Messages in this thread | | | Date | Fri, 29 Apr 2016 09:20:06 +0200 | From | Jacek Anaszewski <> | Subject | Re: [PATCH v3 1/3] leds: triggers: Allow to switch the trigger to "panic" on a kernel panic |
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Hi Ezequiel,
Thanks for the update. It's indeed reasonable to have all the switching infrastructure in ledtrig-panic.c.
I've noticed two minor issues below.
On 04/29/2016 12:03 AM, Ezequiel Garcia wrote: > This commit adds a new led_cdev flag LED_PANIC_INDICATOR, which > allows to mark a specific LED to be switched to the "panic" > trigger, on a kernel panic. > > This is useful to allow the user to assign a regular trigger > to a given LED, and still blink that LED on a kernel panic. > > Signed-off-by: Ezequiel Garcia <ezequiel@vanguardiasur.com.ar> > --- > drivers/leds/led-triggers.c | 2 +- > drivers/leds/leds.h | 1 + > drivers/leds/trigger/Kconfig | 3 +++ > drivers/leds/trigger/ledtrig-panic.c | 47 ++++++++++++++++++++++++++++++++++++ > include/linux/leds.h | 1 + > 5 files changed, 53 insertions(+), 1 deletion(-) > > diff --git a/drivers/leds/led-triggers.c b/drivers/leds/led-triggers.c > index 2181581795d3..55fa65e1ae03 100644 > --- a/drivers/leds/led-triggers.c > +++ b/drivers/leds/led-triggers.c > @@ -26,7 +26,7 @@ > * Nests outside led_cdev->trigger_lock > */ > static DECLARE_RWSEM(triggers_list_lock); > -static LIST_HEAD(trigger_list); > +LIST_HEAD(trigger_list); > > /* Used by LED Class */ > > diff --git a/drivers/leds/leds.h b/drivers/leds/leds.h > index db3f20da7221..7d38e6b9a740 100644 > --- a/drivers/leds/leds.h > +++ b/drivers/leds/leds.h > @@ -30,5 +30,6 @@ void led_set_brightness_nosleep(struct led_classdev *led_cdev, > > extern struct rw_semaphore leds_list_lock; > extern struct list_head leds_list; > +extern struct list_head trigger_list; > > #endif /* __LEDS_H_INCLUDED */ > diff --git a/drivers/leds/trigger/Kconfig b/drivers/leds/trigger/Kconfig > index beac8c31c51b..4e4521c9072a 100644 > --- a/drivers/leds/trigger/Kconfig > +++ b/drivers/leds/trigger/Kconfig > @@ -121,6 +121,9 @@ config LEDS_TRIGGER_PANIC > depends on LEDS_TRIGGERS > help > This allows LEDs to be configured to blink on a kernel panic. > + Enabling this option will allow to mark certain LEDs as 'panic-indicators',
s/"panic-indicators"/panic indicators/
I understand that you referred here to the DT property name, but this is not obvious at first glance, and it is an implementation detail.
> + allowing to blink them on a kernel panic, even if they are set to > + a different trigger. > If unsure, say Y. > > endif # LEDS_TRIGGERS > diff --git a/drivers/leds/trigger/ b/drivers/leds/trigger/ledtrig-panic.c > index 627b350c5ec3..3e447bd2064a 100644 > --- a/drivers/leds/trigger/ledtrig-panic.c > +++ b/drivers/leds/trigger/ledtrig-panic.c > @@ -11,10 +11,54 @@ > > #include <linux/kernel.h> > #include <linux/init.h> > +#include <linux/notifier.h> > #include <linux/leds.h> > +#include "../leds.h" > > static struct led_trigger *trigger; > > +/* > + * This is a called in a special context by the atomic panic
s/is a/is/
> + * notifier. This means the trigger can be changed without > + * worrying about locking. > + */ > +static void led_trigger_set_panic(struct led_classdev *led_cdev) > +{ > + struct led_trigger *trig; > + > + list_for_each_entry(trig, &trigger_list, next_trig) { > + if (strcmp("panic", trig->name)) > + continue; > + if (led_cdev->trigger) > + list_del(&led_cdev->trig_list); > + list_add_tail(&led_cdev->trig_list, &trig->led_cdevs); > + > + /* Avoid the delayed blink path */ > + led_cdev->blink_delay_on = 0; > + led_cdev->blink_delay_off = 0; > + > + led_cdev->trigger = trig; > + if (trig->activate) > + trig->activate(led_cdev); > + break; > + } > +} > + > +static int led_trigger_panic_notifier(struct notifier_block *nb, > + unsigned long code, void *unused) > +{ > + struct led_classdev *led_cdev; > + > + list_for_each_entry(led_cdev, &leds_list, node) > + if (led_cdev->flags & LED_PANIC_INDICATOR) > + led_trigger_set_panic(led_cdev); > + return NOTIFY_DONE; > +} > + > +static struct notifier_block led_trigger_panic_nb = { > + .notifier_call = led_trigger_panic_notifier, > +}; > + > static long led_panic_blink(int state) > { > led_trigger_event(trigger, state ? LED_FULL : LED_OFF); > @@ -23,6 +67,9 @@ static long led_panic_blink(int state) > > static int __init ledtrig_panic_init(void) > { > + atomic_notifier_chain_register(&panic_notifier_list, > + &led_trigger_panic_nb); > + > led_trigger_register_simple("panic", &trigger); > panic_blink = led_panic_blink; > return 0; > diff --git a/include/linux/leds.h b/include/linux/leds.h > index 19eb10278bea..7e9fb00e15e8 100644 > --- a/include/linux/leds.h > +++ b/include/linux/leds.h > @@ -50,6 +50,7 @@ struct led_classdev { > #define LED_SYSFS_DISABLE (1 << 22) > #define LED_DEV_CAP_FLASH (1 << 23) > #define LED_HW_PLUGGABLE (1 << 24) > +#define LED_PANIC_INDICATOR (1 << 25) > > /* Set LED brightness level > * Must not sleep. Use brightness_set_blocking for drivers >
-- Best regards, Jacek Anaszewski
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