
+ if (disk->write_ios != write_ios) {
+ disk->write_act = true;
+ disk->write_ios = write_ios;
+ } else {
+ disk->write_act = false;
+ }
+
+ disk->generation = generation;
+}
+
+static void blkdev_process(struct work_struct *const work)
+{
+ static unsigned int generation;
+
+ struct ledtrig_blkdev_led *led;
+ struct ledtrig_blkdev_link *link;
+ unsigned long delay;
+
+ if (!mutex_trylock(&ledtrig_blkdev_mutex))
+ goto exit_reschedule;
+
+ hlist_for_each_entry(led, &ledtrig_blkdev_leds, leds_node) {
+
+ hlist_for_each_entry(link, &led->disks, led_disks_node) {
+
+ struct ledtrig_blkdev_disk *const disk = link->disk;
+
+ if (disk->generation != generation)
+ blkdev_update_disk(disk, generation);
+
+ if (disk->read_act && blkdev_read_mode(led->mode)) {
+ blkdev_blink(led);
+ break;
+ }
+
+ if (disk->write_act && blkdev_write_mode(led->mode)) {
+ blkdev_blink(led);
+ break;
+ }
+ }
+ }
+
+ ++generation;
+
+ mutex_unlock(&ledtrig_blkdev_mutex);
+
+exit_reschedule:
+ delay = READ_ONCE(ledtrig_blkdev_interval);
+ WARN_ON_ONCE(!schedule_delayed_work(&ledtrig_blkdev_work, delay));
+}
--
2.31.1