From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jacek Anaszewski Subject: Re: [PATCH v3 1/3] leds: triggers: Allow to switch the trigger to "panic" on a kernel panic Date: Fri, 06 May 2016 11:03:42 +0200 Message-ID: <572C5DEE.3070307@samsung.com> References: <1461881020-13964-1-git-send-email-ezequiel@vanguardiasur.com.ar> <1461881020-13964-2-git-send-email-ezequiel@vanguardiasur.com.ar> <57230B26.9010300@samsung.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-reply-to: <57230B26.9010300-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org> Sender: devicetree-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Ezequiel Garcia Cc: linux-leds-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Richard Purdie , Kumar Gala , Ian Campbell , Mark Rutland , Pawel Moll , Rob Herring , Pavel Machek List-Id: devicetree@vger.kernel.org On 04/29/2016 09:20 AM, Jacek Anaszewski wrote: > 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. Since the merge window is imminent, I've addressed those issues by myself and applied the patch set to the for-next branch of linux-leds.git. Thanks, Jacek Anaszewski > 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 >> --- >> 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 >> #include >> +#include >> #include >> +#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 >> > -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html