Commit c398960c authored by Thomas Gleixner's avatar Thomas Gleixner
Browse files

tick: Document protections for tick related data 



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

Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20201117132006.197713794@linutronix.de
parent f73f64d5

kernel/time/tick-common.c

+3 −1
Original line number Diff line number Diff line
@@ -27,7 +27,9 @@ 
 */

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_period;

kernel/time/tick-sched.c

+3 −1
Original line number Diff line number Diff line
@@ -44,7 +44,9 @@ struct tick_sched *tick_get_tick_sched(int cpu) 


#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;