[v3,4/6] block: introduce LED block device activity trigger
diff mbox series

Message ID 1565459703-30513-5-git-send-email-akinobu.mita@gmail.com
State New
Headers show
Series
  • introduce LED block device activity trigger
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Commit Message

Akinobu Mita Aug. 10, 2019, 5:55 p.m. UTC
This allows LEDs to be controlled by block device activity.

We already have ledtrig-disk (LED disk activity trigger), but the lower
level disk drivers need to utilize ledtrig_disk_activity() to make the
LED blink.

The LED block device trigger doesn't require the lower level drivers to
have any instrumentation. The activity is collected by polling the disk
stats.

Example:

echo block-nvme0n1 > /sys/class/leds/diy/trigger

Cc: Frank Steiner <fsteiner-mail1@bio.ifi.lmu.de>
Cc: Jacek Anaszewski <jacek.anaszewski@gmail.com>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Dan Murphy <dmurphy@ti.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: "James E.J. Bottomley" <jejb@linux.ibm.com>
Cc: "Martin K. Petersen" <martin.petersen@oracle.com>
Cc: Hannes Reinecke <hare@suse.com>
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
---
* v3
- Add ABI documentation
- Add more detail to Kconfig help text

 .../ABI/testing/sysfs-class-led-trigger-blk        |  37 ++++
 block/genhd.c                                      |   2 +
 drivers/leds/trigger/Kconfig                       |   9 +
 drivers/leds/trigger/Makefile                      |   1 +
 drivers/leds/trigger/ledtrig-blk.c                 | 225 +++++++++++++++++++++
 include/linux/genhd.h                              |   3 +
 include/linux/leds.h                               |  27 +++
 7 files changed, 304 insertions(+)
 create mode 100644 Documentation/ABI/testing/sysfs-class-led-trigger-blk
 create mode 100644 drivers/leds/trigger/ledtrig-blk.c

Comments

Jacek Anaszewski Aug. 12, 2019, 7:28 p.m. UTC | #1
Hi Akinobu,

Thank you for the update. I have one more remark to this patch
below.

On 8/10/19 7:55 PM, Akinobu Mita wrote:
> This allows LEDs to be controlled by block device activity.
> 
> We already have ledtrig-disk (LED disk activity trigger), but the lower
> level disk drivers need to utilize ledtrig_disk_activity() to make the
> LED blink.
> 
> The LED block device trigger doesn't require the lower level drivers to
> have any instrumentation. The activity is collected by polling the disk
> stats.
> 
> Example:
> 
> echo block-nvme0n1 > /sys/class/leds/diy/trigger
> 
> Cc: Frank Steiner <fsteiner-mail1@bio.ifi.lmu.de>
> Cc: Jacek Anaszewski <jacek.anaszewski@gmail.com>
> Cc: Pavel Machek <pavel@ucw.cz>
> Cc: Dan Murphy <dmurphy@ti.com>
> Cc: Jens Axboe <axboe@kernel.dk>
> Cc: "James E.J. Bottomley" <jejb@linux.ibm.com>
> Cc: "Martin K. Petersen" <martin.petersen@oracle.com>
> Cc: Hannes Reinecke <hare@suse.com>
> Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
> ---
> * v3
> - Add ABI documentation
> - Add more detail to Kconfig help text
> 
>  .../ABI/testing/sysfs-class-led-trigger-blk        |  37 ++++
>  block/genhd.c                                      |   2 +
>  drivers/leds/trigger/Kconfig                       |   9 +
>  drivers/leds/trigger/Makefile                      |   1 +
>  drivers/leds/trigger/ledtrig-blk.c                 | 225 +++++++++++++++++++++
>  include/linux/genhd.h                              |   3 +
>  include/linux/leds.h                               |  27 +++
>  7 files changed, 304 insertions(+)
>  create mode 100644 Documentation/ABI/testing/sysfs-class-led-trigger-blk
>  create mode 100644 drivers/leds/trigger/ledtrig-blk.c
> 
[...]
> +EXPORT_SYMBOL_GPL(ledtrig_blk_unregister);
> diff --git a/include/linux/genhd.h b/include/linux/genhd.h
> index 8b5330d..b2c934e 100644
> --- a/include/linux/genhd.h
> +++ b/include/linux/genhd.h
> @@ -17,6 +17,7 @@
>  #include <linux/percpu-refcount.h>
>  #include <linux/uuid.h>
>  #include <linux/blk_types.h>
> +#include <linux/leds.h>
>  #include <asm/local.h>
>  
>  #ifdef CONFIG_BLOCK
> @@ -219,6 +220,8 @@ struct gendisk {
>  	int node_id;
>  	struct badblocks *bb;
>  	struct lockdep_map lockdep_map;
> +
> +	struct ledtrig_blk led;

Please rename this property to led_trig to reflect
its purpose accurately.

>  };
>  
>  static inline struct gendisk *part_to_disk(struct hd_struct *part)
> diff --git a/include/linux/leds.h b/include/linux/leds.h
> index 9b2bf57..395fa61 100644
> --- a/include/linux/leds.h
> +++ b/include/linux/leds.h
> @@ -517,4 +517,31 @@ static inline void ledtrig_audio_set(enum led_audio type,
>  }
>  #endif
>  
> +struct gendisk;
> +
> +#ifdef CONFIG_LEDS_TRIGGER_BLOCK
> +
> +struct ledtrig_blk {
> +	struct led_trigger trig;
> +};
> +
> +int ledtrig_blk_register(struct gendisk *disk);
> +void ledtrig_blk_unregister(struct gendisk *disk);
> +
> +#else
> +
> +struct ledtrig_blk {
> +};
> +
> +static inline int ledtrig_blk_register(struct gendisk *disk)
> +{
> +	return 0;
> +}
> +
> +static inline void ledtrig_blk_unregister(struct gendisk *disk)
> +{
> +}
> +
> +#endif /* CONFIG_LEDS_TRIGGER_BLOCK */
> +
>  #endif		/* __LINUX_LEDS_H_INCLUDED */
>
Pavel Machek Aug. 13, 2019, 10:33 a.m. UTC | #2
On Sun 2019-08-11 02:55:01, Akinobu Mita wrote:
> This allows LEDs to be controlled by block device activity.
> 
> We already have ledtrig-disk (LED disk activity trigger), but the lower
> level disk drivers need to utilize ledtrig_disk_activity() to make the
> LED blink.
> 
> The LED block device trigger doesn't require the lower level drivers to
> have any instrumentation. The activity is collected by polling the disk
> stats.
> 
> Example:
> 
> echo block-nvme0n1 > /sys/class/leds/diy/trigger

Some machines have lots of block devices... Should we perhaps have
"echo block > trigger; echo nvme0n1 > device"?

Best regards,
									Pavel
Akinobu Mita Aug. 13, 2019, 3:40 p.m. UTC | #3
2019年8月13日(火) 19:33 Pavel Machek <pavel@ucw.cz>:
>
> On Sun 2019-08-11 02:55:01, Akinobu Mita wrote:
> > This allows LEDs to be controlled by block device activity.
> >
> > We already have ledtrig-disk (LED disk activity trigger), but the lower
> > level disk drivers need to utilize ledtrig_disk_activity() to make the
> > LED blink.
> >
> > The LED block device trigger doesn't require the lower level drivers to
> > have any instrumentation. The activity is collected by polling the disk
> > stats.
> >
> > Example:
> >
> > echo block-nvme0n1 > /sys/class/leds/diy/trigger
>
> Some machines have lots of block devices... Should we perhaps have
> "echo block > trigger; echo nvme0n1 > device"?

I originally considered doing so, just like ledtrig-netdev. However, it
turned out that we needed an additional mechanism to mediate between
the led trigger registration and the block device unregistration.

Patch
diff mbox series

diff --git a/Documentation/ABI/testing/sysfs-class-led-trigger-blk b/Documentation/ABI/testing/sysfs-class-led-trigger-blk
new file mode 100644
index 0000000..73472c3
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-class-led-trigger-blk
@@ -0,0 +1,37 @@ 
+What:		/sys/class/leds/<led>/interval
+Date:		Aug 2019
+KernelVersion:	5.4
+Contact:	linux-leds@vger.kernel.org
+Description:
+		Specifies the duration of the LED blink in milliseconds.
+		Defaults to 50 ms.
+
+What:		/sys/class/leds/<led>/read
+Date:		Aug 2019
+KernelVersion:	5.4
+Contact:	linux-leds@vger.kernel.org
+Description:
+		Signal data read on the block device.
+		If set to 0, the LED will not blink on data read.
+		If set to 1 (default), the LED will blink for the milliseconds
+		specified in interval to signal data read.
+
+What:		/sys/class/leds/<led>/write
+Date:		Aug 2019
+KernelVersion:	5.4
+Contact:	linux-leds@vger.kernel.org
+Description:
+		Signal data written on the block device.
+		If set to 0, the LED will not blink on data written.
+		If set to 1 (default), the LED will blink for the milliseconds
+		specified in interval to signal data written.
+
+What:		/sys/class/leds/<led>/discard
+Date:		Aug 2019
+KernelVersion:	5.4
+Contact:	linux-leds@vger.kernel.org
+Description:
+		Signal data discarded on the block device.
+		If set to 0, the LED will not blink on data discarded.
+		If set to 1 (default), the LED will blink for the milliseconds
+		specified in interval to signal data discarded.
diff --git a/block/genhd.c b/block/genhd.c
index 54f1f0d3..1c68861 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -745,6 +745,7 @@  static void __device_add_disk(struct device *parent, struct gendisk *disk,
 
 	disk_add_events(disk);
 	blk_integrity_add(disk);
+	ledtrig_blk_register(disk);
 }
 
 void device_add_disk(struct device *parent, struct gendisk *disk,
@@ -766,6 +767,7 @@  void del_gendisk(struct gendisk *disk)
 	struct disk_part_iter piter;
 	struct hd_struct *part;
 
+	ledtrig_blk_unregister(disk);
 	blk_integrity_del(disk);
 	disk_del_events(disk);
 
diff --git a/drivers/leds/trigger/Kconfig b/drivers/leds/trigger/Kconfig
index ce9429c..e399a11 100644
--- a/drivers/leds/trigger/Kconfig
+++ b/drivers/leds/trigger/Kconfig
@@ -144,4 +144,13 @@  config LEDS_TRIGGER_AUDIO
 	  the audio mute and mic-mute changes.
 	  If unsure, say N
 
+config LEDS_TRIGGER_BLOCK
+	bool "LED Block device Trigger"
+	depends on BLOCK
+	help
+	  This allows LEDs to be controlled by block device activity.
+	  This trigger doesn't require the lower level drivers to have any
+	  instrumentation. The activity is collected by polling the disk stats.
+	  If unsure, say Y.
+
 endif # LEDS_TRIGGERS
diff --git a/drivers/leds/trigger/Makefile b/drivers/leds/trigger/Makefile
index 733a83e..60200eb 100644
--- a/drivers/leds/trigger/Makefile
+++ b/drivers/leds/trigger/Makefile
@@ -15,3 +15,4 @@  obj-$(CONFIG_LEDS_TRIGGER_PANIC)	+= ledtrig-panic.o
 obj-$(CONFIG_LEDS_TRIGGER_NETDEV)	+= ledtrig-netdev.o
 obj-$(CONFIG_LEDS_TRIGGER_PATTERN)	+= ledtrig-pattern.o
 obj-$(CONFIG_LEDS_TRIGGER_AUDIO)	+= ledtrig-audio.o
+obj-$(CONFIG_LEDS_TRIGGER_BLOCK)	+= ledtrig-blk.o
diff --git a/drivers/leds/trigger/ledtrig-blk.c b/drivers/leds/trigger/ledtrig-blk.c
new file mode 100644
index 0000000..d5808c9
--- /dev/null
+++ b/drivers/leds/trigger/ledtrig-blk.c
@@ -0,0 +1,225 @@ 
+// SPDX-License-Identifier: GPL-2.0
+// LED Kernel Blockdev Trigger
+// Derived from ledtrig-netdev.c
+
+#include <linux/atomic.h>
+#include <linux/genhd.h>
+#include <linux/leds.h>
+#include <linux/workqueue.h>
+#include "../leds.h"
+
+enum ledtrig_blk_attr {
+	LEDTRIG_BLK_READ,
+	LEDTRIG_BLK_WRITE,
+	LEDTRIG_BLK_DISCARD
+};
+
+struct ledtrig_blk_data {
+	struct delayed_work work;
+	struct led_classdev *led_cdev;
+
+	atomic_t interval;
+	u64 last_activity;
+
+	unsigned long mode;
+};
+
+static ssize_t ledtrig_blk_attr_show(struct device *dev, char *buf,
+				     enum ledtrig_blk_attr attr)
+{
+	struct ledtrig_blk_data *trig_data = led_trigger_get_drvdata(dev);
+
+	return sprintf(buf, "%u\n", test_bit(attr, &trig_data->mode));
+}
+
+static ssize_t ledtrig_blk_attr_store(struct device *dev, const char *buf,
+				      size_t size, enum ledtrig_blk_attr attr)
+{
+	struct ledtrig_blk_data *trig_data = led_trigger_get_drvdata(dev);
+	unsigned long state;
+	int ret;
+
+	ret = kstrtoul(buf, 0, &state);
+	if (ret)
+		return ret;
+
+	if (state)
+		set_bit(attr, &trig_data->mode);
+	else
+		clear_bit(attr, &trig_data->mode);
+
+	return size;
+}
+
+static ssize_t read_show(struct device *dev, struct device_attribute *attr,
+			 char *buf)
+{
+	return ledtrig_blk_attr_show(dev, buf, LEDTRIG_BLK_READ);
+}
+static ssize_t read_store(struct device *dev, struct device_attribute *attr,
+			  const char *buf, size_t size)
+{
+	return ledtrig_blk_attr_store(dev, buf, size, LEDTRIG_BLK_READ);
+}
+static DEVICE_ATTR_RW(read);
+
+static ssize_t write_show(struct device *dev, struct device_attribute *attr,
+			  char *buf)
+{
+	return ledtrig_blk_attr_show(dev, buf, LEDTRIG_BLK_WRITE);
+}
+static ssize_t write_store(struct device *dev, struct device_attribute *attr,
+			   const char *buf, size_t size)
+{
+	return ledtrig_blk_attr_store(dev, buf, size, LEDTRIG_BLK_WRITE);
+}
+static DEVICE_ATTR_RW(write);
+
+static ssize_t discard_show(struct device *dev, struct device_attribute *attr,
+			    char *buf)
+{
+	return ledtrig_blk_attr_show(dev, buf, LEDTRIG_BLK_DISCARD);
+}
+static ssize_t discard_store(struct device *dev, struct device_attribute *attr,
+			     const char *buf, size_t size)
+{
+	return ledtrig_blk_attr_store(dev, buf, size, LEDTRIG_BLK_DISCARD);
+}
+static DEVICE_ATTR_RW(discard);
+
+static ssize_t interval_show(struct device *dev, struct device_attribute *attr,
+			     char *buf)
+{
+	struct ledtrig_blk_data *trig_data = led_trigger_get_drvdata(dev);
+
+	return sprintf(buf, "%u\n",
+		       jiffies_to_msecs(atomic_read(&trig_data->interval)));
+}
+static ssize_t interval_store(struct device *dev, struct device_attribute *attr,
+			      const char *buf, size_t size)
+{
+	struct ledtrig_blk_data *trig_data = led_trigger_get_drvdata(dev);
+	unsigned long value;
+	int ret;
+
+	ret = kstrtoul(buf, 0, &value);
+	if (ret)
+		return ret;
+
+	/* impose some basic bounds on the timer interval */
+	if (value >= 5 && value <= 10000) {
+		cancel_delayed_work_sync(&trig_data->work);
+		atomic_set(&trig_data->interval, msecs_to_jiffies(value));
+		schedule_delayed_work(&trig_data->work,
+				      atomic_read(&trig_data->interval) * 2);
+	}
+
+	return size;
+}
+static DEVICE_ATTR_RW(interval);
+
+static struct attribute *ledtrig_blk_attrs[] = {
+	&dev_attr_read.attr,
+	&dev_attr_write.attr,
+	&dev_attr_discard.attr,
+	&dev_attr_interval.attr,
+	NULL
+};
+ATTRIBUTE_GROUPS(ledtrig_blk);
+
+static void ledtrig_blk_work(struct work_struct *work)
+{
+	struct ledtrig_blk_data *trig_data =
+		container_of(work, struct ledtrig_blk_data, work.work);
+	struct gendisk *disk = container_of(trig_data->led_cdev->trigger,
+					    struct gendisk, led.trig);
+	u64 activity = 0;
+
+	if (test_bit(LEDTRIG_BLK_READ, &trig_data->mode))
+		activity += part_stat_read(&disk->part0, ios[STAT_READ]);
+	if (test_bit(LEDTRIG_BLK_WRITE, &trig_data->mode))
+		activity += part_stat_read(&disk->part0, ios[STAT_WRITE]);
+	if (test_bit(LEDTRIG_BLK_DISCARD, &trig_data->mode))
+		activity += part_stat_read(&disk->part0, ios[STAT_DISCARD]);
+
+	if (trig_data->last_activity != activity) {
+		unsigned long interval;
+
+		led_stop_software_blink(trig_data->led_cdev);
+		interval = jiffies_to_msecs(atomic_read(&trig_data->interval));
+		led_blink_set_oneshot(trig_data->led_cdev, &interval, &interval,
+				      0);
+
+		trig_data->last_activity = activity;
+	}
+
+	schedule_delayed_work(&trig_data->work,
+			      atomic_read(&trig_data->interval) * 2);
+}
+
+static int ledtrig_blk_activate(struct led_classdev *led_cdev)
+{
+	struct ledtrig_blk_data *trig_data;
+
+	trig_data = kzalloc(sizeof(*trig_data), GFP_KERNEL);
+	if (!trig_data)
+		return -ENOMEM;
+
+	trig_data->mode = BIT(LEDTRIG_BLK_READ) | BIT(LEDTRIG_BLK_WRITE) |
+			  BIT(LEDTRIG_BLK_DISCARD);
+
+	atomic_set(&trig_data->interval, msecs_to_jiffies(50));
+	trig_data->last_activity = 0;
+	trig_data->led_cdev = led_cdev;
+
+	INIT_DELAYED_WORK(&trig_data->work, ledtrig_blk_work);
+
+	led_set_trigger_data(led_cdev, trig_data);
+
+	schedule_delayed_work(&trig_data->work,
+			      atomic_read(&trig_data->interval) * 2);
+
+	return 0;
+}
+
+static void ledtrig_blk_deactivate(struct led_classdev *led_cdev)
+{
+	struct ledtrig_blk_data *trig_data = led_get_trigger_data(led_cdev);
+
+	cancel_delayed_work_sync(&trig_data->work);
+	kfree(trig_data);
+}
+
+int ledtrig_blk_register(struct gendisk *disk)
+{
+	int ret;
+
+	disk->led.trig.name = kasprintf(GFP_KERNEL, "block-%s",
+					disk->disk_name);
+	if (!disk->led.trig.name)
+		return -ENOMEM;
+
+	disk->led.trig.activate = ledtrig_blk_activate;
+	disk->led.trig.deactivate = ledtrig_blk_deactivate;
+	disk->led.trig.groups = ledtrig_blk_groups;
+
+	ret = led_trigger_register(&disk->led.trig);
+	if (ret) {
+		kfree(disk->led.trig.name);
+		disk->led.trig.name = NULL;
+	}
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(ledtrig_blk_register);
+
+void ledtrig_blk_unregister(struct gendisk *disk)
+{
+	if (!disk->led.trig.name)
+		return;
+
+	led_trigger_unregister(&disk->led.trig);
+	kfree(disk->led.trig.name);
+	disk->led.trig.name = NULL;
+}
+EXPORT_SYMBOL_GPL(ledtrig_blk_unregister);
diff --git a/include/linux/genhd.h b/include/linux/genhd.h
index 8b5330d..b2c934e 100644
--- a/include/linux/genhd.h
+++ b/include/linux/genhd.h
@@ -17,6 +17,7 @@ 
 #include <linux/percpu-refcount.h>
 #include <linux/uuid.h>
 #include <linux/blk_types.h>
+#include <linux/leds.h>
 #include <asm/local.h>
 
 #ifdef CONFIG_BLOCK
@@ -219,6 +220,8 @@  struct gendisk {
 	int node_id;
 	struct badblocks *bb;
 	struct lockdep_map lockdep_map;
+
+	struct ledtrig_blk led;
 };
 
 static inline struct gendisk *part_to_disk(struct hd_struct *part)
diff --git a/include/linux/leds.h b/include/linux/leds.h
index 9b2bf57..395fa61 100644
--- a/include/linux/leds.h
+++ b/include/linux/leds.h
@@ -517,4 +517,31 @@  static inline void ledtrig_audio_set(enum led_audio type,
 }
 #endif
 
+struct gendisk;
+
+#ifdef CONFIG_LEDS_TRIGGER_BLOCK
+
+struct ledtrig_blk {
+	struct led_trigger trig;
+};
+
+int ledtrig_blk_register(struct gendisk *disk);
+void ledtrig_blk_unregister(struct gendisk *disk);
+
+#else
+
+struct ledtrig_blk {
+};
+
+static inline int ledtrig_blk_register(struct gendisk *disk)
+{
+	return 0;
+}
+
+static inline void ledtrig_blk_unregister(struct gendisk *disk)
+{
+}
+
+#endif /* CONFIG_LEDS_TRIGGER_BLOCK */
+
 #endif		/* __LINUX_LEDS_H_INCLUDED */