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tick: Document protections for tick related data

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The protection rules for tick_next_period and last_jiffies_update are blury
at best. Clarify this.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20201117132006.197713794@linutronix.de
This commit is contained in:
Thomas Gleixner 2020-11-17 14:19:44 +01:00
parent f73f64d568
commit c398960cd8
2 changed files with 6 additions and 2 deletions
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4
kernel/time/tick-common.c
View file

@ -27,7 +27,9 @@
*/ */
DEFINE_PER_CPU(struct tick_device, tick_cpu_device); DEFINE_PER_CPU(struct tick_device, tick_cpu_device);
/* /*
* Tick next event: keeps track of the tick time * Tick next event: keeps track of the tick time. It's updated by the
* CPU which handles the tick and protected by jiffies_lock. There is
* no requirement to write hold the jiffies seqcount for it.
*/ */
ktime_t tick_next_period; ktime_t tick_next_period;
ktime_t tick_period; ktime_t tick_period;

4
kernel/time/tick-sched.c
View file

@ -44,7 +44,9 @@ struct tick_sched *tick_get_tick_sched(int cpu)
#if defined(CONFIG_NO_HZ_COMMON) || defined(CONFIG_HIGH_RES_TIMERS) #if defined(CONFIG_NO_HZ_COMMON) || defined(CONFIG_HIGH_RES_TIMERS)
/* /*
* The time, when the last jiffy update happened. Protected by jiffies_lock. * The time, when the last jiffy update happened. Write access must hold
* jiffies_lock and jiffies_seq. tick_nohz_next_event() needs to get a
* consistent view of jiffies and last_jiffies_update.
*/ */
static ktime_t last_jiffies_update; static ktime_t last_jiffies_update;