![Kees Cook](/assets/img/avatar_default.png)
In preparation for unconditionally passing the struct timer_list pointer to all timer callbacks, switch to using the new timer_setup() and from_timer() to pass the timer pointer explicitly. Cc: Richard Purdie <rpurdie@rpsys.net> Cc: Pavel Machek <pavel@ucw.cz> Cc: Willy Tarreau <w@1wt.eu> Cc: linux-leds@vger.kernel.org Signed-off-by: Kees Cook <keescook@chromium.org> Signed-off-by: Jacek Anaszewski <jacek.anaszewski@gmail.com>
276 lines
8 KiB
C
276 lines
8 KiB
C
/*
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* Activity LED trigger
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*
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* Copyright (C) 2017 Willy Tarreau <w@1wt.eu>
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* Partially based on Atsushi Nemoto's ledtrig-heartbeat.c.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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*/
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#include <linux/init.h>
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#include <linux/kernel.h>
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#include <linux/kernel_stat.h>
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#include <linux/leds.h>
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#include <linux/module.h>
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#include <linux/reboot.h>
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#include <linux/sched.h>
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#include <linux/slab.h>
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#include <linux/timer.h>
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#include "../leds.h"
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static int panic_detected;
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struct activity_data {
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struct timer_list timer;
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struct led_classdev *led_cdev;
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u64 last_used;
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u64 last_boot;
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int time_left;
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int state;
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int invert;
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};
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static void led_activity_function(struct timer_list *t)
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{
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struct activity_data *activity_data = from_timer(activity_data, t,
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timer);
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struct led_classdev *led_cdev = activity_data->led_cdev;
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struct timespec boot_time;
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unsigned int target;
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unsigned int usage;
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int delay;
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u64 curr_used;
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u64 curr_boot;
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s32 diff_used;
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s32 diff_boot;
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int cpus;
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int i;
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if (test_and_clear_bit(LED_BLINK_BRIGHTNESS_CHANGE, &led_cdev->work_flags))
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led_cdev->blink_brightness = led_cdev->new_blink_brightness;
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if (unlikely(panic_detected)) {
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/* full brightness in case of panic */
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led_set_brightness_nosleep(led_cdev, led_cdev->blink_brightness);
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return;
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}
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get_monotonic_boottime(&boot_time);
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cpus = 0;
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curr_used = 0;
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for_each_possible_cpu(i) {
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curr_used += kcpustat_cpu(i).cpustat[CPUTIME_USER]
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+ kcpustat_cpu(i).cpustat[CPUTIME_NICE]
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+ kcpustat_cpu(i).cpustat[CPUTIME_SYSTEM]
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+ kcpustat_cpu(i).cpustat[CPUTIME_SOFTIRQ]
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+ kcpustat_cpu(i).cpustat[CPUTIME_IRQ];
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cpus++;
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}
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/* We come here every 100ms in the worst case, so that's 100M ns of
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* cumulated time. By dividing by 2^16, we get the time resolution
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* down to 16us, ensuring we won't overflow 32-bit computations below
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* even up to 3k CPUs, while keeping divides cheap on smaller systems.
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*/
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curr_boot = timespec_to_ns(&boot_time) * cpus;
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diff_boot = (curr_boot - activity_data->last_boot) >> 16;
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diff_used = (curr_used - activity_data->last_used) >> 16;
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activity_data->last_boot = curr_boot;
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activity_data->last_used = curr_used;
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if (diff_boot <= 0 || diff_used < 0)
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usage = 0;
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else if (diff_used >= diff_boot)
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usage = 100;
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else
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usage = 100 * diff_used / diff_boot;
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/*
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* Now we know the total boot_time multiplied by the number of CPUs, and
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* the total idle+wait time for all CPUs. We'll compare how they evolved
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* since last call. The % of overall CPU usage is :
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*
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* 1 - delta_idle / delta_boot
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*
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* What we want is that when the CPU usage is zero, the LED must blink
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* slowly with very faint flashes that are detectable but not disturbing
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* (typically 10ms every second, or 10ms ON, 990ms OFF). Then we want
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* blinking frequency to increase up to the point where the load is
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* enough to saturate one core in multi-core systems or 50% in single
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* core systems. At this point it should reach 10 Hz with a 10/90 duty
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* cycle (10ms ON, 90ms OFF). After this point, the blinking frequency
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* remains stable (10 Hz) and only the duty cycle increases to report
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* the activity, up to the point where we have 90ms ON, 10ms OFF when
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* all cores are saturated. It's important that the LED never stays in
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* a steady state so that it's easy to distinguish an idle or saturated
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* machine from a hung one.
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*
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* This gives us :
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* - a target CPU usage of min(50%, 100%/#CPU) for a 10% duty cycle
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* (10ms ON, 90ms OFF)
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* - below target :
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* ON_ms = 10
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* OFF_ms = 90 + (1 - usage/target) * 900
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* - above target :
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* ON_ms = 10 + (usage-target)/(100%-target) * 80
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* OFF_ms = 90 - (usage-target)/(100%-target) * 80
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*
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* In order to keep a good responsiveness, we cap the sleep time to
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* 100 ms and keep track of the sleep time left. This allows us to
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* quickly change it if needed.
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*/
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activity_data->time_left -= 100;
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if (activity_data->time_left <= 0) {
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activity_data->time_left = 0;
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activity_data->state = !activity_data->state;
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led_set_brightness_nosleep(led_cdev,
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(activity_data->state ^ activity_data->invert) ?
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led_cdev->blink_brightness : LED_OFF);
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}
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target = (cpus > 1) ? (100 / cpus) : 50;
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if (usage < target)
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delay = activity_data->state ?
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10 : /* ON */
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990 - 900 * usage / target; /* OFF */
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else
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delay = activity_data->state ?
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10 + 80 * (usage - target) / (100 - target) : /* ON */
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90 - 80 * (usage - target) / (100 - target); /* OFF */
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if (!activity_data->time_left || delay <= activity_data->time_left)
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activity_data->time_left = delay;
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delay = min_t(int, activity_data->time_left, 100);
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mod_timer(&activity_data->timer, jiffies + msecs_to_jiffies(delay));
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}
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static ssize_t led_invert_show(struct device *dev,
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struct device_attribute *attr, char *buf)
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{
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struct led_classdev *led_cdev = dev_get_drvdata(dev);
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struct activity_data *activity_data = led_cdev->trigger_data;
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return sprintf(buf, "%u\n", activity_data->invert);
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}
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static ssize_t led_invert_store(struct device *dev,
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struct device_attribute *attr,
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const char *buf, size_t size)
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{
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struct led_classdev *led_cdev = dev_get_drvdata(dev);
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struct activity_data *activity_data = led_cdev->trigger_data;
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unsigned long state;
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int ret;
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ret = kstrtoul(buf, 0, &state);
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if (ret)
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return ret;
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activity_data->invert = !!state;
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return size;
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}
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static DEVICE_ATTR(invert, 0644, led_invert_show, led_invert_store);
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static void activity_activate(struct led_classdev *led_cdev)
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{
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struct activity_data *activity_data;
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int rc;
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activity_data = kzalloc(sizeof(*activity_data), GFP_KERNEL);
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if (!activity_data)
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return;
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led_cdev->trigger_data = activity_data;
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rc = device_create_file(led_cdev->dev, &dev_attr_invert);
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if (rc) {
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kfree(led_cdev->trigger_data);
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return;
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}
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activity_data->led_cdev = led_cdev;
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timer_setup(&activity_data->timer, led_activity_function, 0);
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if (!led_cdev->blink_brightness)
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led_cdev->blink_brightness = led_cdev->max_brightness;
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led_activity_function(&activity_data->timer);
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set_bit(LED_BLINK_SW, &led_cdev->work_flags);
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led_cdev->activated = true;
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}
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static void activity_deactivate(struct led_classdev *led_cdev)
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{
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struct activity_data *activity_data = led_cdev->trigger_data;
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if (led_cdev->activated) {
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del_timer_sync(&activity_data->timer);
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device_remove_file(led_cdev->dev, &dev_attr_invert);
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kfree(activity_data);
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clear_bit(LED_BLINK_SW, &led_cdev->work_flags);
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led_cdev->activated = false;
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}
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}
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static struct led_trigger activity_led_trigger = {
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.name = "activity",
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.activate = activity_activate,
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.deactivate = activity_deactivate,
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};
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static int activity_reboot_notifier(struct notifier_block *nb,
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unsigned long code, void *unused)
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{
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led_trigger_unregister(&activity_led_trigger);
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return NOTIFY_DONE;
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}
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static int activity_panic_notifier(struct notifier_block *nb,
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unsigned long code, void *unused)
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{
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panic_detected = 1;
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return NOTIFY_DONE;
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}
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static struct notifier_block activity_reboot_nb = {
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.notifier_call = activity_reboot_notifier,
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};
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static struct notifier_block activity_panic_nb = {
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.notifier_call = activity_panic_notifier,
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};
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static int __init activity_init(void)
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{
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int rc = led_trigger_register(&activity_led_trigger);
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if (!rc) {
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atomic_notifier_chain_register(&panic_notifier_list,
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&activity_panic_nb);
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register_reboot_notifier(&activity_reboot_nb);
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}
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return rc;
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}
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static void __exit activity_exit(void)
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{
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unregister_reboot_notifier(&activity_reboot_nb);
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atomic_notifier_chain_unregister(&panic_notifier_list,
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&activity_panic_nb);
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led_trigger_unregister(&activity_led_trigger);
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}
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module_init(activity_init);
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module_exit(activity_exit);
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MODULE_AUTHOR("Willy Tarreau <w@1wt.eu>");
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MODULE_DESCRIPTION("Activity LED trigger");
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MODULE_LICENSE("GPL");
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