Messages in this thread | | | Date | Tue, 24 Apr 2012 18:32:10 +0200 | From | Alexander Holler <> | Subject | Re: [PATCH v2] leds: heartbeat: stop on shutdown |
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Am 24.04.2012 17:24, schrieb Shuah Khan: > On Tue, 2012-04-24 at 17:07 +0200, Alexander Holler wrote: >> A halted kernel should not show a heartbeat. >> >> Signed-off-by: Alexander Holler <holler@ahsoftware.de> >> --- >> drivers/leds/ledtrig-heartbeat.c | 18 +++++++++++++++++- >> 1 files changed, 17 insertions(+), 1 deletions(-) >> >> diff --git a/drivers/leds/ledtrig-heartbeat.c b/drivers/leds/ledtrig-heartbeat.c >> index 759c0bb..1c05bd9 100644 >> --- a/drivers/leds/ledtrig-heartbeat.c >> +++ b/drivers/leds/ledtrig-heartbeat.c >> @@ -18,6 +18,7 @@ >> #include <linux/timer.h> >> #include <linux/sched.h> >> #include <linux/leds.h> >> +#include <linux/reboot.h> >> #include "leds.h" >> >> struct heartbeat_trig_data { >> @@ -101,13 +102,28 @@ static struct led_trigger heartbeat_led_trigger = { >> .deactivate = heartbeat_trig_deactivate, >> }; >> >> +static int heartbeat_reboot_notifier(struct notifier_block *nb, >> + unsigned long code, void *unused) >> +{ >> + led_trigger_unregister(&heartbeat_led_trigger); >> + return NOTIFY_DONE; >> +} >> + >> +static struct notifier_block heartbeat_reboot_nb = { >> + .notifier_call = heartbeat_reboot_notifier, >> +}; >> + >> static int __init heartbeat_trig_init(void) >> { >> - return led_trigger_register(&heartbeat_led_trigger); >> + int rc = led_trigger_register(&heartbeat_led_trigger); >> + if( ! rc ) >> + register_reboot_notifier(&heartbeat_reboot_nb); > > Do you need to check return value here? I see return value being checked > in some places in the kernel and not in others. Not checking is fine for > now since register_reboot_notifier() always returns 0. > > Maybe adding return handling might not be a bad idea to be consistent > with other places that do check.
What to do if it fails? As long as unregister_reboot_notifier() doesn't do something bad with non-registered notifiers (which it doesn't), I would let the init still succeed. And to not unregister a non-registered-reboot_notifier, a long-living bool would be needed.
> FYI - Andrew Morton is handling led patches these days. You might want > to send include him <akpm@linux-foundation.org>
I have added him to CC, thanks.
Regards,
Alexander
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